Natural selection drives the link between male immune function and reproductive potential

2005 ◽  
Vol 83 (7) ◽  
pp. 1012-1014 ◽  
Author(s):  
Kenneth M Fedorka ◽  
Marlene Zuk ◽  
Timothy A Mousseau
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Reproductive Potential ◽  
Nuptial Gift ◽  
Honest Signal ◽  
Male Behavior ◽  
Nuptial Gifts ◽  
The Gift ◽  
Selection For ◽  
Allonemobius Socius

In the ground cricket Allonemobius socius (Scudder 1877), males provide females with a hemolymph-based nuptial gift. The size of the gift depends on when copulation is terminated, which can be controlled by either sex. Here we show that more immunocompetent males provide larger nuptial gifts, increasing their reproductive potential. To address if this pattern was the consequence of sexual selection for an honest signal (i.e., females assess mate immune quality through the hemolymph), we examined which sex controlled gift size. We found that the probability that males initiated the end of copulation increased when gift size was small (stereotypical of less immunocompetent males). Thus, early termination of copulation was the consequence of male behavior, suggesting that the association between immunocompetence and gift size was not due to sexual selection, but to natural selection for male vigor.

scholarly journals Natural and sexual selection act on different axes of variation in avian plumage color

2015 ◽  
Vol 1 (2) ◽  
pp. e1400155 ◽  
Author(s):  
Peter O. Dunn ◽  
Jessica K. Armenta ◽  
Linda A. Whittingham
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Habitat Type ◽  
Sexual Differences ◽  
Plumage Color ◽  
Evolutionary Transitions ◽  
Testes Size ◽  
Selection For ◽  
Bird Coloration ◽  
Natural And Sexual Selection

The bright colors of birds are often attributed to sexual selection on males, but in many species both sexes are colorful and it has been long debated whether sexual selection can also explain this variation. We show that most evolutionary transitions in color have been toward similar plumage in both sexes, and the color of both sexes (for example, bright or dull) was associated with indices of natural selection (for example, habitat type), whereas sexual differences in color were primarily associated with indices of sexual selection on males (for example, polygyny and large testes size). Debate about the evolution of bird coloration can be resolved by recognizing that both natural and sexual selection have been influential, but they have generally acted on two different axes: sexual selection on an axis of sexual differences and natural selection on both sexes for the type of color (for example, bright or dull).

A Shape to Die for?

2021 ◽  
pp. 481-510
Author(s):  
Graham Mitchell
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Surface Water ◽  
Alternative Hypothesis ◽  
Natural Habitat ◽  
Large Body ◽  
Male And Female ◽  
Large Size ◽  
Selection For ◽  
Competition For Resources

The product of natural selection over at least 15 million years is the elongated, slender shape of giraffes that fits the natural habitat giraffes now occupy. What selection pressures operated to produce their shape? Their shape is partly the product of gravity and could have been an accidental by-product of selection for a large body mass and the protection from predation that large size brings, but the prevailing explanation is that their shape confers a browsing advantage. Preferred browse is concentrated at a height easily reached by giraffes but not by other browsers and natural selection would have favored those giraffes that could reach it. An alternative hypothesis is that their shape confers thermoregulatory benefits in addition to improved vigilance. Another hypothesis is that a long neck evolved to counter long legs allowing giraffes to drink surface water. An attractive hypothesis is that their shape is a product of ‘runaway’ sexual selection by females for males with long heavy necks, but analysis of this hypothesis has shown that the morphology of male and female giraffe does not differ. Nevertheless, all these possibilities could have contributed. A consequence of selection for their shape is over-specialization: giraffes seem to be inextricably dependent on a narrow diet, a diet that is subject to the vagaries of climate and competition for resources. The greatest threat to their survival is, therefore, their shape.

scholarly journals Condition-dependent differences in male vibratory pre-copulatory and copulatory courtship in a nuptial gift-giving spider

2020 ◽  
Vol 74 (11) ◽  
Author(s):  
Monika J. B. Eberhard ◽  
Alexandra Machnis ◽  
Gabriele Uhl
Keyword(s):  
Mate Choice ◽  
Female Mate Choice ◽  
Vibrational Communication ◽  
Nuptial Gift ◽  
Gift Giving ◽  
Nuptial Gifts ◽  
Male Condition ◽  
Vibrational Signals ◽  
Copulatory Courtship ◽  
The Gift

Abstract Condition-dependent secondary sexual traits and signals are often crucial for mate choice decisions. Nuptial gifts, provided by the male to the female during mating, may represent an indicator of male condition, especially if production of the gift is energetically costly. Additionally, other signalling modalities may well play a role in mate choice in such systems. Females of the nursery web spider Pisaura mirabilis preferably mate with males that provide a prey item wrapped in silk. Apart from the nuptial gift, vibrational signals employed during courtship and mating may reveal additional information about male condition. We tested condition-dependence of male vibrational signals of well-fed versus starved males, when in contact with female dragline silk and during mating trials. Our results show that vibrational signals are produced in P. mirabilis, both during pre-copulatory courtship and during copulation. Male courtship signals were condition-dependent: males in good condition initiated signalling earlier and emitted more vibrational pulses than poor-condition males. They were also more likely to be accepted by the female for copulation. We additionally identified vibrational signals during copulation. These signals were different from pre-copulatory courtship vibrations but did not differ between the treatment groups. This study shows that vibrational communication plays an important role before and during copulation in P. mirabilis. It sets the stage for further experiments on spider biotremology associated with nuptial gift giving behaviour. Significance statement Male courtship behaviour can indicate a male’s condition and quality and be subject to female mate choice. Vibrational communication during mating plays a crucial role in many animal species. Spiders are known to be extremely sensitive towards vibrations, and there is evidence that vibratory signals are also used during courtship. Here, we study the nuptial gift-giving spider Pisaura mirabilis in which courtship entails providing a nuptial gift by the male to the female. The gift quality determines on the probability and duration of mating. We investigated the role of vibrational behaviour in this species by standardizing nuptial gifts. Our study demonstrates that vibratory signals comprise information about the male’s condition, that signals are also produced during mating and that courtship and copulatory signals are strikingly different. We suggest that vibrational communication provides important condition-dependent traits for female mate choice in addition to the nuptial gift.

scholarly journals Sperm storage mediated by cryptic female choice for nuptial gifts

2013 ◽  
Vol 280 (1772) ◽  
pp. 20131735 ◽  
Author(s):  
Maria J. Albo ◽  
Trine Bilde ◽  
Gabriele Uhl
Keyword(s):  
Hatching Success ◽  
Sperm Storage ◽  
Copulation Duration ◽  
Nuptial Gift ◽  
Gift Giving ◽  
Nuptial Gifts ◽  
Egg Hatching ◽  
Different Types ◽  
The Gift ◽  
Pisaura Mirabilis

Polyandrous females are expected to discriminate among males through postcopulatory cryptic mate choice. Yet, there is surprisingly little unequivocal evidence for female-mediated cryptic sperm choice. In species in which nuptial gifts facilitate mating, females may gain indirect benefits through preferential storage of sperm from gift-giving males if the gift signals male quality. We tested this hypothesis in the spider Pisaura mirabilis by quantifying the number of sperm stored in response to copulation with males with or without a nuptial gift, while experimentally controlling copulation duration. We further assessed the effect of gift presence and copulation duration on egg-hatching success in matings with uninterrupted copulations with gift-giving males. We show that females mated to gift-giving males stored more sperm and experienced 17% higher egg-hatching success, compared with those mated to no-gift males, despite matched copulation durations. Uninterrupted copulations resulted in both increased sperm storage and egg-hatching success. Our study confirms the prediction that the nuptial gift as a male signal is under positive sexual selection by females through cryptic sperm storage. In addition, the gift facilitates longer copulations and increased sperm transfer providing two different types of advantage to gift-giving in males.

Darwinian Evolutionary Theory

2018 ◽  
Author(s):  
Michael Ruse
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Middle Class ◽  
Evolutionary Theory ◽  
Scientific Community ◽  
Homo Sapiens ◽  
Origin Of Species ◽  
Theory Of Evolution ◽  
Descent Of Man

Charles Robert Darwin, the English naturalist, published On the Origin of Species in 1859 and the follow-up work The Descent of Man in 1871. In these works, he argued for his theory of evolution through natural selection, applying it to all organisms, living and dead, including our own species, Homo sapiens. Although controversial from the start, Darwin’s thinking was deeply embedded in the culture of his day, that of a middle-class Englishman. Evolution as such was an immediate success in scientific circles, but although the mechanism of selection had supporters in the scientific community (especially among those working with fast-breeding organisms), its real success was in the popular domain. Natural selection, and particularly the side mechanism of sexual selection, were known to all and popular themes in fiction and elsewhere.

Natural Selection of Reproductive Rates and Breeding Times and Its Effect on Sexual Selection

1972 ◽  
Vol 106 (949) ◽  
pp. 368-379 ◽  
Author(s):  
Peter O'Donald
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Reproductive Rates ◽  
Selection Of

scholarly journals Natural selection increases female fitness by reversing the exaggeration of a male sexually selected trait

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kensuke Okada ◽  
Masako Katsuki ◽  
Manmohan D. Sharma ◽  
Katsuya Kiyose ◽  
Tomokazu Seko ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Experimental Evolution ◽  
Genetic Correlations ◽  
Lifetime Reproductive Success ◽  
Fundamental Theory ◽  
Female Fitness ◽  
Male Trait ◽  
Flour Beetles ◽  
Male Specific

AbstractTheory shows how sexual selection can exaggerate male traits beyond naturally selected optima and also how natural selection can ultimately halt trait elaboration. Empirical evidence supports this theory, but to our knowledge, there have been no experimental evolution studies directly testing this logic, and little examination of possible associated effects on female fitness. Here we use experimental evolution of replicate populations of broad-horned flour beetles to test for effects of sex-specific predation on an exaggerated sexually selected male trait (the mandibles), while also testing for effects on female lifetime reproductive success. We find that populations subjected to male-specific predation evolve smaller sexually selected mandibles and this indirectly increases female fitness, seemingly through intersexual genetic correlations we document. Predation solely on females has no effects. Our findings support fundamental theory, but also reveal unforseen outcomes—the indirect effect on females—when natural selection targets sex-limited sexually selected characters.

scholarly journals Thermal Preferences of Cowpea Seed Beetles (Callosobruchus maculatus): Effects of Sex and Nuptial Gift Transfers

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 310
Author(s):  
Dariusz Krzysztof Małek ◽  
Marcin Czarnoleski
Keyword(s):  
Water Balance ◽  
Callosobruchus Maculatus ◽  
Thermal Environment ◽  
Nuptial Gift ◽  
Thermal Preference ◽  
Nuptial Gifts ◽  
Insect Performance ◽  
Evaporative Water ◽  
Thermal Preferences ◽  
Seed Beetles

The thermal environment influences insect performance, but the factors affecting insect thermal preferences are rarely studied. We studied Callosobruchus maculatus seed beetles and hypothesized that thermal preferences are influenced by water balance, with individuals with limited water reserves preferring cooler habitats to reduce evaporative water loss. Adult C. maculatus, in their flightless morph, do not consume food or water, but a copulating male provides a female with a nuptial gift of ejaculate containing nutrients and water. We hypothesized that gift recipients would prefer warmer habitats than gift donors and that both sexes would plastically adjust their thermal preferences according to the size of the transferred gift. We measured the thermal preference in each sex in individuals that were mated once or were unmated. In the mated group, we measured the sizes of the nuptial gifts and calculated proportional body mass changes in each mate during copulation. Supporting the role of water balance in thermal preference, females preferred warmer habitats than males. Nevertheless, thermal preferences in either sex were not affected by mating status or gift size. It is likely that high rates of mating and gift transfers in C. maculatus living under natural conditions promoted the evolution of constitutive sex-dependent thermal preferences.

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