Lecture 5

Question 1

How does the Biological Species Concept define a species?

Answer 1

species are groups of potentially interbreeding populations that are reproductively isolated from other such groups; applies well for sexually reproducing animals, but not so much for asexually reproducing organisms

Question 2

How does the Phylogenetic Species Concept define a species?

Answer 2

a species is the smallest possible group descending form a common ancestor and recognizable by unique, derived traits; useful for systematics because it focuses on phylogenetic history

Question 3

How does the General Lineage Species Concept define a population?

Answer 3

species are metapopulations that exchange allele frequency enough to comprise the same gene pool; a metapopulation is a group of spatially separated populations of the same species that interact at some level

Question 4

What is speciation?

Answer 4

the evolutionary process by which new species arise

Question 5

What is allopatric speciation?

Answer 5

speciation that occurs as a result of geographic isolation

Question 6

What is a prezygotic reproductive barrier?

Answer 6

barriers that prevent a zygote from forming

Question 7

What are the pre-mating prezygotic reproductive barriers?

Answer 7

1. timing of reproduction - i.e. spawning times occur at different times of day for different cnidarian species
2. pollinator isolation - i.e. some species of flowers only attract hummingbirds, while the other may only attract bees; therefore, there is no cross-pollination occurring
3. distinct courtship rituals - i.e. female blue footed boobies only respond to the specific mating dance performed by male blue footed boobies

Question 8

What are the post-mating prezygotic reproductive barriers?

Answer 8

1. copulatory behavioral isolation - mating between species causes damage to the female reproductive tract, resulting in eggs not being fertilized by deposited sperm
2. gametic incompatibility - sperm or pollen from one species fails to penetrate and fertilize the proteins on the exterior of an egg of another species

Question 9

What are postzygotic reproductive barriers?

Answer 9

fertilization can happen, but zygote may not fully develop; may result in the formation of hybrids, but they often have low fitness, meaning they will die young or be sterile
1. hybrid inviability
2. hybrid sterility
3. ecological inviability
4. behavioral sterility

Question 10

What is sympatric speciation?

Answer 10

reproductive isolation that evolves without geographic barriers (i.e. cichlids)