Evolution, Natural Selection, Adaptation

Wildlife Biology Midterm

What are proximate/mechanism questions?

How?

What are ultimate/origin questions?

Why?

What is evolution?

Change in gene frequencies over time in a population

What are the four primary processes that result in a change in gene frequencies over time in a population?

Mutation, Gene flow, Genetic Drift, Natural Selection

What is gene flow?

Movement of alleles in and out of a population

What is genetic drift?

Change in allele frequency over generations

What are adaptations the result of?

Natural selection

When is a trait an adaptation?

If it confers a greater probability of survival and successful reproduction

Are adaptations necessarily an ideal or optimal state?

NO

Individuals do NOT evolve and do NOT adapt, but what do they possess?

Morphological, behavioral, and physiological adaptations

What are some characteristics of an adaptation?

Emerges slowly over time and is generally NOT reversible

What is acclimatization?

Functional compensation over a period of days to weeks in response to a complex suite of factors (usually reversible)

What is acclimation?

Functional change over a period of days to weeks when variables are manipulated experimentally (usually reversible)

What are some reasons why animals don’t possess every adaptation imaginable?

• Costs and tradeoffs

• Limits to adaptations (functional, ecological, historical)

What are functional limits to adaptation?

Genetic/physiological limit

What are ecological limits to adaptation?

Range and demographic constraints

What are historical limits to adaptation?

Previous adaptations might prevent new adaptations, animals limited by developmental pathways

What is fitness?

The ability of an individual to survive and reproduce (lifetime reproductive output)

What are Darwin’s 4 postulates?

1. Individuals within a species are variable

2. Some of these variations are heritable

3. In every generation, more offspring are produced than can survive

4. Survival and reproduction are not random

What is the 1st key aspect on how natural selection works?

Populations evolve over time as natural selection acts on individuals

What is the 2nd key aspect on how natural selection works?

Natural selection acts on phenotypes, but evolution consists of changes in gene frequencies

What is the 3rd key aspect on how natural selection operates?

Natural selection is “backwards looking” (each generation is product of selection in previous generation

What is the 4th key aspect on how natural selection operates?

Natural selection acts on existing traits

What is the 5th key aspect on how natural selection works?

Evolution by natural selection is not random

What is the 6th key aspect on how natural selection works?

Natural selection works on individuals, not groups

What is artificial selection?

Intentional breeding

What is sexual selection?

Some individuals are better at acquiring mates than others

What does sexual selection often lead to?

Sexual dimorphisms

What is intrasexual selection?

Selection due to interactions between individuals of the same sex

What is intersexual competition?

Selection due to interactions between individuals of the opposite sex

How do sexual and natural selection differ?

Sexual selection:

• Differential mating advantages

• Traits showy, elaborate, appear costly, wasteful, risky

Natural selection:

• Differential survival and reproduction

• Traits appear functional, practical, economical