Adaptation to a novel family environment involves both apparent and cryptic phenotypic changes.

Matthew Schrader,Benjamin J M Jarrett,Darren Rebar,Rebecca M Kilner

doi:10.1098/rspb.2017.1295

Abstract

Cryptic evolution occurs when evolutionary change is masked by concurrent environmental change. In most cases, evolutionary changes in the phenotype are masked by changing abiotic factors. However, evolutionary change in one trait might also be masked by evolutionary change in another trait, a phenomenon referred to as evolutionary environmental deterioration. Nevertheless, detecting this second type of cryptic evolution is challenging and there are few compelling examples. Here, we describe a likely case of evolutionary environmental deterioration occurring in experimental burying beetle (Nicrophorus vespilloides) populations that are adapting to a novel social environment that lacks post-hatching parental care. We found that populations rapidly adapted to the removal of post-hatching parental care. This adaptation involved clear increases in breeding success and larval density (number of dispersing larvae produced per gram of breeding carcass), which in turn masked a concurrent increase in the mean larval mass across generations. This cryptic increase in larval mass was accomplished through a change in the reaction norm that relates mean larval mass to larval density. Our results suggest that cryptic evolution might be commonplace in animal families, because evolving trophic and social interactions can potentially mask evolutionary change in other traits, like body size.

Highlights

Cryptic evolution occurs when evolutionary change in a trait is masked by a concurrent change in an environmental factor that influences that trait [1,2,3]
The social interactions that arise during parental care can generate cryptic evolution, few studies have tested whether evolutionary change in one component of the family environment masks an evolutionary change in an interacting trait
Our results indicate that as the No Care populations adapted to the removal of care, the social environment experienced by larvae changed, with larval interactions becoming more competitive with the rise in larval density

Summary

Introduction

Cryptic evolution occurs when evolutionary change in a trait is masked by a concurrent change in an environmental factor that influences that trait [1,2,3]. An evolutionary increase in a trait such as brood size may lead to environmental deterioration by increasing competition between developing young This change in the social environment could in turn mask evolutionary changes in an interacting trait such as offspring size that may be under directional selection. Evolutionary changes in the social environment may be an especially important driver of cryptic evolution in animals with parental care In these species, offspring often develop in a nursery where diverse social interactions are played out among the family members [8]. The social interactions that arise during parental care can generate cryptic evolution, few studies have tested whether evolutionary change in one component of the family environment masks an evolutionary change in an interacting trait. Our results provide a likely example of cryptic evolution driven by ‘evolutionary environmental deterioration’ [3]

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Results

Discussion