Data from: Use of a rostral appendage during social interactions in the Ecuadorian Anolis proboscis

The use of sexually selected characters in inter- and intra-sexual interactions has long been of interest to evolutionary biologists. Recently, a distinction between sexually selected traits as ornaments versus weapons has been advanced. We investigated the behaviour of an enigmatic lizard with a prominent sexually dimorphic trait in an effort to describe whether the trait was the product of sexual selection and further whether it functioned as a weapon or an ornament. The subject of our study was the Ecuadorian proboscis anole (Anolis proboscis), a slow-moving cryptic species endemic to the north-western slopes of the Andes in Ecuador. Males, but not females, of this species bear a rostral appendage that has been described as an exaggerated trait resulting from sexual selection. However, a thorough description of the use of the rostral appendage in social interactions is lacking. Here, we describe social interactions of this species during 11 male–female courtships and mating interactions, as well as three male–male agonistic interactions. We describe four types of displays by males, many involving the rostral appendage. We found that the rostral appendage is used as an ornament in social displays but not as a weapon in combat. We also show that, unlike other lizards with rostral appendages, male A. proboscis hatch with this structure already developed.

性选择性状在异性间与同性间互动中的应用，长期以来都是进化生物学家的研究热点。近年来，学界已提出将性选择性状划分为装饰性状与武器性状的区分标准。本研究针对一种拥有显著性二态性状的神秘蜥蜴，旨在探究该性状是否由性选择塑造，并进一步明确其功能究竟为武器还是装饰。本研究的对象为厄瓜多尔长吻安乐蜥（Anolis proboscis），这是一种行动迟缓、具隐蔽性的物种，仅分布于厄瓜多尔安第斯山脉西北坡。该物种仅雄性具有吻突（rostral appendage），该结构被认为是性选择塑造的夸张性状。然而，目前仍缺乏关于该吻突在社会互动中使用方式的详尽描述。本文中，我们对该物种的社会互动行为进行了系统记录与描述：共记录到11次雌雄求偶与交配互动，以及3次雄性间的争斗互动，并识别出雄性的四种展示行为，其中多数涉及吻突的运用。研究结果表明，该吻突在社会展示中作为装饰性状发挥作用，而非在争斗中作为武器。此外，我们还发现，与其他具有吻突的蜥蜴不同，雄性厄瓜多尔长吻安乐蜥的吻突在孵化时即已发育完全。