Evolutionary Biology Final

Final Bio Review Concepts and Terms

Sympatric

Two species without a geographical border.

Allopatric divergence

Separated geographically and become two new species

Reproductive Isolation in Finches

1. Allopatric divergence in songs due to habitat resources.

   1. Further divergence in sympatry due to competition on beak side (and thus song)

Second Contact: Fusion

2 groups not reproductively isolated.

Secondary Contact: Hybrid Zone

Offspring formed at low level (only happens sometimes)

Secondary Contact: Reinforcement

Selection against hybrids because their fitness is not as good. Selected for same mates of same spp.

Costs of Interspecific Competition

1. Energy spent on defense

2. Risk of injury during defense

3. Time spent on defense

4. faster growth = better competition BUT less energy for reproduction

Character Displacement

Different phenotypes in sympatry same location. Specialize because of competition.

Life History

• Age at Maturity (when they can reproduce)

• Size reproduced + Number of offspring

• Parental Care

• Life Span

High Extrinsic Mortality Rate

Favors traits that increase reproductive output early in life (Large # of offspring, early maturity)

Trade-offs of large number of offspring and early maturity:

• Smaller offspring

• Limited parental care

• Lower energy for maintenance

Antagonistic Pleiotropy

One gene, many traits, benefits and costs associated with it.

Costs of Male Traits in Sexual Selection

Energetic Costs/Increased Predation Risk - negative effects limit how extreme a trait can get.

Male competition

Males may guard a harem of females or a resource that females need.

Sperm Competition

In species where females mate w/ MULTIPLE males sperm must compete to fertilize female’s eggs (in some cases removal of sperm is possible)

Selected For: larger # of sperm, and faster swimming sperm.

Sexual Conflict

Favor in one sex costs in other, ex. when male traits harm the female or limit female choice.

Direct benefits of female choice

• Food

• High quality nests

• Reduced risk of diseases (choosing healthy males)

Indirect benefits of female choice

High quality genes for offspring. (Predisposition or sensory cues)

Mullerian Mimics - MUTUALISTIC MIMICRY

Two or more TOXIC species with matching coloration patterns.

Both Individuals benefit, predators learn faster.

Leads to convergent evolutionary patterns in multiple environments.

Favors more common patterns.

Positive Frequency Dependent Selection; Reinforces coloration similarities.

Batesian Mimics - ANTAGONISTIC MIMICRY

One species resembles a toxic species but doesn’t produce toxin themselves.

Negative Frequency Dependent Selection; new patterns by toxic species, mimic will copy in turn.

Coevolutionary Alteration

Switching to least defended prey at that moment in time. Predator will switch back if the other is less defended and one is more. (DEFENSE IS COSTLY FOR PREY)

Coevolutionary Escalation

Predator consistently targets a particular prey species and both evolve higher counter measures to each other.

Evolution can only occur if

Individuals in a popn. DIFFER from each other

Phenotypic Variation

Displayed traits (morphological structures, physiological, behavior)

Genotype

Alleles of genes that code for proteins

Gene Expression

When, Where, How much a gene is expressed.

Acquired Traits

Based on individuals actions or experiences

Germ-Line Mutations

Those that affect the gametes and can be passed from parent to offspring

Somatic Mutations

Affects cells of the body of an organism (Aren’t passed on)

Transcription Factors

• activator proteins

• enhancer sequences

• repressor proteins

• silencer sequences

Discrete Traits

Those with few distinct phenotypes

Continuous distribution

Polygenic, affected by multiple genes and depends on alleles and their interactions.

Directional Selection

One extreme of a distribution

Stabilizing Selection

Middle of distribution

Disruptive Selection

Both extremes of distribution

Phenotypic Plasticity

Same genotype has different phenotypes in different environments

Cooperative breeding is favored by what conditions

1. limited nesting sites or few high-quality breeding territory available.

2. Cooperation required for defense from predation or conspecific intruders.

3. Cooperation required for nest construction or food provisions.