Conspecific familiarity and shoaling preferences in a wild guppy population

Abstract

In nature, social groups of animals are typically nonrandom associations of individuals. Such group associations may in part be based on social familiarity among individuals, acquired through repeated past encounters and behavioural experiences with each other. The factors that potentially affect the tendency to associate with familiar individuals remain poorly understood. Here, we investigated whether shoaling preferences based on presumed familiarity occur in wild adult guppies (Poecilia reticulata) originating from a Trinidadian population that experiences relatively low predation intensity from fishes and whether any such preferences differ between the sexes. When tested shortly after being collected in the field, neither males nor females clearly preferred to shoal with familiar same-sex conspecifics (collected from the same pool in the river) over unfamiliar ones (from different pools). Importantly, our results differ from those previously reported for guppies originating from the same population as ours and for a high predation risk population in Trinidad, suggesting that the development of social familiarity and its role in the formation of shoals in nature vary both within and among populations in the guppy. We provide plausible explanations for these observed populational differences in shoaling preferences in the guppy and discuss certain ecological factors that may affect the development and expression of shoaling preferences based on familiarity in nature.Résumé : En nature, les groupes sociaux d'animaux sont typiquement des associations non aléatoires d'individus. Ces associations de groupe peuvent en partie se baser sur la familiarité sociale entre les individus acquise au cours de rencontres répétées dans le passé et d'expériences comportementales mutuelles. Les facteurs qui peuvent influencer cette tendance à s'associer à des animaux familiers restent mal compris. Notre étude examine s'il y a des préférences basées sur une familiarité présumée dans la formation de bancs chez des guppys (Poecilia reticulata) adultes sauvages provenant d'une population au Trinidad qui ne subit qu'une faible pression de prédation de la part des poissons; elle évalue aussi s'il y a des différences dans les préférences entre les mâles et les femelles. Dans des tests de formation de bancs, peu après leur récolte sur le terrain, ni les mâles, ni les femelles ne montrent de tendances claires à s'associer plus à des guppys familiers de même sexe (issus de la même fosse dans la rivière) qu'à des guppys étrangers (provenant de fosses différentes). Ce qui est intéressant, c'est que nos résultats diffèrent de résultats publiés sur des guppys provenant de la même population et sur une autre population de Trinidad, mais à fort risque de prédation; il semble donc que le développement de la familiarité sociale et son rôle dans la formation des bancs chez le guppy en nature peut varier au sein d'une même population et d'une population à une autre. Nous avançons des explications plausibles de ces diffé-rences de préférence entre le...

Shoaling Decisions in Angelfish: The Roles of Social Status and Familiarity

“…This finding is also at variance with previous results in angelfish (Gómez‐Laplaza 2005). It may be that in the present absent‐predator situation, the antipredator benefits of familiarity are reduced, being lower for dominant than for subordinate angelfish (Godin et al. 2003).…”

Nonadditive effects of group membership can lead to additive group phenotypes for anti‐predator behaviour of guppies,Poecilia reticulata

“…, 2003) and familiarity (Croft et al. , 2006); however, the degree to which they exhibit these preferences varies within and among populations (Godin et al. , 2003).…”

“…The social context a guppy experiences is likely to vary widely as well. Guppies prefer to school with varying numbers of conspecifics based on the predation regime they experience (Magurran & Seghers, 1991) and may choose with whom to school based on size (Croft et al, 2003) and familiarity (Croft et al, 2006); however, the degree to which they exhibit these preferences varies within and among populations (Godin et al, 2003). Additionally, although fish are less commonly found alone, populations frequently become highly dispersed following heavy rainfall and when small pools are cut off from main water supplies during dry periods, isolating individuals or extremely small groups (B.H.…”

Social Recognition of Conspecifics

“…Nevertheless, the tendency to associate with familiars may vary between populations according to predator densities (Magurran et al 1994). The adaptive benefits of familiarity should theoretically increase in line with predation threat -where predation pressure is low, shoaling tendencies and the preference for familiar individuals may be correspondingly low (Godin et al 2003). Recent research by Kydd & Brown (2009) on the rainbowfish, Melanotaenia duboulayi, lends support to this idea.…”