‘Cold Spots’ Not Hotspots Key to Rapid Biodiversification
12/10/2020
LSU Museum of Natural Science researchers have discovered that bird species, such
as the White-browed purpletuft pictured here, may have more opportunity to rapidly
diversify in "cold spots," like deserts and mountaintops, rather than biodiversity
hotspots, like the Amazon rainforest. BATON ROUGE – The Amazon rainforest may be a hotspot for animal and plant diversity,
but this week, LSU scientists report that new species actually form there less often
than previously thought. Places like deserts and mountaintops that do not have a lot
of species provide more opportunity for rapid diversification. This paradox of diversity
– that new species form at a faster pace in “cold spots” than hotspots – was reported
this week in the journal Science.
A multinational team of scientists studied diversity in a major group of tropical
birds and they found that although coldspots might be extreme with dry, unstable environments,
they are also relatively empty, giving new species the elbow room to evolve. In contrast,
biodiversity hotspots like the Amazon rainforest are the result of the gradual accumulation
of species over time.
“Our results reveal a model in which species are forming faster in environmental extremes
but have accumulated in moderate environments to form tropical biodiversity hotspots,”
said Robb Brumfield, the LSU Department of Biological Sciences Roy Paul Daniels Professor,
LSU Museum of Natural Science Curator of Genetic Resources and LSU College of Science
Associate Dean of Research & Administration, who is a senior author on the paper published
in Science.
This paradox was revealed because of samples in the vast collections maintained by
natural history museums. The LSU Museum of Natural Science and its frozen tissues
collection, which is the oldest and largest of its kind in the world, contributed
tissues for 747 of the 1,287 bird species that are part of this study. The LSU sampling
represented 24 countries.
“The remarkable sampling in this study comes from 40 years of fieldwork by curators,
students, staff and others, who spent huge amounts of time and money, and risked their
personal health, collecting specimens from around the world,” said co-author Fred
Sheldon, the LSU Department of Biological Sciences George H. Lowery, Jr. Professor
and LSU Museum of Natural Science Curator of Genetic Resources.
Lead authors and LSU alumni Michael Harvey, who is an assistant professor at the University
of Texas at El Paso, and Gustavo Bravo, who is a postdoctoral researcher at Harvard
University, spent many months lugging around the essential, heavy cryogenic storage
units filled with liquid nitrogen to preserve tissue samples up remote streams in
Amazonia and into rugged mountain ranges in the Andes.
By analyzing the DNA from these museum tissue samples, the authors were able to map
the genetic relationships of a predominant group of tropical birds called the suboscine
passerines, which represent roughly one out of every three species of birds in the
American tropics. Suboscines vary widely in characteristics and habitats — from the
Andean snow line to lowland Amazonia and from cloud forests to deserts.
“This shows that conservation efforts to save the rapidly changing tropical landscape
need to focus not only on the species-rich Amazon, but also on regions that are less
diverse but contribute disproportionally to the generation of new species, like the
wind-swept, cold puna of the Andes Mountains,” Brumfield said.
Notably, many of the ornithologists involved in this study are from groups historically
underrepresented in the sciences including Latinx and women researchers.
“This paper marks not only a change in our understanding of evolution in the tropics
but also an acknowledgement and valuation of the diversity of culture, expertise and
perspective in the field of ornithology,” said a senior author Liz Derryberry, formerly
a postdoctoral researcher at the LSU Museum of Natural Science, who is an associate
professor at the University of Tennessee at Knoxville.
Additional Link:
The evolution of a tropical biodiversity hotspot, will be published in Science on Dec. 11: https://science.sciencemag.org/cgi/doi/10.1126/science.aaz6970
Contact Alison Satake
LSU Media Relations
510-816-8161
asatake@lsu.edu