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

Abstract

Novo, M., Almodó var, A. & Díaz-Cosín, D. J. (2009). High genetic divergence of hormogastrid earthworms (Annelida, Oligochaeta) in the central Iberian Peninsula: evolutionary and demographic implications. -Zoologica Scripta, 38, 537-552. Hormogastridae earthworms are highly important for the functioning of the Mediterranean soil system. However, little is known about the species distribution and genetic diversity of these soil invertebrates. In the present study, the genetic differentiation and gene flow were studied among populations of hormogastrids from the central Iberian Peninsula. A 648-bp portion of the mitochondrial cytochrome c oxidase I gene was sequenced for 82 individuals from 7 localities, resulting in the identification of 38 haplotypes exclusive to localities. All of the individuals were morphologically identified as Hormogaster elisae, but the high genetic divergence found among populations (up to 20.20%) suggests the occurrence of more than one cryptic species within this region. Further analysis of the phylogenetic relationships revealed six different evolutionary lineages coincident with geographical location, including the two nearest populations Molar and Redueñ a as one evolutionary unit. From these results, at least three new species could be inferred, in addition to the morphospecies H. elisae s.s. Partitioning of genetic variance among populations indicated that isolation by distance was the primary agent for differentiation of the investigated hormogastrid populations. Our data suggest that the evolutionary lineages for H. elisae s.l. originated between the late Miocene and the early Pleistocene, but that mtDNA genealogies coalesce on a more recent scale of a few thousand years.

Living on a volcano’s edge: genetic isolation of an extremophile terrestrial metazoan

“…In fact, the more studies are performed on annelids the more clear it becomes that cryptic speciation is not an uncommon phenomenon in this phylum (Pfenninger and Schwenk, 2007;Hilário et al, 2010). Earthworms have been the target of several comprehensive phylogenetic studies using both mitochondrial and nuclear markers revealing high intraspecies genetic diversity (Velavan et al, 2007;Fernández et al, 2011) and deeply divergent genetic lineages, possibly in some cases corresponding to cryptic species (Novo et al, 2009;Pérez-Losada et al, 2009;Andre et al, 2010). Whether or not these lineages found in P. corethrurus warrant the status of (cryptic) species must wait for further genetic and breeding evidence as well as a more intensive sampling which goes beyond the aims of the present study.…”

“…However, discordance between nuclear and mitochondrial gene genealogies is common because of various processes such as differences in mutation rates, the effect of stochastic demographic processes or incomplete lineage sorting (Hebert et al, 2004;Caitlin and John, 2011;Orozco-terWengel et al, 2011). Nonetheless, deep divergence in mtDNA sequences between related individuals is often taken as evidence for the existence of cryptic species (King et al, 2008;Novo et al, 2009;Andre et al, 2010;James et al, 2010). In addition to the mitochondrial markers, methods based on variable PCR amplification such as Amplified Fragment Length Polymorphisms (AFLPs; (Vos et al, 1995)) can provide a rapid and affordable approach to detect polymorphism in a population on a genomic scale (Campbell et al, 2003) and therefore provide a broader genetic characterization and discrimination within and between populations.…”

Variability of sexual organ possession rates and phylogenetic analyses of a parthenogenetic Japanese earthworm, Amynthas vittatus (Oligochaeta: Megascolecidae)

“…However, unfortunately we could not discover the population, which performed biparental sexual reproduction without parthenogenesis, at the basal position of our phylogenetic tree. The genetic distances between A. vittatus haplotypes were lower (0.00-0.13) than those of other species within the same genus (0.15-0.16 [Admassu et al, 2006]; 0.16-0.23 [Huang et al, 2007]; 0.15-0.244 [Chang et al, 2007]; 0.15-0.28 [Chang et al, 2008]; 0.16-0.22 [Novo et al, 2009]). Moreover, H1 haplotype individuals were found at sites 13 and 14 as well as sites 8-10 (Fig.…”

“…Recently, numerous molecular phylogenetic studies on earthworms have been conducted (Jamieson et al, 2002;Pop et al, 2003Pop et al, , 2007Heethoff et al, 2004;Pérez-Losada et al, 2005Chang et al, , 2007Chang et al, , 2008Chang et al, , 2009Admassu et al, 2006;Huang et al, 2007;King et al, 2008;Cameron et al, 2008;Minamiya et al, 2009;Richard et al, 2009;Novo et al, 2009Novo et al, , 2010Knott and Haimi, 2010). Many of these studies used the mitochondrial DNA (mtDNA) cytochrome oxidase subunit I (COI) gene (Pop et al, 2003(Pop et al, , 2007Pérez-Losada et al, 2005Admassu et al, 2006;Chang et al, 2007Chang et al, , 2008Chang et al, , 2009Huang et al, 2007;King et al, 2008;Cameron et al, 2008;Minamiya et al, 2009;Rougerie et al, 2009;Novo et al, 2009Novo et al, , 2010Knott and Haimi, 2010) because of the ease of primer design and the range of phylogenetic signals and rapid evolutionary rate of this gene (Hebert et al, 2003). To clarify the phylogenetic relationships of A. vittatus with different degree of degraded reproductive organs, we examined the morphological variations, such as the possession rate of both the male and spermathecal pores in A. vittatus found in various locations in Sendai city around Mt.…”

Macroecological inferences on soil fauna through comparative niche modeling: The case of Hormogastridae (Annelida, Oligochaeta)

“…This study could be potentially useful as a base for wide-scale ecological inferences in other groups of earthworms and soil fauna, a key element on most ecosystems around the world. The Central Iberia clade corresponds to the H. elisae morphospecies, which comprises at least five cryptic lineages [24]. [7] included several new populations, which considerably widened its known range; their genetic variability is currently being …”