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Climate Change Found to Have Significant Effects on Biodiversity in Tropical Mountains

Climate change makes animals in the tropical mountains incapable of adapting extreme changes in their environment / Photo by Roman Mikhailiuk via 123RF

 

A new study published in the Proceedings of the National Academy of Sciences found factors that aid in developing biodiversity of species in tropical mountain also make these species more vulnerable to climate change. Researchers from Cornell University, Colorado State University (CSU), Universidad San Francisco de Quito in Ecuador, and the University of Nebraska­–Lincoln gathered data from Colorado Rocky Mountains streams and in the Ecuadorian Andes for a period of two years. This is according to a report by United Press International.

 

Isolation and New Species

The researchers found that animals residing in tropical mountains are incapable of adapting to extreme changes in the climate, which keeps these species isolated in a certain ecosystem and unlikely to travel to other locations. Over time, that geographic sluggishness can hinder the animals' gene flow and keep out other species from nearby communities.

The lack of different seasons and temperatures in these environments also led these species to adapt in their narrow niches as well as developing the proper conditions for new species to arise in these locations. On the other hand, those who live in temperate regions are exposed to different seasons with varying temperatures. This allows these species to become more adapted to a wider range of temperatures and also allows them to move between locations.

These well-adapt animals also share genes more expectantly between populations, making their population more homogenous and much less diverse compared to tropical species.

The Cornell Chronicle reports that the same characteristics that make tropical mountains to be one of the most biodiverse ecosystems on the planet are also the reason why species that reside in them to be more vulnerable to rapid climate changes.


Comparing Rates

In the study, the investigators compared rates that new species develop in three kinds of aquatic stream insects—mayflies (Ephemeroptera), stoneflies (Plecoptera) and caddisflies (Trichoptera) — in a controlled area and in a tropical mountain area. The results found indications for similar orders in other species found in tropical mountains.

The interdisciplinary team of physiologists, geneticists and genomics specialists, population biologists, and taxonomists from the said institutions also tested each of the species' tolerance in temperature as well as assessing the genetics of their populations to outline the animals' range of movement.

Senior co-author and Goldwin-Smith Professor in the Department of Ecology and Evolutionary Biology Kelly Zamudio said bugs in the tropics have a "narrow thermal breadth" due to the fact that they don't get too hot or too cold since the tropical areas are not as seasonal compared to the northern temperate zones.

“We also found that they move less up and down the side of the mountain, and there are more species [on tropical mountains] as a result. Nobody had tested all three of those patterns in the same system before.”

Findings of the latest study support and demonstrate the mechanisms that were used as the basis for a 1967 paper that envisioned these dynamics. The 51-year-old paper was made by Dan Janzen wherein he proposed a unifying framework that relates to latitudinal differences in climate variations to elevational trends in biodiversity.

The recent study shows that tropical species in three different populations have a more limited thermal breadth, decreased dispersal, and higher population structure, and higher cryptic diversity and speciation rates.


Vulnerable to Changes

Due to their inability to withstand massive alterations in changes and their restricted movement, tropical species are much more vulnerable to fast temperature shifts caused by anthropogenic climate change. Zamudio said it is "paradoxical" that the similar traits that caused the rise of many species are the same factors that can put these animals in peril while being in the tropics.

Biologists from CSU led their colleagues when they gathered samples of insect communities in streams every 500 meters of elevation change in Colorado and Ecuador during the two-year period. Upon gathering the samples for both locations, a team of taxonomists examined the number of specific species that were present. The scientists also searched for "cryptic diversity"—populations are starting to veer into so they could create new species—but such location is yet to be found.

Zamudio's team worked with Chris Funk, professor of biology at CSU, to arrange swaths of the genomes of the collected insect species to determine just how much gene-sharing have happened within their populations.

"We found that in the tropics, there is a lot less sharing of genes across these populations up and down the side of the mountain, and the number of migrants is much smaller,” said the senior co-author.

Future research could integrate testing to find out if there are existing similar patterns for other mountain species, which includes terrestrial animals, and additional presumptions of which populations species will be deemed to be the most endangered.

The study, according to the researchers, "advances the understanding of how climate variability shapes global diversity patterns, moving beyond simple correlations, to mechanistic links between climate, local adaptation, dispersal, and montane species richness."

 

Tropical species are more vulnerable to fast temperature shifts caused by climate change / Photo by Andrei Gilbert via Shutterstock

 

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