Bio 112 Final Exam

What is the evidence that species change through time?

1. Fossil records and geological time.

2. Extinction

3. Transitional features

4. Vestigial traits.

How does the fossil record support that species change over time?

We can see the layers that form in sedimentary rocks, which take a long time to form, this shows that earth must be old.

How does extinction support that species change over time?

Most species to live have become extinct. Large distinct species show that extinction must occur meaning species are dynamic. Example: Irish elk.

How does transitional features support that species change over time?

The law of succession shows that fossils in certain areas resemble those in others, this shows that traits change over time.

How do vestigial traits support that species change over time?

They are traits that have been last over time, proving that species change.

What is the evidence that species are related by common ancestry?

1. Biogeography

2. Homology

3. Internal consistency

How does biogeography support that species are related by common ancestry?

Similar species that are still distinct are often found in similar areas. Example: Galapagos mockingbirds

How does homology support that species are related by common ancestry?

Because there is similarity in DNA sequences (genetic homolog), traits are seen in the embryos of different species (developmental homology), there are similarities in adult morphology (structural homology).

How does internal consistency support that all species develop from the same common ancestry?

There is evidence that all animals are just modified forms of each other. Example: Whales evolved from a terrestrial ancestor.

What are some common misconceptions about evolution?

Evolutionary changes occur in individuals, evolution is goal directs moving from lower to higher organisms, and evolution perfects organisms.

What are the four evolutionary mechanisms?

Natural selection, genetic drift, gene flow, and mutation.

What is natural selection?

When certain alleles are favoured while others are disfavoured. It causes genetic variation to either maintain, increase or decrease. Increases fitness.

What is genetic drift?

Random changes in allele frequencies. Reduces genetic variation. Is random for fitness, but usually decreases.

What is gene flow?

Movement of alleles between populations. Increases genetic variation by introducing new alleles or decreases by removing alleles. Random for change in fitness.

What is mutation?

Random production of new alleles. Increases genetic variation. Random for fitness, most lower fitness.

What is directional selection?

When one extreme is favours and the average shifts in one direction. Variation decreases. Ex. Soap bugs and ground finches.

What is stabilizing selection?

Maintains average and loses extremes. Genetic variation is reduced. ex. birthweight in babies.

What is disruptive selection?

When both extremes are favoured and average decreases. Increases genetic variation. Ex. fish gill rakers.

What is balancing selection?

There is no favoured phenotype. variation is maintained. ex. guppies and snails.

What is inbreeding?

Mating between relatives. Increases homozygosity and decreases heterozygosity. mean trait varies, genetic variation decreases.

What is assortative mating?