Chapter 8: Mating Systems, Sexual Selection, and Chromosomal Genetics

Flashcards covering mating systems, female choice hypotheses, sexual selection dynamics, karyotypes, and chromosomal genetics.

How do female robberflies utilize food gifts during mating?

The female accepts prey from a male and mates with him while feeding; once she finishes eating, she kicks him off and seeks another partner.

What deceptive mating strategy is practiced by approximately $10\%$ of male robberflies?

They fluff up saliva to form an empty saliva ball and mate with the female while she attempts to consume it.

Under what primary condition is monogamy typically observed across animal species, especially in birds?

Monogamy is most common when males actively contribute to raising offspring through feeding or protection.

Why is monogamy the only viable reproductive strategy for emperor penguins?

The male's brood pouch can only accommodate a single egg, requiring parents to trade off caring for the egg and foraging at sea for months at a time.

What behavior do male wolves exhibit toward an ovulating alpha female to prevent extra-pair copulation?

Mate guarding, where the male mates with her multiple times a day and continuously prevents other males from approaching.

What anatomical structures located on the head does a male black widow spider use for mating?

Two aedeagi (structures analogous to penises).

What occurs when a male black widow spider inserts both of his aedeagi during copulation?

Both aedeagi break off inside the female, ending his ability to mate; he then performs a cartwheel to place his abdomen in front of her mouth to be eaten, providing energy for her eggs.

Why do females generally exercise mate choice rather than males?

Females have a significantly larger biological investment (energy-dense eggs, prolonged gestation, and nursing) compared to inexpensive sperm.

How do seahorses diverge from the typical pattern of male versus female parental investment?

The female deposits her eggs into a pouch on the male's belly, and the male carries the developing eggs and gives birth.

What are the three main hypotheses proposed to explain female mate choice?

The good genes hypothesis, the good health hypothesis, and the handicap hypothesis.

How does the resplendent quetzal serve as an example of the handicap hypothesis?

Its bright coloration and extremely long tail make it slow in flight and conspicuous to predators, proving that surviving with such a physical handicap signals superior genes and health.

In the "T-shirt study," what biological factor was associated with a female rating a male's scent as attractive?

A high degree of difference in immune system genes between the male and the female.

In a sexual selection positive feedback loop, what distinct traits do sons and daughters inherit from a female choosing exaggerated male ornaments?

Sons inherit the exaggerated physical trait (such as larger antlers or longer tails), while daughters inherit the preference for that exaggerated trait.

What is a karyotype?

An organized visual display of an individual's chromosomes arranged in order of size from largest to smallest.

What is the genetic term for different versions or forms of the same gene?

An allele.

What specific region on the Y chromosome contains the genes responsible for triggering male development via testosterone production?

The SRY region.

Which human chromosome is the largest and contains the highest amount of genetic information?

Chromosome $1$.

What chromosomal abnormality causes Down syndrome?

Trisomy $21$, the presence of three copies of chromosome $21$.

What is a Barr body?

An inactivated X chromosome in female cells that has been condensed and permanently turned off.

What physical trait is commonly noted in males possessing an XYY chromosomal arrangement?

They tend to be taller than average while appearing and functioning normally.