Biology Unit 9 - Evolution and the Basis of Life

What is evolution?

The cumulative change in heritable characteristics of a population across successive generations

What is a gene pool?

The different alleles that are in a population

What is a population?

A group of individuals from the same species

What is a species?

a group of organisms that can breed with each other

What are differential selective pressures?

Things that can effect the frequency of alleles in a gene pool (like natural selection)

What were 4 observations that Darwin gained from the finches?

1. variation of alleles within a species
2. Traits are inherited
3. There are more offspring than the environment can support
4. Many offspring do not survive

What is homology?

Similarity due to shared ancestry between two animals with similar structures or DNA

What is analogy?

Showing similar function but not because of shared ancestry and are not anatomically the same structure

What is a phylogenetic tree?

The way that we organize evolutionary history

What is biogeogrophy?

Animals retain the same DNA or physical structures due to current or pa**st** geographic location.

What is natural selection?

the change in the composition of the gene pool due to differentially selective environmental pressures

What is relative fitness?

The average number of offspring produced by individuals with one genotype or phenotype compared to the average number of offspring produced by individuals with another geno/phenotype

What is an adaptation?

A trait that is the result of natural selection

What is genetic drift?

The change in the gene pool NOT due to relative fitness

What is p + q = 1 used for

It is used for allele frequency: how much one trait is shown over the other in a population

What is p^2 + 2pq +q^2 used for?

It is used for genotype frequency: how often each genotype happens throughout the population

What is speciation?

When a new species emerges and their breeding becomes isolated

What is the biological species concept?

Animals that have physically/could theoretically interbreed in nature: for example, crows in US vs. UK are still the same species but they don’t fly across the ocean and interbreed, but they are still counted as the same species.

What are the 5 assumptions necessary for the Hardy Weinberg Equation?

No natural selection, no mutation, random mating, infinite population size, no migration

Why can no population meet the 5 assupmtions?

All of those things are a part of nature and are always happening

What is stabilizing selection?

When natural selection favors intermediate traits, and extremes are removed

What is directional selection?

Extreme is favored and population shifts towards one extreme or another

What is disruptive selection?

Extremes favored and intermediate is removed

What is a prezygotic isolation barrier?

It is possible that they could breed, but they don’t/can’t because of a physical barrier.

Examples of prezygotic isolation barriers

Temporal - time based (different breeding seasons), Geographic, Behavioral, Mechanical

What is a postzygotic isolation barrier?

Species made a baby, but it cannot reproduce or cannot survive

What are the two types of speciation?

Allopatric and Sympatric

What is allopatric speciation

When there is a geographic barrier (no access to reproduction)

What is sympatric speciation?

When there is a reproductive barrier (chromosomal error/mutation). This is when they are in the same location

What is genetic variation?

Differences in DNA sequences in a population, or the amount of alleles to choose from in a gene pool.

How does sexual reproduction effect genetic variation?

It creates genetic variation because of independent assortment and choosing a mate