Untangling the ecology, taxonomy, and evolution of the Chaetogaster limnaei (Oligochaeta: Annelida) species complex by Kristin Forgrave
Abstract:
The oligochaete Chaetogaster limnaei has two subspecies, an ectosymbiont and
endoparasite, which are distinguished by the location where they are found in their host snail
Physa gyrina, as well as morphological and diet differences. This study investigated the
molecular differences between the two subspecies, using mitochondrial COI primers, to
understand the evolution patterns between the two and see if they should be reclassified as
separate species. Molecular analysis indicated that the external symbiont evolved first, and the
endoparasite evolved from it and is not specific to the kidney. It can live in the kidney or
externally, whereas the ectosymbiont can only live externally. The complexity of the
phylogenetic tree indicated that these two subspecies may be too closely related to be separate
species.