The role of complex cues in social and reproductive plasticity

Abstract

Phenotypic plasticity can be a key determinant of fitness. The degree to which the expression of plasticity is adaptive relies upon the accuracy with which information about the state of the environment is integrated. This step might be particularly beneficial when environments, e.g. the social and sexual context, change rapidly. Fluctuating temporal dynamics could increase the difficulty of determining the appropriate level of expression of a plastic response. In this review, we suggest that new insights into plastic responses to the social and sexual environment (social and reproductive plasticity) may be gained by examining the role of complex cues (those comprising multiple, distinct sensory components). Such cues can enable individuals to more accurately monitor their environment in order to respond adaptively to it across the whole life course. We briefly review the hypotheses for the evolution of complex cues and then adapt these ideas to the context of social and sexual plasticity. We propose that the ability to perceive complex cues can facilitate plasticity, increase the associated fitness benefits and decrease the risk of costly ‘mismatches’ between phenotype and environment by (i) increasing the robustness of information gained from highly variable environments, (ii) fine-tuning responses by using multiple strands of information and (iii) reducing time lags in adaptive responses. We conclude by outlining areas for future research that will help to determine the interplay between complex cues and plasticity.

Phenotypic plasticity in response to climate change: the importance of cue variation

“…We find little evidence for multiple redundant climatic cues, but we cannot exclude that some other, unmeasured cues, such as tree phenology, could also be important in determining laying date [74]. Although partial redundancy should increase the reliability of the information [57], information acquisition is also expected to be costly [98]. An open remaining question is thus the circumstances under which we can expect organisms to use several, partly redundant sources of information, and whether this could mitigate the effects of global change.…”

“…Some mechanisms may mitigate the loss of reliability in some cues. First, the potentially negative effects of loss of reliability of a particular environmental variable as a cue could be greatly alleviated if organisms are using multiple cues, because partial redundancy in information from different environmental sources may increase the robustness of the signal [57]. For example, in the above-mentioned case of the coral reef damselfish, the loss of olfactory cue in dead coral water can be compensated by the use of visual cues [40].…”

Combined cues of male competition influence spermatozoal investment in a moth

“…(see results in Bretman, Gage, et al, 2011; Maguire et al, 2015) and the spider Schizocosa ocreata (Uetz, Clark, Kane, & Stoffer, 2019) also suggest that combined cues may enhance males' response to sperm competition environment. According to the backup signal hypothesis, the receivers should obtain more certain information on their socio‐sexual environment and adjust their resource allocation to reproduction with more confidence because detection of increasing number of cues carrying the same message may have synergistic impact on males' response (Dore et al, 2018; Partan & Marler, 1999). However, there is no evidence that combined cues could enhance production of apyrene in their lifetime (Figure 3B), probably because apyrenes play relatively minor roles in sperm competition (Konagaya & Watanabe, 2015; Mongue, Hansen, Gu, Sorenson, & Walters, 2019; Sakai et al, 2019; Thorburn, Knell, & Parrett, 2018).…”

Female sperm storage mediates post‐copulatory costs and benefits of ejaculate anticipatory plasticity in the guppy

“…As predicted, improved ejaculate quality comes at a cost in sperm viability that negatively affects fertilization success after FSS. These results highlight the importance of considering all the potential fitness consequences of a strategic adjustment of ejaculate quality in response to a changing social environment (Dore et al., 2018; Kelly & Jennions, 2011; Magris, Chimetto, Rizzi, & Pilastro, 2018). Although ejaculate anticipatory responses are obviously expected to increase overall male reproductive fitness, they also imply costs (e.g., Bretman, Fricke, & Chapman, 2009; Silva et al., 2019).…”