Phylogeographic patterning in a freshwater crab species (Decapoda: Potamonautidae:Potamonautes) reveals the signature of historical climatic oscillations

Abstract

Aim The phylogeographic relationships among populations of the common Cape River crab, Potamonautes perlatus, are examined to investigate whether the contemporary population genetic structure is congruent with the hypothesized hydrographic evolution of drainage systems established during the Pliocene, or whether it reflects an older Miocene climatic amelioration.Location 139 samples of P. perlatus were collected from 31 populations distributed among the five major perennial drainage systems and a number of smaller catchments in the Western and Eastern Cape, South Africa.Methods Phylogeographic analysis using parsimony, maximum likelihood, minimum evolution and Bayesian inferences was employed for the 16S rRNA mtDNA gene region, while bootstrapping and posterior probabilities were used to assess the robustness of clades. In addition, nested clade analysis was performed in an attempt to disentangle the contemporary and historical factors that have sculpted genealogical relationships among conspecific populations of P. perlatus.Results Phylogenetic topologies were congruent irrespective of the evolutionary method employed. Two highly distinct reciprocally monophyletic clades characterized by marked levels of corrected sequence divergence were present, with no shared haplotypes between the two major phylogroups. Phylogroup one comprises the populations of the westward-flowing drainages (mainly the Berg and Olifants drainages), and phylogroup two comprises all of the southwardflowing drainages and can further be divided into two subclades -one containing the Breede River populations, and the other containing the Gamtoos and Gourits drainage systems. The nested clade analysis demonstrated restricted gene flow and long-distance dispersal for a number of higher clade levels. The higher-level groups and results for the total cladogram suggest either fragmentation or isolation by distance.Main conclusions Freshwater crabs are generally highly philopatric, and dispersal, although not common, has occurred historically. The westward-flowing drainages (Berg, Olifants, Eerste, Liesbeeck and Tokai) are isolated from the southward-flowing drainages by the Cape Fold Mountains, while the southwardflowing drainages have a number of tributaries that extend into the low-lying regions, allowing for gene flow between these three major drainages systems (Breede, Gamtoos and Gourits). Among the westward-flowing drainages, a more intensive sampling regime is required to understand evolutionary relationships. Our molecular results suggest that the observed patterns pre-date the formation of contemporary hydrographic patterns in the Cape. This suggests that an older Late Miocene event has severely impacted the contemporary population structure

Population genetic structure and demographic history of the freshwater crab Potamon elbursi (Brachyura: Potamidae) from the Alborz Mountains in northern Iran

“…our results show that the populations of P. elbursi are genetically structured, with the existence of locally private haplotypes in two out of six populations. This finding is perfectly in line with the reproductive biology and limited dispersion ability of freshwater crabs, since they are known to be highly philopatric (i.e., individuals remaining or returning to their point of origin or birthplace) and mostly confined to their provenance freshwater systems (e.g., Daniels et al, 2006 for Potamonautidae). They have also direct development resulting in extended maternal care (Ng, 1988).…”

“…occasionally, freshwater crabs may cross short land bridges during periods of heavy rainfall, when headwaters of these populations originate from the same mountain regions (Daniels, 1998(Daniels, , 2006Cook et al, 2008;Poettinger et al, 2011;schubart et al, 2011;Keikhosravi and schubart, 2014;schubart and santl, 2014). Assuming that P. elbursi disperses by walking in the vicinity of rivers, we would have expected more genetic homogeneity in nearby populations of the two different drainage systems (i.e., Jajrood and Taleghan) and among populations of the same river system (e.g., Taleghan and Mollali), because this dispersal favours gene flow among geographically close and connected rivers.…”

Disentangling the divergence and cladogenesis in the freshwater crab species (Potamonautidae:Potamonautes perlatus sensu lato) in the Cape Fold Mountains, South Africa, with the description of two novel cryptic lineages

“…Daniels et al, 2007;Swart, Tolley & Matthee, 2009;Stanley et al, 2011), but there have only been limited studies on invertebrates. Freshwater invertebrates, such as freshwater crabs and crayfish, are ideal animals for examining the influence of hydrological networks on genetic partitioning because these animals have direct development and complete their life cycle in freshwater, and are incapable of prolonged survival in sea water, rendering their evolutionary patterning closely linked with their freshwater habitat (Daniels, 2003;Daniels et al, 2006a;Klaus et al, 2009Klaus et al, , 2010Toon et al, 2010).…”

“…Major periods of cladogenesis of taxa along the CFM are estimated to have occurred between the Miocene and Late Pleistocene, and the contemporary drainage patterns and distribution of many faunal groups were established by the Late Pliocene (Deacon, 1983;Partridge & Maud, 1987;Waters & Cambray, 1997;Linder, 2003;Daniels, Gouws & Crandall, 2006a). The arrangement of the CFM has been associated with breaks in the genetic structuring of freshwater vertebrates (e.g.…”

Revalidation and redescription of Potamon elbursi Pretzmann, 1976 (Brachyura, Potamidae) from Iran, based on morphology and genetics

“…The explained mode of distribution raises the question of why these two evolutionary significant lineages partially share the same watershed system. The apparent gene flow between populations of the Isfahan Basin and peripheral regions of the neighbouring watershed system (Euphrates-Tigris) can be explained by the proximity of some headwaters of both drainage systems, as it is generally believed that freshwater crabs are able to cross small land bridges between headwaters when humidity is sufficiently high [21,22]. As an alternative explanation, a series of manmade tunnels (Kuhrang tunnels) redirecting water of the Kuhrang River from the Euphrates-Tigris drainage system towards the main river of the Isfahan drainage could serve this purpose (i.e.…”