Visual and olfactory cues of predation affect body and brain growth in the guppy

Abstract

1.Phenotypic plasticity requires animals to acquire reliable environmental information. When multiple sources of information agree, cues should be perceived as reliable and induce a relatively strong response. Conversely, where stimuli conflict, animals must weigh the accuracy of the sources of information and responses should be reduced. 2.Availability of reliable information is often considered a limitation on plasticity, yet how animals integrate seemingly contradictory or incomplete information remains enigmatic, as empirical tests are scarce. 3.We tested how incomplete information determines phenotypic plasticity by simulating predation risk during early ontogeny of guppies (Poecilia reticulata). We exposed guppy fry to a combination of visual and/or olfactory cues of the predatory pike cichlid (Crenicichla alta), and monitored growth of the body and brain. After five weeks of exposure, guppies were returned to common no-risk conditions and their activity rates were monitored for four weeks post-treatment. 4.Visual predator exposure more strongly affected development; reducing body size of adult males and increasing brain size in females. However, there was little evidence for the hypothesised additive effect, with the combined treatment not inducing a larger effect than when only receiving olfactory or visual treatments. 5.While there was consistent individual variation in activity rates, this was unaffected by developmental risk and uncorrelated with the growth parameters. 6.Our results demonstrate the differential reliability of cues during development. Visual exposure to a predator was a highly reliable environmental cue, while environmental certainty was unaffected by combined stimuli.

Understanding the unexplained: The magnitude and correlates of individual differences in residual variance

“…As the CV P is standardized by the mean rIIV, this would reduce the estimate of individual variation in rIIV, rather than add to it. However, care should be taken with this result as field studies typically used different assays; for example, studies of boldness were typically based on flight initiation distance(Allan et al, F I G U R E 1 1: Western fence lizard (Sceloporus occidentalis;Adolph & Pickering, 2008), 2: chacma baboon (Papio ursinus;Allan et al, 2020), 3: mosquitofish (Gambusia holbrooki;Biro & Adriaenssens, 2013), 4: Ward's damselfish (Pomacentrus bankanensis;Biro et al, 2010), 5: guppy (Poecilia reticulata;Biro et al, 2016), 6: hermit crab (Pagurus bernhardus;Bridger et al, 2015), 7: hermit crab (P. bernhardus;Briffa, 2013), 8: hermit crab (P. bernhardus;Briffa et al, 2013), 9: house sparrow (Passer domesticus;Careau, Hoye, et al, 2014), 10: marsh periwinkle (Littoraria irrorata;Cornwell et al, 2018), 11: marsh periwinkle (L. irrorata;Cornwell et al, 2020), 12: house mouse (Mus musculus;Eisenmann et al, 2009), 13: three-spined stickleback (Gasterosteus aculeatus;Fürtbauer et al, 2015), 14: shore crab (Carcinus maenas;Fürtbauer, 2015), 15: dog (Canis familiaris; Goold & Newberry, 2017), 16: guppy (P. reticulata;Herczeg et al, 2019), 17: brown bear (Ursus arctos;Hertel, Royauté, et al, 2020), 18: African elephant (Loxodonta africanus;Hertel, Niemelä, et al, 2020), 19: Namibian rock agama (Agama planiceps;Highcock & Carter, 2014), 20: slater (Armadillidium vulgare;Horváth et al, 2019), 21: fallow deer (Dama dama;Jennings et al, 2013), 22: three-spined stickleback (G. aculeatus;Jolles et al, 2019), 23: guppy (P. reticulata;Kurvers et al, 2018), 24: yellow-bellied marmot (Marmota flaviventris;Martin et al, 2017), 25: guppy (P. reticulata;Mitchell et al, 2016), 26: zebra fish (Danio rerio;Mitchell, Dujon, et al, 2020), 27: guppy (P. reticulata;, 28: guppy (P. reticulata;Mitchell, Lefèvre, et al, 2020), 29: eastern chipmunk (Tamias striatus;Montiglio et al, 2015), 30: hermit crab (P. bernhardus;…”