With the iconic polar bear on thin ice, as global warming melts away its hunting ground, how will other Arctic mammals fare? Computer modelling allows us ways to predict how species have responded to climate change in the past, and what the outcome will be for them in the future.
Now, a new set of models have been developed to predict responses of cold-adapted species, especially in the face of current global warming. Previously, the “expansion-contraction” model was the only model used in Europe to study species’ responses to glacial-interglacial cycles. However, that model is more suitable for tropical and temperate species, and not so applicable for Arctic species.
“Arctic species suffer the most due to global climate warming and without a doubt, people are responsible for this trend,” says author Dr Joanna Stojak, from the Polish Academy of Sciences (Poland). “We cannot go back, but hopefully we can still prevent the next massive extinction. And the best start is to understand how climate warming influences Arctic taxa.”
To make this new model, the biogeographic history of cold-adapted land mammal species was described, enabling responses to glacial cycles and climate fluctuations to be identified. From this research, three new response models were identified:
- Extinction and genetic diminution
- Extinction and replacement
- Contraction and gene transfer
In the “extinction and genetic diminution” response, previously widespread populations went locally extinct, biogeographic ranges contracted, and remaining populations became characterised by low genetic diversity. This is the case for the narrow-headed vole (Lasiopodomys gregalis), Northern collared lemming (Dicrostonyx spp.) and the Norway lemming (Lemmus lemmus).
For species like the Arctic fox (Vulpes lagopus), wolverine (Gulo gulo) and reindeer (Rangifer tarandus), their response fitted an “extinction and replacement” pattern, where some local populations went extinct, but were replaced by migrating lineages seeking refuge from elsewhere. In contrast, the mountain hare (Lepus timidus) and the sable (Martes zibellina) were best modelled by “contraction and gene transfer”, where the biogeographic ranges of these species contracted, while temperate species expanded, leading to gene transfer between Arctic and more temperate species.
“We took a closer look at past and present changes in the genetic diversity of different cold-adapted species and how their ranges were changing along with changing climate,” says Stojak. “It was very exciting to see that different taxa responded differently, yet still we were able to identify clear and common patterns.”
These models come at a crucial time for understanding the different ways cold-adapted species may respond to human-induced climate change and will help inform better decision-making for biodiversity and habitat conservation for species most at risk.
This work has been published in Mammal Review.
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Qamariya Nasrullah holds a PhD in evolutionary development from Monash University and an Honours degree in palaeontology from Flinders University.
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