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Presentation on Selection
Natural and artificial selection both involve the differential reproduction of organisms with certain traits compared to others in a population. In natural selection, traits that help organisms survive and reproduce are passed on more often, while in artificial selection humans choose which traits to promote or reduce in domesticated species. Both processes can lead to changes in the traits of a population over multiple generations through the selective reproduction of organisms with favorable characteristics.
Ecosystem And Natural Selection - Biology
Ecosystem,Natural Selection, Charles Darwin, Founder's Effect, Niche,Isolation,Balancing,Diversifying,Directional Selection.
02 domestication
This document discusses the process of plant domestication. It begins by defining domestication and explaining how early humans selected traits like large plant parts and thick flesh in domesticated food plants. It then provides details on the benefits of domestication, the five levels of domestication, and the domestication syndrome. The document also examines outstanding questions in domestication research and insights from archeological and genetic studies. Specifically, it notes how domestication traits are influenced by a small number of regulatory genes and allows for rapid evolution.
Invasive plants: identities, issues and theory Nenhc 2014
This document provides information about bioeradication as an alternative to classical biocontrol for invasive species. It defines key terms like bioeradicant and bioeradication system. The document argues that bioeradication uses native species to drive non-native invasives to extinction, minimizing risks compared to introducing non-native biocontrols. It also notes that bioeradication systems are hard to identify but may already be in place for many invasives. As an example, it describes observing a complete bioeradication system targeting the invasive tree Ailanthus altissima in North America.
Invasive plants: identities, issues and theory NENHC 2014
This document provides an introduction to the concepts of bioeradication and biocontrols. It discusses using native organisms to drive non-native invasive species extinct from an ecosystem, aiming to restore balance, as an alternative to introducing additional non-native biocontrols. The document uses Ailanthus altissima as a case study, outlining the native moth, mite, fungi and deer that form a bioeradication system currently eradicating the tree locally. It advocates increasing native plant nectar sources to support the bioeradicant moth populations. Finally, it briefly summarizes weaknesses and potential bioeradicants for other invasive plants like multiflora rose.
Domestication In Crop Plants GPB 202
This document discusses plant domestication and the process of domestication. It defines domestication as bringing wild plant species under human management through genetic modification to meet human needs. Key points:
- About 150 plant species are commercially grown for food globally, supplying most of our caloric needs.
- Domestication has led to 10,000-fold increase in human population in last 10,000 years by providing more reliable food sources.
- Humans selected plants for traits like high calorie output and balanced nutrition.
- Domestication involves both natural selection by the environment and artificial selection by humans for desirable traits.
- Traits selected during domestication include reduced seed shattering/dorm
Natural selection
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.
natural selection tutorial general Biology 2
This document provides an overview of evolution and natural selection. It discusses how Darwin proposed natural selection as the mechanism for evolution, with genetic variation within populations and environmental pressures resulting in some individuals being better able to survive and reproduce. Over generations, this leads to adaptation and potentially speciation. The document also notes other factors like genetic drift, mutation, and migration that can influence gene frequencies randomly or non-randomly. It provides examples like genetic bottlenecks and founder effects to illustrate these concepts. An interactive quiz is included to help reinforce the key points.
Recommended
Presentation on Selection
Natural and artificial selection both involve the differential reproduction of organisms with certain traits compared to others in a population. In natural selection, traits that help organisms survive and reproduce are passed on more often, while in artificial selection humans choose which traits to promote or reduce in domesticated species. Both processes can lead to changes in the traits of a population over multiple generations through the selective reproduction of organisms with favorable characteristics.
Ecosystem And Natural Selection - Biology
Ecosystem,Natural Selection, Charles Darwin, Founder's Effect, Niche,Isolation,Balancing,Diversifying,Directional Selection.
02 domestication
This document discusses the process of plant domestication. It begins by defining domestication and explaining how early humans selected traits like large plant parts and thick flesh in domesticated food plants. It then provides details on the benefits of domestication, the five levels of domestication, and the domestication syndrome. The document also examines outstanding questions in domestication research and insights from archeological and genetic studies. Specifically, it notes how domestication traits are influenced by a small number of regulatory genes and allows for rapid evolution.
Invasive plants: identities, issues and theory Nenhc 2014
This document provides information about bioeradication as an alternative to classical biocontrol for invasive species. It defines key terms like bioeradicant and bioeradication system. The document argues that bioeradication uses native species to drive non-native invasives to extinction, minimizing risks compared to introducing non-native biocontrols. It also notes that bioeradication systems are hard to identify but may already be in place for many invasives. As an example, it describes observing a complete bioeradication system targeting the invasive tree Ailanthus altissima in North America.
Invasive plants: identities, issues and theory NENHC 2014
This document provides an introduction to the concepts of bioeradication and biocontrols. It discusses using native organisms to drive non-native invasive species extinct from an ecosystem, aiming to restore balance, as an alternative to introducing additional non-native biocontrols. The document uses Ailanthus altissima as a case study, outlining the native moth, mite, fungi and deer that form a bioeradication system currently eradicating the tree locally. It advocates increasing native plant nectar sources to support the bioeradicant moth populations. Finally, it briefly summarizes weaknesses and potential bioeradicants for other invasive plants like multiflora rose.
Domestication In Crop Plants GPB 202
This document discusses plant domestication and the process of domestication. It defines domestication as bringing wild plant species under human management through genetic modification to meet human needs. Key points:
- About 150 plant species are commercially grown for food globally, supplying most of our caloric needs.
- Domestication has led to 10,000-fold increase in human population in last 10,000 years by providing more reliable food sources.
- Humans selected plants for traits like high calorie output and balanced nutrition.
- Domestication involves both natural selection by the environment and artificial selection by humans for desirable traits.
- Traits selected during domestication include reduced seed shattering/dorm
Natural selection
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.
natural selection tutorial general Biology 2
This document provides an overview of evolution and natural selection. It discusses how Darwin proposed natural selection as the mechanism for evolution, with genetic variation within populations and environmental pressures resulting in some individuals being better able to survive and reproduce. Over generations, this leads to adaptation and potentially speciation. The document also notes other factors like genetic drift, mutation, and migration that can influence gene frequencies randomly or non-randomly. It provides examples like genetic bottlenecks and founder effects to illustrate these concepts. An interactive quiz is included to help reinforce the key points.
Selection, type of selection, patterns of selection and their effect on popul...
This document discusses different types of selection and their effects on populations. It describes three main types of selection:
1. Natural selection, which is based on survival of the fittest in a given environment. Only the most adapted individuals survive to reproduce.
2. Artificial selection, which is selection done by breeders to achieve specific objectives. Breeders choose which individuals get to reproduce.
3. Three patterns of selection are described - directional selection which changes the population mean over generations, disruptive selection which favors two extreme types, and stabilizing selection which favors intermediate types close to the population mean.
Locating and Using Native Biocontrols for Invasive Non-native Plants, a New...
theory, practice and examples of using native organisms and organism systems to control invasive non-native plants vs. traditional biocontrol
Selection pressure
Selection pressure refers to factors in an organism's environment that give certain variations an advantage, pushing evolution in a direction. Random mutations occur during reproduction, and favorable mutations that increase survival and reproduction will become more common through natural selection over generations. A selection pressure can be anything consistent that impacts survival and reproduction rates, like availability of resources, presence of predators, or competition. Selection operates at the individual level, favoring traits that increase individual fitness even if they harm the species as a whole.
in natural selection, explain what is a sexual selection, neutral va.pdf
in natural selection, explain what is a sexual selection, neutral variation and balancing selection
Solution
The concept of natural selection explains that how a species can have breeding populations
adapted to local conditions. Based on the principle of natural selection the selection of genotypes
occurs and that would result in offspring with better reproductive capabilities. Natural selection
always results in better survival of an organism, so the genetic changes driven by the natural
selection make the species to adapt to the local conditions so that they can survive. These species
may exhibit high genetic variation may be because out breeding, but gradually due to the
inbreeding in these adapted species, the genetic variation will be minimized and they evolve as a
separate species.
The sexual selection refers that a species which exhibit dominant sexual characters to the
opposite partner has the ability to mate with female and expand its gene pool.
Natural variation: In variation selection, the traits within the organisms undergo mutations to
allow the organism to best adapt to the environment by means of natural selection (Darwinian
evolution), these mutations are inherited by the nest generation offspring. In case of
transformational selection or Lamarck’s theory, the individual organisms change by inheriting
the transformations within a generation.
The three types of selection that we observe in speciation are disruptive selection, stabilizing
selection and directional selection. Disruptive selection occurs due to the selection for the
extreme values of traits instead of intermediate values. This divides the population into two
different groups. Disruptive selection is one of the main driving forces of sympatric speciation,
which occurs when there are no physical barriers that prevent species to mate together. The
occurrence of speciation may be depending on the availability of different food sources and
existence of different shelters. When comes to the balanced selection the allele frequencies
remain contestant throughout the evolution..
Chapt04 lecture
The document provides an overview of key concepts related to evolution, biological communities, and species interactions. It discusses evolution and natural selection, ecological niches, species interactions like competition and predation, community properties, how communities change over time through succession, and factors that influence where organisms can live.
selection in nature
This document discusses different types of natural selection and their effects on populations and species evolution over time. It describes directional selection as favoring one extreme trait, stabilizing selection as favoring intermediate traits and eliminating extremes, and disruptive selection as favoring opposite trait extremes. Natural selection can lead to adaptation, radiation of new species from a single ancestor, regression of unnecessary traits, convergence of unrelated species, coevolution between interacting species, and extinction of non-adapted species. Sexual selection also influences evolution by favoring traits that increase mating success even if they reduce survival.
Allelic frequency
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.
Population Ecology
The document discusses several key topics in population ecology:
1) Population ecology is the study of population growth and interactions. The size of a population is determined by births, deaths, immigration and emigration.
2) Populations can experience exponential or logistic growth depending on available resources. Carrying capacity is the maximum population size an environment can sustain.
3) Density-dependent factors like competition, predation, and parasitism regulate population size by increasing mortality at high densities. Density-independent factors like weather impact populations regardless of density.
About natural selectionOne subtle but important point is that alth.pdf
About natural selection
One subtle but important point is that although natural selection occurs through interactions
between individua lorganisms and
their environment, individuals do not evolve. Rather, it is the population that evolves over time.
A second key point is that
natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even if
a trait is heritable, if all the individuals in a population are genetically identical for that trait,
evolution by natural selection cannot occur.
Third, remember that environmental factors vary from place to place and over time. A trait that is
favorable in one place or time may be useless—or even detrimental—in other
places or times. Natural selection is always operating, but which traits are favored depends on
the context in which a species lives and mates.
someone can explain what that means? with easy example..bio is too hard....
Solution
Natural selection occurs through interactions between individual organisms and their
environment, individuals do not evolve. Rather, it is the population that evolves over time.
The statement is very simple and easily understood. By natural selection we understand that it is
the forces of the nature including both biotic and abiotic factors that influence the growth ,
development and perpetuation of an organism .Which means according to Darwin\'s theory the
survival of the fittest is operative. Only organisms that can adapt and change will survive and are
established in population.
For ex In Asian lady bird beetles there is a variation in the spot pattern and color if one of the
color is favored in nature by helping the organism to survive the predators will establish itself
among the population and if successfully reproduces over a period of time it establishes itself as
successful variant.
This can alos be understood with another example : Darwin\'s finches are a type of finches native
to galapagos island . Much study is done regarding the evolution of the birds beak.This bird are
medium in size and feeds on nuts when birds of bigger size entered the island and competed with
the native birds for the nuts the larger bids drove the smaller native birds and ate all the large
nuts to withstand the competetion the smaller birds evolved smaller beaks to enable them to feed
on smaller nuts and this evolution has happened over a period of time and in the population of
native finches and established itself as a new trait.
Natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even ifa trait is heritable, if all the individuals in a population
are genetically identical for that trait, evolution by natural selection cannot occur.
This means that in any group of organisms having similar traits the chances of evolution is less
however if the same species migrates to a different environment in order to establish itself in that
environment .
Bioeradication
Bioeradication versus Biocontrol, definitions, theory and practice. This is a preliminary theoretical discussion of the use of native organisms to eradicate non-native invasive organisms from ecosystems as opposed to using non-natives to attempt control of other non-natives.
crop weed competition - by Anjali (IGKV RAIPUR, C.G)
This document discusses weed interference and competition in crops. It defines key terms like interference, competition, critical period of weed competition, and weed shift. It explains that competition is the struggle for limited resources like water, nutrients, light and space between crops and weeds. The critical period is when maximum competition occurs. Environmental, crop and weed factors influence competition. Weed shifts occur when management does not control the entire weed community. Rotating herbicides and using proper rates and timing can help prevent shifts in weed populations.
Evolution2
Genetic variation exists extensively in populations. For example, fruit flies differ genetically at around 25% of loci between any two flies. Genetic variation arises from mutation and sexual recombination of existing alleles. Natural selection does not eliminate all unfavorable genotypes due to factors like diploidy preserving recessive alleles and balanced polymorphisms maintaining diversity. Selection coefficients measure relative fitness, and directional, stabilizing, and disruptive selection shape populations over time.
Biocontrol and Bioeradication PPT given Nov. 21, 2013
Biocontrol and Bioeradication research presented to the Muhlenberg Botany Society on Nov. 21, 2013 focusing on using native organisms to eradicate non-native invasive plants. This presentation describes my latest research on a variety of plants such as Ailanthus altissima, Rosa multiflora, ,
naturalselection2016-160210163545 (1).pptx
This document discusses Darwin's theory of evolution by natural selection. It explains that organisms vary in traits, and traits that increase survival and reproduction in the current environment will be passed on to offspring, leading to evolution of new species over time as environments change. The key mechanisms are overpopulation causing competition over limited resources, variation in traits among individuals, and survival of the fittest where individuals with advantageous traits are more likely to survive and pass on those traits.
Bioeradication white paper
This is a short paper on Bioeradication containing definitions and theory. It is a work in progress which is being further developed throughout the field season of 2015 and ... .
evolution2.pdf
This document discusses evolution through natural selection. It provides background on key concepts like fitness, variation, competition, and adaptation. It also presents three case studies as examples:
1) Sickle cell anemia, where the sickle cell trait provides resistance to malaria, keeping the frequency of that genotype high.
2) The peppered moth, where the frequency of light and dark moths changed with the environment during the Industrial Revolution due to camouflage and predation.
3) Darwin's finches in the Galapagos, where different beak shapes evolved on different islands adapted to local food sources like insects versus seeds.
Ecology PowerPoint
The document outlines several key concepts in ecology and conservation including:
1. Factors that affect the distribution of plant and animal species such as temperature, water, light, soil pH, breeding sites, and food supply.
2. Methods for measuring ecological concepts like biomass, primary production, trophic levels, and ecological succession.
3. The major biomes of the world and how abiotic factors like temperature and rainfall affect their distribution.
4. Reasons for biodiversity conservation using rainforests as an example, including ethical, ecological, economic, and aesthetic arguments. Accelerating extinction rates are threatening many species.
Expression analysis of water stress related genes in tomato plant 2019
“Expression analysis of water stress related genes in Tomato
plants” submitted to the CSIR-NEIST, Jorhat and is a record of an original work done by
me under the guidance of Dr Ratul Saikia, Sr. Principal Scientist of Biological Sciences
And Technology Division(BSTD), CSIR-NEIST.
Natural selection
This document discusses key concepts of evolution through natural selection including overpopulation, variation, survival of the fittest, and the formation of new species. It explains how organisms tend to overproduce offspring leading to competition over limited resources. Individuals within a population vary in traits and advantageous variations increase the chances of survival and are passed on, known as survival of the fittest. Over time, inheritance of advantageous traits can lead to the evolution of new species through adaptive radiation.
2011 invitro-selection
This document discusses in vitro screening, which is an investigation of a large number of organisms to identify a particular property. It defines selection as the process by which some individuals contribute more offspring than others based on intrinsic differences in survival and fertility. Screening is examining properties and performance of individuals under various conditions to evaluate them. The document then discusses various selection methods like mass selection, negative selection which culls poorly developed individuals, and positive selection which chooses best individuals. It notes advantages of in vitro selection like freedom from environmental effects and ability to handle large populations in a small space. Various targets of in vitro selection are mentioned from whole plants to tissues to single cells to DNA. Important to note that in vitro tolerance may not always translate to field
Chapter wise All Notes of First year Basic Civil Engineering.pptx
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
More Related Content
Similar to Selection pressure and its types.pptx PBG
Selection, type of selection, patterns of selection and their effect on popul...
This document discusses different types of selection and their effects on populations. It describes three main types of selection:
1. Natural selection, which is based on survival of the fittest in a given environment. Only the most adapted individuals survive to reproduce.
2. Artificial selection, which is selection done by breeders to achieve specific objectives. Breeders choose which individuals get to reproduce.
3. Three patterns of selection are described - directional selection which changes the population mean over generations, disruptive selection which favors two extreme types, and stabilizing selection which favors intermediate types close to the population mean.
Locating and Using Native Biocontrols for Invasive Non-native Plants, a New...
theory, practice and examples of using native organisms and organism systems to control invasive non-native plants vs. traditional biocontrol
Selection pressure
Selection pressure refers to factors in an organism's environment that give certain variations an advantage, pushing evolution in a direction. Random mutations occur during reproduction, and favorable mutations that increase survival and reproduction will become more common through natural selection over generations. A selection pressure can be anything consistent that impacts survival and reproduction rates, like availability of resources, presence of predators, or competition. Selection operates at the individual level, favoring traits that increase individual fitness even if they harm the species as a whole.
in natural selection, explain what is a sexual selection, neutral va.pdf
in natural selection, explain what is a sexual selection, neutral variation and balancing selection
Solution
The concept of natural selection explains that how a species can have breeding populations
adapted to local conditions. Based on the principle of natural selection the selection of genotypes
occurs and that would result in offspring with better reproductive capabilities. Natural selection
always results in better survival of an organism, so the genetic changes driven by the natural
selection make the species to adapt to the local conditions so that they can survive. These species
may exhibit high genetic variation may be because out breeding, but gradually due to the
inbreeding in these adapted species, the genetic variation will be minimized and they evolve as a
separate species.
The sexual selection refers that a species which exhibit dominant sexual characters to the
opposite partner has the ability to mate with female and expand its gene pool.
Natural variation: In variation selection, the traits within the organisms undergo mutations to
allow the organism to best adapt to the environment by means of natural selection (Darwinian
evolution), these mutations are inherited by the nest generation offspring. In case of
transformational selection or Lamarck’s theory, the individual organisms change by inheriting
the transformations within a generation.
The three types of selection that we observe in speciation are disruptive selection, stabilizing
selection and directional selection. Disruptive selection occurs due to the selection for the
extreme values of traits instead of intermediate values. This divides the population into two
different groups. Disruptive selection is one of the main driving forces of sympatric speciation,
which occurs when there are no physical barriers that prevent species to mate together. The
occurrence of speciation may be depending on the availability of different food sources and
existence of different shelters. When comes to the balanced selection the allele frequencies
remain contestant throughout the evolution..
Chapt04 lecture
The document provides an overview of key concepts related to evolution, biological communities, and species interactions. It discusses evolution and natural selection, ecological niches, species interactions like competition and predation, community properties, how communities change over time through succession, and factors that influence where organisms can live.
selection in nature
This document discusses different types of natural selection and their effects on populations and species evolution over time. It describes directional selection as favoring one extreme trait, stabilizing selection as favoring intermediate traits and eliminating extremes, and disruptive selection as favoring opposite trait extremes. Natural selection can lead to adaptation, radiation of new species from a single ancestor, regression of unnecessary traits, convergence of unrelated species, coevolution between interacting species, and extinction of non-adapted species. Sexual selection also influences evolution by favoring traits that increase mating success even if they reduce survival.
Allelic frequency
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.
Population Ecology
The document discusses several key topics in population ecology:
1) Population ecology is the study of population growth and interactions. The size of a population is determined by births, deaths, immigration and emigration.
2) Populations can experience exponential or logistic growth depending on available resources. Carrying capacity is the maximum population size an environment can sustain.
3) Density-dependent factors like competition, predation, and parasitism regulate population size by increasing mortality at high densities. Density-independent factors like weather impact populations regardless of density.
About natural selectionOne subtle but important point is that alth.pdf
About natural selection
One subtle but important point is that although natural selection occurs through interactions
between individua lorganisms and
their environment, individuals do not evolve. Rather, it is the population that evolves over time.
A second key point is that
natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even if
a trait is heritable, if all the individuals in a population are genetically identical for that trait,
evolution by natural selection cannot occur.
Third, remember that environmental factors vary from place to place and over time. A trait that is
favorable in one place or time may be useless—or even detrimental—in other
places or times. Natural selection is always operating, but which traits are favored depends on
the context in which a species lives and mates.
someone can explain what that means? with easy example..bio is too hard....
Solution
Natural selection occurs through interactions between individual organisms and their
environment, individuals do not evolve. Rather, it is the population that evolves over time.
The statement is very simple and easily understood. By natural selection we understand that it is
the forces of the nature including both biotic and abiotic factors that influence the growth ,
development and perpetuation of an organism .Which means according to Darwin\'s theory the
survival of the fittest is operative. Only organisms that can adapt and change will survive and are
established in population.
For ex In Asian lady bird beetles there is a variation in the spot pattern and color if one of the
color is favored in nature by helping the organism to survive the predators will establish itself
among the population and if successfully reproduces over a period of time it establishes itself as
successful variant.
This can alos be understood with another example : Darwin\'s finches are a type of finches native
to galapagos island . Much study is done regarding the evolution of the birds beak.This bird are
medium in size and feeds on nuts when birds of bigger size entered the island and competed with
the native birds for the nuts the larger bids drove the smaller native birds and ate all the large
nuts to withstand the competetion the smaller birds evolved smaller beaks to enable them to feed
on smaller nuts and this evolution has happened over a period of time and in the population of
native finches and established itself as a new trait.
Natural selection can amplify or diminish only those heritable traits that differ among the
individuals in a population. Thus, even ifa trait is heritable, if all the individuals in a population
are genetically identical for that trait, evolution by natural selection cannot occur.
This means that in any group of organisms having similar traits the chances of evolution is less
however if the same species migrates to a different environment in order to establish itself in that
environment .
Bioeradication
Bioeradication versus Biocontrol, definitions, theory and practice. This is a preliminary theoretical discussion of the use of native organisms to eradicate non-native invasive organisms from ecosystems as opposed to using non-natives to attempt control of other non-natives.
crop weed competition - by Anjali (IGKV RAIPUR, C.G)
This document discusses weed interference and competition in crops. It defines key terms like interference, competition, critical period of weed competition, and weed shift. It explains that competition is the struggle for limited resources like water, nutrients, light and space between crops and weeds. The critical period is when maximum competition occurs. Environmental, crop and weed factors influence competition. Weed shifts occur when management does not control the entire weed community. Rotating herbicides and using proper rates and timing can help prevent shifts in weed populations.
Evolution2
Genetic variation exists extensively in populations. For example, fruit flies differ genetically at around 25% of loci between any two flies. Genetic variation arises from mutation and sexual recombination of existing alleles. Natural selection does not eliminate all unfavorable genotypes due to factors like diploidy preserving recessive alleles and balanced polymorphisms maintaining diversity. Selection coefficients measure relative fitness, and directional, stabilizing, and disruptive selection shape populations over time.
Biocontrol and Bioeradication PPT given Nov. 21, 2013
Biocontrol and Bioeradication research presented to the Muhlenberg Botany Society on Nov. 21, 2013 focusing on using native organisms to eradicate non-native invasive plants. This presentation describes my latest research on a variety of plants such as Ailanthus altissima, Rosa multiflora, ,
naturalselection2016-160210163545 (1).pptx
This document discusses Darwin's theory of evolution by natural selection. It explains that organisms vary in traits, and traits that increase survival and reproduction in the current environment will be passed on to offspring, leading to evolution of new species over time as environments change. The key mechanisms are overpopulation causing competition over limited resources, variation in traits among individuals, and survival of the fittest where individuals with advantageous traits are more likely to survive and pass on those traits.
Bioeradication white paper
This is a short paper on Bioeradication containing definitions and theory. It is a work in progress which is being further developed throughout the field season of 2015 and ... .
evolution2.pdf
This document discusses evolution through natural selection. It provides background on key concepts like fitness, variation, competition, and adaptation. It also presents three case studies as examples:
1) Sickle cell anemia, where the sickle cell trait provides resistance to malaria, keeping the frequency of that genotype high.
2) The peppered moth, where the frequency of light and dark moths changed with the environment during the Industrial Revolution due to camouflage and predation.
3) Darwin's finches in the Galapagos, where different beak shapes evolved on different islands adapted to local food sources like insects versus seeds.
Ecology PowerPoint
The document outlines several key concepts in ecology and conservation including:
1. Factors that affect the distribution of plant and animal species such as temperature, water, light, soil pH, breeding sites, and food supply.
2. Methods for measuring ecological concepts like biomass, primary production, trophic levels, and ecological succession.
3. The major biomes of the world and how abiotic factors like temperature and rainfall affect their distribution.
4. Reasons for biodiversity conservation using rainforests as an example, including ethical, ecological, economic, and aesthetic arguments. Accelerating extinction rates are threatening many species.
Expression analysis of water stress related genes in tomato plant 2019
“Expression analysis of water stress related genes in Tomato
plants” submitted to the CSIR-NEIST, Jorhat and is a record of an original work done by
me under the guidance of Dr Ratul Saikia, Sr. Principal Scientist of Biological Sciences
And Technology Division(BSTD), CSIR-NEIST.
Natural selection
This document discusses key concepts of evolution through natural selection including overpopulation, variation, survival of the fittest, and the formation of new species. It explains how organisms tend to overproduce offspring leading to competition over limited resources. Individuals within a population vary in traits and advantageous variations increase the chances of survival and are passed on, known as survival of the fittest. Over time, inheritance of advantageous traits can lead to the evolution of new species through adaptive radiation.
2011 invitro-selection
This document discusses in vitro screening, which is an investigation of a large number of organisms to identify a particular property. It defines selection as the process by which some individuals contribute more offspring than others based on intrinsic differences in survival and fertility. Screening is examining properties and performance of individuals under various conditions to evaluate them. The document then discusses various selection methods like mass selection, negative selection which culls poorly developed individuals, and positive selection which chooses best individuals. It notes advantages of in vitro selection like freedom from environmental effects and ability to handle large populations in a small space. Various targets of in vitro selection are mentioned from whole plants to tissues to single cells to DNA. Important to note that in vitro tolerance may not always translate to field
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Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
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Selection pressure and its types.pptx PBG
- 1. Selection pressure and its types Submitted By: Abdul Basit Submitted To: Miss Sadia
- 2. Selection Pressure Selection pressure regarded as a force that causes a particular organism to evolve in a certain direction. It is not a physical force but an interaction between natural variation in a specie and factors in its environment that cause a certain form to have an advantage over from the others.
- 3. Types of selection pressure 1. Artificial Selection 2. Directional Selection 3. Stabilizing Selection 4. Disruptive Selection
- 4. Artificial Selection This is the method thorough which most of modern domestic breeds of animals and crop plants were created. In artificial selection human choose specific traits to either retain or eliminate from the gene pool of breeding population, because this process is closely monitored, changes in population can be seen easily.
- 5. Directional Selection The directional theory states that an extreme phenotype is favored over other phenotypes and causes allele frequency to shift over time in favor of extreme phenotype. In other words, If a particular trait is favorable, it will be expressed at the most beneficial frequency in the population
- 6. Stabilizing Selection Stabilizing selection can be thought of as “middle-of-the-road” selection, meaning a non-extreme trait is favored instead of one of the two extreme traits. An example of this is plant height. In a population of plants, those that are short may not get enough sunlight, but those that are tall may be subjected to wind damage. This results in an increase in the number of medium-height plants and a decrease in very tall and very short plants. Because most traits do not change drastically over time, stabilizing selection is considered to be the most common mechanism for natural selection.
- 7. Disruptive Selection This type of natural selection is bimodal and favors both extreme traits in a population. For example, in a population of plants, there are some pollinators that visit the tallest plants, a different species of pollinator visits medium-height plants and a third species of pollinator that prefers the shortest plants. If the pollinator that prefers medium-height plants is removed, natural selection would select against medium-height plants and the overall plant population would move toward having only tall and short plants, the two extreme phenotypes.
- 8. Selection differential The difference between the average value of a quantitative character in a whole population and the average of those selected to reproduce the next generation