This document discusses key patterns and processes of evolution including:
1) Macroevolution occurs over long periods of time and involves changes across species, while microevolution is small-scale changes within a species.
2) Speciation requires reproductive isolation that separates gene pools into different species.
3) Extinction patterns include background extinction and mass extinctions caused by events like asteroids or climate change.
4) Evolutionary rates can be gradual or punctuated by long stable periods followed by rapid change.
This presentation file has these contents:
Evolution
Convergent Evolution
Analogous structures
Divergent Evolution
Homologous structures
Parallel Evolution
Coevolution
Types of Evolution
Macroevolution
Microevolution
Importance of pattern of evolution
This presentation file has these contents:
Evolution
Convergent Evolution
Analogous structures
Divergent Evolution
Homologous structures
Parallel Evolution
Coevolution
Types of Evolution
Macroevolution
Microevolution
Importance of pattern of evolution
Analogous structures are those structures in different species which perform the same function, have similar appearance and structure but are not evolved together; therefore do not share a common ancestor.
Source:http://explainry.com/biology/analogous-structures/
Analogous structures are those structures in different species which perform the same function, have similar appearance and structure but are not evolved together; therefore do not share a common ancestor.
Source:http://explainry.com/biology/analogous-structures/
SOMEONE HELP Complete sentences, stating the differences and relati.pdfexpressionnoveltiesk
SOMEONE HELP: Complete sentences, stating the differences and relationships between the
two terms, and give specific examples where appropriate.
1. gene flow / genetic drift
2. sexual selection / artificial selection
3. ring species / biological species concept
4. hybrid inviability / temporal isolation
5. autopolyploidy / allopatric speciation
6. molecular clock / cladogram
7. gradualism / uniformitarianism
8. extreme thermophiles / viroids
9. HIV / Creutzfeld-Jakob disease
10. biofilm / microbial fuel cell
Solution
Q.No 1
Genetic drift is a mechanism of evolution of biological species that takes place because of the
change in the frequency of alleles in a population. These changes in the allele frequency in a
population occur randomly. One very common example to describe the genetic drift would be
that most of the human families have different number of boys and girls, as the X or Y alleles
have been passed differently into the new generation from the parents. Although the X and Y
alleles do not really contribute for the evolution, the frequency changes in other alleles would
have a considerable effect for evolution.
Gene flow is a process of evolution that takes place when genes or alleles move from one
population to another. It is also known as the Gene Migration, and that could cause changes in
the allele frequency as well as some variations in the gene pool of both populations. There are
some good examples to support this phenomenon from humans regarding a developed immunity
for malaria among new Western Africans after their parents mated with Europeans who initially
had the immunity. It is interesting to notice that gene flow could take place between two species,
as well.
Q.No 2
Sexual selection enhances mating success or the number of copulations, while natural selection
tends to produce well-adapted individuals to their environment. Sexual selection does not adapt
the individuals to their environment. Unlike sexual selection, natural selection acts on traits
which increase the fitness of members in a population. Certain adaptations have been derived
from the sexual selection which could never have been arisen from natural selection alone (Ex:
the neck of the giraffe, various plumages of most male birds etc.). Generally sexual selection
depends on the success of one sex while natural selection depends on the success of both sexes in
relation to the general condition of life. In most of the animals, certain traits related to their
sexual selection process do not express their characteristics until the organism is able to mate,
but naturally selected traits may occur at birth of the organism during the process of natural
selection.
Q.No 3
A ring species is a connected series of neighbouring populations, each of which can interbreed
with closely sited related populations, but for which there exist at least two \"end\" populations in
the series, which are too distantly related to interbreed, though there is a potential gene flow
between e.
This is PPT on Evolution. This is just and introductory PPT. Soon There will be a PPT with much more on Evolution. Hope That you all like it. please like and share. each like Counts.
It states that the present day complex plants and animals have evolved from earlier simpler forms of life by gradual changes. SEQUENTIAL EVOLUTION ,DIVERGENT EVOLUTION, Theories of evolution.
1. Patterns and Processes of Evolution
Macroevolutionary Patterns
Large-scale (more than a single species)
Occurs over long periods of time
Microevolution
Small-scale (within a single species)
Forms variations in populations
1
2. Speciation – Isolating Mechanism
Species – group of organisms that interbreed to
produce fertile offspring under normal conditions –
share a common gene pool
Speciation – formation of a new species
Requires reproductive isolation – organisms
do not interbreed; gene pools become separate
Behavioral
Geographic
Temporal
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3. Patterns of Extinction
Background Extinction – “business as
usual” extinction – slow and steady
Mass Extinction – many species become
extinct over a short period of time
Causes:
Asteroid
Volcanic eruptions
Moving continents
Changing sea levels 3
4. Rates of Evolution
Gradualism – change in species is slow and
steady
Punctuated Equilibrium – long periods of
stability followed by short periods of rapid change
4
8. The Role of Genes in Evolution
In terms of genetics, evolution is the change in
the frequency of alleles in a population’s
gene pool
Natural selection leads to that change
8
9. Genetic Drift
Random change in allele frequency – changes in
the gene pool of a small population due to chance
Types of Genetic Drift:
Bottleneck Effect – change in allele
frequency following dramatic reduction in
population size
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10. Genetic Drift
Founder Effect – small group colonizes a
new habitat
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11. Molecular Evolution
Molecular Clocks – use mutation rates
in DNA to estimate time two species have
been evolving independently
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12. Molecular Evolution: Hox Genes
Genes which control an organism’s basic body plan
Anterior/posterior ends
Limbs, wings
small sequence changes during embryological
development can cause large changes in adults
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