Question 1

Which of the following best describes how organismal traits influence relative fitness in the context of natural and sexual selection?

Accepted Answer

Traits influence both survival and fecundity through natural selection, and mating and fertilization through sexual selection.

Question 2

In the process of speciation, which step is most directly associated with the evolution of reproductive isolation?

Accepted Answer

Reproductive isolation.

Question 3

According to Haldane’s rule, which sex is most likely to be infertile in hybrid offspring between two sister species of mammals?

Accepted Answer

The heterogametic sex (XY males).

Question 4

Which of the following is a plausible explanation for why male sterility is more common in Drosophila hybrids, according to the 'faster male' theory?

Accepted Answer

Genes related to spermatogenesis evolve quickly and interact poorly in hybrids.

Question 5

Which of the following best describes adaptive radiation in cichlid fish?

Accepted Answer

Adaptive radiation involves adaptation to empty niches, morphological radiation due to key innovations, and diversification of male color patterns.

Question 6

What is the primary function of prezygotic barriers in speciation?

Accepted Answer

They reduce the transfer of gametes between species, preventing mating or fertilization.

Question 7

Which scenario best illustrates ecological speciation?

Accepted Answer

Barriers to gene flow evolve between populations as a result of ecologically based divergent selection between environments.

Question 8

In the Bateson-Dobzhansky-Muller (BDM) model, what is the main cause of extrinsic inviability in hybrids?

Accepted Answer

Genes from one population perform worse in the other due to local adaptation.

Question 9

Which equation best represents the relationship between fitness and beak size in a population exploiting two resources, as shown in the first image?

Accepted Answer

Fitness is maximized at two distinct beak sizes corresponding to two resources: $$f(x) = a_1$ e$$^{-((x - m_1)^2)/2\sigma_1^2}$$ + a_2$ e$$^{-((x - m_2)^2)/2\sigma_2^2}$$

Question 10

Which of the following is a real-world example of premating, prezygotic isolation?

Accepted Answer

Two bird species breed at different times of the year, preventing interbreeding.

Question 11

In stickleback fish, what is the main driver of body size divergence between benthic and limnetic forms?

Accepted Answer

Natural selection for resource specialization in different habitats.

Question 12

Which of the following best explains the role of female choice in promoting speciation?

Accepted Answer

Female choice can drive divergence in mating traits, leading to reproductive isolation.

Question 13

Which of the following is a plausible outcome of reinforcement in a hybrid zone?

Accepted Answer

Prezygotic isolation evolves more rapidly in sympatry, reducing hybridization.

Question 14

Which factor is most likely to explain why adaptive radiation occurs in some lineages but not others?

Accepted Answer

Both extrinsic environmental factors and intrinsic lineage-specific traits interact to influence diversification.

Question 15

Which of the following equations best describes the probability of spawning in stickleback males as shown in the Paxton Lake graph?

Accepted Answer

Probability is higher for benthic males with benthic females and for limnetic males with limnetic females: $$P_{spawn} = f_{match}(species)$$

Question 16

Which of the following best describes the process of ecological speciation in crossbills?

Accepted Answer

Speciation is driven by divergent selection on trophic morphology and mating signals in different environments.

Question 17

Which of the following is a plausible mechanism for male mate choice contributing to reproductive isolation?

Accepted Answer

Males prefer females of their own population, reducing gene flow between populations.

Question 18

Which of the following best describes the relationship between sexual selection and signal evolution during speciation in birds?

Accepted Answer

Sexual selection accelerates signal evolution, leading to greater phenotypic divergence between species.

Question 19

Which of the following is a real-world example of postmating, prezygotic isolation?

Accepted Answer

Copulation occurs, but no transfer of male gametes due to physical incompatibilities.

Lec 39s

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