A review of molecular markers used for Annelid phylogenetics

Abstract

Annelida, one of the most successful animal phyla, exhibits an amazing variety of morphological forms. Disparity between some of the forms is so great that until molecular tools were used, some annelid lineages (for example, echiurids and pogonophorans) were not commonly recognized as belonging to the group. Although it is easy to assign annelids to a given family, understanding the deeper relationships within the group has been difficult. The main working hypothesis for annelid phylogeny is based on morphological cladistic analysis. However, the recent work using molecular tools has caused a revision of our view of annelid evolutionary history. For example, Scolecida and Palpata appear not to be natural groups, and the phylogenetic positions of some aberrant taxa (for example, Siboglinidae, Poeobius, Pisione) have been determined. Herein, we discuss some of the main molecular markers that have been used to elucidate annelid phylogeny and the contribution that such work is making to our understanding. A table highlighting the molecular literature and the genes used is included.

High genetic divergence of hormogastrid earthworms (Annelida, Oligochaeta) in the central Iberian Peninsula: evolutionary and demographic implications

“…Applicability of COI sequence data to infer population divergence and genetic structure has been previously proven, due to the high mutation rate of this sequence (Halanych & Janosik 2006) making COI a very useful gene in phylogenetic studies, such as the present one. Most of the observed substitutions in the sequences generated from all H. elisae specimens, occurred in the expected third position.…”

“…2005; Oceguera‐Figueroa et al. 2005; Halanych & Janosik 2006), specifically within earthworms (Pop et al. 2003; Chang & Chen 2005; Csuzdi et al.…”

“…2005; Huang et al. 2007), due to a high rate of mutation, particularly in third codon positions (Halanych & Janosik 2006). Moreover, studies on various groups of animals have shown that a 650‐bp fragment of this gene is generally effective as a barcode sequence, providing more than 95% species‐level resolution (Hebert et al.…”

Chaetal arrangement in Orbiniidae (Annelida, Polychaeta) and its significance for systematics

“…No unique Wne structural feature has been found for the branchiae of Orbiniidae and Paraonidae. The monophyly of Scolecida, in which Orbiniidae, Paraonidae and other sedentary polychaetes without head appendages are grouped, is not supported by molecular data (Rousset et al 2007;Halanych and Janosik 2006;Hall et al 2004;Bleidorn et al 2003) and is in conXict with several ultrastructural Wndings (Bartolomaeus 1998; Bartolomaeus et al 2005). Thus, the position of Orbiniidae within Polychaeta is still very uncertain.…”

Multiple introns in a deep-sea Annelid (Decemunciger: Ampharetidae) mitochondrial genome

“…In organic-fall and cold-seep habitats, these polychaetes can show remarkable abundances and diversity and may be important for organic-matter degradation 8, 9 . However, as with many other deep-sea taxa, there is limited understanding of their diversity and evolution, requiring additional study including use of informative molecular markers 10, 11 . Despite their high diversity and abundance in the deep-sea, a limited number of polychaete taxa have been molecularly characterized from deep-sea ecosystems and from chemosynthetic habitats 12–14 .…”