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-the study of the processes that change the gene frequencies
Allele frequency equation (for a):
a = freq aa + .5(freq Aa)
Allele frequency equation (for A):
A = freq AA + .5(freq Aa)
Geneotype frequencies equal
# of individuals/total population
A2 + 2Aa + a2 = 1
-calculates mating in one generation and allows the calculation of allele frequencies in the next generation
Examples of continuous traits
Examples of Discontinuous traits
- -finger number
- -tongue rolling
Costs and benefits of mate guarding
- • Benefit = prevent other males from mating with female and sharing paternity of eggs
- • Cost = Can’t mate with other females while mate guarding
- -When females outnumber males,
- costs>benefits of mate guarding
- -When males outnumber females,
- benefits>costs of mate guarding
Constraints on adaption
- • Correlated characters
- • Disequilibrium
- • Genetic drift
- • Local vs global optima
- • External force
-refers to a difference between the observed and the expected ratios of genotypes within a given population
- -Traits that influence the presence of other traits are correlated, either positively or negatively.
- -If selection acts on a trait that is correlated with another, it is possible that the second trait may become maladaptive
-random changes in allele frequencies
Biological Species concept
- -Organisms are classified in the same species if they are potentially capable of interbreeding and producing fertile offspring.
- -Reproductive isolation maintains species boundaries
Ecological Species Concept
- -organisms adapted to a particular set of resources, called a niche, in the environment.
- -Natural selection maintains species boundaries
-The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier or reproductive isolation
- -populations are not isolated by a physical barrier and are instead "beside" each other
- -Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population’s range.
- -population must be continuous
- -partial isolation
- -selection leads to speciation
- -the individuals in the population are not separated at all and all live in the "same place"
- -no isolation
- -selection leads to speciation
-An outcome of competition in which two species living in the same area have evolved differences in morphology or other characteristics that lessen competition for food resources.
Possibilities of how human bipedalism evolved
- 1. Humans evolved from knuckle-walker
- 2. knuckle-walking evolved independently in chimps and gorillas
How things are related to one another
what we call things
Ancestral vs Derived Traits
- 1. Ancestral traits are those that two species share because of common ancestry.
- Ex. All birds have wings because their common ancestor did. They are ancestral traits.
- 2. Derived traits evolved in one species after it branched off from others.
- Ex. bats' evolved separately from birds' wings. They are derived traits
- -most useful when comparing very similar species to determine taxonomic relationships. (How closely they are related)
- -process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
- Ex. Birds and bats wings
- -when two species share a structure that arises from the same origin but may have a different function.
- -For example, hair on mammals is homologous. Porcupine spikes are used for defense and sea otter fur is used for insulation.
- -when species share a structure that has evolved independently and may have the same function.
- -For example, birds and bats’ ability to fly is analogous
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