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March 27, 2019

UMass Boston researchers find temperate climates better for amphibian microbiomes than the tropics


  • Boston
Postdoc Molly Bletz is co-lead author of new paper in Nature Ecology & Evolution

A team of international researchers led by two researchers at UMass Boston have found there’s a correlation between where amphibians are living and the organisms living on their skin. These findings could help researchers fight amphibian-killing fungi.

Molly Bletz, a postdoctoral research associate in the Woodhams Lab, is the co-lead author of a paper published in Nature Ecology & Evolution last month. Bletz and the other researchers were able to show that skin microbiomes, or the group of microscopic organisms that live on host animals, were more diverse in environments that had distinct seasons and colder winters compared to environments with warm winters and less temperature variation over the course of the year.

Bletz and Assistant Professor of Biology Douglas Woodhams, one of two co-senior authors, said this is the first time that researchers have been able to make a temperature connection to microbiomes. More than 2,300 amphibians—frogs, toads, and salamanders—were studied all over the world.

“One of the main findings, I think, was that biodiversity of the microbiome on hosts is really in this gradient from the temperate zone where it’s most diverse to the tropics where it’s the least diverse, which is the opposite of every other organism,” Woodhams said. “If you think of mammals or you think or amphibians themselves or any vertebrate, they’re all most diverse in the tropics. And so this is the opposite trend for microbes, which is, I think, pretty interesting.”

As for why this is the case, Woodhams and Bletz have a few ideas.

“We think that probably the different seasons allow for different types of microbes to shift from time to time and so you have more diversity because of the different temperature characteristics,” Woodhams said.

Added Bletz, “There’s dormancy, competition, and thermal growth optimum, this idea that bacteria have this ideal growing temperature. ... Bacteria can basically go into its little shell and hang out there and become active when it’s optimal.” 

Bletz said that these findings are critical as researchers look at ways to control, prevent, and fight amphibian-killing fungi.

“Global amphibian decline, driven by globally invasive skin pathogens Batracochytridium dendrobatedis (Bd) and Batrachochytrium salamandrivorans (Bsal), is a conservation challenge that has resulted in countless declines and even extinctions of amphibians across the globe,” Bletz said. “Amphibian skin microbiota are critical for amphibian health, and provide an important line of defense against skin pathogens like Bd and Bsal.”

Meanwhile, the work in this area continues. The day after the Nature Ecology & Evolution article came out, Woodhams was a coauthor on a review paper in Experimental Biology and Medicine on ways that the microbiome can be shaped to help disease management in amphibians and other animals.

Jordan Kueneman of the Smithsonian Tropical Research Institute in Panama is the other co-lead author of the Nature Ecology & Evolution paper; Miguel Vences of Technische Universität Braunschweig in Germany is the other co-senior author. Other contributors are from institutions ranging from the University of Alabama to Seoul National University.