Behavioral optimization of camouflage in remote Sahara-Sahel rodent communities

How organisms respond to environment change is one of the most important puzzles in evolutionary biology. The main challenge to uncover genomic mechanisms that underpin adaptation is that the microevolutionary responses to climate change are difficult to discover due to slow rate of changes. To circumvent this problem one can investigate taxa that persisted throughout past severe climatic changes.

In this project we will test the effect of past climatic changes on the genomic architecture of adaptation using common Sahara desert specialist Jaculus jaculus. Sahara since the Mid-Upper Pliocene went thought several climate changes. Those caused changes in velocity of sediment depositions generated by erosion, leading to the formation of bare, rocky and dry sandy areas and dune systems, the habitats of recently discovered two divergent genetic lineages, or cryptic species, within Jaculus jaculus. Those species specialized to explore two divergent habitat types (dark rock and light sand) and evolved the coat-habitat colour matching. Intriguingly both habitat types form mosaic throughout Sahara, and its extent is affected by changes in climate in the region, causing frequent overlap between the two species distributions. This led us to purpose that divergent selection on camouflage, and habitat specialization, could have driven molecular divergence in this system. However light and dark colour phenotypes occur within both species. Thus, it is not known if camouflage drives further divergence between species, or if it inhibits speciation by allowing gene flow between the same colour morphs from the two species. Considering those observations, and the fact that the quality and quantity of available habitats is affected by climate change, it is essential to ask the question: what is the role of climate changes in shaping the genomic background of a key fitness trait, like camouflage, behavioural habitat specialization or adaptation to extreme desert conditions?

To answer these questions we will apply an interdisciplinary approach (population genomics, transcriptomics, and ecological modelling) to investigate ecological and evolutionary mechanisms behind adaptation and diversification in extreme and variable desert conditions. In 6 tasks (T) of our project we will: T1 - supplement an existing sample collection, T2 - estimate phenotypic variation and habitat structure, T3 - identify spatial genetic and demographic trends, T4 - find species areas of sympatry and species ranges changes during climatic changes, T5 - detect specific gene expression, and T6 - identify genomic regions associated with functions.

We will provide detailed first insights into the genomic architecture of traits associated with adaptation and diversification in an organism that has experienced extreme climatic conditions and changes. The results will provide evidence for the mechanisms of adaptive responses to changing climate, to predict species ability to sustain habitat alteration.