Why are there more species in some parts of the world and fewer in others? Biodiversity is not consistent across the globe – for instance, more than two-thirds of the world’s species live in the tropics.
Jaron Adkins, a postdoctoral scientist in the Department of Watershed Sciences and the Ecology Center at Utah State University, is the lead author of a recently published study exploring biodiversity patterns.
“So there's kind of this hump-shaped pattern of diversity where it's high at the equator and low at the poles. That's something that biologists and ecologists have been aware of for a few 100 years now," Adkins said.
To explore ecological factors driving patterns of mammalian biodiversity, Adkins and his associates analyzed global climate data.
“We found that mammal diversity was at its maximum in places that have intermediate precipitation seasonality,” Adkins said.
“Precipitation seasonality” refers to how annual rainfall is distributed throughout the year.
“So a semi-arid place can have low seasonality, as can a tropical rainforest," Adkins said. "On the other extreme, ecosystems for example that have monsoon seasons, where they get all of their rainfall within a few months, have high seasonality."
Places with intermediate precipitation seasonality have even distribution of wet and dry seasons.
Climate change is altering where and how much precipitation falls across the globe. As the effects of climate change worsen, Adkins expects biodiversity to change as well.
“So our study is showing that precipitation seasonality is incredibly important for ecosystems, at least in its effects on diversity. And given that that is likely to change under climate change, we think that it's really important for other scientists to start thinking more about precipitation seasonality,” Adkins said.
