What are the benefits of parental care? The importance of parental effects on developmental rate.

Hope Klug,Michael B Bonsall

doi:10.1002/ece3.1083

Hope Klug, Michael B Bonsall

Open Access

https://doi.org/10.1002/ece3.1083

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Abstract

The evolution of parental care is beneficial if it facilitates offspring performance traits that are ultimately tied to offspring fitness. While this may seem self-evident, the benefits of parental care have received relatively little theoretical exploration. Here, we develop a theoretical model that elucidates how parental care can affect offspring performance and which aspects of offspring performance (e.g., survival, development) are likely to be influenced by care. We begin by summarizing four general types of parental care benefits. Care can be beneficial if parents (1) increase offspring survival during the stage in which parents and offspring are associated, (2) improve offspring quality in a way that leads to increased offspring survival and/or reproduction in the future when parents are no longer associated with offspring, and/or (3) directly increase offspring reproductive success when parents and offspring remain associated into adulthood. We additionally suggest that parental control over offspring developmental rate might represent a substantial, yet underappreciated, benefit of care. We hypothesize that parents adjust the amount of time offspring spend in life-history stages in response to expected offspring mortality, which in turn might increase overall offspring survival, and ultimately, fitness of parents and offspring. Using a theoretical evolutionary framework, we show that parental control over offspring developmental rate can represent a significant, or even the sole, benefit of care. Considering this benefit influences our general understanding of the evolution of care, as parental control over offspring developmental rate can increase the range of life-history conditions (e.g., egg and juvenile mortalities) under which care can evolve.

Highlights

Ecology and Evolution published by John Wiley & Sons Ltd
We explored the following scenarios in which care serves to increase offspring egg survival and/or alter relative developmental rates: parental care (1) decreases egg death rate, (2) increases the proportion of time spent in the egg stage and decreases the proportion of time spent in the juvenile stage, (3) decreases the proportion of time spent in the egg stage and increases the proportion of time spent in the juvenile stage, (4) decreases egg death rate, increases the proportion of time spent in the egg stage and decreases the proportion of time spent in the juvenile stage, and (5) decreases egg death rate, decreases the proportion of time spent in the egg stage, and increases the proportion of time spent in the juvenile stage
The specific finding that parental control of offspring development rate can alone favor the evolution of parental care and/or alter the life-history conditions under which care will be selected for is, to our knowledge, novel and might help explain natural patterns of care

Summary

Introduction

Patterns of parental care are hugely diverse (Ridley 1978; Baylis 1981; Tallamy 1984; Clutton-Brock 1991: Rosenblatt 2003; Balshine 2012; Royle et al 2012; Trumbo 2012), and parental care is thought to have emerged independently multiple times (Rosenblatt and Snowdon 1996; Mank et al 2005). Parental care is beneficial to parents if it increases offspring survival, growth and/or quality (i.e., offspring performance), and offspring lifetime reproductive success (Clutton-Brock 1991; Rauter and Moore 2002; Alonso-Alvarez and Velando 2012; Klug et al 2012; Royle et al 2012).

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