Sexually selected UV signals in the tropical ornate jumping spider, Cosmophasis umbratica may incur costs from predation

Abstract

Sexually selected ornaments and signals are costly to maintain if they are maladaptive in nonreproductive contexts. The jumping spider Cosmophasis umbratica exhibits distinct sexual dichromatism with males displaying elaborate UV body markings that signal male quality. Female C. umbratica respond favorably to UV-reflecting males and ignore males that have their UV masked. However, Portia labiata, a UV-sensitive spider-eating specialist and a natural predator of C. umbratica, is known to use UV reflectance as a cue when hunting prey. We investigated the cost of these UV signals in C. umbratica in terms of their predation risk. Under experimental conditions, three choice scenarios were presented to P. labiata individuals. Choices by P. labiata were made between male C. umbratica with and without the UV signal; a UV-reflecting male and non-UV-reflecting female; and a UV-masked male and female. The presence and absence of UV signals was manipulated using an optical filter. Portia labiata exhibited a strong bias toward UV+ individuals. These results suggest the sexually selected trait of UV reflectance increases the visibility of males to UV-sensitive predators. The extent of this male-specific UV signal then is potentially moderated by predation pressure. Interestingly though, P. labiata still preferred males to females irrespective of whether UV reflectance was present or not. This suggests P. labiata can switch cues when conditions to detect UV reflectance are not optimal.

Sexual dimorphism in the Arachnid orders

“…For example, only male Cosmophasis umbratica have body parts that reflect UV light ( Lim & Li, 2006 ). Salticids are capable of detecting light well within the UV spectrum ( Peaslee & Wilson, 1989 ), and female C. umbratica exhibit a preference for UV-reflecting mates as opposed to those with UV-reflecting capabilities masked ( Bulbert et al, 2015 ). Such research highlights the importance of considering other potential modalities for dimorphism that are less obvious to the human observer ( Huber, 2005 ).…”

Predator personality and prey behavioural predictability jointly determine foraging performance

“…In this study we addressed this issue using Portia labiata, a specialized spider-eating jumping spider (Araneae: Salticidae), as the predator, and Cosmophasis umbratica, an ornate jumping spider, as the prey37. Portia labiata is well known for its high cognitive ability and complicated foraging strategies383940.…”

Broad‐scale variation in sexual dichromatism in songbirds is not explained by sex differences in exposure to predators during incubation

“…horns in beetles; Emlen et al 2005). There can also be major differences between sexes in colors (sexual dichromatism) in animals as diverse as fish (Kodric-Brown 1998), frogs (Bell andZamudio 2012), lizards (McCoy et al 2009) and some invertebrates (Allen et al 2011, Bulbert et al 2015. Sexual dichromatism is particularly striking in birds (Hill and McGraw 2006), occurring in more than 40% of songbirds (Price and Birch 1996).…”