Chapter 9 Worksheet, Rubenstein & Alcock PDF

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Chapter 9 worksheet questions and answers for BIO 371 with Dr. Burk....

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BIO/EVS 371. Animal Behavior. Fall 2020.

Name: Kathleen Bracken

Worksheet for Chapter Nine of Rubenstein & Alcock. (15 points possible.) Answers are worth one point each unless otherwise indicated. 1.) How does variance in reproductive success compare between male and female Satin Bowerbirds? Female Satin Bowerbirds are much choosier with mates than males are. Males display very elaborate courtship rituals, such as decorating their bowers with blue objects, and performing a series of movements and sounds. Females simply browse several males’ bowers, not even mating with them until after the first round of visitations. After courting with the male, she flies away and raises the offspring on her own, the male to never see the offspring or her again.

2.)

What does your book call "The Fundamental Asymmetry of Sex"?

The “Fundamental Asymmetry of Sex” argues that eggs are expensive, but sperm are cheap. In sexual species, eggs are larger than sperm, which are usually just big enough to contain the male’s DNA and enough energy to fuel the journey to an egg.

3.)

As used by Robert Trivers, define "Parental Investment".

Parental investment is the parental game of weighing the costs and benefits of caring for young that is dominated by expenditures of time and energy and risks taken by a parent to help existing offspring at the expense of reducing future reproductive opportunities.

4.)

What is the "Operational Sex Ratio"?

The “Operational Sex Ratio” is the ratio of sexually active males to sexually receptive females.

5.)

Give two examples of species with "Sex Role Reversal".

One example of a species with “Sex Role Reversal” is the long-tailed dancy fly (Rhamphomyia longicauda). Another species with “Sex Role Reversal” is the pipefish ( Syngnathus typhle).

6.)

Under what circumstance does sexual dimorphism in body size evolve?

Sexual dimorphism in body size evolves when intrasexual selection on male body size is strong.

7.)

(2 points). Explain the difference between "Conditional Mating Tactics" and "Alternative Mating Strategies".

2 “Conditional Mating Tactics” are phenotypes that are the result of a single genetically based program or strategy. Individuals that are unlikely to be successful competing against others of their own sex for a mate adopt alternative tactics that allow them to gain some reduced level of reproductive success (which is better than none at all). “Alternative Mating Strategies” are behavioral polymorphisms that have a strong genetic component and are therefore inflexible and fixed throughout an individual’s life.

8.) What are the three alternative mating tactics (conditional tactics) of Panorpa scorpionflies? One alternative mating tactic of Panorpa scorpionflies is that they aggressively defend dead insects, which is a food resource highly attractive to receptive females. A second alternative mating tactic is secreting saliva on leaves and waiting for females to come and consume the nutritional gift. The third alternative mating tactic is grabbing the female and forcing them to copulate.

9.)

What form does sperm competition take in the Black-winged damselfly?

In the Black-winged damselfly, males try to physically remove rival gametes from their mate’s body before transferring their own.

10.) What "direct benefit resource" is provided to females by male red-backed spiders? The direct benefit resource provided to females by male red-backed spiders is that the male sacrifices himself to be eaten by the female after copulation. After the male is done transferring sperm into both of the female spider’s sperm receptacles, the male performs a somersault and throws his body into the female’s jaws. About 2/3rds of the time she is accepts and consumes the male.

11.) (2 points) What is the "Hamilton/Zuk Hypothesis" with regard to mate choice? Of the three general models of mate choice, which would the Hamilton/Zuk model exemplify? The “Hamilton/Zuk Hypothesis” says that the expression of particular male traits is associated with resistance to parasites or other pathogens. Researchers argued that, due to the physiological stress caused by infections, brightly colored feathers are difficult to produce and maintain when a bird is parasitized. Hamilton and Zuk found that the predicted correlation between plumage brightness and the incidence of blood parasites in a large sample of bird species, supporting the view that males at special risk of parasitic infection engage in a competition that signals their condition to choosy females. Of the three general models of mate choice, the Hamilton/Zuk model would exemplify the good genes model.

12.) (2 points) Explain the difference between the "Runaway Model" and the "Chase-Away Model" of sexual selection.

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The “Runaway Model” of sexual selection says that when female mating preferences for certain male attributes create a positive feedback loop favoring both males with these attributes and females that prefer them. Female choice creates a genetic link between mate choice by females and the male trait and, because of this correlation, leads to the coevolution of preferences for more and more extreme traits over time. The “Chase-Away Model” of sexual selection says an antagonistic coevolutionary relationship between males and females in which some male traits that attract females may actually be disadvantageous to the female. A male might be able to induce a female mate with him even though he might not be able to provide the genetic or material benefits offered by other males of his species....