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Patrick Gautier Kurtulus Olgun Nazan Uzum Claude Miaud 《Behavioral ecology and sociobiology》2006,59(6):836-841
Gregarious behaviour (i.e. living in groups in contrast to a solitary life) is commonly observed in mammals, but rarely documented
in amphibians. Environmental features and/or animal mutual attractions can promote the formation of aggregations that may
both reduce the risks of dehydration and predation and increase mate access and fitness. Luschan’s salamander (Mertensiella luschani) lives in permanently arid Mediterranean environments; individuals shelter in cracks and crevices and leave only during favourable
periods. In this study we examined the role of chemical tracks, in self and conspecific recognition (i.e. gregarious/solitary
behaviour), on the social structure of this species. Our results show that juveniles and adults of both sexes use chemical
scents deposited on substrate to relocate their shelter. In contrast to numerous other salamander species, Luschan’s salamanders
also use social information, conveyed by conspecific scents, to identify a safe shelter. Furthermore, this scent marking does
not play a role in sexual attraction but allows sex discrimination. This species exhibits gregarious behaviour (i.e. conspecific
attraction) as a possible adaptation to dry environments. We discuss both ultimate and proximate factors in the evolution
from a solitary to a gregarious life. 相似文献
2.
Hirofumi Michimae 《Behavioral ecology and sociobiology》2006,60(2):205-211
Alternative phenotypes in natural populations can arise from either genetic polymorphism or an environmentally induced phenotype, that is, polyphenism. Evolutionary models of polyphenism developed by theoretical studies predict that polyphenism is favored when there are environment-dependent fitness trade-offs between alternatives and that the threshold frequency for a facultative switch between alternative phenotypes is adjusted in accordance with different selection regimes. The broad-headed (alternative) larval morph of Hynobius retardatus, which is induced by crowding with conspecifics or heterospecific anuran (Rana pirica) larvae, is a representative example of cannibalistic polyphenism. Morph induction by such proximate factors must reflect evolutionary (conditional frequency-dependent) processes. To clarify the role of frequency-dependent processes in polyphenism, I investigated the occurrence rate of the broad-headed morph under experimental crowding conditions (low conspecific, high conspecific, and high heterospecific densities) using larvae from eight natural populations with different larval densities of conspecifics and heterospecifics, and found interpopulational differences in the expression of the morph. Thus, there is a larval density-dependent equilibrium frequency of the morph in each pond, suggesting that the local switch point for morph induction was modified by selection to produce evolved differences between ponds. The evolution of such interpond differences has three necessary conditions: (1) There are pond-dependent fitness trade-offs between alternatives, (2) The maintenance of the morph is costly, and (3) The presence of conspecific or, especially, heterospecific larvae provides a reliable cue to the receiver. 相似文献
3.
The relative roles of kinship and familiarity in affecting an individual’s growth and fitness are not easy to disentangle.
Not only is an individual more likely to have prior behavioral interactions with conspecifics in close proximity, it may also
be related (in terms of kinship) to those nearby conspecifics. While some studies have inferred that kin discrimination affects
fitness correlates, other studies found that familiarity alone can reduce aggressive interactions, thus increasing fitness.
These studies have all focused on intra-age class pairs or groups. However, many animals interact with conspecifics from different
cohorts. In many populations, adults of Plethodon cinereus territorially defend rocks and logs that retain moisture and food resources. We investigated whether juveniles of P. cinereus grew more in the presence of adults that were relatives or familiar. We collected pairs of juveniles and adults found under
the same cover objects in the forest (familiar) and pairs of juveniles and adults found under different cover objects, approximately
10 m apart (unfamiliar). We determined parentage and relatedness of the adult–juvenile pairs and then placed these pairs in
semi-natural mesocosms for 17 days. We found that juveniles housed with familiar adults had significantly greater increases
in mass and snout–vent length than juveniles housed with unfamiliar adults in 2006 but not in 2007. Relatedness had no effect
on growth. In addition, juveniles cohabitating with adults were not more likely to be their offspring. At least under certain
environmental conditions, familiarity with adults, independent of relatedness or parentage, increased the growth of juvenile
salamanders. 相似文献
4.
Howard H. Whiteman John D. Krenz Raymond D. Semlitsch 《Behavioral ecology and sociobiology》2006,60(1):52-61
The study of reproductive isolation as a prerequisite to sympatric speciation has been limited by the focus on species that
have already experienced such isolation. However, a complete understanding of how such processes evolve depends on observing
taxa before they complete the speciation process. We studied the potential for sexual isolation in the polyphenic mole salamander,
Ambystoma talpoideum, using a series of laboratory and field experiments. This species consists of aquatic paedomorphic adults and terrestrial
metamorphic adults which are exhibited by both sexes and which mate in the same aquatic habitat. Previous field studies on
this species suggested that intermorph breeding would be less common during the winter months, because paedomorphic adults
begin breeding in early autumn and thus may have less energy available for reproduction in the winter. Laboratory experiments
conducted during the winter showed that the mating behavior of paedomorphic males occurred at a much lower frequency than
that of metamorphic males. In contrast, field experiments that best mimicked natural conditions revealed symmetric intermorph
breeding and included multiple paternity shared among males of each morph. This and other studies suggest that there is little
evidence of sexual isolation among morphs based on behavioral interactions alone. However, the potential for partial isolation
still occurs because of temporal and spatial differences in the frequencies of each morph in nature. Our results suggest that
further studies on this system, and other similar polyphenisms, may provide valuable insight into the mechanisms that underlie
the evolution of reproductive isolation. 相似文献
5.
Organisms in natural habitats participate in complex ecological interactions that include competition, predation, and foraging.
Under natural aquatic environmental conditions, amphibian larvae can simultaneously receive multiple signals from conspecifics,
predators, and prey, implying that predator-induced morphological defenses can occur in prey and that prey-induced offensive
morphological traits may develop in predators. Although multiple adaptive plasticity, such as inducible defenses and inducible
offensive traits, can be expected to have not only ecological but also evolutionary implications, few empirical studies report
on species having such plasticity. The broad-headed larval morph of Hynobius retardatus, which is induced by crowding with heterospecific anuran (Rana pirica) larvae, is a representative example of prey-induced polyphenism. The morph is one of two distinct morphs that have been
identified in this species; the other is the typical morph. In this paper, we report that typical larval morphs of Hynobius can respond rapidly to a predatory environment and show conspicuous predator-induced plasticity of larval tail depth, but
that broad-headed morphs cannot respond similarly to a predation threat. Our findings support the hypothesis that induction
or maintenance of adaptive plasticity (e.g., predator-induced polyphenism) trades off against other adaptive plastic responses
(e.g., prey-induced polyphenism). For a species to retain both an ability to forage for larger prey and an ability to more
effectively resist predation makes sense in light of the range of environments that many salamander larvae experience in nature.
Our results suggest that the salamander larvae clearly discriminate between cues from prey and those from predators and accurately
respond to each cue; that is, they adjust their phenotype to the current environment. 相似文献
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