Adaptation to climate change particularly difficult in peripheral areas

Rainbowfish, Photo: KLIVV/Vetmeduni Vienna

Rainbowfish, Photo: KLIVV/Vetmeduni Vienna  1

A study led by Vetmeduni Vienna that was recently published in the journal Molecular Ecology shows that populations at the edge of their range are particularly vulnerable to changing climates. According to the researchers, these new findings, obtained from studying rainbowfish in Australia, have implications for predicting the adaptive resilience of species and managing biodiversity in times of climate change.

The impact of increasing global temperatures is evident in most of the world’s ecosystems, but very little is known about how climatic variation influences natural selection and adaptive resilience across latitudes. An international research team led by Vetmeduni Vienna therefore investigated the differences in adaptive diversity of populations along a latitudinal region spanning temperate to subtropical climates. “We generated and integrated information from environmental mapping, phenotypic variation and genome-wide data from across the geographical range of the rainbowfish Melanotaenia duboulayi,” says study director Steve Smith from the Konrad Lorenz Institute of Ethology at Vetmeduni Vienna.

Limited adaptive resilience to climate change at range margins

After controlling for spatial population structure of the rainbowfish, a small freshwater fish that has its natural habitat in eastern Australia, the researchers detected strong interactions between genotypes and environment associated with variation in stream flow and temperature. They also found that some of the hydroclimate-associated genes interacted within functional protein networks that contain genes of adaptive significance for projected future climates in rainbowfish. Hydroclimatic selection was also associated with variation in phenotypic traits, including traits known to affect fitness of rainbowfish exposed to different flow environments.

Another finding was that populations exposed to extremes of important environmental variables showed stronger adaptive divergence and less variation in climate-associated genes compared to populations at more central latitudes. Steve Smith: “Our findings suggest that populations that evolved at environmental range margins and at geographical range edges may be more vulnerable to changing climates, a finding with implications for predicting adaptive resilience and managing biodiversity under climate change.” This is important because evolutionary responses are generally considered a prerequisite for long-term persistence of biodiversity, especially during ongoing and projected scenarios of increasing frequency and severity of extreme climate events.

Better assessment of the adaptive resilience of species by linking genomics with eco-evolutionary models

Rapid habitat alteration is a global ecological phenomenon. In this context, the study describes a strategy for cataloguing adaptive genetic diversity to climate change across the range of ecologically important non-model species. Such catalogues can be improved with the addition of population data sets based on whole genomes, which can provide a high-resolution record of variants across the genome and structural information about causative genes. “Linking genomics with eco-evolutionary models would provide powerful opportunities for tracking and predicting adaptive responses and vulnerability to climate change along latitudinal gradients,” says Steve Smith.

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