Moura Rafael R, Gonzaga Marcelo O
Pos-graduacao em Ecologia e Conservaçao de Recursos Naturais, Universidade Federal de Uberlandia, Campus Umuarama, Bloco 2D, Uberlandia, MG, CEP 38400-902, Brazil.
Instituto de Biologia, Universidade Federal de Uberlandia, Campus Umuarama, Bloco 2D, Uberlandia, MG, CEP 38400-902, Brazil.
Naturwissenschaften. 2017 Apr;104(3-4):28. doi: 10.1007/s00114-017-1448-6. Epub 2017 Mar 13.
Males should be more selective when they have a high investment in reproduction, especially in species with biparental or paternal care. In this context, male mate choice can promote size-assortative mating (SAM) when (1) large males win intrasexual disputes, (2) large females are more fecund, and (3) males prefer larger females to smaller ones. In the spider Manogea porracea, males exhibit high reproductive investment by building their webs above those of females and exhibiting extended care of offspring in the absence of females. Under these circumstances, we expect the occurrence of SAM and male preference for large females. Herein, we performed observations and experiments in the field to evaluate the hypotheses that (1) M. porracea mates assortatively by size and (2) SAM is influenced by male mate choice. Furthermore, we measured variables that could affect mating patterns, the sex ratios, and densities of both sexes. Pairing in M. porracea was positively size-assortative in 2012, but not in 2013. Large males won most disputes for mates and preferred larger females, which produced more eggs. The inconsistency in detection of SAM was due to population dynamics, namely variations in sex ratio and population density across the breeding season. Furthermore, we found that the significance of male mate choice on sexual selection of body size in M. porracea strongly depends on the competition intensity for mating opportunities. The traditional sexual selection hypothesis of SAM needs to be reviewed and must include measures of competition intensity.
当雄性在繁殖中投入较高时，尤其是在双亲抚育或父性抚育的物种中，它们应该更加挑剔。在这种情况下，当满足以下条件时，雄性配偶选择可以促进体型选配交配（SAM）：（1）大型雄性在同性竞争中获胜；（2）大型雌性繁殖力更强；（3）雄性更喜欢大型雌性而非小型雌性。在蜘蛛Manogea porracea中，雄性通过在雌性的蛛网之上构建自己的蛛网，并在雌性不在场时对后代进行长期抚育，表现出较高的繁殖投入。在这些情况下，我们预期会出现体型选配交配以及雄性对大型雌性的偏好。在此，我们在野外进行了观察和实验，以评估以下假设：（1）Manogea porracea按体型进行选配交配；（2）体型选配交配受雄性配偶选择的影响。此外，我们测量了可能影响交配模式、性别比例以及两性密度的变量。2012年，Manogea porracea的配对呈正体型选配，但2013年并非如此。大型雄性在大多数配偶争夺中获胜，并且更喜欢大型雌性，因为大型雌性产卵更多。体型选配交配检测结果的不一致是由于种群动态，即在整个繁殖季节中性别比例和种群密度的变化。此外，我们发现雄性配偶选择对Manogea porracea体型性选择的重要性很大程度上取决于交配机会的竞争强度。传统的体型选配交配性选择假设需要重新审视，并且必须纳入竞争强度的衡量指标。
