Selection on male size, leg length and condition during mate search in a sexually highly dimorphic orb-weaving spider
Selection on male size, leg length and condition during mate search in a sexually highly dimorphic orb-weaving spider
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DOI：
10.1007/s00442-004-1756-3
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发表时间：
2005-02-01
期刊：
影响因子：
2.7
通讯作者：
Fairbairn, DJ
中科院分区：
文献类型：
--
作者：
Foellmer, MW;Fairbairn, DJ
在极端女性偏向的性别大小二型性(SSD)在动物中的适应性意义的假说中，配偶搜索起着核心作用。蜘蛛(蜘蛛目)是唯一自由生活的陆地分类群，在那里极端的SSD是常见的。“重力假说”指出，在雄性必须爬到雌性的物种中，在寻找配偶的过程中，雄性的体型较小，因为身体长度与垂直结构上的可达到速度成反比。然而，男性的运动能力也可能取决于相对腿长。在这里，我们研究了高度二态的球状编织蜘蛛Argiope aurantia在寻找配偶时对雄性身体大小和腿长的选择，使用多变量方法来区分针对不同大小组成部分的选择。此外，我们还考察了男性体型和能量储备之间的比例关系，以及能量损失的差异性。成年雄性在漫游时不取食，因此依赖于大小的差异储能能力可能会影响雄性在寻找配偶时的表现。与预测相反的是，在两个群体中的一个群体中，体型较大的人更受青睐，这是因为选择了更长的腿。在第二个群体中，雄性体型不在选择范围内，但我们检测到对更长的第三条腿的直接选择。雄性在寻找配偶的过程中失去了能量储备，但这与雄性的大小无关，存储容量与大小成等距关系。因此，交配搜索不太可能导致选择较小的雄性蜘蛛，但支持这样的假设，即雄性蜘蛛相对较长的腿反映了一种适应搜索的形态。
Mate search plays a central role in hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) in animals. Spiders (Araneae) are the only free-living terrestrial taxon where extreme SSD is common. The "gravity hypothesis" states that small body size in males is favoured during mate search in species where males have to climb to reach females, because body length is inversely proportional to achievable speed on vertical structures. However, locomotive performance of males may also depend on relative leg length. Here we examine selection on male body size and leg length during mate search in the highly dimorphic orb-weaving spider Argiope aurantia, using a multivariate approach to distinguish selection targeted at different components of size. Further, we investigate the scaling relationships between male size and energy reserves, and the differential loss of reserves. Adult males do not feed while roving, and a size-dependent differential energy storage capacity may thus affect male performance during mate search. Contrary to predictions, large body size was favoured in one of two populations, and this was due to selection for longer legs. Male size was not under selection in the second population, but we detected direct selection for longer third legs. Males lost energy reserves during mate search, but this was independent of male size and storage capacity scaled isometrically with size. Thus, mate search is unlikely to lead to selection for small male size, but the hypothesis that relatively longer legs in male spiders reflect a search-adapted morphology is supported.