Variation in mandible development and its relationship to dependence on parents across burying beetles

Background: In species with parental care, there is striking variation in offspring dependence at birth, ranging from feeding independence to complete dependency on parents for nutrition. Frequently, highly dependent offspring further evolve reductions or alterations of morphological traits that would otherwise promote self-sufficiency. Here, we examine evidence for morphological evolution associated with dependence in burying beetles (Nicrophorus spp.), in which dependence upon parents appears to have several independent origins. In many species precocial first instar larvae can survive without parenting, but several altricial species die at this stage on their own. We focused specifically on the mandibles, which are expected to be related to feeding ability and therefore independence from parents.
Results: We find no evidence that the size of the mandible is related to dependence on parents. However, we do find a developmental and phylogenetic correlation between independence ...

研究背景：在存在亲本抚育行为的物种中，子代出生时的依赖程度存在显著差异，范围从觅食完全独立到完全依赖亲本获取营养。通常，高度依赖亲本的子代还会演化出相关形态特征的退化或改变——而这些特征原本可帮助其实现自给自足。本研究聚焦于埋葬甲属（Nicrophorus spp.）物种中与子代依赖行为相关的形态演化证据，该类群中亲本依赖的演化似乎曾多次独立起源。在多数物种中，早成性的一龄幼虫可脱离亲本抚育存活，但部分晚成性物种在该阶段无法独自存活。我们特别关注了上颚这一结构——因其被认为与觅食能力相关，进而与子代脱离亲本的独立性有关。
研究结果：我们未发现上颚尺寸与子代亲本依赖程度存在关联的证据。然而，我们确实发现了子代独立生存能力与……之间存在发育和系统发育层面的相关性。