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Every species has had to find the right environment and avoid uninhabitable situations throughout their history. Many animals and plants will find their home less welcoming as the climate changes.
Animals can seek shelter in the short-term, while plants can prevent drying out by closing their small pores on the leaves. These behavioural responses may not be sufficient over a longer time. To escape harsh environments, some species may have to migrate to better habitats.
Large swathes on Earth’s surface were inhospitable by large numbers of animals and plants during glacial times. Populations began to migrate away from their original ranges or died off. Many people would move to more hospitable areas in order to survive these harsh climate conditions.
These areas were call refugia, and their presence was essential for the survival of many species. This may made more difficult by the rapid increase in global temperatures and recent human activity.
Locating The Refugia Species
A species’ genome often contains evidence for historic climate refugia. A refugium’s population will usually be smaller than its parent population. The expanding population will lose genetic diversity through genetic drift and inbreeding. We can find potential refugia by sequencing multiple individuals from different species to determine the genetic diversity hotspots.
My colleagues and me recently conduct research on population genetic diversity within the narrow-leaf Hopbush, an Australian native plant that was use in beer-making by early European Australians. The hopbush found in a variety of habitats including woodlands and rocky outcrops at mountain ranges. It has a large distribution throughout central and southern Australia. The hopbush is an extremely hardy species that can withstand drought.
The Flinders Ranges population had higher genetic diversity than the ones to the east, which suggests that they are remnants of an old refugee. Mountain ranges can be a refuge for species, as they only require them to move a short distance up or down the slope in order to maintain their ideal climatic conditions.
The peak of the last Ice Age in Australia led to dry conditions in the middle. Many animal and plant species began to migrate southwards, seeking refuge in southern regions that were more humid. An area known as Adelaide Geosyncline in the south-central region has been recognize as an important historical refuge for many animal and plant species. The area includes two mountain ranges of significant importance: Mount Lofty and Flinders.
The Future Is Your Refuge
Refugia at higher elevations and towards the poles are good options for those experiencing high temperatures. These shifts are already evident in species distributions Species.
However, migrating up a mountain could lead to a dead end. Eventually, species reach the top and are unable to move on. The American Pika is a cold-adapted relative to rabbits and lives in mountainous areas in North America. Because of extreme heat in many alpine areas, it has been force to flee from its former home.
Furthermore, species are forced to migrate rapidly due to the unprecedent global temperature rise. This is combined with the destruction of natural habitats by agriculture and urbanization, which can lead to migration to suitable refugia becoming impossible for many species.
Although evidence is not available for both climate change and habitat fragmentation, it is clear that the consequences are severe. Modeling the combined effects of climate change, habitat fragmentation and drought on British butterflies led to widespread population extinction predictions by 2050.
The Adelaide Geosyncline is the focus of our study. It has been extremely fragmented since European settlement. There are only 10% of the remaining native forests in some areas. Because of this, the few remaining patches of native vegetation have been left very fragmented. These pockets will limit migration and gene flow, which could impact species like the hopbush’s survival chances.
While refugia may have been able to save species in the past and some poleward or up-slope shifts may offer temporary refuge for others, global temperatures will continue to rise and more species will be force beyond their limits.