Asian-led research uncovered divergent adaptations in rodent species through genetic sequencing and found how they have
adapted to the arid lands and extreme climate of the deserts of Inner Mongolia, China. The study showcases a path to understanding how climate change may challenge animals at a genetic level. Could this field protect species against future
extinctions?
Desert animals have evolved certain features to acclimatise to extreme temperatures, aridity and water scarcity. To cope some rodents exhibit nocturnal activity and hide in burrows all day—changing their metabolism and water retention
abilities.
A Lesser Egyptian Jerboa (Jaculus jaculus )—not a Central Asian Jerboa. The jerboa is one of the species from the Dipodidae superfamily genomically profiled to study adaptative mechanisms that help rodents survive dry and cold desert
environments. | Cataloging
Nature / Unsplash
Scientists from the Key Laboratory of Zoological Systematics and Evolution, and the Novogene Bioinformatics Institute in China collaborated with the Jacob Blaustein Institutes for Desert Research in Israel to investigate the adaptive
mechanisms of some of these rodents, including the Northern three-toed jerboa (Dipus sagitta, DS), Siberian jerboa (Orientallactaga sibirica, OS), Midday jird (Meriones meridianus, MM), and Desert hamster
(Phodopus roborovskii, PR).
These four sympatric—meaning they occur in the same area—desert rodents inhabit the Eurasian inland, from Tianshan, Dalaihubu, and Xilinhot, Inner Mongolia, China. This unique landscape is arid and cold, where nomadic horse-riding tribes
peoples lived in the rough steppes.
‘Desert animals have evolved certain features to acclimatise to extreme temperatures, aridity and water scarcity.’
Although these rodents evolved different physical traits, habitat choices and activity patterns, they come from the same desert climate niche and historic geological background dating back to the late Miocene. For these reasons, these
rodent species were selected to study divergent adaptations in Inner Mongolian deserts.
Divergence
is when ‘two or more populations of an ancestral species accumulate independent genetic changes through time’. These changes can happen when populations become isolated and genetically distinct. Sometimes, the environment can be the cause
of these differences arising.
The environment in Central Asia has seen magnificent changes during a peculiar geological time, explaining the present-day arid conditions from Siberia to the Sahara desert.
The Tianshan Mountains in Inner Mongolia, China. | Yang Shuo / Unsplash
The Gobi desert in Central Asia was not always so arid. The aridification of Central Asia may have occurred in the late Mid-Late Miocene during a global cooling period which reduced the atmospheric water vapour, drying up the desert. A
change in topography also resulted in what is now known as the snow-capped Tianshan Mountains.
These research groups found, through genomic sequencing, that these desert rodents living in such cold and dry climates have divergent adaptative metabolic pathways affecting thermogenesis, including DNA repair and protein synthesis and
degradation required for survival in cold deserts.
‘Although these rodents evolved different physical traits, habitat choices and activity patterns, they come from the same desert climate niche and historic geological background… ’
The evolutionary history revealed phylogenetic relationships between the rodents. During geological changes, the Miocene epoch is responsible for the adaptive mechanisms of present-day Jerboas, Gerbils and Hamsters.
Among the functions of the genes studied were metabolic pathways involved in prostaglandins—lipid-based compounds released during tissue damage or infection—found in many desert species such as the dromedary, Tarim red deer and Saudi
Arabian indigenous chickens.
These compounds influencing endothelial and vascular smooth muscle cells can indirectly regulate blood pressure, water retention and reabsorption, and immediate hypersensitivity reactions. Therefore selective signalling of vasodilation
could contribute to the management of desert airborne dust.
Similarly, prostaglandins and other compounds play a role in thermoregulation and various other pathways allow some rodents to reduce signs of fever and inflammation. Results showed that prostaglandin regulation is highly active in these
desert rodents and therefore an important adaptation to cope with desert environments.
Desert rodents tend to be nocturnal to avoid the heat, but in Eurasian deserts with extremely cold weather, the thermostasis pathways are specific and target brown adipose tissue activity, increasing heat generation. During changing
temperatures, they can quickly induce shivering to keep warm. These mechanisms also help rodents adapt to sustain long periods of low food intake.
‘This research group found through genomic sequencing that these desert rodents living in cold and dry climates, have divergent adaptative metabolic pathways.’
They also identified genetic pathways to cope with water scarcity. For example, the ‘proteins-for-water’ transition to break down protein during early resource restriction may be a water source for desert species.
These adaptative mechanisms were surprisingly different from the evolutionary routes taken by larger mammals. Instead of producing heat, mammals’ genetic makeup is geared towards storing fat to maintain their body temperature.
The genome isolation of these four desert rodents shows how parallel genetic divergence can lead to the same adaptative mechanisms to survive in extreme climates. Desertification in response to climate change in Central Asia is expanding;
the areas at risk are those bordering places like the Gobi and other deserts. Genomics research may have an untapped potential to protect species in the current climate change scenario.
Featured Image: Yang Shuo | Unsplash / Alastair Rae | Flickr
Boundless (n.d.) ‘18.4D: Gene Duplications and Divergence,’ LibreTexts. Available at:
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Yang, J., Yang, K. & Wang, C. (2023) How desertification in northern China will change under a rapidly warming climate in the near future (2021–2050). Theor Appl Climatol, Article 151, Pages 935–948.
