Tropical mountain species at the center of climate change

The absence of varied seasons and temperatures in the tropical mountains has led to the creation of species highly adapted to their narrow niches, thus creating the conditions conducive to the emergence of new species in these areas, according to a new study published in the Proceedings of the National Academy of Sciences.

Yet the same characteristics that make tropical mountains among the world's most biodiverse ecosystems also make the species living there more vulnerable to rapid climate change, the study reveals.

The research compares species evolution rates in three types of aquatic water-course insects: ephemeral (Ephemeroptera), sandflies (Plecoptera) and Trichoptera (Trichoptera) – in temperate mountainous regions and tropical. The results have implications for similar models in other tropical mountain species.

An interdisciplinary team of physiologists, genetics and genomics specialists, population biologists and taxonomists from four universities collected samples and data from mountain streams in the Colorado Rocky Mountains and the Ecuadorian Andes over a two-year period .

"Because the tropics are not as seasonal as the more northerly temperate zones, tropical insects can not be too cold or too hot and therefore have a narrow thermal width," said Kelly Zamudio, a professor in the Department of Tropical Medicine. Ecology and Evolution Biology of Cornell University and co-lead author of the study. "We also found that they were moving less on the side of the mountain and that there were more species [on tropical mountains] Therefore. Nobody had tested these three models in the same system before. "

The results corroborate and reveal the mechanisms behind a classic 1967 article that predicts this dynamic.

Tolerance factors for temperature and range of motion also affect how species in each of these areas will respond to climate change. Because tropical species can not withstand large temperature changes and have limited movement, they are much more sensitive to rapid changes in temperature due to anthropogenic climate change.

"It is truly paradoxical that the same factors that lead to many species are those that will endanger these species in the tropics," said Zamudio.

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More information:
Nicholas R. Polato et al., Close thermal tolerance and low dispersion result in higher speciation in tropical mountains. Proceedings of the National Academy of Sciences (2018). DOI: 10.1073 / pnas.1809326115