Evolution of microgastropods (Ellobioidea, Carychiidae): integrating taxonomic, phylogenetic and evolutionary hypotheses

Abstract

BackgroundCurrent biodiversity patterns are considered largely the result of past climatic and tectonic changes. In an integrative approach, we combine taxonomic and phylogenetic hypotheses to analyze temporal and geographic diversification of epigean (Carychium) and subterranean (Zospeum) evolutionary lineages in Carychiidae (Eupulmonata, Ellobioidea). We explicitly test three hypotheses: 1) morphospecies encompass unrecognized evolutionary lineages, 2) limited dispersal results in a close genetic relationship of geographical proximally distributed taxa and 3) major climatic and tectonic events had an impact on lineage diversification within Carychiidae.ResultsInitial morphospecies assignments were investigated by different molecular delimitation approaches (threshold, ABGD, GMYC and SP). Despite a conservative delimitation strategy, carychiid morphospecies comprise a great number of unrecognized evolutionary lineages. We attribute this phenomenon to historic underestimation of morphological stasis and phenotypic variability amongst lineages. The first molecular phylogenetic hypothesis for the Carychiidae (based on COI, 16S and H3) reveals Carychium and Zospeum to be reciprocally monophyletic. Geographical proximally distributed lineages are often closely related. The temporal diversification of Carychiidae is best described by a constant rate model of diversification. The evolution of Carychiidae is characterized by relatively few (long distance) colonization events. We find support for an Asian origin of Carychium. Zospeum may have arrived in Europe before extant members of Carychium. Distantly related Carychium clades inhabit a wide spectrum of the available bioclimatic niche and demonstrate considerable niche overlap.ConclusionsCarychiid taxonomy is in dire need of revision. An inferred wide distribution and variable phenotype suggest underestimated diversity in Zospeum. Several Carychium morphospecies are results of past taxonomic lumping. By collecting populations at their type locality, molecular investigations are able to link historic morphospecies assignments to their respective evolutionary lineage. We propose that rare founder populations initially colonized a continent or cave system. Subsequent passive dispersal into adjacent areas led to in situ pan-continental or mountain range diversifications. Major environmental changes did not influence carychiid diversification. However, certain molecular delimitation methods indicated a recent decrease in diversification rate. We attribute this decrease to protracted speciation.

Groping through the black box of variability: An integrative taxonomic and nomenclatural re-evaluation of Zospeum isselianum Pollonera, 1887 and allied species using new imaging technology (Nano-CT, SEM), conchological, histological and molecular data (Ellobioidea, Carychiidae)

“…New access to new means of interpretation has provided a refreshing taxonomic perspective for these microscopic ellobioid snails. Considering the results of Weigand et al (2013) and our conchological investigations here, we find no reason to maintain the two subspecies entities currently comprising the Z. alpestre complex of the Eastern Alpine region. This study reduces the volume of previous Z. alpestre-laden eras by narrowing the status to two valid species: Z. kupitzense and Z. alpestre for this region.…”

“…Our dataset consists of 16 Zospeum specimens (Table 2). These specimens either originate from previous studies (see Weigand et al 2011Weigand et al , 2013 or were sampled within the scope of this study (Table 2). Table 2.…”

“…Individual BOLD-ID. (http://www.boldsystems.org/) of each specimen and a link to the broader study of Weigand et al (2013) are given. New material of the present study is indicated by an asterisk (*).…”

Revision of the genus complex Gibbula: an integrative approach to delineating the Eastern Mediterranean genera Gibbula Risso, 1826, Steromphala Gray, 1847, and Phorcus Risso, 1826 using DNA-barcoding and geometric morphometrics (Vetigastropoda, Trochoidea)

“…Methodology in recent years using genetic data has revealed cryptic species and questionable species delineation in several gastropod taxa (e.g. Delicado and Ramos 2012;Weigand et al 2013). Therefore, species identification and delineation by shell morphology alone is often mistrusted if not supported by additional lines of evidence, such as DNA-barcoding or morphometric data.…”

First record of Carychium minimum Müller, 1774 in New Brunswick, Canada (Mollusca: Gastropoda: Ellobioidea)

“…The terrestrial snail genus Carychium Müller, 1774, is a relatively small group of microsnails belonging to the family Ellobiidae or Carychiidae within the superfamily Ellobioidea (Bouchet et al 2005;Martins 2007;Weigand et al 2013) that in North America is known by just eight native and two introduced species (Pilsbry 1948;Turgeon et al 1998). Carychium minimum Müller, 1774 ( Figure 1) is native over much of Europe and parts of western Asia (Egorov 2007;Welter-Schultes 2012), and is introduced to North America where it was first reported over 100 years ago (Clapp 1912).…”