Hunt James H
Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri, 63121.
Evolution. 1999 Feb;53(1):225-237. doi: 10.1111/j.1558-5646.1999.tb05348.x.
The multiple independent origins of eusociality in the insect order Hymenoptera are clustered in only four of more than 80 families, and those four families are two pairs of closely related taxa in a single part of the order. Therefore, although ordinal-level characteristics can contribute to hymenopteran eusocial evolution, more important roles have been played by traits of infraordinal taxa that contain the eusocial forms. Many factors have been proposed and discussed, but assessments of traits' salience to eusocial evolution have heretofore not been joined to phylogenetics. In the present analysis, cladograms of superfamilies and families of Hymenoptera and of the family Vespidae are used to ordinate the appearance of traits that play roles in vespid eusociality. Proximity of traits' first appearance to the origin of eusocial Vespidae is taken as one measure of traits' salience to vespid eusocial evolution. Traits that subtend only eusocial taxa and that are uniquely associated with eusociality have foundations in more general traits that subtend more inclusive taxa. No single trait is uniquely causative of vespid eusocial evolution. High-salience traits that closely subtend vespid eusociality include nesting, oviposition into an empty nest cell, progressive provisioning of larvae, adult nourishment during larval provision malaxation, and inequitable food distribution among nestmates. The threshold characteristic of Polistes-grade eusociality is life-long alloparental brood care by first female offspring who remain, uninseminated, at their natal nest. Traits directly associated with occurrence of such workers are larva-adult trophallaxis, which can foster relatively low larval nourishment early in a colony cycle, and protogyny and direct larval development, which combine to yield restricted mating opportunities for female offspring that are the first to emerge in the colony cycle. Trait mapping suggests no role for asymmetry of relatedness due to haplodiploidy, but it suggests high salience for haplodiploidy as a mechanism enabling the production of all-female clutches of first offspring.
膜翅目昆虫中群居性的多个独立起源仅集中在80多个科中的4个科，而这4个科是该目一个单一部分中的两对亲缘关系密切的类群。因此，尽管目级特征可能有助于膜翅目昆虫的群居进化，但包含群居形式的亚目类群的特征发挥了更重要的作用。人们已经提出并讨论了许多因素，但迄今为止，对特征在群居进化中的显著性评估尚未与系统发育学结合起来。在本分析中，膜翅目总科和科以及胡蜂科的分支图被用来排列在胡蜂群居性中起作用的特征的出现顺序。特征首次出现与群居胡蜂科起源的接近程度被用作衡量特征对胡蜂群居进化显著性的一个指标。仅存在于群居类群且与群居性独特相关的特征，其基础是存在于更广泛类群中的更普遍特征。没有单一特征是胡蜂群居进化的唯一原因。与胡蜂群居性密切相关的高显著性特征包括筑巢、在空巢室中产卵、逐步为幼虫提供食物、在为幼虫准备食物时成虫进行营养加工以及巢友间食物分配不均。黄胡蜂级群居性的阈值特征是未受精的雌性后代留在其出生巢穴中进行终生异亲育幼。与这种工蜂出现直接相关的特征包括幼虫与成虫之间的交哺现象，这在群体周期早期可促进相对较低的幼虫营养水平，以及雌性先熟和直接幼虫发育，这两者结合导致在群体周期中最早出现的雌性后代的交配机会受限。特征映射表明，单倍二倍体导致的亲缘关系不对称不起作用，但它表明单倍二倍体作为一种机制具有很高的显著性，能够产生全雌性的首批后代。
