The sicker sex Zuk, Marlene
PLOS pathogens,
01/2009, Letnik:
5, Številka:
1
Journal Article
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Female reproductive success is limited by the number of offspring a female can produce and rear. Because they are the sex that supplies the nutrient-rich egg, and often the sex that cares for the ...young, females will usually leave the most genes in the next generation by having the highest quality young they can; the upper limit to the quantity is usually rather low. The underlying assumption is that organisms have a finite pool of energy or resources to draw from, and therefore must allocate that energy to different tasks. Because the resources used for one function are unavailable to another, trade-offs between traits such as growth rate and body size, or between the size and number of offspring, are expected.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Female choice can drive the evolution of extravagant male traits. In invertebrates, the influence of prior social experience on female choice has only recently been considered. To better understand ...the evolutionary implications of experience-mediated plasticity in female choice, we investigated the effect of acoustic experience during rearing on female responsiveness to male song in the field cricket Teleogryllus oceanicus. Acoustic experience has unique biological relevance in this species: a morphological mutation has rendered over 90 per cent of males on the Hawaiian island of Kauai silent in fewer than 20 generations, impeding females' abilities to locate potential mates. Females reared in silent conditions mimicking Kauai were less discriminating of male calling song and more responsive to playbacks, compared with females that experienced song during rearing. Our results to our knowledge, are the first demonstration of long-term effects of acoustic experience in an arthropod, and suggest that female T. oceanicus may be able to compensate for the reduced availability of long-range male sexual signals by increasing their responsiveness to the few remaining signallers. Understanding the adaptive significance of experience-mediated plasticity in female choice provides insight into processes that facilitate rapid evolutionary change and shape sexual selection pressure in natural populations.
Developmental plasticity allows juvenile animals to assess environmental cues and adaptively shape behavioral and morphological traits to maximize fitness in their adult environment
1. Sexual ...signals are particularly conspicuous cues, making them likely candidates for mediating such responses. Plasticity in male reproductive traits is a common phenomenon, but empirical evidence for signal-mediated plasticity in males is lacking. We tested whether experience of acoustic sexual signals during juvenile stages influences the development of three adult traits in the continuously breeding field cricket
Teleogryllus oceanicus: male mating tactics, reproductive investment, and condition. All three traits were affected by juvenile acoustic experience. Males of this species produce a long-range calling song to attract receptive females, but they can also behave as satellites by parasitizing other males' calls
2. Males reared in an environment mimicking a population with many calling males were less likely to exhibit satellite behavior, invested more in reproductive tissues, and attained higher condition than males reared in a silent environment. These results contrast with other studies
3 and demonstrate how the effects of juvenile social experience on adult male morphology, reproductive investment, and behavior may subsequently influence sexual selection and phenotypic evolution.
► Sexual signals provide information about the social environment to developing animals ► Juvenile male field crickets use those signals to shape adult reproductive traits ► Acoustic experience decreases the likelihood of adopting satellite mating tactics ► However, acoustic experience increases condition and investment in reproductive tissues
Sexual signals are often critical for mate attraction and reproduction, although their conspicuousness exposes them to parasites and predators. We document the near-disappearance of song, the sexual ...signal of crickets, and its replacement with a novel silent morph, in a population subject to strong natural selection by a deadly acoustically orienting parasitoid fly. On the Hawaiian Island of Kauai, more than 90% of male field crickets (Teleogryllus oceanicus) shifted in less than 20 generations from a normal-wing morphology to a mutated wing that renders males unable to call (flatwing). Flatwing morphology protects male crickets from the parasitoid, which uses song to find hosts, but poses obstacles for mate attraction, since females also use the males' song to locate mates. Field experiments support the hypothesis that flatwings overcome the difficulty of attracting females without song by acting as 'satellites' to the few remaining callers, showing enhanced phonotaxis to the calling song that increases female encounter rate. Thus, variation in behaviour facilitated establishment of an otherwise maladaptive morphological mutation.
Dry conditions liberate female toads to drive sexual selection of male mates
If there is one thing that biologists used to agree on, it was that mating between two animals of different species yields ...unfavorable results. (Plants have a dodgy reputation for insouciant polyploidy and hence have often been ignored.) Basic biology classes teach that different species usually cannot interbreed successfully and that rarely produced crossbred offspring (hybrids) are often infertile or of lower fitness. Now, on page 1377 of this issue, Chen and Pfennig (
1
) contradict conventional wisdom about the disadvantages of hybridization and provide a connection between species diversification, sexual selection, and, ultimately, the context dependence of behavioral evolution.
Exploitation of sexual signals by predators or parasites increases costs to signalers, creating opportunities for establishment of alternative reproductive tactics (ARTs). In field crickets, males ...calling may attract acoustically orienting parasitoid flies. Alternatively, males behaving as satellites forgo calling and attempt to intercept females attracted to callers. We modeled the contribution of calling versus satellite behavior to male reproductive success in the larger context of variation in ecology (parasitism rate, background mortality), demography (density, sex ratio), and female behavior (phonotaxis, mating choosiness). Male mating success was most influenced by number of females (standardized effect size 0.42), followed by female choosiness (0.33), background mortality (−0.31), number of males (−0.28), and parasitism rate (−0.21). The smallest effects were phonotaxis (0.10) and satellite behavior (−0.09). Although satellite behavior ameliorated negative effects of parasitism, its comparative effect was slight. ARTs seem most likely to evolve and persist when a single selection pressure on signaling is particularly strong.
Plasticity in female mate choice can fundamentally alter selection on male ornaments, but surprisingly few studies have examined the role of social learning in shaping female mating decisions in ...invertebrates. We used the field cricket Teleogryllus oceanicus to show that females retain information about the attractiveness of available males based on previous social experience, compare that information with incoming signals and then dramatically reverse their preferences to produce final, predictable, mating decisions. Male ornament evolution in the wild may depend much more on the social environment and behavioural flexibility through learning than was previously thought for non-social invertebrates. The predictive power of these results points to a pressing need for theoretical models of sexual selection that incorporate effects of social experience.
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