Data from: Weapon allometry varies with latitude in the New Zealand giraffe weevil

Animal body size commonly shows a relationship with latitude to the degree that this phenomenon is one of the few ‘rules’ discussed in evolutionary ecology: Bergmann's rule. Although exaggerated secondary sexual traits frequently exhibit interesting relationships with body size (allometries) and are expected to evolve rapidly in response to environmental variation, the way in which allometry might interact with latitude has not been addressed. We present data showing latitudinal variation in body size and weapon allometry for the New Zealand giraffe weevil (Lasiorhynchus barbicornis). Males display an extremely elongated rostrum used as a weapon during fights for access to females. Consistent with Bergmann's rule, mean body size increased with latitude. More interestingly, weapon allometry also varied with latitude, such that lower latitude populations exhibited steeper allometric slopes between weapon and body size. To our knowledge, this is the first study to document a latitudinal cline in weapon allometry and is therefore a novel contribution to the collective work on Bergmann's rule and secondary sexual trait variation.

动物体型通常与纬度存在关联，这一现象是进化生态学中为数不多被广泛探讨的“法则”之一，即伯格曼法则（Bergmann's rule）。尽管夸张的次生性征常与体型呈现出颇具研究价值的异速生长（allometry）关系，且被认为会随环境变化快速演化，但异速生长与纬度之间的相互作用方式尚未得到系统研究。本研究以新西兰长颈鹿象鼻虫（Lasiorhynchus barbicornis）为研究对象，提供了其体型与武器异速生长的纬度变异数据。该物种雄性个体拥有极度延长的喙部，该结构在争夺配偶的打斗中充当武器。研究结果符合伯格曼法则：种群平均体型随纬度升高而增大。更为有趣的是，武器异速生长也随纬度发生变化，低纬度种群的武器与体型间的异速生长斜率更为陡峭。据我们所知，本研究是首个记录武器异速生长纬度梯度的学术工作，因此为伯格曼法则及次生性征变异的相关研究提供了全新的研究视角与学术贡献。