Aridity promotes bet hedging via delayed hatching: a case study with two temporary pond crustaceans along a latitudinal gradient
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Climate change does affect not only average rainfall and temperature but also their variation, which can reduce the predictability of suitable conditions for growth and reproduction. This situation is problematic for inhabitants of temporary waters whose reproductive success depends on rainfall and evaporation that determine the length of the aquatic phase. For organisms with long-lived dormant life stages, bet hedging models suggest that a fraction of these should stay dormant during each growing season to buffer against the probability of total reproductive failure in variable environments. Thus far, however, little empirical evidence supports this prediction in aquatic organisms. We study geographic variation in delayed hatching of dormant eggs in natural populations of two crustaceans, Branchinella longirostris and Paralimnadia badia, that occur in temporary rock pools along a 725 km latitudinal aridity gradient in Western Australia. Consistent with bet hedging theory, populations of both species were characterised by delayed hatching under common garden conditions and hatching fractions decreased towards the drier end of the gradient where the probability of reproductive success was shown to be lower. This decrease was most pronounced in the species with the longer maturation time, presumably because it is more sensitive to the higher prevalence of short inundations. Overall, these findings illustrate that regional variation in climate can be reflected in differential investment in bet hedging and hints at a higher importance of delayed hatching to persist when the climate becomes harsher. Such strategies could become exceedingly relevant as determinants of vulnerability under climate change.
KeywordsDiapause Risk spreading Climate change Life history Australia
Tom Pinceel is currently funded by a postdoctoral fellowship from the Research Foundation Flanders (FWO, 12F0716N). This research received additional funding from the Research Foundation Flanders (3E090007 and 3E110799) and the Excellence Center ‘Eco and socio-evolutionary dynamics’ (PF/10/007) of the KU Leuven Research Fund. The authors thank Dr. Falko Buschke and Dr. Joost Vanoverbeke for their advice with regard to the data analyses, Prof. Luc De Meester for his valuable feedback on an early version of the manuscript and Prof. Brian Timms for his guidance and advice during the sampling campaign. We thank the Department of Environment and Conservation of Western Australia for issuing permits.
Author contribution statement
TP, BV and LB conceived and designed the experiments. TP, BV and LB performed the sampling. WH and TP performed the experiments. KT performed the hydrological modelling. TP, KT and WH analysed the data. All authors wrote the manuscript.
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