MSU research reveals new insights into species diversity

New research led by Michigan State University scientists has found that species hailing from the tropics are less variable than those farther from the equator, which may affect their ability to survive environmental changes.

January 29, 2018 - Author: James Dau

EAST LANSING, Mich. – New research led by Michigan State University (MSU) scientists has found that species hailing from the tropics are less variable than those farther from the equator, which may affect their ability to survive environmental changes.

With support from the National Science Foundation’s National Ecological Observatory Network (NEON), the multi-institutional team of researchers completed a yearlong study of bird specimens held in worldwide museum collections. Data from the collections were made available through VertNet, a web-based archive of biodiversity information. The team examined how body size varied among individuals within tropical species, then compared them to closely related species in regions farther north or south.

Quentin Read, research associate in the lab of MSU Department of Forestry assistant professor Phoebe Zarnetske, is the study’s lead author.

“There has been a lot of thought in ecology that if species in the tropics have less variability among their individual members, they’ll be more sensitive to environmental changes,” Read said. “We compared the distribution of body sizes between the two groups of birds and found those in the tropics were, in fact, more homogenous.”

The tropics feature far less seasonal variability and a more stable food supply than other climate zones, factors that Read believes may contribute to the development of more specialized, more homogenous species. This leaves them vulnerable to shifting environmental conditions to which they are not adapted, such as those resulting from climate change, whereas their brethren from more temperate regions evolved to thrive under seasonal variations in weather and food availability.

“An average change of 4 degrees means more in the tropics than it does, say, in Michigan,” Read said. “Organisms that have more variability are more inherently capable of dealing with changing conditions.”

While the essential idea underscoring the study – that tropical species feature less diversity than closely related ones from elsewhere on Earth – is over 50 years old, it had yet to be tested on a global scale, something now possible through web-based archives such as VertNet.

“If we can understand where species are more sensitive to environmental change, we can better prioritize conservation efforts,” Zarnetske said. “Diversity within a species has value in itself, and studies like this help us understand why it exists and how it develops.”

This study was only the first in what Read, Zarnetske and their team hope will become a larger effort that takes their findings into the field. Though the museum specimens, some of which date back as much as 100 years, provide a baseline, they reflect the climate and conditions of the times in which they were collected. Measuring birds currently living in the wild would allow the scientists to confirm their findings and determine how the species may have changed in the intervening years. Incorporating other traits, such as beak length and wingspan, which reflect specific aspects of feeding and mobility, would allow the team to consider additional ways that the species may respond to environmental change.

“Conducting broad-scale studies like this help us think about how species shift and change on a global scale,” Zarnetske said. “We’re taking ideas that, in years past, could only be directly examined at a smaller scale and using them to tackle global issues.”


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