Is macroevolution simply “microevolution over very long periods of t.pdfarishmarketing21
Is macroevolution simply “microevolution over very long periods of time?” What processes or
events become very important at the macroevolutionary scale, where the fossil record gives
evidence of different species, genera, families, and higher taxa replacing others?
Solution
It is not macroevolution simply “microevolution over very long periods of time but
microevolution is leading to macroevolution and speciation over very long periods of time.
\"Gradualism and the primacy of natural selection followed by Speciation and genome
reorganization due to genetic drift\" are the processes or events that become very important at the
macroevolutionary scale, where the fossil record gives evidence of different species, genera,
families, and higher taxa replacing others. For example, micro-evolutionary changes that
accumulate within two organisms of opposite sex may cause macro-evolutionary changes in the
offspring produced by their mating. The offspring greatly varies genetically from their parents
and is special enough to result in speciation; this is called “macroevolution.”
In Darwin\'s theory, the microevolutionary changes observed in the phenotypic features of the
“finches”, beaks, tortoises and coral reefs that are observable during a scientist’s lifetime provide
support for Darwin’s view that all life is connected in a branching pattern of phylogenetic tree.
According to Darwin, natural selection including genetic variations is leading to “branching
pattern” in the origin of species. He concluded in his lifetime microevolutionay observation base
on gradualism of species evolution with “branching interrelationships” among all living beings
by meticulous “metaphor of branching pattern” as described below.
Darwin’s theory of gradualism and evolution:
Darwin uses Gradualsim and he proposed that the gradual changes associated with variations of a
species through evolution to get adapted to the present ecosystem with no much transitional
forms. Human evolution based on the gradualism and their adaptations are extremely complex.
Initially in the gradualism, natural selection operates to obtain specific traits according to biome,
ecosystem because of large-scale events followed by formation of rivers, water availability and
habitat formation. Humans did not evolve from primates until just 7 million years ago; while life
appeared on earth 3.5 billion years ago. Humans are well adapted for the environment and
developed their adaptation features as per interspecific and intraspecific genetic variations. If the
evolution time-line compressed to a calendar year, the first organism would appear around
March and Humans would not appear until December 31.
Darwin has developed a meticulous scientific theory about the exact biological evolution of a
species and he explained the evolution of modern species over a long period from a common
ancestor base on morphological convergent & divergent features as explained below.
Descent with modification from a common ance.
Is macroevolution simply “microevolution over very long periods of t.pdfarishmarketing21
Is macroevolution simply “microevolution over very long periods of time?” What processes or
events become very important at the macroevolutionary scale, where the fossil record gives
evidence of different species, genera, families, and higher taxa replacing others?
Solution
It is not macroevolution simply “microevolution over very long periods of time but
microevolution is leading to macroevolution and speciation over very long periods of time.
\"Gradualism and the primacy of natural selection followed by Speciation and genome
reorganization due to genetic drift\" are the processes or events that become very important at the
macroevolutionary scale, where the fossil record gives evidence of different species, genera,
families, and higher taxa replacing others. For example, micro-evolutionary changes that
accumulate within two organisms of opposite sex may cause macro-evolutionary changes in the
offspring produced by their mating. The offspring greatly varies genetically from their parents
and is special enough to result in speciation; this is called “macroevolution.”
In Darwin\'s theory, the microevolutionary changes observed in the phenotypic features of the
“finches”, beaks, tortoises and coral reefs that are observable during a scientist’s lifetime provide
support for Darwin’s view that all life is connected in a branching pattern of phylogenetic tree.
According to Darwin, natural selection including genetic variations is leading to “branching
pattern” in the origin of species. He concluded in his lifetime microevolutionay observation base
on gradualism of species evolution with “branching interrelationships” among all living beings
by meticulous “metaphor of branching pattern” as described below.
Darwin’s theory of gradualism and evolution:
Darwin uses Gradualsim and he proposed that the gradual changes associated with variations of a
species through evolution to get adapted to the present ecosystem with no much transitional
forms. Human evolution based on the gradualism and their adaptations are extremely complex.
Initially in the gradualism, natural selection operates to obtain specific traits according to biome,
ecosystem because of large-scale events followed by formation of rivers, water availability and
habitat formation. Humans did not evolve from primates until just 7 million years ago; while life
appeared on earth 3.5 billion years ago. Humans are well adapted for the environment and
developed their adaptation features as per interspecific and intraspecific genetic variations. If the
evolution time-line compressed to a calendar year, the first organism would appear around
March and Humans would not appear until December 31.
Darwin has developed a meticulous scientific theory about the exact biological evolution of a
species and he explained the evolution of modern species over a long period from a common
ancestor base on morphological convergent & divergent features as explained below.
Descent with modification from a common ance.
Overview
In simpler terms, Evolutionary Genetics is the study to understand how genetic
variation leads to evolutionary change.
Evolutionary Genetics attempts to account for evolution in terms of changes in gene
and genotype frequencies within populations and the processes that convert the
variation with populations into more or less permanent variation between species.
The central challenge of Evolutionary Genetics is to describe how the evolutionary
forces shape the patterns of biodiversity.
Evolutionary Genetics majorly deals with;
a. Evolution of genome structure
b. The genetic basis of speciation and adaptation
c. Genetic change in response to selection within populations
Evolution occurs when heritable characteristics of a species change.
The fossil record provides evidence for evolution.
Selective breeding of domesticated animals shows that artificial selection can cause evolution.
Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
Populations of a species can gradually diverge into separate species by evolution.
Continuous variation across the geographical range of related populations matches the concept of gradual divergence.
What scientific mechanism for evolution did Charles Darwin and Alfred.pdfmeerobertsonheyde608
What scientific mechanism for evolution did Charles Darwin and Alfred Wallace propose in
1858? Describe how this concept works. What is the difference between microevolution and
macroevolution?
Solution
1. Charles Darwin during 1858 had proposed the Theory of Evolution by Natural Selection,
where he has said that organisms change over time as a result of changes in heritable physical or
behavioral traits. Changes that allow an organism to better adapt to its environment will help it
survive and have more offspring.
Alfred Wallace who is also called the Father of Biogeography, studied the geographical
distribution of animal species and said the evolution is caused due to environmental pressures on
varieties of species it forces different species to adapt themselves to the local conditions, leading
to different populations in different locations.
Both groups of scientists have said that natural selection is the single most and important factor
in evolutionary changes seen in species.
Scientifically, This concept works due to different phenomenon such as:
a)Mutation- It is the Sudden change in the genetic makeup of an organism.And it is the driving
force of evolution, which influences the population’s gene pool.The change in the genetic
makeup of organism which favors the life of species makes it the fittest to survive!
b)Genetic Drift-It can occur when a small group of individuals leaves a population and
establishes a new one in a geographically isolated region.It occurs in a large population and helps
the population to survive.
c)Natural selection-This happens when populations of organisms are subjected to the
environment. The fittest creatures are more likely to survive and pass their genes to their
offspring, producing a population that is better adapted to the environment.
2.MicroEvolution-Microevolution is defined as changes in gene frequency in a population from
one generation to the next.These small changes in species occur by recombining existing genetic
material within the group of same species.
Micro Evolution is caused due to Mutation, Migration or Gene Flow, Genetic Drift and Selection
(natural and artificial).
Macro Evolution: It refers to major evolutionary changes over time, the origin of new types of
organisms from previously existing, but different, ancestral types.It is an evolution on a larger
scale where we find the descent of many species from one common ancestor over billions of
years.It is very difficult to see the Macro Evolution happening because it takes a longer time to
happen. But Instead, we can reconstruct the history of life using all available evidence like
geology, fossils, and living organisms..
Overview
In simpler terms, Evolutionary Genetics is the study to understand how genetic
variation leads to evolutionary change.
Evolutionary Genetics attempts to account for evolution in terms of changes in gene
and genotype frequencies within populations and the processes that convert the
variation with populations into more or less permanent variation between species.
The central challenge of Evolutionary Genetics is to describe how the evolutionary
forces shape the patterns of biodiversity.
Evolutionary Genetics majorly deals with;
a. Evolution of genome structure
b. The genetic basis of speciation and adaptation
c. Genetic change in response to selection within populations
Evolution occurs when heritable characteristics of a species change.
The fossil record provides evidence for evolution.
Selective breeding of domesticated animals shows that artificial selection can cause evolution.
Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
Populations of a species can gradually diverge into separate species by evolution.
Continuous variation across the geographical range of related populations matches the concept of gradual divergence.
What scientific mechanism for evolution did Charles Darwin and Alfred.pdfmeerobertsonheyde608
What scientific mechanism for evolution did Charles Darwin and Alfred Wallace propose in
1858? Describe how this concept works. What is the difference between microevolution and
macroevolution?
Solution
1. Charles Darwin during 1858 had proposed the Theory of Evolution by Natural Selection,
where he has said that organisms change over time as a result of changes in heritable physical or
behavioral traits. Changes that allow an organism to better adapt to its environment will help it
survive and have more offspring.
Alfred Wallace who is also called the Father of Biogeography, studied the geographical
distribution of animal species and said the evolution is caused due to environmental pressures on
varieties of species it forces different species to adapt themselves to the local conditions, leading
to different populations in different locations.
Both groups of scientists have said that natural selection is the single most and important factor
in evolutionary changes seen in species.
Scientifically, This concept works due to different phenomenon such as:
a)Mutation- It is the Sudden change in the genetic makeup of an organism.And it is the driving
force of evolution, which influences the population’s gene pool.The change in the genetic
makeup of organism which favors the life of species makes it the fittest to survive!
b)Genetic Drift-It can occur when a small group of individuals leaves a population and
establishes a new one in a geographically isolated region.It occurs in a large population and helps
the population to survive.
c)Natural selection-This happens when populations of organisms are subjected to the
environment. The fittest creatures are more likely to survive and pass their genes to their
offspring, producing a population that is better adapted to the environment.
2.MicroEvolution-Microevolution is defined as changes in gene frequency in a population from
one generation to the next.These small changes in species occur by recombining existing genetic
material within the group of same species.
Micro Evolution is caused due to Mutation, Migration or Gene Flow, Genetic Drift and Selection
(natural and artificial).
Macro Evolution: It refers to major evolutionary changes over time, the origin of new types of
organisms from previously existing, but different, ancestral types.It is an evolution on a larger
scale where we find the descent of many species from one common ancestor over billions of
years.It is very difficult to see the Macro Evolution happening because it takes a longer time to
happen. But Instead, we can reconstruct the history of life using all available evidence like
geology, fossils, and living organisms..
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Unveiling the Energy Potential of Marshmallow Deposits.pdf
Evolution (Lecture 1) a concept in biology.pptx
1. Pre-Darwinian Ideas about Evolution
Evolution?
The term evolution is derived from
two Latin words – e
= from; volvere = to roll and means
the act of unrolling or unfolding,
Evolution is the accumulation of
inherited changes within a population
over time OR Evolution has been
defined as a gradual orderly change
from one condition to another
Pre-Darwinian Ideas about
Evolution
The historical development of evolutionary
thought:
Jean Baptiste de Lamarck was the first
scientist to propose that organisms undergo
change over time as a result of some natural
phenomenon rather than divine intervention.
Lamarck thought that organisms were
endowed with a vital force that drove them
to change toward greater complexity over
time. He thought that organisms could pass
traits acquired during their lifetimes to their
offspring.
Pre-Darwinian Ideas about Evolution
2. Pre-Darwinian Ideas about Evolution
Charles Darwin’s observations while
voyaging on the HMS Beagle were the
basis for his evolutionary theory.
Darwin tried to explain the similarities
between animals and plants of the arid
Galápagos Islands and the humid South
American mainland.
Charles Darwin (1859) has defined
evolution as "descent with
modification", i.e., closely related
species resembling one another because
of their inheritance and differing from
one another because of the hereditary
differences accumulated during the
separation of their ancestors
Darwin was influenced by artificial
selection, in which breeders develop
many varieties of domesticated plants
and animals in just a few generations.
Darwin applied Thomas Malthus’s ideas
on the natural increase in human
populations to natural populations.
Darwin was influenced by the idea that
Earth was extremely old, an idea
promoted by Charles Lyell and other
geologists.
Pre-Darwinian Ideas about Evolution
3. Evolution
Explain the four premises of evolution by natural
selection as proposed by Charles Darwin.
Charles Darwin and Alfred Russel Wallace
independently proposed evolution by natural
selection, which is based on four observations.
First, the reproductive ability of each species
causes its populations to have the potential to
geometrically increase in number over time.
Second, genetic variation exists among the
individuals in a population
Third, organisms compete with one another for the
resources needed for life, such as food, living
space, water, and light.
Fourth, offspring with the most favorable
combination of inherited characteristics are most
likely to survive and reproduce, passing those
genetic characteristics to the next generation.
Natural selection results in adaptations,
evolutionary modifications that improve the
chances of survival and reproductive success in a
particular environment.
Over time, enough changes may accumulate in
geographically separated populations to produce
new species.
4. Evolution
Darwin proposed that evolution occurs by natural selection
a. Overproduction
The reproductive ability of each species has the potential to
cause its population to geometrically increase over time. A
female oyster lays about 1,00000 eggs, and a female cod
produces perhaps 40 million eggs!
In each case, however, only about some offspring survive to
reproduce. Thus, in every generation each species has the
capacity to produce more offspring than can survive.
b. Variation
The individuals in a population exhibit variation. Each
individual has a unique combination of traits, such as size,
color, ability to tolerate harsh environmental conditions, and
resistance to certain parasites or infections. Some traits improve
an individual’s chances of survival and reproductive success,
whereas others do not.
Genetic variation in emerald tree boas
These snakes, all the same species (Corallus caninus), were caught in a
small section of forest in French Guiana.
Many snake species exhibit considerable variation in their coloration and
patterns.
5. Evolution
Darwin proposed that evolution occurs by natural selection
C. Limits on population growth, or a struggle for existence.
There is only so much food, water, light, growing space, and other
resources available to a population, so organisms compete with one
another for these limited resources.
Because there are more individuals than the environment can
support, not all survive to reproduce.
Other limits on population growth include predators, disease
organisms, and unfavorable weather conditions.
D. Differential reproductive success.
Those individuals that have the most favorable combination of
characteristics (those that make individuals better adapted to their
environment) are more likely to survive and reproduce.
Offspring tend to resemble their parents because the next generation
inherits the parents’ genetically based traits.
6. Evolution
Compare the modern synthesis with Darwin’s
original view of evolution.
The modern synthesis combines Darwin’s
evolutionary theory by natural selection with
modern genetics to explain why individuals in
a population vary and how species adapt to
their environment.
Mutation provides the genetic variability that
natural selection acts on during evolution.
7. Evolution
Evidence for Evolution
Summarize the evidence for evolution obtained
from the fossil record.
Direct evidence of evolution comes from fossils, the remains
or traces of ancient organisms.
Layers of sedimentary rock normally occur in their sequence
of deposition, with the more recent layers on top of the
older, earlier ones.
Index fossils characterize a specific layer over large
geographic areas.
Radioisotopes present in a rock provide a way to accurately
measure the rock’s age.
Index fossils (also known as guide fossils or indicator fossils)
are fossils used to define and identify geologic periods (or
faunal stages). Index fossils must have a short vertical range,
wide geographic distribution and rapid evolutionary trends.
Viviparus glacialis
Tiglian
(Early Pleistocene)
0.5 million years ago
8. Evolution
Define biogeography and describe how the
distribution of organisms supports evolution.
Biogeography, the geographic distribution
of organisms, affects their evolution.
Areas that have been separated from the
rest of the world for a long time contain
organisms that have evolved in isolation
and are therefore unique to those areas.
At one time the continents were joined to
form a supercontinent.
Continental drift, which caused the
various landmasses to break apart and
separate, has played a major role in
evolution.
9. Evolution - Evidences
Describe the evidence for evolution
derived from comparative anatomy.
Homologous features have basic
structural similarities even though the
structures may be used in different ways
because homologous features derive
from the same structure in a common
ancestor, i.e divergent evolution
Evolutionary affinities exist among the
organisms that have homologous
features.
10. Evolution - evidences
Describe the evidence for
evolution derived from
comparative anatomy.
Analogous features evolved
independently to have similar
functions in distantly related
organisms.
Analogous features demonstrate
convergent evolution, in which
organisms with separate ancestries
adapt in similar ways to comparable
environmental demands.
11. Evolution - EVIDENCES
Describe the evidence for evolution derived from comparative anatomy.
Vestigial structures are nonfunctional or degenerate remnants of structures that
were present and functional in ancestral organisms.
Structures occasionally become vestigial as species adapt to different modes of life.
all pythons have remnants of hind-limb bones
embedded in their bodies.
12. Evolution - evidences
Briefly explain how developmental biology provide
insights into the evolutionary process.
Development in different animals is controlled by the same
kinds of genes, which indicates that these animals have a
shared evolutionary history.
The accumulation of genetic changes since organisms
diverged, or took separate evolutionary pathways, has
modified the pattern of development in more complex
vertebrate embryos.
Development of fish fins, chicken wings, and human limbs
Fish, chickens, and humans are vertebrates with strikingly similar
genes. although the early embryos of these organisms are much
alike, the areas colored orange follow different developmental
pathways, resulting in fins, wings, or limbs.
13. Evolution - Evidences
Briefly explain how molecular biology provide insights into
the evolutionary process.
Molecular evidence for evolution includes the universal
genetic code and the conserved sequences of amino acids in
proteins and of nucleotides in DNA.
Evolutionary changes are often the result of mutations in
genes that affect the orderly sequence of events during
development.
Differences in DNA nucleotide sequences as evidence of
evolutionary relationships
14. Evolution- Microevolution
Microevolution is a change in allele or
genotype frequencies over time within a
population.
How each of the following micro
evolutionary forces alters allele frequencies
in populations: nonrandom mating, mutation,
genetic drift, gene flow, and natural selection.
In nonrandom mating individuals select
mates on the basis of phenotype, indirectly
selecting the corresponding genotype(s).
Inbreeding is the mating of genetically
similar individuals that are more closely
related than if they had been chosen at
random from the entire population.
Inbreeding in some populations causes
inbreeding depression, in which inbred
individuals have lower fitness (relative
ability to make a genetic contribution to the
next generation) than non-inbred individuals.
15. Evolution-Mechanisms of Evolution
In assortative mating individuals select mates
by their phenotypes. Both inbreeding and
assortative mating increase the frequency of
homozygous genotypes.
Mutations, unpredictable changes in DNA, are
the source of new alleles. Mutations increase
the genetic variability acted on by natural
selection.
Genetic drift is a random change in the allele
frequencies of a small population. Genetic drift
decreases genetic variation within a population,
and the changes caused by genetic drift are
usually not adaptive.
A sudden decrease in population size caused by
adverse environmental factors is known as a
bottleneck.
Genetic drift
Mutations
16. Evolution
The founder effect is genetic
drift that occurs when a small
population colonizes a new
area.
Gene flow, a movement of
alleles caused by the migration
of individuals between
populations, causes changes in
allele frequencies.
Natural selection causes
changes in allele frequencies
that lead to adaptation.
Natural selection operates on
an organism’s phenotype, but it
changes the genetic
composition of a population in a
favorable direction for a
particular environment.
Gene flow
Founder effect
Natural selection
17. Evolution
Distinguish among
stabilizing selection,
directional selection,
and disruptive
selection.
Stabilizing selection
favors the mean at
the expense of
phenotypic extremes.
Directional selection
favors one phenotypic
extreme over another,
causing a shift in the
phenotypic mean.
Disruptive selection
favors two or more
phenotypic extremes.
Selective Pressures
Selective pressures: External forces which
affect an organism’s ability to survive in a
given environment.
•Selection pressures can be negative
(decreases the fitness of a trait) or positive
(increases the fitness of a trait)
Examples of selection pressures:
Predators, availability of resources,
disease, accumulation of wastes, abiotic
factors (climate, CO2 levels), natural
disasters.
Looking at populations – we can see how
populations shift based on pressure. The
group shows the variation in a population
and the effect of pressure on populations
Directional Selection: The pressures favor
one “extreme” of the trait in a population.
Stabilizing Selection: If conditions stable
for a long time, pressure favors
“moderates”
Disruptive Selection: The pressure favors
both extremes as they both give benefits
18. Evolution
Genetic Variation in Populations
Describe the nature and extent of genetic variation, including
genetic polymorphism, balanced polymorphism, neutral
variation, and geographic variation.
Genetic polymorphism is the presence of genetic variation
within a population.
Balanced polymorphism is a special type of genetic
polymorphism in which two or more alleles persist in a
population over many generations as a result of natural
selection.
Heterozygote advantage occurs when the heterozygote
exhibits greater fitness than either homozygote.
In frequency dependent selection, a genotype’s selective value
varies with its frequency of occurrence.
Neutral variation is genetic variation that confers no
detectable selective advantage.
Geographic variation is genetic variation that exists among
different populations within the same species.
A cline is a gradual change in a species’ phenotype and
genotype frequencies through a series of geographically
separate populations.
Genetic polymorphism