Evolution Week 7 Flashcards
Give the formula for Component of Phenotypic Variation.
Vp = Vg + Ve
Vp - total phenotypic variance in population
Vg - variance due to genetic differences
Ve - variance due to environmental differences
What are the modes of selection?
Directional, stabilizing and disruptive
Define stabilizing selection.
Intermediate phenotypes are more fit than ones at either extreme.
Define directional selection.
One extreme phenotype is more fit than all the other phenotypes.
Define disruptive selection.
Both extreme phenotypes are more fit than those in the middle.
What 3 things need to happen for natural selection to occur?
Genetic variation
Heritability of traits
Nonrandom survival of offspring
What is countershading? Give an example.
The protective coloration of some animals in which parts normally in shadow are light and those exposed to the sky are dark.
Oldfield deer mice have a dark brown coat, a light grey belly.
Name 2 random and 2 non-random processes.
Random: Mutations and genetic drift
Non-Random: Natural selection and gene flow
Explain mutation in beach mice.
A random mutation in one or more of the genes affecting coat coloration caused light coloration in the coat of the mutant mouse.
Explain natural selection in beach mice.
Beach mice with mutations that produced light coat color had higher survival and reproductive success than dark beach mice.
What do ultimate explanations address?
The adaptive value of the trait, exploring how the trait increases evolutionary fitness in a specific environment.
What do proximate explanations address?
The mechanisms that produce the trait, including its genetic, developmental, or physiological basis.
Define evolutionary fitness.
Measures the relative ability of an individual to produce viable, fertile offspring, relative to other individuals in the population.
An adaptation increases what?
An individual’s evolutionary fitness relative to other individuals in the population.
Why do Japanese cranes breed in spring and early summer?
Breeding is most likely to be
successful in spring and early
summer.
