Species richness, distribution and genetic diversity of <it>Caenorhabditis</it> nematodes in a remote tropical rainforest

• Main Authors: Félix Marie-Anne, Jovelin Richard, Ferrari Céline, Han Shery, Cho Young Ran, Andersen Erik C, Cutter Asher D, Braendle Christian
• Format: Article
• Language: English
• Published: BMC 2013-01-01
• Series: BMC Evolutionary Biology
• Subjects: <it>Caenorhabditi</it>s; Species richness; Population structure; <it>C. briggsae</it>; Nucleotide diversity
• Online Access: http://www.biomedcentral.com/1471-2148/13/10

<p>Abstract</p> <p>Background</p> <p>In stark contrast to the wealth of detail about <it>C. elegans</it> developmental biology and molecular genetics, biologists lack basic data for understanding the abundance and distribution of <it>Caenorhabditis</it> species in natural areas that are unperturbed by human influence.</p> <p>Methods</p> <p>Here we report the analysis of dense sampling from a small, remote site in the Amazonian rain forest of the Nouragues Natural Reserve in French Guiana.</p> <p>Results</p> <p>Sampling of rotting fruits and flowers revealed proliferating populations of <it>Caenorhabditis</it>, with up to three different species co-occurring within a single substrate sample, indicating remarkable overlap of local microhabitats. We isolated six species, representing the highest local species richness for <it>Caenorhabditis</it> encountered to date, including both tropically cosmopolitan and geographically restricted species not previously isolated elsewhere. We also documented the structure of within-species molecular diversity at multiple spatial scales, focusing on 57 <it>C. briggsae</it> isolates from French Guiana. Two distinct genetic subgroups co-occur even within a single fruit. However, the structure of <it>C. briggsae</it> population genetic diversity in French Guiana does not result from strong local patterning but instead presents a microcosm of global patterns of differentiation. We further integrate our observations with new data from nearly 50 additional recently collected <it>C. briggsae</it> isolates from both tropical and temperate regions of the world to re-evaluate local and global patterns of intraspecific diversity, providing the most comprehensive analysis to date for <it>C. briggsae</it> population structure across multiple spatial scales.</p> <p>Conclusions</p> <p>The abundance and species richness of <it>Caenorhabditis</it> nematodes is high in a Neotropical rainforest habitat that is subject to minimal human interference. Microhabitat preferences overlap for different local species, although global distributions include both cosmopolitan and geographically restricted groups. Local samples for the cosmopolitan <it>C. briggsae</it> mirror its pan-tropical patterns of intraspecific polymorphism. It remains an important challenge to decipher what drives <it>Caenorhabditis</it> distributions and diversity within and between species.</p>