Environmental change as a driver of diversification in temporary aquatic habitats: does the genetic structure of extant fairy shrimp populations reflect historic aridification?

Abstract

Summary Over the past 65 my, the Australian continent experienced a pronounced shift from predominantly wet, tropical, conditions to a much drier climate. Little is known, however, about the effect of this important continent‐wide event on freshwater organisms and ecosystems. Fairy shrimps (Crustacea; Anostraca) are ancient and specialist inhabitants of temporary and saline aquatic habitats that typically prevail under semiarid conditions. Therefore, they present suitable evolutionary models to study scenarios of historic environmental change and the impact of a drying climate on aquatic ecosystems in particular. Focussing on both macro‐ and micro‐evolution in the fairy shrimp genus Branchinella and using mitochondrial DNA data (16S and COI), we evaluated whether patterns of contemporary genetic variation reflect historic climate change. There is a close match between episodes of Cenozoic climate change and macro‐evolutionary diversification in Australian fairy shrimps, presumably mediated by a progressive increase in the abundance and diversity of temporary aquatic habitats on the continent. Micro‐evolutionary patterns reflect both range expansion and recent contraction, linked to extreme drying events during the Pleistocene glacial periods. This study effectively illustrates the potential long‐term effects of environmental change on the diversity and the evolutionary trajectories of the fauna of temporary waters. Moreover, it demonstrates the importance of adaptation to new environments and non‐adaptive processes, such as divergence in isolation, for explaining extant diversity patterns in this particular environment.

Hydrological stability drives both local and regional diversity patterns in rock pool metacommunities

“…This interpretation is reliant on the assumption that dispersal limitation is not an issue and that the spatial scale does not impede colonization. Studies of the genetic structure of poorly dispersed plankton populations in this system show that rock pools on the inselbergs in this study have been colonized for at least several million years and that colonization of all suitable habitats happened in a relatively short window of time (Zofkova and Timms , Pinceel et al ). Additionally, the fact that the taxa which are absent from the less hydrologically stable metacommunities in the north are also absent from shallow unstable habitats in the south is consistent with environmental limitation rather than dispersal limitation.…”

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation

“…Under this scenario, global aridification events, which are broadly recognized as drivers of diversification in aquatic taxa (e.g. Pinceel et al, 2013;Dorn et al, 2014), could have been particularly relevant in the case of saline environments as one of the main forces for the colonization and further diversification in these systems (Arribas et al, 2014). Further studies on the temporal sequence of evolution of desiccation resistance and salinity tolerance in aquatic lineages could provide important insights for understanding the role of these mechanisms in driving evolution in inland waters.…”

Tolerance of disease‐vector mosquitoes to brackish water and their osmoregulatory ability

“…Although osmoregulatory mechanisms have been extensively studied in marine organisms, knowledge of these mechanisms in freshwater organisms is more limited compared with marine and brackish species. Particularly, the relationship between osmoregulation and salinity tolerance is not well known in freshwater species, despite the fact that salinity tolerance is an important determinant of local adaptation and evolutionary history (Munoz et al 2008, Pinceel et al 2013, Arribas et al 2014. Wigglesworth carried out the first pioneering study on osmoregulation in Aedes aegypti and Culex pipiens larvae (Wigglesworth 1938).…”