This study analyzes the mechanisms of sexual selection in blue-footed boobies through three stages: pre-copulation, post-copulation/pre-fertilization, and post-fertilization. Blue-footed boobies exhibit mutual mate selection between males and females based on foot color, with brighter green feet indicating better health. Females may also adjust their parental investment based on male foot color as a signal of his genetic quality. While socially monogamous, extra-pair mating does occur in boobies based on mate attractiveness. Their level of bi-parental care and environmental factors influence their mating behaviors.
This document provides information about genetic variation and evolution. It discusses how genetic variation arises from mutations and gene shuffling during sexual reproduction. It also describes how natural selection and genetic drift can change allele frequencies in a population over generations, resulting in evolution. Key factors that can lead to the formation of new species like geographic isolation and reproductive isolation are also summarized. Studies on Darwin's finches provide evidence of natural selection shaping beak traits in response to environmental pressures like food availability.
Lesson 1 of an A Level teaching resource, produced in conjunction with the Charles Darwin Trust, that uses Darwin's work on pigeon breeding and the work of contemporary scientists to explore genetics and evolution.
This first lesson covers the topics of artificial selection and genetics.
The accompanying teacher's notes can be found on our website at www.linnean.org/funkypigeons
The document discusses factors that can alter allelic frequencies in a population. It describes six main factors: 1) Mutation introduces new alleles, 2) Genetic drift like bottle neck effects can change frequencies randomly, 3) Migration through gene flow affects frequencies, 4) Natural selection increases frequencies of beneficial alleles and decreases unfavorable ones, 5) Non-random mating influences which individuals reproduce more, and 6) Inbreeding increases homozygosity. These genetic and evolutionary factors all impact the proportion of alleles in a population over time.
This document discusses factors that affect genetic variation and change in populations, including evolution, natural selection, mutations, migration, and genetic drift. It provides details on each factor and how they influence allele frequencies in a gene pool over multiple generations, leading to evolution and potentially new species. Examples are given to illustrate concepts like founder effects and bottleneck effects on small populations.
Understanding the basic principles of population genetics and its applicationAlexander Decker
This document discusses key concepts in population genetics, including:
- Gene pool, gene frequency, genetic equilibrium, genetic drift, natural selection, isolation
- Hardy-Weinberg principle, which states that gene frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences
- How Hardy and Weinberg used Punnett squares and equations to mathematically prove the principle based on observations of dominant and recessive alleles in a population
- An example application of using the Hardy-Weinberg equation to determine the number of heterozygotes and homozygous individuals for a dominant trait in a population
1. Evolution is the process by which life on Earth has changed over time from early forms to the diversity seen today.
2. Charles Darwin proposed the theory of evolution by natural selection in 1859, suggesting that species evolve over generations through natural selection of inheritable traits that increase survival and reproduction.
3. Speciation, the evolution of new species, occurs when reproductive barriers emerge to prevent interbreeding between populations, most often due to geographical isolation or adaptation to new environments.
This document discusses variation and evolution. It explains that variation exists between individuals and can be continuous or discontinuous. Variation can be influenced by genes, environment, or both. Evolution occurs as allele frequencies change over generations through natural selection and genetic drift. Speciation may occur when reproductive isolation develops between populations.
This document provides information about genetic variation and evolution. It discusses how genetic variation arises from mutations and gene shuffling during sexual reproduction. It also describes how natural selection and genetic drift can change allele frequencies in a population over generations, resulting in evolution. Key factors that can lead to the formation of new species like geographic isolation and reproductive isolation are also summarized. Studies on Darwin's finches provide evidence of natural selection shaping beak traits in response to environmental pressures like food availability.
Lesson 1 of an A Level teaching resource, produced in conjunction with the Charles Darwin Trust, that uses Darwin's work on pigeon breeding and the work of contemporary scientists to explore genetics and evolution.
This first lesson covers the topics of artificial selection and genetics.
The accompanying teacher's notes can be found on our website at www.linnean.org/funkypigeons
The document discusses factors that can alter allelic frequencies in a population. It describes six main factors: 1) Mutation introduces new alleles, 2) Genetic drift like bottle neck effects can change frequencies randomly, 3) Migration through gene flow affects frequencies, 4) Natural selection increases frequencies of beneficial alleles and decreases unfavorable ones, 5) Non-random mating influences which individuals reproduce more, and 6) Inbreeding increases homozygosity. These genetic and evolutionary factors all impact the proportion of alleles in a population over time.
This document discusses factors that affect genetic variation and change in populations, including evolution, natural selection, mutations, migration, and genetic drift. It provides details on each factor and how they influence allele frequencies in a gene pool over multiple generations, leading to evolution and potentially new species. Examples are given to illustrate concepts like founder effects and bottleneck effects on small populations.
Understanding the basic principles of population genetics and its applicationAlexander Decker
This document discusses key concepts in population genetics, including:
- Gene pool, gene frequency, genetic equilibrium, genetic drift, natural selection, isolation
- Hardy-Weinberg principle, which states that gene frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences
- How Hardy and Weinberg used Punnett squares and equations to mathematically prove the principle based on observations of dominant and recessive alleles in a population
- An example application of using the Hardy-Weinberg equation to determine the number of heterozygotes and homozygous individuals for a dominant trait in a population
1. Evolution is the process by which life on Earth has changed over time from early forms to the diversity seen today.
2. Charles Darwin proposed the theory of evolution by natural selection in 1859, suggesting that species evolve over generations through natural selection of inheritable traits that increase survival and reproduction.
3. Speciation, the evolution of new species, occurs when reproductive barriers emerge to prevent interbreeding between populations, most often due to geographical isolation or adaptation to new environments.
This document discusses variation and evolution. It explains that variation exists between individuals and can be continuous or discontinuous. Variation can be influenced by genes, environment, or both. Evolution occurs as allele frequencies change over generations through natural selection and genetic drift. Speciation may occur when reproductive isolation develops between populations.
The document discusses several key concepts related to evolution and gene frequencies:
1. Evolution occurs through genetic changes being passed down between generations within a population. The Hardy-Weinberg theorem states that allele frequencies will remain stable under certain assumptions, such as large population size and no migration, mutation, or selection.
2. Genetic drift, founder and bottleneck effects, and low population size can reduce genetic variation within a population. Gene flow between populations impacts allele frequencies.
3. Mutation introduces new variations and increases genetic diversity over time. Natural selection leads to changes in allele frequencies if some phenotypes are more successful at reproducing. Selection can be directional, disruptive, or stabilizing.
Lesson 2 of an A Level teaching resource, produced in conjunction with the Charles Darwin Trust, that uses Darwin's work on pigeon breeding and the work of contemporary scientists to explore genetics and evolution.
This second lesson covers the topic of genetics.
The accompanying teacher's notes can be found on our website at www.linnean.org/funkypigeons
Macro evolution-natural-selection-speciationTauqeer Ahmad
Populations, rather than individuals, are the units of evolution. A population is a group of interbreeding individuals of the same species living in the same area. Five agents can drive microevolution within a population: mutation, genetic drift, gene flow, non-random mating, and natural selection. Natural selection leads to differential reproductive success and is the only agent that can result in adaptation to the environment.
The document discusses the history and concepts of heterosis or hybrid vigor in plant breeding. It covers pre-Mendelian observations of hybrid vigor in the 1700s and 1800s. It then discusses the early 20th century work of scientists like Shull, East, and Jones who studied heterosis and coined related terms. The document also summarizes various theories for the genetic and physiological basis of heterosis, such as dominance, overdominance, and epistasis hypotheses. It discusses evidence from studies of embryos, seedlings, biochemistry, and gene interactions that help explain the mechanisms behind heterosis. While the full basis is still unknown, heterosis continues to be widely used in crop breeding.
This Presentation is especially for the grade 10 as it is informaive and can be used for the CBSE syllabus of india ( of course ). hope this helps you alot and if any problems please let me know from the comments section below.................peace out......... and message me at bavitharavi@hotmail.com. this is also the chpter 9 of the cbse gr 10 science book biology.
Intraspecific variation refers to differences that occur within a species. Variation can be caused by both genetic and environmental factors. Genetic factors include differences in alleles that cause phenotypic variations like eye color. Environmental factors influence phenotypes as well, such as how temperature affects the fur color of Himalayan rabbits. Often variation is a combination of both genetic and environmental influences, such as how genetics and nutrition interact to determine a person's height. Genetic variation within and between populations can be measured to understand intraspecific variation.
This document discusses genetic and non-genetic sources of variation within populations. It defines variation and describes the main types as genotypic and phenotypic. The key causes of genetic variation are mutations, gene flow, genetic drift, sexual reproduction and recombination during meiosis. Non-genetic sources include environmental factors, age, social influences, habitat, density and trauma. Variation is important for evolution as it provides genetic diversity for natural selection to act upon, allowing populations to adapt to changing environments over time.
1. The document compares rates of extra-pair paternity (EPP) in three socially monogamous bird species: the mountain bluebird, little auk, and zebra finch.
2. Rates of EPP were found to be high (72% of broods) in mountain bluebirds, low (2% of copulations) in little auks, and varied between low rates in wild zebra finches (1.7% of offspring) versus high rates (28% of offspring) in captive zebra finches.
3. Traits like plumage ornamentation in male mountain bluebirds and songs in male zebra finches may increase reproductive success through EPP by
Mechanisms of Evolution: Population Selection and ChangePaulVMcDowell
The document discusses several key mechanisms of evolution:
1. Mutations introduce new genetic variations within populations.
2. Natural selection leads to changes in populations over generations as certain traits increase chances of survival and reproduction.
3. Gene flow spreads variations between populations through migration and interbreeding.
4. Genetic drift causes random fluctuations in allele frequencies that can accumulate over time, especially in small, isolated populations.
1) The document discusses factors that can initiate microevolutionary changes by altering gene frequencies in populations. These include mutation, gene flow, natural selection, non-random mating, and genetic drift.
2) Five conditions must be met for a population to maintain Hardy-Weinberg equilibrium: no mutation, random mating, no natural selection, large population size, and no gene flow. Deviations from any of these conditions can lead to evolutionary changes by changing allele and genotype frequencies over time.
3) Specific factors that can drive evolutionary changes include mutation, which introduces new variants; gene flow through migration; natural selection favoring certain genotypes; non-random mating patterns; and genetic drift through random processes in small populations
The Grand Canyon separates two populations of squirrels, the Albert and Kaibab squirrels. The canyon acts as a geographic barrier that has led to allopatric speciation as the squirrel populations evolved independently on either side over time with limited gene flow between them.
1. The document discusses factors that can initiate microevolution by changing gene frequencies in populations.
2. It explains that microevolution occurs within populations and involves changes in gene frequency over time due to factors like mutation, natural selection, genetic drift, non-random mating, and gene flow.
3. For a population to evolve, at least one of the five conditions of Hardy-Weinberg equilibrium must be absent - no mutations, random mating, no natural selection, extremely large population size, or no gene flow.
The document discusses several concepts related to evolution of populations including gene pools, genetic variation, natural selection, genetic drift, and speciation. Gene pools contain alleles that vary in frequency. Genetic variation arises from mutations and genetic shuffling during reproduction. Natural selection can act on single-gene or polygenic traits through directional, stabilizing, or disruptive selection. Genetic drift is random changes in allele frequency. Speciation occurs when populations become reproductively isolated through mechanisms like behavioral, geographic, or temporal isolation.
1. The document discusses several examples of evolution occurring within populations through natural selection, including experiments with guppy fish populations where traits like age of sexual maturity changed in response to different predator environments.
2. It also summarizes various mechanisms of evolution like mutation, gene flow, genetic drift, and sexual selection that can drive changes in populations.
3. There is ongoing debate about whether speciation occurs gradually over long periods or through more punctuated periods of rapid change in response to environmental shifts.
Darwin explored ideas about evolution through natural selection. His observations of finches in the Galapagos led him to predict that one species can evolve into another through natural selection. Natural selection is the process by which organisms with traits best suited to their environment survive and reproduce, passing on those favorable traits. Darwin proposed that small, inherited variations combined with differential reproductive success could result in the emergence of new species over generations.
Chapter 19 Heredity Lesson 5 - Discontinuous and Continuous Variationj3di79
There are two types of variation: discontinuous and continuous. Discontinuous variation results in distinct phenotypes controlled by one or a few genes, like pea plant height. Continuous variation produces a spectrum of intermediate phenotypes controlled additively by many genes, such as human skin color. Continuous traits can also be influenced by the environment, unlike discontinuous traits. Both natural and artificial selection can act on variations to influence evolution over generations.
Mutations and genetic recombination introduce genetic variation within populations. Natural selection acts on this variation, favoring traits that increase reproductive success. Over generations, this leads to adaptation and evolution of populations as allele frequencies change. Genetic drift also causes random changes in allele frequencies, especially in small, isolated populations. Gene flow moves alleles between populations through migration.
This document discusses mechanisms of reproductive isolation that can lead to the formation of new species. It describes two types of isolating mechanisms - prezygotic, which prevent interspecies mating and fertilization, and postzygotic, which prevent hybrid zygotes from developing into healthy adults. Examples of prezygotic mechanisms include ecological, temporal, behavioral, mechanical, and gametic isolation. Postzygotic mechanisms include zygote mortality, hybrid inviability, and hybrid infertility.
The four evolutionary forces are natural selection, gene flow, genetic drift, and mutation. Charles Darwin and Alfred Russell Wallace independently developed the theory of evolution by natural selection. Natural selection is the process by which organisms best adapted to their environment tend to survive and pass on their genes more than others. Mutation introduces new genetic variation, while genetic drift and population bottlenecks can cause changes in allele frequencies in small, isolated populations. The evolutionary force that causes the fastest change in gene frequency is natural selection because it can eliminate entire traits from a population. Sickle cell anemia is caused by a mutation in the hemoglobin gene and is maintained in some populations because it provides resistance to malaria.
Raghavendra Swami is seeking a career opportunity with growth potential. He has over 16 years of experience in print media, biotech, FMCG and engineering education. His skills include strong analytics, business acumen, computer proficiency, positive attitude, and ability to meet deadlines. His work experience includes roles in media affairs, entrepreneurship development, management studies teaching, and sales/marketing. He holds an MBA in International Business and is pursuing a PhD.
Este documento describe un proyecto de aprendizaje colaborativo sobre el turismo, la cultura y la gastronomía del Perú. Los estudiantes trabajarán en equipos para diseñar actividades interactivas usando la herramienta Educaplay sobre diferentes destinos peruanos, evaluarán los trabajos de los otros equipos, y realizarán una autoevaluación de su propio desempeño.
The document discusses several key concepts related to evolution and gene frequencies:
1. Evolution occurs through genetic changes being passed down between generations within a population. The Hardy-Weinberg theorem states that allele frequencies will remain stable under certain assumptions, such as large population size and no migration, mutation, or selection.
2. Genetic drift, founder and bottleneck effects, and low population size can reduce genetic variation within a population. Gene flow between populations impacts allele frequencies.
3. Mutation introduces new variations and increases genetic diversity over time. Natural selection leads to changes in allele frequencies if some phenotypes are more successful at reproducing. Selection can be directional, disruptive, or stabilizing.
Lesson 2 of an A Level teaching resource, produced in conjunction with the Charles Darwin Trust, that uses Darwin's work on pigeon breeding and the work of contemporary scientists to explore genetics and evolution.
This second lesson covers the topic of genetics.
The accompanying teacher's notes can be found on our website at www.linnean.org/funkypigeons
Macro evolution-natural-selection-speciationTauqeer Ahmad
Populations, rather than individuals, are the units of evolution. A population is a group of interbreeding individuals of the same species living in the same area. Five agents can drive microevolution within a population: mutation, genetic drift, gene flow, non-random mating, and natural selection. Natural selection leads to differential reproductive success and is the only agent that can result in adaptation to the environment.
The document discusses the history and concepts of heterosis or hybrid vigor in plant breeding. It covers pre-Mendelian observations of hybrid vigor in the 1700s and 1800s. It then discusses the early 20th century work of scientists like Shull, East, and Jones who studied heterosis and coined related terms. The document also summarizes various theories for the genetic and physiological basis of heterosis, such as dominance, overdominance, and epistasis hypotheses. It discusses evidence from studies of embryos, seedlings, biochemistry, and gene interactions that help explain the mechanisms behind heterosis. While the full basis is still unknown, heterosis continues to be widely used in crop breeding.
This Presentation is especially for the grade 10 as it is informaive and can be used for the CBSE syllabus of india ( of course ). hope this helps you alot and if any problems please let me know from the comments section below.................peace out......... and message me at bavitharavi@hotmail.com. this is also the chpter 9 of the cbse gr 10 science book biology.
Intraspecific variation refers to differences that occur within a species. Variation can be caused by both genetic and environmental factors. Genetic factors include differences in alleles that cause phenotypic variations like eye color. Environmental factors influence phenotypes as well, such as how temperature affects the fur color of Himalayan rabbits. Often variation is a combination of both genetic and environmental influences, such as how genetics and nutrition interact to determine a person's height. Genetic variation within and between populations can be measured to understand intraspecific variation.
This document discusses genetic and non-genetic sources of variation within populations. It defines variation and describes the main types as genotypic and phenotypic. The key causes of genetic variation are mutations, gene flow, genetic drift, sexual reproduction and recombination during meiosis. Non-genetic sources include environmental factors, age, social influences, habitat, density and trauma. Variation is important for evolution as it provides genetic diversity for natural selection to act upon, allowing populations to adapt to changing environments over time.
1. The document compares rates of extra-pair paternity (EPP) in three socially monogamous bird species: the mountain bluebird, little auk, and zebra finch.
2. Rates of EPP were found to be high (72% of broods) in mountain bluebirds, low (2% of copulations) in little auks, and varied between low rates in wild zebra finches (1.7% of offspring) versus high rates (28% of offspring) in captive zebra finches.
3. Traits like plumage ornamentation in male mountain bluebirds and songs in male zebra finches may increase reproductive success through EPP by
Mechanisms of Evolution: Population Selection and ChangePaulVMcDowell
The document discusses several key mechanisms of evolution:
1. Mutations introduce new genetic variations within populations.
2. Natural selection leads to changes in populations over generations as certain traits increase chances of survival and reproduction.
3. Gene flow spreads variations between populations through migration and interbreeding.
4. Genetic drift causes random fluctuations in allele frequencies that can accumulate over time, especially in small, isolated populations.
1) The document discusses factors that can initiate microevolutionary changes by altering gene frequencies in populations. These include mutation, gene flow, natural selection, non-random mating, and genetic drift.
2) Five conditions must be met for a population to maintain Hardy-Weinberg equilibrium: no mutation, random mating, no natural selection, large population size, and no gene flow. Deviations from any of these conditions can lead to evolutionary changes by changing allele and genotype frequencies over time.
3) Specific factors that can drive evolutionary changes include mutation, which introduces new variants; gene flow through migration; natural selection favoring certain genotypes; non-random mating patterns; and genetic drift through random processes in small populations
The Grand Canyon separates two populations of squirrels, the Albert and Kaibab squirrels. The canyon acts as a geographic barrier that has led to allopatric speciation as the squirrel populations evolved independently on either side over time with limited gene flow between them.
1. The document discusses factors that can initiate microevolution by changing gene frequencies in populations.
2. It explains that microevolution occurs within populations and involves changes in gene frequency over time due to factors like mutation, natural selection, genetic drift, non-random mating, and gene flow.
3. For a population to evolve, at least one of the five conditions of Hardy-Weinberg equilibrium must be absent - no mutations, random mating, no natural selection, extremely large population size, or no gene flow.
The document discusses several concepts related to evolution of populations including gene pools, genetic variation, natural selection, genetic drift, and speciation. Gene pools contain alleles that vary in frequency. Genetic variation arises from mutations and genetic shuffling during reproduction. Natural selection can act on single-gene or polygenic traits through directional, stabilizing, or disruptive selection. Genetic drift is random changes in allele frequency. Speciation occurs when populations become reproductively isolated through mechanisms like behavioral, geographic, or temporal isolation.
1. The document discusses several examples of evolution occurring within populations through natural selection, including experiments with guppy fish populations where traits like age of sexual maturity changed in response to different predator environments.
2. It also summarizes various mechanisms of evolution like mutation, gene flow, genetic drift, and sexual selection that can drive changes in populations.
3. There is ongoing debate about whether speciation occurs gradually over long periods or through more punctuated periods of rapid change in response to environmental shifts.
Darwin explored ideas about evolution through natural selection. His observations of finches in the Galapagos led him to predict that one species can evolve into another through natural selection. Natural selection is the process by which organisms with traits best suited to their environment survive and reproduce, passing on those favorable traits. Darwin proposed that small, inherited variations combined with differential reproductive success could result in the emergence of new species over generations.
Chapter 19 Heredity Lesson 5 - Discontinuous and Continuous Variationj3di79
There are two types of variation: discontinuous and continuous. Discontinuous variation results in distinct phenotypes controlled by one or a few genes, like pea plant height. Continuous variation produces a spectrum of intermediate phenotypes controlled additively by many genes, such as human skin color. Continuous traits can also be influenced by the environment, unlike discontinuous traits. Both natural and artificial selection can act on variations to influence evolution over generations.
Mutations and genetic recombination introduce genetic variation within populations. Natural selection acts on this variation, favoring traits that increase reproductive success. Over generations, this leads to adaptation and evolution of populations as allele frequencies change. Genetic drift also causes random changes in allele frequencies, especially in small, isolated populations. Gene flow moves alleles between populations through migration.
This document discusses mechanisms of reproductive isolation that can lead to the formation of new species. It describes two types of isolating mechanisms - prezygotic, which prevent interspecies mating and fertilization, and postzygotic, which prevent hybrid zygotes from developing into healthy adults. Examples of prezygotic mechanisms include ecological, temporal, behavioral, mechanical, and gametic isolation. Postzygotic mechanisms include zygote mortality, hybrid inviability, and hybrid infertility.
The four evolutionary forces are natural selection, gene flow, genetic drift, and mutation. Charles Darwin and Alfred Russell Wallace independently developed the theory of evolution by natural selection. Natural selection is the process by which organisms best adapted to their environment tend to survive and pass on their genes more than others. Mutation introduces new genetic variation, while genetic drift and population bottlenecks can cause changes in allele frequencies in small, isolated populations. The evolutionary force that causes the fastest change in gene frequency is natural selection because it can eliminate entire traits from a population. Sickle cell anemia is caused by a mutation in the hemoglobin gene and is maintained in some populations because it provides resistance to malaria.
Raghavendra Swami is seeking a career opportunity with growth potential. He has over 16 years of experience in print media, biotech, FMCG and engineering education. His skills include strong analytics, business acumen, computer proficiency, positive attitude, and ability to meet deadlines. His work experience includes roles in media affairs, entrepreneurship development, management studies teaching, and sales/marketing. He holds an MBA in International Business and is pursuing a PhD.
Este documento describe un proyecto de aprendizaje colaborativo sobre el turismo, la cultura y la gastronomía del Perú. Los estudiantes trabajarán en equipos para diseñar actividades interactivas usando la herramienta Educaplay sobre diferentes destinos peruanos, evaluarán los trabajos de los otros equipos, y realizarán una autoevaluación de su propio desempeño.
Este curso enseña sobre los sistemas de telefonía fija y móvil. Cubre temas como protocolos de comunicación, diseño de infraestructuras de telecomunicaciones, funcionamiento de centrales telefónicas, estándares de telefonía móvil como GSM, y nuevas tecnologías como VoIP. El curso dura 200 horas y está dirigido a personas interesadas en aprender sobre el funcionamiento interno de las redes de telefonía y telecomunicaciones.
The Western Power Distribution site needed a solution to prevent creosote pollution from its pole storage area before an upcoming ISO 14001 audit. Capture Green was engaged to design and install a secondary containment and water remediation system before the audit. The system included two large storage bays lined with an impermeable membrane and a water retention area. A stillage was constructed to hold the poles above the liner. Contaminated water was treated in a remediation chamber before discharge. The system allowed compliance with environmental regulations and was less costly than a concrete alternative.
Dokumen ini merupakan lembar eksperimen tentang pengaruh tegangan input AC terhadap penguatan pada rangkaian common-collector dengan resistor pembagi tegangan 56 kΩ. Eksperimen dilakukan dengan mengubah tegangan masukan antara 100 mV hingga 500 mV dan mengukur penguatan tegangan keluaran. Hasil diukur dan dicatat untuk dianalisis hubungan antara tegangan masukan dan penguatan.
The document summarizes key concepts related to evolution including:
1. Evolution occurs as genetic changes in a population over time lead to changes in traits and gene frequencies. Equilibrium is when a population's gene pool is stable.
2. Natural selection drives evolution when heritable traits that increase survival and reproduction become more common in a population. Variation, reproductive competition, and heritability are required.
3. Isolation, including geographic, ecological, behavioral and reproductive barriers, can lead to genetic changes and speciation as populations diverge independently.
4. Evidence for evolution includes homologous structures, the fossil record, molecular and genetic similarities, geographic distribution patterns, and examples of artificial and natural selection
The Dodo was a flightless bird that was endemic to the island of Mauritius. It stood about 1 meter tall and weighed between 10-18 kg. Its exact appearance is uncertain as it is only known from 17th century drawings, paintings, and accounts. It is believed to have had brownish-grey plumage, yellow feet, a tufted tail, and a grey naked head with a black, yellow, and green beak. It became extinct in the late 17th century due to hunting and destruction of habitat by humans and invasive species. One account from 1598 provides a description of the Dodo.
OCCURENCE OF EVOLUTION.pptx how does evolution happensBaltazarRosales1
This document discusses several key concepts related to the occurrence and mechanisms of evolution:
1. It outlines Jean Baptiste de Lamarck and Charles Darwin's influential theories of evolution, including Lamarck's theories of need, use and disuse, and acquired characteristics as well as Darwin's theory of natural selection.
2. It explores the genetic basis of evolution through concepts like population genetics, gene flow, allele frequencies, non-random mating, and the Hardy-Weinberg equilibrium.
3. It examines various evolutionary patterns such as natural selection, genetic drift, speciation, punctuated equilibrium, microevolution, coevolution, convergent evolution, and adaptive radiation.
Species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups. The biological species concept has been prevalent in the evolutionary literature for the last several decades and is emphasized in many college-level biology courses. It is probably the species concept most familiar to biologists in diverse fields, such as conservation biology, forestry, fisheries, and wildlife management. Species defined by the biological species concept have also been championed as units of conservation. The species concept for most phycologists is based on the morphological characters and hence the term ‘species’ means morphospecies. On the other hand, for evolutionary biologists, the term means biological species that can be defined as a reproductive community of populations (reproductively isolated from others) that occupy a specific niche in Nature.
The document compares rates of extra-pair paternity (EPP) in three socially monogamous bird species: the mountain bluebird, little auk, and zebra finch. EPP was found to be high in mountain bluebirds, with 72% of broods containing an extra-pair offspring. In little auks, over 60% of birds engaged in extra-pair copulation but only 2% of copulations resulted in offspring due to high rates of within-pair copulation. Rates of EPP in wild zebra finches were also low at 1.7% of offspring, whereas captive zebra finches showed much higher EPP. The document discusses how EPP can increase variation in male
Newell et al. 2013 - pewee polygyny and double broodingAngela Johnson
This document summarizes a study that documented the first confirmed cases of polygyny and double brooding in the Eastern Wood-Pewee bird species. During a four-year study involving color-banding and nest monitoring of Eastern Wood-Pewees, researchers observed a male provisioning at two concurrently active nests, confirming polygyny. They also observed a female successfully fledging two broods from the same nest, confirming double brooding. Rates of polygyny were estimated at 6-22% and double brooding may have been as high as 6-12%. Both polygyny and double brooding appeared to increase reproductive success for males and females.
1) The document discusses heredity and evolution, including the accumulation of variation during reproduction and its effects over generations.
2) It covers Mendel's experiments which established the rules of inheritance and traits being passed from parents to offspring.
3) Evolution occurs as generations accumulate subtle variations, with some helping organisms survive and pass on their traits while others do not, not impacting survival.
1) The study observed the parental behaviors of field sparrows, specifically their nestling feeding frequency relative to the age of the parents.
2) Prior studies only categorized parents as second-year birds or older, but this study was able to determine the exact age of each parent up to their sixth year, allowing observation of feeding patterns among parents of varied precise ages.
3) Preliminary results agreed with prior findings that feeding frequency increases with nestling age, and suggested a tendency for older male and female sparrows to pair up and a positive relationship between feeding frequency and number of nestlings.
The document discusses evidence for evolution from the fossil record, distribution of fossils, and succession of forms over time. It describes Lamarck's theory of acquired traits being passed to offspring and Darwin and Wallace's theory of natural selection. Key evidence includes homologous and vestigial structures, similarities in embryology and macromolecules providing evidence that evolution has occurred and living things share common ancestors. Patterns of evolution include convergent, divergent and coevolution resulting from changing environmental pressures.
This document summarizes key concepts from a chapter on evolution of populations, including:
1) Genetic variation arises from mutations and genetic shuffling during sexual reproduction, providing raw materials for natural selection.
2) Natural selection can lead to changes in allele frequencies over generations, resulting in evolutionary adaptation.
3) Reproductive isolation of populations through mechanisms like geographic barriers can lead to the formation of new species over long periods of time, as seen with Darwin's finches in the Galapagos Islands.
The document provides an overview of key concepts and evidence related to evolution including:
1) Evolution is the process of cumulative change in heritable traits of a population over generations. Natural selection is the mechanism that drives evolutionary change as it favors traits that increase survival and reproduction.
2) Evidence for evolution includes observations of domesticated animals, homologous structures between species, the fossil record showing ancestral relationships, and DNA/genetic evidence confirming shared ancestry.
3) Darwin's theory of evolution by natural selection proposed that populations evolve over time as favorable inherited traits become more common through differential reproduction of individuals based on their adaptation to the environment.
Drosophila melanogaster, or the fruit fly, is used to study genetics through laboratory experiments observing inheritance patterns across generations. The document describes experiments crossing fruit flies with different traits, such as eye color and wing shape. The results show that some traits, like white eyes and short wings, are inherited together, indicating genetic linkage. Other traits, like dumpy wings and brown eyes, also show linkage. The experiments support Mendel's laws of inheritance and provide insights into how traits are passed down from parents to offspring.
1) The document discusses the differences between choice mate and predation. It provides examples of sexual selection through mate choice in animals and how brightly colored males are chosen by females.
2) It then describes two experiments that test the influences of mate choice and predation on animals. One study found that a spider acquires odors from the mosquitoes it eats that makes it more attractive to mates. The other found that female swordtail fish change their mate preferences after exposure to predator videos.
3) The document seeks to explain mate choice and sexual selection in animals using examples from field and laboratory experiments that show how both mate choice and predation influence evolution.
1) The document discusses how sperm have evolved traits that drive speciation and the evolution of new species. Sperm are small, motile, and genetically diverse due to meiosis, putting selection pressure on diploid cells.
2) Experiments on fruit flies showed that sexual selection and male mating behaviors were important determinants of reproductive influence, not sperm size or number.
3) Studies suggest population size can be used to trace evolutionary traits related to sexual selection, though genetic drift must be ruled out as the sole cause of any evolutionary processes observed.
The document outlines learning outcomes related to defining and explaining variation. It discusses how variation occurs within and between species, and can be continuous or discontinuous. Both genetic and environmental factors are described as causes of variation. Examples of continuous and discontinuous traits in plants and animals are provided.
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1. ABSTRACT
Sexual selection is the competition seen within a species in order to reproduce successfully.
These pressures in a species have been classified by three different mechanisms: pre-copulation,
post-copulation/pre-fertilization, and post-fertilization pressures. We used these three
classifications to analyze the sexual selection of the blue-footed booby (Sula nebouxii). The
booby is a prime candidate for this study as they have been shown to have intrasexual selection
in both sexes, participate in extra-pair mating, and continually reassess their current pairings.
This study also compared these selection pressures to other seabirds, the Laysan albatross
(Diomedea immutabilis) and the emperor penguin (Aptenodytes forsteri), to show the differences
across species. This uniqueness of the boobies can be seen in their selection of mates by foot
color and courtship dance, but not in their sexual dimorphic calls. We conclude with a call to
action against climate change as boobies reproductive success is intensively linked to ocean
temperatures and food availability.
The importance of sexual selection on a species has been studied since Charles Darwin in his
book published in 1871 called “The descendant of man, and selection in relation to sex.” Since
then, many studies have gone on to support Darwin’s views on sexual selection and continue to
discover more intricacies involved. The basis of sexual selection is due to the competition for
mates in order to successfully reproduce and pass on their genes. Sexual selection can be seen at
three separate times: pre-copulation, post-copulation/pre-fertilization, and post-fertilization
(Cunningham and Burkhead 1998). The mechanisms controlling sexual selection vary greatly
2. from species to species and many species still remain unstudied. In this paper we will focus on
the topic of sexual selection in relation to the blue-footed booby (Sula nebouxii).
The blue-footed booby is a socially monogamous seabird that is found on arid islands off the
coast of Central and South America (Harris 2001). The booby is widely recognized because both
males and females have blue feet that they use in their courtship displays. After courtship and
copulation, females lay two eggs 5-7 days apart (Harris 2001). Once the chicks hatch these birds
practice bi-parental care of the young and take turns feeding and guarding the young (Nelson
1978). Boobies are monogamous for life and can liveto around 18 years of age (Kim et al.
2011). The sexual selection pressures in this species were, until recently, thought to be
completely based onintrasexual selection but a study by Torres and Velandon (2005) found it to
be mutual selection in both species. In this study we aim to focus on the mechanisms of sexual
selection at the 1) pre-copulation, 2) post-copulation/pre-fertilization, and 3) post-fertilization, in
boobies. The main question of this study is: what variables influence the sexual selection in the
blue-footed booby? We will look to explain this selection by three unique traits of the booby
which are their feet, mating ritual, and calls. FEET
Foot color-
Female blue-footed boobies use foot color to select their mates and to constantly reassess these
pairing. Foot color plays an important role in this reassessment because the preferred bright
green foot color is also an indicator of good health. While blue pigmentation was discovered to
be structural and based entirely on genetics, green has beenselected for because yellow
pigmentation in the feet is an indicator that carotenoids are present. Carotenoids are can only be
produced through a good diet and are essential in the immune system.Therefore, well-fed and
3. healthy boobies are the only ones that are capable of allocating this yellow pigmentation to their
feet, and are seen as more desirable to the opposite sex. The selection of females for mates with a
greener foot coloration serves as a type of pre-copulation sexual selection. This coloration is
highly susceptible to environmental conditions though, and can take as little as 48 hours to
change the color of their feet (Torres and Velando 2003). Velando, Beamonte-Barrientos, and
Torres (2006) tested the influence of carotenoids after pairs had been established and the first
egg was laid. The males’ feet were painted a duller blue color as a signal of “bad health” in
accordance with a previous study by the same authors in 2003. Upon return to the nest,the mates
of the experimental males laid eggs that were smaller in volume than the control males.
Thisindicates that the females had adjusted their level of parental investment based on the
males’ foot color. This example shows that foot color can also be an example of post-fertilization
sexual selection.
There are several reasons females might adjust investment based on the presumed state of their
male partner. First, male and female boobies are equal partners in the rearing of chicks. If the
male is presumed to be unfithe cannot do his share in caring for the chick.. Additionally, weak
males are not desirable donors of genetic material. Old or sickly males’ genetic material is worth
less, and if a female perceives her young are not going to have the best chances, she immediately
lowers her investment. Decreasing the second egg size therefore isvery important, because in
broods with two chicks of significantly different sizes the larger chick will often commit
siblicide.. In blue-footed boobies siblicide will not occur when the chicks are comparable sizes..
By laying a smaller egg upon re-assessment of her partner, the female is choosing to only have
one chick sired by that particular father, ensuring she does not waste too many of her own
resources caring for substandard chicks by herself(Velando et al. 2006).The parental investment
4. in relation to foot color is also supported by Velando et al. (2005) in their cross-fostering
experiment comparing the foot color of the foster father and the genetic father. The results were
such that the both fathers’ sexual ornamentation accounted for 32% of variance in chick
condition. This shows that those with more attractive coloration sire healthier chicks and prove
to be more attentive fathers (Velando et al. 2005).Though blue-footed boobies are considered
socially monogamous, foot color can also affect the incidence of extra-pair mates, especially in
females. In some cases, females have been observed engaging in up to seven extra-pair
copulations with neighboring males during a single breeding season (Osorio-Beristain and
Drummond 1998). The occurrence of extra-pair matings has also been linked to the sexual
attractiveness of females, as females with brighter feet have been shown to attract more extra-
pair mates. Males with brighter feet are also less likely to be cuckolded (Torres and Velando
2005).
Female ornamentation-
Ornamentation is the use of brightly colored visual displays commonly seen in the males of a
species in order to attract females (Darwin 1871). This form of sexual selection has been
extensively studied and can be observed across the animal kingdom (Amundsen 2000). Female
ornamentation is not as common as males, but it is far from rare. When females adopt the same
elaborate coloration of the males it was thought that the favorable traits were highly heritable and
were therefore “accidentally” inherited by the females. This idea was presented by Charles
Darwin (1871) and was called “the laws of inheritance”. Darwin’s law of inheritance is not
widely accepted anymore as scientists continue to learn more about the role of female
ornamentation. In a study by Torres and Velando (2005) they showed that females’ blue feet
were a factor in the males’ choice for a partner as female with darker feet participated
5. significantly less in courtship with their mate (figure 2)This study also showed that the color of
the females’ feet greatly affected the chance of courting with extra-pair mates. More attractive
females were 5.4 times more likely to be courted by a male besides their mate (Torres and
Velando 2005). Males’ choice of a specific female based on foot color is another example of pre-
copulation sexual selection. This mutual selection of males and females has not been well
studied in birds, but has been found to be correlated with bi-parental care and is this is another
likely cause of the boobies mutual ornamentation (Guerra and Drummond 1995, Amundsen
2000).
Bi-parental care and monogamy-
Bi-parental care plays a large role in the monogamous nature of the blue-footed booby. Bi-
parental care is often an indicator of whether a certain species is monogamous, and the extent of
obligate parental care influences the amount of polygyny within a breeding colony. The level of
breeding synchronicity also influences polygyny in the breeding system, as well as the sex ratios
within a certain colony. Therefore, birds with a longer period of bi-parental care, synchronous
breeding seasons, and even-sex ratios are unlikely to participate in polygyny, whereas in colonies
with uneven sex ratios, asynchronous seasons, or uneven parental investment will likely have
some degree of extra-pair mating (Tershy and Croll 2000).
A good example of strict monogamy is the emperor penguin (Aptenodytes forsteri). Since their
harsh environment mandates breeding synchronicity and they have an equal amount of
investment by both parents, there is no recorded incidence of extra pair mating in this species.
This is also evidentby the lack of sexual dimorphism within the species, indicating the equal
nature of a permanently mated male and female pairing. (Jenouvrier et al. 2010) Boobies,
however, do not have this extreme level of synchronicity, and it is suggested that the amount of
6. breeding synchronicity varies per colony. They also often have uneven sex ratios that make it
easier to engage in extra-pair mating even though they share in parental effort. This is evidenced
by a particularly unusual case study where several blue-footed booby nests were observed being
shared, each time with two females and one male. This unusual group nesting behavior was said
to be a result of more females than males in the breeding colony, and while it resulted in more
females having mates, it did not improve overall breeding success. One trio of parents were
reported to have successfully raised three chicks, while the others either broke up prior to
incubation or abandoned the nest, resulting in no reproductive success. (Castillo-Guerrero et al.
2005)
Though monogamy is favored in marine bird species, there are some trade-offs that suggest
promiscuity can also be beneficial. It has been hypothesized that monogamy evolved in boobies
and other seabirds because their dependence on the ocean mandates one parent toleave the nest
for long periods of time, making it impossible to rear the chick without aid from both parents.
Unlike many monogamous seabirds (including other species of boobies), blue-footed boobies are
capable of raising more than one nestling to adulthood. This is due to the fact that boobies
typically live in places where food is abundant, like the Galápagos.Boobies are sexually
dimorphic in their size and foraging behavior, with the larger females bringing home greater
catches and males foraging more frequently from closer distances. (Wittenberger and Tilson
1980) However, boobies are not strictly monogamous, and while there are theories about the
benefits of promiscuity and extra-pair mating, it is not certain why blue-footed boobies
developed this behavior. As discussed earlier, constant re-assessment of pairs and the ability to
move on to new partners does allow females to ensure the highest quality of her chicks. Extra-
7. pair mating can also serve to increase genetic diversity and ensure those individuals who were
unable to find mates before the abilityto pass on theirgenes.
Blue-footed boobies are also interesting because the females are typically up to 30% larger than
males and therefore are the determining sex when it comes to extra-pair copulations. While it is
questionable if females increase their fecundity by engaging in these behaviors, it is suggested
that females may participate in extra-pair mating during her fertile period to increase the genetic
quality of her offspring (Osorio-Beristain and Drummond 1998). It is also probable that male age
has an effect on extra-pair mating in females, as male attractiveness and overall fitness decrease
as males become senescent at around 10 years of age. As pairs have been known to spend an
average of 5-6 breeding seasons together, it is likely that males become senescent in this time
and increase the likelihood of extra-pair mating by females (Kim et al. 2011). Taking on extra-
pair mates due to the altered condition of the male is a further example of constant reassessment
of the pair as well as post-fertilization sexual selection.
MATING RITUAL
The Bonds of Dance
Courtship displays are another way that females of a species have been shown to choose their
mates. These dances involve complicated auditory and visual stimuli in the attempt of winning a
mate ( ). These types of courtship rituals can be found in mammals, reptiles, amphibians, fish,
and some insects, but is predominantly found in birds ( ). One such example of this can be
seen in the dance of the Laysan albatross (Diomedea immutabilis). The courtship displays
involves a variable pattern of movements with correlated honks and whistles that are performed
by both the male and females (Meseth 1975). The origin of these movements is thought to be
derived from other behaviors such as nest building, comforting behaviors, and locomotion that
8. were adapted to serve a reproductive purpose (Meseth 1975). The dance of the blue-footed
boobies shows many parallels to the Laysan Albatross, with some key differences.
Blue-footed boobies have four main actions in their courtship ritual: landing, presenting nesting
material, parading, and sky-pointing (Nelson 1978). The following description is from a personal
observation made on Isabela Island, Galapagos Islands. The first step is always initiated by a
male where he lands in front of the female with his feet splayed in front of him. He then presents
a gift in the form of a stick or other nesting material to the female. The male then will flaunt his
feet to the female in a high stepping display called parading. This exaggerated stepping is usually
done in conjunction with a high pitched whistled call. The final move of this sequence is a
motion called the “sky point” where the male and female boobies will lift their heads toward the
sky while opening their wings. When a female accepts a male she will follow his lead and
accompany his whistle with her trumpet (Nelson 1978). This dance does not always lead to
copulation, but that is the end goal (Osorio-Beristain and Drummond 1998). The order of these
motions does not vary, unlike the dance of the albatross (Meseth 1975). Similar to the
aforementioned albatross, the motions in the boobies dances have probably transformed from
other behaviors. The presenting of nesting material to the female is most likely derived from dual
parental investment in the raising of the young. The parading must be used to display their blue
foot as it is the main visual cue for sexual selection. The albatross described by Meseth (1975)
also did a motion similar to sky pointing that he attributed to a pre-flight motion. Like the
albatross, boobies are monogamous birds and will perform their courtship dances at the
beginning of a breeding season to reaffirm previous breeding pairs (Meseth 1975).
CALLS
Sexually Dimorphic Calls-
9. Calls in birds are most commonly used by males to attract a mate, but these signals have been
shown to also be used for mate recognition and pair bond maintenance in many species
(Dentressangle et al. 2012). The call of many penguins species (Spheniscidae) have been shown
to serve all of these purposes (Robinson et al. 1993). Robinson et al. (1993) suggests that the
evolution of these individualized calls was mainly influenced by the noisy environment of the
nesting colonies. Like penguins, Blue-footed boobies are monogamous colonial nesting seabirds
with bi-parental care (Nelson 1978). For these reasons it is also suggested that boobies developed
their individual sexual dimorphic calls. Unlike penguins though, the difference of the calls
between the species is greatly noticeable. Female boobies produce a loud trumpet sound while
males have a high pitched whistle (Nelson 1978). These calls are used during the courtship ritual
as well as a greeting back to the nest after a foraging trip (Nelson 1978). Dentressangle et al.
(2012) showed that calls can vary individually on 10 acoustic variables and that mates could
recognize these minute differences. This recognition is imperative as the main visual cues in the
boobies, their blue foot, are highly variable based on their health status (Torres and Velando
2003). In order to achieve these individualized calls females tend to vary the harmony and pitch,
while males change the frequency of their whistle (Dentressangle et al. 2012). While it is still
unknown why the calls vary between sex, it is thought to be because of the size dimorphismin
females that are usually 30% larger than males (Dentressangle et al. 2012). It has not been shown
if these calls influence the formation of new pairs, but it is essential to maintain a breeding pair
from year to year. Therefore, unlike other species the call of the blue-footed booby is not thought
to be a pre-copulation form of sexual selection.
Conclusion:
10. Our goals in this study were to highlight the unique aspects of sexual selection in the blue-footed
booby, as well as determine the devices driving this selection. We also strove to answer the ways
in which sexual selection is manifested in blue-footed boobies, and how these birds are unique in
their mating behaviors in comparison to other marine bird species.
Blue-footed boobies are incredibly unique in their mating behaviors as compared to other
seabirds. Sexual selection by these birds is a multi-faceted process that includes assessment of
foot color by both females and males in order to determine health, virility, and parental
investment in chicks, as well as an evaluation of the potential partner’s courtship dance. Blue-
footed boobies also frequently reassess their partners once mated and throughout their time
together in order to determine parental investment and the frequency of extra-pair mating. Calls,
though important in identification and reaffirming pair bonds, do not play a large role in
courtship like they do in other bird species.
Through our research on mating behaviors in blue-footed boobies, we became aware of how El
Niño and climate change events can seriously impact reproductive success in this incredibly
selective species. In learning about how malnutrition and lack of carotenoids in the system can
result in a failure to court, we realized that El Niño events, which cause serious food shortages,
can seriously reduce mating success. Wingfield et al. (1998) recorded that the 1992 El Niño
resulted in 100% breeding failure in blue-footed boobies for that year. That year, ocean surface
temperature raised an average of 1ºC, yet resulted in less pairs mating and an 89% abandonment
of nests if eggs were laid; of those not abandoned the rest of the chicks all died before they could
fledge (Wingfield et al. 1998). (Wingfield et al. 1998) This led us to look toward the future of
blue-footed boobies, as a likely increase in ocean temperature caused by climate change will
cause a collapse of their whole breeding system. We feel that research on these creatures is
11. invaluable as much is left unknown about them and especially about their sexual selection. We
believe that this is a critical point worldwide and if we are to take strides to reduce our global
impact, it must be soon, as even 1ºC can make the difference between life and death for the blue-
footed booby.