Wheeler and colleagues pooled data of a different sortsamples from a diverse array of animalsto 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 Systme dAires Protges de Ma
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American Museum of Natural History