BMEN 515 Lecture Notes - Sexual Selection, Mate Choice, Limiting Factor

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amberkangaroo332

26 Feb 2013

School

University of Calgary

Department

Biomedical Engineering

Course

BMEN 515

Professor

William Huddleston

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Document Summary

There is a great variety of species in which male reproductive success is limited by opportunities to mate but in which males are unable to monopolize either females themselves or any resource vital to females. When males cannot monopolize access to females, they often compete by advertising for mates: basically when they can"t own them, they got to buy them. Read example on female red-collared widow birds on pg. 416-417: females find males with long tails sexy. Read example on gray tree frogs and their mating calls on pg. 417-419: female gray tree frogs prefer males with longer calls than males with shorter calls. Choosy females may get better genes for their offspring. The displays given by males are indicators of genetic quality. Five aspects of offspring performance related to fitness: larval growth rate faster is better, time to metamorphosis shorter is better, mass at metamorphosis bigger is better, larval survival, post-metamorphic growth faster is better.

Related Questions

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A crucial assumption underlying most models of sexual selection is that sexual advertisements honestly reflect the phenotypic and/or genetic quality of their bearers (1). Here we show that experimental activation of the immune system is rapidly mirrored in the expression of a carotenoid-based secondary sexual trait in male blackbirds (Turdus merula). This result shows that sexual advertisement honestly signals male health and can be reliably used by conspecifics as a cue of individual quality during intra- and/or intersexual interactions. Male blackbirds exhibit a black plumage with a yellow to orange bill, whereas females are brownish with a brown bill. Recent studies have suggested that bill color is a sexually selected trait in blackbirds (2, 3). For example, resident male blackbirds are more aggressive to mounts with orange bills than to mounts with yellow bills (2). Bill pigmentation might therefore provide a signal used during contests between males (2). In addition, male blackbirds with orange bills are mated with females in better body condition and fledge more offspring than males with yellow bills (3). Overall, these results suggest a role for bill color in sexual selection, possibly as an indicator of male phenotypic quality. Carotenoids are common components of colored signals used in animal communication (4). They are also important in the up-regulation of various aspects of the immune functioning (5) and cellular protection against free radicals (6). This suggests that a trade-off may exist between allocation of carotenoids to sexual signaling versus immune defenses (4). Using an autosampler high-performance liquid chromatographer, we determined the presence of carotenoids deposited in the bill of male blackbirds [see note (S1)] (7). The analysis of the absorption spectrum revealed the presence of - and -carotene, -cryptoxanthin, zeaxanthin, and lutein (Fig. 1A). To investigate whether bill color reflects immune status, we immunized captive male blackbirds with a suspension of sheep red blood cells (SRBC) in both spring 1999 (n 19) and spring 2002 (n 13). A control group (n 15) was injected with a phosphate-buffered saline solution (PBS) for control in 2002. Only the 2002 birds were used as a direct test of the hypothesis that immune activation reduces the expression of the secondary sexual trait, by comparing changes in bill color for SRBC and PBS males. Birds immunized with SRBC in both years (n 32) were used to assess the effect of anti-SRBC immune response on bill color [see note (S2)] (7). The humoral immune response against SRBC was determined 7 days after the challenge with a haemagglutination technique. Birds immunized with SRBC displayed a significant decrease in bill color [repeated measurements analysis of variance, F(1,26) 14.34, P 0.0008; Fig. 1, B, C, and D], which was independent of initial bill color and was not associated with a decrease in body mass (P 0.1). In addition, among immunized males, the likelihood of becoming duller was significantly correlated with the intensity of the anti-SRBC response as determined from the haemagglutination test (logistic regression, Wald 2 5.12, P 0.023, n 32), whereas neither year nor initial bill color entered the logistic regression model (P 0.1). Overall, these results demonstrate the existence of a trade-off between sexual advertisement and immune activation in male blackbirds. This finding has important consequences for both the evolution of secondary sexual traits and the cost of immune function. Assessment of opponent quality during male-male competition or mate quality during female choice based on a dynamic trait, such as bill color, might have evolved if it honestly reflects health status of the individual (1). The activation of the immune system by an infectious process is rapidly mirrored in the color of the bill. Contrary to feather ornaments that are produced during the annual molt, dynamic traits might therefore convey a continual update on male health. Carotenoids, such as astaxanthin, lutein, and -carotene, used for sexual signaling have been shown to enhance in vitro and in vivo antibody production to SRBC (8) and to provide protection against free radicals (6). Our results suggest that the activation of the immune system withdraws carotenoids to enhance immune functioning as well as to deal with free radicals produced during the immune response, at the expense of sexual signaling.

aquamarinewallaby935

The male elephant seal (l) is much larger than the female (r) of the species. Males spend very little time raising their young. You would correctly predict that the maleâs size is due primarily to _________ and that he is ___________in his mating habits.

a) natural selection; monogamous

b) sexual selection; polygamous

c) natural selection; polygamous

d) sexual selection; monogamous

The Good Genes Hypothesis would account for which of the following characteristics of males that attract the most females?

a) Peacock tails, which prevent males from seeing behind them when they court

b) Sailfin molly, a dorsal-finned fish, which are enormous and easily spotted by predators

c) Guppy tailfins, which reduce their swimming speed.

d) Gray tree frogs, that call the longest and produce offspring that mature quickest

e) Fish that produce bright colors, yet have very weak immune systems.

In mice, a recessive autosomal allele (o) results in obesity because the mice are unable to produce the hormone leptin from their fat cells.Normal mice with the dominant allele (O) do produce leptin. Homozygous recessive (oo) obese mice injected with leptin are observed to lose weight.

In a cross between two mice that are heterozygous for the obesity gene (Oo), you would predict which one of the following?

a) All the offspring will be obese.

b) All the offspring will be normal.

c) 50% of offspring will be able to produce leptin.

d) Obese offspring would eat less and burn more calories if injected with leptin.

e) Fat cells in obese mice release more leptin than those of their normal parents.

A scientist discovers a new mutant mouse that he calls âChunkyâ because they are 80% heavier than normal mice. Which one or more of the following predictions would be correct?

a) Chunky mice could have the âddâ genotype.

b) Normal mice produce more thyroxin (thyroid hormone) than Chunky mice.

c) Glycolysis would occur more rapidly in Chunky mice than normal mice.

d) A protein that blocks leptin receptors would promote weight loss in all Chunky mice.

e) Both (a) & (b) are correct.

When she was 6 months old, your cat was surgically altered so that they could not reproduce. This required a small incision into the catâs abdomen to remove the ovaries. This incision healed by a type of cell division called ______.

a) endocytosis b) meiosis c) mitosis d) exocytosis e) fusion

sapphirehound48

Random, chance events that change allele frequencies are knownas:

A. Gene flow

B. Genetic drift

C. Natural selection

D. Balancing selection

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Question 21 pts

What type of selection acts to maintain the two extremephenotypic variants in a population?

A. Disruptive selection

B. Directional selection

C. Positive selection

D. Artificial selection

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Question 31 pts

Approximately, how much of our DNA is shared with our closestrelatives, chimpanzees?

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Question 41 pts

The large canines of male baboons are likely the result of________, while the fact that some male baboons are very colorfulis probably the result of _______.

A. Mutation; balancing selection

B. Gene flow; sexual dimorphism

C. Male competition; female choice

D. Mate choice; genetic drift

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Question 51 pts

Negative assortative mating results in an increased frequency ofhomozygous genotypes within a population.

True

False

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Question 61 pts

Genetic evidence suggests that humans and Neandertals neverinterbred.

True

False

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Question 71 pts

The specific variant of the FOXP2 gene associated with languageacquisition in humans is found in both humans and Neandertals.

True

False

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Question 81 pts

Industrial melanism describes the change in moth color from paleto dark after pollution from factories resulted in coating treetrunks with a layer of dark soot. Which statement is trueconcerning industrial melanism?

A. After pollution levels increased, all moths became darkercolored because soot got on their wings

B. The dark moths survived better after pollution levelsincreased because they were not poisoned by the pollutants

C. Individual moths changed their color in response to thepollution

D. Dark moths were present in the population before pollutionlevels increased

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Question 91 pts

Patterns of evolution can be seen above the species level

True

False

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Question 101 pts

Inbreeding is problematic because it increases the probabilitythat offspring inherit two copies of a recessive mutation thatcauses disease.