Worms without borders: genetic diversity patterns in four Brazilian Ototyphlonemertes species (Nemertea, Hoplonemertea)

Abstract

Understanding the evolutionary processes from recent demographic history is especially difficult for interstitial organisms due to their poorly known natural history. In this study, the genetic variation and population history of the four Ototyphlonemertes (Diesing in Sitz ber Math Nat Kl Akad Wiss Wien 46:413-416, 1863) species were evaluated from samples collected along the Brazilian coast (between 27°31 0 S and 13°00 0 W) in 2006. The mitochondrial region cytochrome c oxidase subunit 3 (COX3) is analyzed to assess the genetic variation of these dioecious species. Although these species have a sympatric distribution along the coast, our data suggest that their levels of differentiation and their demographic histories differ sharply. There is strong evidence of gene flow among demes in O. erneba and O. evelinae, and their level of structuring is much lower than for the other two species. Indeed, the COX3 fragment reveals cryptic lineages in O. lactea and O. parmula. The results seem to contradict the high genetic structuring and low intrapopulational variability expected with the ecological constriction and habitat discontinuity faced by these organisms, meaning that there might be gene flow among populations or their dispersal capability has been underestimated.

Phylogeography of the marine interstitial nemertean Ototyphlonemertes parmula (Nemertea, Hoplonemertea) reveals cryptic diversity and high dispersal potential

“…Few molecular studies of Ototyphlonemertes exist (see Envall and Sundberg 1998;Andrade et al 2011). A study based on 16S rRNA (Envall and Sundberg 1998) found that morphological species are paraphyletic on a populationlevel phylogeny, a result consistent with a morphologybased phylogenetic study (Envall and Norenburg 2001) that revealed a high degree of homoplasy in morphological characters.…”

“…Lineage A shows no evidence of structuring along the east coast of Florida, so the restricted distribution of lineage B1 is somewhat puzzling. If populations are mixed by ongoing dispersal, we would expect to find individuals of lineages A and B1 in similar proportions at all east coast Florida sites (see also Andrade et al 2011). However, our sampling may not be representative of the actual proportions, especially if habitat partitioning is present.…”

“…Nonetheless, individuals may be eroded from the sediment by wave or current action or dispersed with suspended sediment (Palmer 1988) as well as on macroalgae and other substrata (Thiel and Gutow 2005;Derycke et al 2008). Relatively few phylogeographic studies of meiofauna exist (see Todaro et al 1996;von Soosten et al 1998;Rocha-Olivares et al 2001;Westheide et al 2003;Castro-Longoria et al 2003;Casu and Curini-Galletti 2004;Derycke et al 2005Derycke et al , 2007Derycke et al , 2008Derycke et al , 2010Casu et al 2009Casu et al , 2011Andrade et al 2011), and fewer still across the otherwise well-studied southeastern US phylogeographic boundary (Schizas et al 1999(Schizas et al , 2002. As a result, we lack a good general understanding of population differentiation in the environment occupied by these organisms.…”

From trochophore to pilidium and back again - a larva’s journey

“…This could explain seemingly paradoxical lack of genetic differentiation between geographically isolated populations of interstitial hoplonemerteans Ototyphlonemertes spp. (Andrade et al, 2011b), which are currently thought to have short-lived larvae and limited potential for dispersal.…”

Editorial: diversity of marine meiofauna on the coast of Brazil

“…In the end of the last century taxonomical and ecological studies on meiofauna taxa again were published regularly(e.g. Todaro & Rocha 2004, 2005, Hooge & Rocha 2006, Amaral & Nalin 2011, Andrade et al 2011, Dal Zotto et al 2013, especially for Nematoda and Copepoda (Carvalho et al 1992;Corbisier 1993Corbisier , 1999Esteves and Genevois 1997;Genevois and Bezerra 1997;Kihara and Rocha 2009;Lotufo and Rocha 1993;Netto et al 1999a, b;Santos et al 1999). According to the ISI Web of Knowledge and Google Scholar, it is only in the last decade that publications on meiofauna by Brazilian authors have been published consistently every year among ISI journals as well as in "gray" literature (Fig.…”