chapter 15

Question 1

what is coevolutionary arms race?

Answer 1

Coevolutionary arms race is when species interact antagonistically in a way that results in each species exerting reciprocal directional selection on the other. This process is neverending because as one species evolves to overcome the weapons of the other, in turn, selection acts to produce new weaponry for its opponent.

Question 2

coevolution

Answer 2

the process of reciprocal evolutionary change between interacting species driven by natural selection

Question 3

reciprocal selection

Answer 3

selection that occurs in 2 species, due to their interactions with one another. Reciprocal selection is a critical prerequisite of coevolution

Question 4

geographic mosaic theory of coevolution

Answer 4

a theory that proposes that the geographic structure of populations is central to the dynamics of coevolution. The direction and intensity of coevolution varies from population to population, and coevolved genes from these populations mix together as a result of gene flow

Question 5

diversifying coevolution

Answer 5

an increase in genetic diversity caused by the heterogeneity of coevolutionary processes across the range of ecological partners (significant differences between populations)

Question 6

retrovirus

Answer 6

an RNA virus that uses an enzyme called reverse transcriptase to become part of the host cell’s DNA. The virus that causes aids, HIV, is a type of retrovirus

Question 7

antagonists

Answer 7

generate negative frequency dependent selection on each other. For example, as the genotype of parasites multiplies, the fitness of the common host decreases so rare host genotypes have a higher fitness than the common one because they will suffer less from the parasites. Another example is the newts ability to produce TTX, so resistance to TTX evolved in the garter snakes. As the resistance in garter snakes increases, the newts evolve to produce even more TTX

Question 8

mutualists

Answer 8

relationships occur when the alleles are favored for selection benefit rather than harm. The most rapid coevolution occurs when the species participate in intimate pairwise interactions with one other species leading to positive frequency dependent selection. An example is the long tongue fly eating the flower nectar and collecting the pollen from the flower to pass it to the next flower. The length of the flies’ tongues evolve along with the depth of the flowers’ tubes they are feeding on.

Question 9

endosymbionts

Answer 9

1. are mutualistic organisms that live within the body or cells of another organism. Examples include microbes in the digestive systems in mammals that help to digest tough plant materials. Another example is the mitochondria of eukaryotic cells.

Question 10

batesian mimicry

Answer 10

Batesian mimicry occurs when a harmless species resembles a harmful or distasteful species, deriving protection from predators. Coevolutionary relationship for model is mostly neutral and sometimes negative, always positive for the mimic and negative for the predator.

Question 11

mullerian mimicry

Answer 11

1. Mullerian mimicry occurs when several harmful or distasteful species resemble each other in appearance, facilitates the learned avoidance or predators. Coevolutionary relatinships for the model and mimic are always positive and negative for the predator.

Question 12

how can coevolution act as an engine for biodiversity

Answer 12

1. Coevolution results in a wide range of ecological outcomes and traits that can sometimes vary among populations as a geographic mosaic. As species coevolve, it can drive speciation and leave its mark on macroevolution by altering rates of diversification.