Climate change and timing of avian breeding and migration: evolutionary versus plastic changes.

Anne Charmantier,Phillip Gienapp

doi:10.1111/eva.12126

Abstract

There are multiple observations around the globe showing that in many avian species, both the timing of migration and breeding have advanced, due to warmer springs. Here, we review the literature to disentangle the actions of evolutionary changes in response to selection induced by climate change versus changes due to individual plasticity, that is, the capacity of an individual to adjust its phenology to environmental variables. Within the abundant literature on climate change effects on bird phenology, only a small fraction of studies are based on individual data, yet individual data are required to quantify the relative importance of plastic versus evolutionary responses. While plasticity seems common and often adaptive, no study so far has provided direct evidence for an evolutionary response of bird phenology to current climate change. This assessment leads us to notice the alarming lack of tests for microevolutionary changes in bird phenology in response to climate change, in contrast with the abundant claims on this issue. In short, at present we cannot draw reliable conclusions on the processes underlying the observed patterns of advanced phenology in birds. Rapid improvements in techniques for gathering and analysing individual data offer exciting possibilities that should encourage research activity to fill this knowledge gap.

Highlights

Changes in the phenology of spring events are among the most frequently reported responses to climate change across all trophic levels and all types of freshwater, terrestrial and marine environments (e.g. Parmesan and Yohe 2003; Root et al 2003; Thackeray et al 2010)
Timing of migration is affected by other environmental variables such as favourable tailwinds (Alerstam 1990) or conditions at stop-over sites or wintering areas (Saino and Ambrosini 2008), which can be affected by climate change partly independently of temperature
When fine-grained environmental variables are used in analyses of individual phenotypic plasticity for avian phenology, they are commonly daily mean temperatures averaged over certain fixed calendar dates, which limits the possibility to extrapolate to other systems

Summary

Introduction

Changes in the phenology of spring events are among the most frequently reported responses to climate change across all trophic levels and all types of freshwater, terrestrial and marine environments (e.g. Parmesan and Yohe 2003; Root et al 2003; Thackeray et al 2010). Two studies analysed phenotypic plasticity in breeding time for the UK great tit population cited above, and depending on the period over which spring temperatures were averaged, individual variation in reaction norm slopes was present (Husby et al 2010) or absent (Charmantier et al 2008). When fine-grained environmental variables are used in analyses of individual phenotypic plasticity for avian phenology, they are commonly daily mean temperatures averaged over certain fixed calendar dates, which limits the possibility to extrapolate to other systems These fixed periods are identical in all years for a given population, for example, from 15 February to 25 April in Husby et al (2010) for the UK great tit population, which means that the predictive value of this proxy will co-vary with the absolute phenological timing in birds. Collective sharing of data in collaborative studies including experts in the analyses of microevolution, plasticity and selection could well soon trigger a multitude of new results and bring this field to a whole new scale

Conclusions and future directions

Findings

Literature cited