Yap Sean, Toh Kai Xin, Puniamoorthy Nalini
Department of Biological Sciences National University of Singapore Singapore.
Ecol Evol. 2024 Oct 14;14(10):e70421. doi: 10.1002/ece3.70421. eCollection 2024 Oct.
Reproductive traits that mediate differential fitness associated with mate acquisition and fertilisation success are often strongly linked to the overall condition. We investigated the effects of resource quality and parental provisioning in the phenotypic expression of sexual and non-sexual traits in a rainforest dung beetle, c.f. (Eschscholtz, 1822) from Singapore. F1 individuals were reared from wild-caught beetles and paired up to produce offspring (F2), and F2 larvae from the same F1 parents were reared on two dung substrates (herbivore and omnivore) in a full-sib design. Sexual traits displayed greater phenotypic variation in response to dung resource quality, with the precopulatory trait (horn length) responding more than the postcopulatory trait (testes weight). Notably, genotype-by-environment interactions between parental lines (genotype) and dung type (environment) affected male body size and horn length only, suggesting sex-specific variance in plasticity associated with sexually selected precopulatory traits. Dung type had significant effects on all measured traits. Offspring that were provisioned higher quality resource (omnivore dung) had larger absolute and relative trait values. Parental lines only significantly affected female body size but none of the male traits, suggesting an important role of environment resource partitioning in determining precopulatory success of male offspring. Parental provisioning of larval resource varied with resource quality and brood sequence. Parents provisioned more dung when herbivore dung was presented than when they were given omnivore dung and provisioned more dung for their earlier broods when using herbivore dung but not omnivore dung. This suggests a trade-off between early offspring fitness and resource quality. We tested directly for genotype-by-environment (G × E) interactions in the expression of several morphological traits relevant to dung beetle fitness and documented that offspring with similar phenotypes may result from completely different parental resource allocation strategies. We discuss the importance of studying parental investment on trait variation and its implications on dung beetle ecology.
介导与配偶获取和受精成功相关的不同适应性的生殖性状通常与整体状况密切相关。我们研究了资源质量和亲代抚育在新加坡一种雨林蜣螂（学名：Catharsius molossus (Eschscholtz, 1822)）的性和非性性状表型表达中的作用。F1代个体由野外捕获的甲虫饲养长大，并配对繁殖后代（F2），同一F1代亲本的F2代幼虫在全同胞设计中以两种粪便底物（食草动物粪便和杂食动物粪便）饲养。性性状对粪便资源质量的反应表现出更大的表型变异，交配前性状（角的长度）的反应比交配后性状（睾丸重量）更明显。值得注意的是，亲本品系（基因型）和粪便类型（环境）之间的基因型-环境相互作用仅影响雄性体型和角的长度，这表明与性选择的交配前性状相关的可塑性存在性别特异性差异。粪便类型对所有测量性状均有显著影响。获得高质量资源（杂食动物粪便）的后代具有更大的绝对和相对性状值。亲本品系仅对雌性体型有显著影响，而对雄性性状均无影响，这表明环境资源分配在决定雄性后代交配前成功方面具有重要作用。亲代对幼虫资源的供给随资源质量和繁殖顺序而变化。当提供食草动物粪便时，亲代提供的粪便比提供杂食动物粪便时更多；在使用食草动物粪便时，亲代对较早繁殖的后代提供更多粪便，但使用杂食动物粪便时并非如此。这表明在后代早期适应性和资源质量之间存在权衡。我们直接测试了与蜣螂适应性相关的几种形态性状表达中的基因型-环境（G×E）相互作用，并记录了具有相似表型的后代可能来自完全不同的亲代资源分配策略。我们讨论了研究亲代投资对性状变异的重要性及其对蜣螂生态学的影响。
