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Pauline Vuarin Roland Allemand Joffrey Moiroux Joan van Baaren Patricia Gibert 《Die Naturwissenschaften》2012,99(11):903-912
Energy allocation is determined by resource availability and trade-offs among traits, and so organisms have to give some traits priority over others to maximize their fitness according to their environment. In this study, we investigated the geographic variations in life history traits and potential trade-offs in populations of the parasitoid Leptopilina heterotoma (Hymenoptera: Figitidae) originating from the north and the south of the Rh?ne–Sa?ne valley (over a gradient of 300?km, South-East France). We measured a set of traits related to reproduction, maintenance, and mobility using several estimators of each of these main functions determined at different times. We did not find any clear differences between populations from contrasting areas, whereas the southern populations, which were all assumed to be exposed to similar environmental conditions, displayed contrasting patterns of energy allocation. Thus, the most likely explanation seems to be that the evolution of the life history of L. heterotoma is probably shaped by local selective pressures, such as microclimate, microhabitats, or intensity of competition, rather than by regional ecological conditions. Using our study as an example, we discuss the interest of considering several traits and using different ways of measuring them, concluding that multiple measurements should be performed in future studies to ensure the robustness of the results. 相似文献
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Environment plays a major role for determining the kind of courtship behaviours or alternative mating tactics employed, but
the effect of physical variables on fitness has received little attention. The Alpine newt courts during both day and night
times and exhibits a complex suite of behaviours involving olfactory, visual and tactile cues. Displaying in both dark and
light conditions may increase the number of mating opportunities and alleviate predation risk, but the frequency and efficacy
of the various tactics deployed may vary across light conditions, leading males to vary their use of these tactics across
different light regimes. To test this hypothesis, we video-recorded sexual encounters at two light intensities in a controlled
experimental design. When courting in the dark, males used comparatively more olfactory rather than visual displays. They
also relied more on positive feedback from the female before releasing a spermatophore for her to pick up. The particular
mix of tactics used under each light condition is likely to be adaptive because in the dark (1) visual communication is hampered,
making olfactory displays possibly more effective and (2) males depositing spermatophores are more likely to lose fertilizations
to competitors. Mating in light and dark conditions has similar reproductive payoffs, which shows that displaying in the dark
is not detrimental and may even be advantageous if predation risk is reduced at night. These results confirm the importance
of taking into account physical variables to understand the evolution of sexual communication in animals. 相似文献
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In holometabolous insects, pupation site selection behaviour has large consequences for survival. Here, we investigated the
combined effects of temperature and parasitism by the parasitoid Asobara tabida on larval pupation behaviour in two of its main Drosophila sp. hosts differing in their climate origin. We found that larvae of Drosophila melanogaster—a species with a (sub)tropical origin—placed at 25°C pupated higher in rearing jars than those placed at 15°C. The opposite
pattern was observed for Drosophila subobscura larvae—a species from temperate regions—which pupated lower, i.e. on or near the substrate at 25°C, than those placed at
15°C. When placed at 25°C, parasitized larvae of both species pupated closer to the substrate than unparasitized ones. Moreover,
the Drosophila larvae that had been exposed and probably stung by A. tabida, but were not parasitized, pupated lower than the control unparasitized larvae. These results provide new insights of host
behaviour manipulation by A. tabida larvae. 相似文献
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