Microevolution is changes in allele frequencies in a population over a short time due to various evolutionary processes. Five agents of change can cause microevolution: mutation, gene flow, genetic drift, non-random mating, and natural selection. Natural selection is the only consistent driver of adaptation, favoring traits that increase an organism's fitness and ability to pass genes to the next generation. Selection can act in three modes: stabilizing selection favors intermediate traits, directional selection moves a trait toward an extreme, and disruptive selection moves a trait toward both extremes.
TO FOLLOW THESE SLIDES you will learn about the adaptive radiations involve in evolution .
yo will learn about the parallel adaptations and its types
speciation role in the evolution
factors
key innvations
to imrove the article involving examples
Founder events
Adaptive plasticity
process of adaptive radiation
Factors promote adaptive radiations
Factors underlying adaptive radiations
defined by 0.S OSBORN
ecological space
geological
climatological
Islands
examplrs: 1.Darwin Finches 2.Cichlid fish genome -adaptive evolution, Stanford scientists
3.Anolis Lizards
Factors promote adaptive radiations
1.Generally speaking, adaptive radiations occur when new, unoccupied ecological niches become accessible to a founder population.
This can happen after a mass extinction during which the previous occupiers of those niches died out.
t can also happen when a colonizing species arrives at an island. (For instance the ancestor of the honeycreepers in Hawaii, or of Darwin's "finches" in the Galapagos)
Honey creeper
Change feeding habitat
At least 56 species of Hawaiian honeycreepers known to have existed, although all but 18 of them are now extinct.
Lack of competition. When a species enters an adaptive zone, it is poorly equipped to compete with species that have become adapted to the same niche.
For example, mudskippers are fish that are making a living on land, but they are marine fish and they don't have to compete against frogs and salamanders, which are restricted to fresh water. That is why we don't see freshwater mudskippers.
process of adaptive radiation
Ecological Release Colonization of species.
Taxon cycle
Habitat varying as population expand- species dispersal.
Adaptive plasticity Phenotypic plasticity(behavior change)
Property of an individual or genotype that may be adaptive, maladaptive or neutral with regard to an individual's fitness.
The particular way an individual's (or genotype's) phenotype varies across environments can be described as a reaction norm (Single genotype-phenotypic expression)
Speciation in adaptive radiation Founder events
Iczn(The International Commission on Zoological Nomenclature )Al Nahian Avro
The International Commission on Zoological Nomenclature (ICZN) acts as adviser and arbiter for the zoological community by generating and disseminating information on the correct use of the scientific names of animals. The ICZN is responsible for producing the International Code of Zoological Nomenclature - a set of rules for the naming of animals and the resolution of nomenclatural problems.
Kinds of taxonomic publications,taxonomic review ,revision, monograph,atlas,s...Anand P P
kinds of taxonomic publication mainly deals with different types of taxonomic publications.the taxonomy deals with several types of publications mainly that help to over all exchange of taxonomic information,its is a world wide taxonomic communication.
TO FOLLOW THESE SLIDES you will learn about the adaptive radiations involve in evolution .
yo will learn about the parallel adaptations and its types
speciation role in the evolution
factors
key innvations
to imrove the article involving examples
Founder events
Adaptive plasticity
process of adaptive radiation
Factors promote adaptive radiations
Factors underlying adaptive radiations
defined by 0.S OSBORN
ecological space
geological
climatological
Islands
examplrs: 1.Darwin Finches 2.Cichlid fish genome -adaptive evolution, Stanford scientists
3.Anolis Lizards
Factors promote adaptive radiations
1.Generally speaking, adaptive radiations occur when new, unoccupied ecological niches become accessible to a founder population.
This can happen after a mass extinction during which the previous occupiers of those niches died out.
t can also happen when a colonizing species arrives at an island. (For instance the ancestor of the honeycreepers in Hawaii, or of Darwin's "finches" in the Galapagos)
Honey creeper
Change feeding habitat
At least 56 species of Hawaiian honeycreepers known to have existed, although all but 18 of them are now extinct.
Lack of competition. When a species enters an adaptive zone, it is poorly equipped to compete with species that have become adapted to the same niche.
For example, mudskippers are fish that are making a living on land, but they are marine fish and they don't have to compete against frogs and salamanders, which are restricted to fresh water. That is why we don't see freshwater mudskippers.
process of adaptive radiation
Ecological Release Colonization of species.
Taxon cycle
Habitat varying as population expand- species dispersal.
Adaptive plasticity Phenotypic plasticity(behavior change)
Property of an individual or genotype that may be adaptive, maladaptive or neutral with regard to an individual's fitness.
The particular way an individual's (or genotype's) phenotype varies across environments can be described as a reaction norm (Single genotype-phenotypic expression)
Speciation in adaptive radiation Founder events
Iczn(The International Commission on Zoological Nomenclature )Al Nahian Avro
The International Commission on Zoological Nomenclature (ICZN) acts as adviser and arbiter for the zoological community by generating and disseminating information on the correct use of the scientific names of animals. The ICZN is responsible for producing the International Code of Zoological Nomenclature - a set of rules for the naming of animals and the resolution of nomenclatural problems.
Kinds of taxonomic publications,taxonomic review ,revision, monograph,atlas,s...Anand P P
kinds of taxonomic publication mainly deals with different types of taxonomic publications.the taxonomy deals with several types of publications mainly that help to over all exchange of taxonomic information,its is a world wide taxonomic communication.
Darwin theory of evolution was the first insight for understanding life on earth. To get more information about Darwin and his work; contact myassignmenthelp.net
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Evolution in small population
by HAIDER ALI
In biology evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection,
The theory of evolution is based on the idea that all species are related and gradually change.
This presentation covers the basic terminology and key parameters of Population Genetics. Presentation is helpful for the students of Life Sciences and Evolutionary biology.
Evolution on how Charles Darwin the father of evolution explained the different types of mechanisms of evolution these are by natural selection, genetic drift, gene flow and many more
Evidence of Evolution by Natural Selection - how basic evolutionary principal...Madison Elsaadi
This PPTP is made for high school teachers wishing to introduce evolutionary concepts and exercises in regular and advance (AP) high school science courses.
2. • Microevolution – A change of allele
frequencies in a population over a short
time. The basis for all large-scale or
macroevolution.
• To fully appreciate evolution, we need to
look not just at the outcomes but also at
the processes that created those
outcomes.
5. Exactly how do
populations evolve?
• There are many
different alleles in a
population but a
frog can only have
two.
• These two frogs
have different
alleles for
coloration.
6. What causes Evolution?
• Five Agents of Change that can alter
allele frequencies
– Mutation
– Gene flow
– Genetic drift
– Non-random mating
– Natural selection
7. Mutation
• Any permanent alterations in the makeup of
DNA.
– They must be heritable
– Base pair, deletion, translocation, etc.
– Most do nothing, a few are harmful, rarely are they
beneficial.
– These mutations are not working to further survival
and reproduction.
– These mutations are not likely to account for a
change in allele frequency.
– These good mutations bring new genetic information
into the genetic pool.
8. Gene Flow
• A change in allele frequency that can
occur when mating with members from
another population occurs.
– The movement of genes from one population
to another.
– Migration – the movement of individuals from
one population into the territory of another.
– Plants migrate, too.
9. The ranges of the Bullock's and Baltimore orioles. The
species overlap in a hybrid zone, where gene flow occurs.
Gene flow
11. Genetic Drift
• The chance alteration of allele
frequencies in a population, with such
alterations having greatest impact on
small populations.
– Bottleneck effect
– Founder’s effect
• A small sample of alleles is likely to yield
a gene pool that is different from the
distribution found in the larger population.
12. If there is a drastic change (disease, migration or natural
catastrophe) in the survival of a large population, there is little
change in the frequency of that population's alleles. In a smaller
population, drastic change can result in loss of an entire allele.
13. • Bottleneck effect – The change in allele
frequency in a population due to chance
following a sharp reduction in the
population size.
• Founder effect – When a small portion of
a population migrates to another area,
starting a new population.
15. Cheetahs survived a drastic bottleneck
in the nineteenth century.
Bottleneck effect
16. Founder effect
This Native American
woman, like all Native
Americans, is a
descendant of people
who crossed the
Bering Strait into
Alaska over 10,000
years ago. No Native
Americans have type B
blood, apparently by
chance, none of the
emigrants had this
blood type.
17. Nonrandom Mating
• Mating in which a given member of a
population is not equally likely to mate
with any other given member.
• Sexual selection is a form of nonrandom
mating. This is mating based on
phenotype, based on the choices made
by the female of the species.
• The male will increase the proportion of
his alleles in the next generation.
18.
19. Natural Selection
• A process in which the differential
adaptation of organisms to their
environment selects those traits that will
be passed on with greater frequency from
one generation to the next.
• Traits of those who are more successful in
reproducing will become more widespread
in a population, the alleles that bring about
these traits will increase in frequency from
one generation to the next.
20. Artificial selection
• Artificial selection:
Humans choose
traits they prefer in
animals or crops and
breed to achieve
those “desirable”
individuals.
21. • Natural selection is the only one of the
five agents of microevolution that
consistently works to adapt organisms to
their environment.
– Genetic drift is random
– Mutation has a negative effect, or no effect
– Gene flow doesn’t necessarily bring in genes
that are better suited to the environment
– Non random mating doesn’t have anything to
do with matching individuals to environment
22. Fitness
• The success of an organism in passing
on its genes to offspring, relative to the
other members of its population.
• The allele frequencies will increase.
• Also known as “survival of the fittest”
23. 1. Large cactus finch (Geospiza
conirostris) 2. Large ground finch
(Geospiza magnirostris) 3. Medium
ground finch (Geospiza fortis)
4. Cactus finch (Geospiza scandens)
5. Sharp-beaked ground finch
(Geospiza difficilis) 6. Small ground
finch (Geospiza fuliginosa)
7. Woodpecker finch (Cactospiza
pallida) 8. Vegetarian tree finch
(Platyspiza crassirostris) 9. Medium
tree finch (Camarhynchus pauper)
10. Large tree finch (Camarhynchus
psittacula) 11. Small tree finch
(Camarhynchus parvulus) 12.
Warbler finch (Certhidia olivacea)
13. Mangrove finch (Cactospiza
heliobates)
24. Three modes of
Natural Selection
• When natural selection operates on
characters that are polygenic and
continuously variable, it can proceed in
one of three ways.
• Does natural selection favor what is
average or what is extreme?
25. Stabilizing Selection
• Intermediate forms are
favored over extreme forms.
• Human baby birth weight.
• Infant deaths are higher at
the extremes of birth weight,
children most likely to survive
have an average birth weight.
• Natural selection is working to
make average birth weights
more common
26.
27. Directional Selection
• When natural selection moves
a character towards one of its
extremes.
• Smoothness of brachiopod
shells took 10 million years to
achieve.
28.
29. Disruptive Selection
• When natural selection moves a
character to both its extremes.
• Occurs much less frequently in
nature.
30. • Finches in West Africa
• When food is scarce, large-
billed birds specialize in
cracking a large seed.
Small-billed birds feed on
soft varieties of seed.
• A bird with an intermediate
sized bill would get less
food and not survive.