Exam 9: Reproductive Strategies

In genetic sex determination, if a genotype of XX is female and XY is male, what will be the natural percentage of female offspring?

Which statement best describes the cost of meiosis?

In honeybees, drones arise from _____ eggs, and workers arise from _____ eggs.

Infanticide by a new dominant male lion confers which primary benefit to the dominant male?

Scientists have found that offspring of male tree frogs with long calls spend more time feeding and grow faster than offspring of male tree frogs with short calls. This supports

Evolution favours hermaphrodism when fitness of the hermaphrodite is _____ fitness of the _____.

In some perfect flowers, the receptiveness of the stigma is delayed until after its anthers have released pollen. This delay prevents

When researchers studied sex ratios in red deer (Cervus elaphus), they found that yearling females selectively aborted male offspring because

When researchers experimentally altered tail lengths of male widow birds (Euplectes progne), they found that females chose males with longer tails even when tail length did not correlate with any tangible benefit to a male's ability to defend territory. What are two possible reasons that females prefer longer tails?

Organisms can avoid self-fertilization by

An animal begins its life as a female. Later the dominant male dies and the female changes sex to become male. This is an example of

Spermatophores are often involved in

In ring-necked pheasants (Phasianus colchicus), long spurs on the lower legs of males are genetically linked to a gene that influences the bird's susceptibility to disease. This is called

Which of the following is a primary sexual characteristic?

Which statement best describes the Red Queen hypothesis?

Females of American crocodiles (Crocodylus acutus) produce on average 50 eggs. Consider one population composed of 13 females and 7 males and another population composed of 9 females and 11 males. Use the number of gene copies for females and males to determine the female and male fitness of each population. Predict what will happen over time to the sex ratio of each population.

What is the most common factor in environmental sex determination?

Which of the following is NOT a genetic mechanism for sex determination?

Topics: Sex ratios of offspring are typically balanced, but they can be modified by natural selection; mating systems describe the pattern of mating between males and females. You discover a new species of wasp with females that lay their eggs inside tree branches. Although the tree material is not a good source of nutrients, the offspring are well protected and are seldom consumed by predators. After the eggs hatch, only the females possess the mouthparts needed to chew through the wood and escape. All of the males die in the nest. However, because the wasps cannot digest and obtain nutrients from the wood, the young females must obtain the strength necessary for eating their way out of the branch by ingesting spermatophores (small packets containing sperm and nutrients) that each male releases in the nest. These spermatophores also fertilize the females. Once a male releases his spermatophore, he dies. Although the spermatophores contain nutrients, the likelihood that a female will escape the nest is highly positively correlated with the number of spermatophores that she ingests. In this wasp species, would you predict a sex ratio bias? Explain why or why not. Would this mating system be classified as promiscuity, polygyny, polyandry, or monogamy?

The evolution of physical traits of males to attract females or to compete with other males to mate with females is known as