Amnh Scientists Grace The Covers Of Both Science And Nature
In an unusual confluence of events, two comprehensive, collaborative projects that include the work of two different curators from the American Museum of Natural History will grace the covers of the journals Science and Nature this week. For the paper in Science, herpetologist and Associate Dean of Science Christopher Raxworthy and colleagues analyzed thousands of species, rather than the more typical few keystone species, to determine a conservation plan for a tropical "hotspot," a biologically rich but threatened region. The research by Ward Wheeler, Curator in the Division of Invertebrate Zoology, also drew from analysis of many taxa: by comparing at the genetic level 77 animals from 21 different phyla, he and his colleagues have redrawn the phylogenetic tree of multicellular animals.
Phelsuma quadriocellata (Four spotted day gecko) from rainforest in Eastern Madagascar (Andasibe region).
Credit: C.J. Raxworthy
A new way to conserve the diverse and unique animals and plants in Madagascar was the goal of Raxworthy's contribution to Science. Madagascar is a global hotspot, with many unique species, and this tropical nation, an island the size of California, has committed to expanding its protected areas to cover 10 percent of the land. The study looked at over 2,300 species and, after finding little correlation between the distribution of ants, frogs, geckos, butterflies, plants, and other groups, used new computer methods to map the regions of the country that could efficiently harbor healthy populations of all species. A bonus was that the new multi-species approach identified regions that have been ignored to date, such as the less glamorous shoreline forests and some neglected mountains. "By analyzing multiple species, we came up with conservation recommendations that are more robust for biodiversity as a whole, and expect that by tweaking and expanding the existing reserve network, we will have a much more efficient system," explains Raxworthy. "Hopefully this study will encourage other tropical countries to try similar approaches that pool data to develop more effective conservation solutions."
Comb jelly (model)
Credit: AMNH / Rod Mickens
Wheeler and colleagues pooled data of a different sort: samples from a diverse array of animals to look at evolutionary relationships from sponges to humans. Genetic sampling allows researchers to see relationships among species that could be hidden from view if not reflected in morphology, or the physical characteristics that are traditionally used to determine phylogeny. This study, as reported in Nature, analyzed some 40 million base pairs of RNA from diverse phyla and used the overlap to reconstruct the family tree. But what Wheeler and colleagues found uprooted parts of the tree of life: sponges, once thought to be basal (diverging earliest from all others in the group) among animals because of their simple organization and lack of a nervous system, were found in this study to be more derived. Comb jellies, a group which includes stingless sea gooseberries, seem to have primitive shared characteristics. These results "point us in a direction for further research," explains Wheeler. "These represent animal phyla, and although their morphologies are well-characterized anatomically, they are very disparate and hard to compare. To deal with this problem, we used genetic data." Other findings that warrant further research: tardigrades (tiny, segmented "water bears" with claws that can suspend life for years in lichen and moss), initially thought to be like insects now seem to be closer to nematodes (annelids, or worms); and true, segmented worms, formerly thought to be related to arthropods may share closer ancestry with mollusks.
The analysis of plant and animal distribution in Madagascar that Raxworthy participated in was conducted by researchers from the Department of Environmental Sciences, Policy, and Management at the University of California, Berkeley, with input from the 20 additional authors, who provided biodiversity information, analytical expertise, and technical assistance. The project was facilitated by Système des Aires Protégées de Madagascar and funded by the MacArthur Foundation. The phylogenomic sampling by Wheeler and colleagues was primarily funded by the National Science Foundation (the Protostome Assembling the Tree of Life Project). The affiliations of other authors include the University of Hawaii, Yale University, Brown University, and Harvard University, among others.
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