Is foraging innovation lost following colonization of a less variable environment? A case study in surface- vs. cave-dwelling Asellus aquaticus.

Gábor Herczeg,Simona Kralj-Fišer,Gergely Horváth,Gergely Balázs,Žiga Fišer,Viktória P Hafenscher

doi:10.1002/ece3.6276

Abstract

Behavioral innovation is a key process for successful colonization of new habitat types. However, it is costly due to the necessary cognitive and neural demands and typically connected to ecological generalism. Therefore, loss of behavioral innovativeness is predicted following colonization of new, simple, and invariable environments. We tested this prediction by studying foraging innovativeness in the freshwater isopod Asellus aquaticus. We sampled its populations along the route of colonizing a thermokarstic water‐filled cave (simple, stable habitat with only bacterial mats as food) from surface habitats (variable environment, wide variety of food). The studied cave population separated from the surface populations at least 60,000 years ago. Animals were tested both with familiar and novel food types (cave food: bacterial mats; surface food: decaying leaves). Irrespective of food type, cave individuals were more likely to feed than surface individuals. Further, animals from all populations fed longer on leaves than on bacteria, even though leaves were novel for the cave animals. Our results support that cave A. aquaticus did not lose the ability to use the ancestral (surface) food type after adapting to a simple, stable, and highly specialized habitat.

Highlights

Behavioral innovation is an individual's invented new behavior or modified old behavior not present previously in the population (Reader, 2003; Reader & Laland, 2003), which seems to be a key asset for success in novel situations and a prerequisite of successful colonization of new habitat types (Mayr, 1965; Morse, 1980)
Behavioral innovation is regarded as a key process for successful colonization of novel habitat types (e.g., Mayr, 1965; Morse, 1980)
Evolutionary analyses of behavioral innovation are almost exclusively based on interspecific comparisons, where separating causation from correlation is notoriously hard

Summary

Introduction

Behavioral innovation is an individual's invented new behavior or modified old behavior not present previously in the population (Reader, 2003; Reader & Laland, 2003), which seems to be a key asset for success in novel situations and a prerequisite of successful colonization of new habitat types (Mayr, 1965; Morse, 1980). Comparative studies revealed a number of correlations with behavioral innovativeness, for instance, showing its positive link to brain size and learning capacity (e.g., Lefebvre, Reader, & Sol, 2004; Overington et al, 2009; Reader & Laland, 2002). Intraspecific studies, between-population comparisons, are scarce at best (Reader, 2003) This is unfortunate, because understanding adaptive evolution of quantitative traits relies on estimating (a) phenotypic variation, (b) selection acting on the variation, (c) the heritable component of the variation, and (d) the genetic underpinnings of the variation. Comparing behavioral innovativeness between locally adapted populations of the same species would be an important addition to understanding the evolution of behavioral innovation

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