(ORDO NEWS) — Canadian scientists have assessed what environmental factors have influenced the evolution of crocodiles in South and North America over the past tens of thousands of years.
It turned out that climate change did not affect these reptiles as much as the lowering of sea levels during the last ice age, which isolated the populations of Caribbean and Pacific crocodiles
Scientists from McGill University (Canada) asked themselves the question: what has been the main driving force behind the evolution of crocodiles over the past thousand years and what has most influenced the populations of these reptiles?
The authors focused on the sharp-snouted crocodiles ( Crocodylus acutus ), which are widespread in South and North America.
The results of the study suggest that changes in temperature and rainfall had little effect on gene flow between crocodile populations, while the main contribution to the evolution of these reptiles was made by sea level changes during the last ice age.
Sharp-snouted crocodiles can tolerate significant temperature fluctuations and are little affected by changes in rainfall.
However, about 20 thousand years ago, a huge amount of water formed vast ice sheets, and sea levels fell by more than 100 meters. This created a geographic barrier that divided the Isthmus of Panama crocodile populations.
Crocodiles are excellent swimmers, but they cannot travel long distances on land. Therefore, during the ice age, the populations of Caribbean and Pacific crocodiles were isolated from each other, which greatly influenced their further evolution.
The scientists also compared the climate hardiness of modern sharp-snouted crocodiles with models of the region’s climate over the past million years.
Apparently, the reptiles easily endured the temperature fluctuations of the Ice Age. However, the effect of sea levels on crocodilian evolution was one of the first known instances of an ice age affecting a tropical species in this way.
Humans now have a much greater influence on sharp-snouted crocodiles, the researchers say, and the findings provide new insights into how environmental factors affect the evolution of these reptiles and where conservation efforts should be focused on specific crocodile populations in Panama.
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