Genetic differentiation and phylogeographical structure of the Brachionus calyciflorus complex in eastern China

Abstract

Spatio-temporal patterns and processes of genetic differentiation in passively dispersing zooplankton are drawing much attention from both ecologists and evolutionary biologists. Two opposite phylogeographical scenarios have already been demonstrated in rotifers, which consist of high levels of genetic differentiation among populations even on small geographical scales on the one hand and the traditionally known cosmopolitanism that is associated with high levels of gene flow and long-distance dispersal via diapausing stages on the other hand. Here, we analysed the population genetic structure and the phylogeography of the Brachionus calyciflorus species complex in eastern China. By screening a total of 318 individuals from ten locations along a 2320-km gradient and analysing samples from two growing seasons, we aimed at focusing on both small- and large-scale patterns. We identified eight cryptic species and verified species status of two of these by sexual reproduction tests. Samples in summer and winter yielded different cryptic species. The distribution patterns of these genetically distinct cryptic species were diverse across eastern China, from full cosmopolitanism to local endemism. The two most abundant cryptic species BcWIII and BcSW showed a pattern of strong genetic differentiation among populations and no significant isolation by distance. Long-distance colonization, secondary contact and recent range expansion are probably responsible for the indistinct pattern of isolation by distance. Our results suggest that geographical distance is more important than temporal segregation across seasons in explaining population differentiation and the occurrence of cryptic species. We explain the current phylogeographical structure in the B. calyciflorus species complex by a combination of recent population expansion, restricted gene flow, priority effects and long-distance colonization.

Differences in life history characteristics among three sympatric evolutionary species of theRotaria rotatoriacomplex

“…According to the procedures detailed in Xiang et al (2011a), DNA was extracted from 33 clones of the R. rotatoria and the partial mitochondrial cytochrome c oxidase subunit I (COI) gene fragment was amplified and sequenced (GenBank No. KT438170-KT438202).…”

“…In the last two decades, many potential cryptic rotifer species which were genetically divergent but morphologically similar have been discriminated and subdivided such as the monogont rotifers through the application of molecular phylogenetics and mating tests (Ciros-P erez et al 2001;G omez et al, 2002b;Derry et al 2003;Gilbert & Walsh 2005;Schr€ oder & Walsh 2007;Xiang et al 2011aXiang et al , 2011b) and the bdelloid rotifers using a coalescent approach Fontaneto et al 2007Fontaneto et al , 2008Fontaneto et al , 2009Fontaneto et al , 2011. The effects of such hidden diversity are usually overlooked in ecological studies.…”

Fifteen species in one: deciphering the Brachionus plicatilis species complex (Rotifera, Monogononta) through DNA taxonomy

“…For the three datasets, the analytical steps were the same and included alignment, selection of the best evolutionary model, and phylogenetic reconstructions through Maximum Likelihood (ML) and Bayesian Inference (BI). For the outgroup, we selected one isolate of the congeneric Brachionus calyciflorus Pallas, 1766 for which both COI and ITS1 existed (isolate XZ8: GU012801, GU232732, Xiang et al, 2011).…”

Coal fly ash effluent affects the distributions of Brachionus calyciflorus sibling species

“…The genetic differentiation among different groups was estimated by the partition of variance components (AMOVA) applying conventional F st statistics using haplotype frequencies as implemented in Arlequin 3.1 (Excoffier and Schneider, 2005). In order to discriminate the lineage relationships among B. calyciflorus sibling species found in this study and proved by Xiang et al (2011), COI gene sequences of B. calyciflorus from Wuhu city were obtained from GenBank (the accession number: GU232703, FJ827008 and FJ826934) and used for phylogenetic analysis. With the rotifer Brachionus plicatilis (Genbank accession number: EF524553) as outgroup, the phylogenetic trees were constructed using maximum-likelihood (ML), maximum-parsimony (MP) and neighbor-joining (NJ) methods by PAUP n 4.0b10 software (Swofford, 2002).…”