The evolution of Queensland spiny mountain crayfish of the genus Euastacus. II. Investigating simultaneous vicariance with intraspecific genetic data

Abstract

Phylogenetic evidence suggested that the Queensland Euastacus diversified through ‘simultaneous vicariance’, where the range of a widespread ancestral Euastacus receded to tops of mountains with the Pliocene warming of the continent and subsequent isolation lead to speciation. Implicit in the simultaneous vicariance hypothesis are three postulates on ancestral history: (1) warm temperatures were effective barriers to ancestral gene flow; (2) the ancestral Euastacus had an extensive contiguous distribution; and (3) there was a single vicariant event associated with Pliocene warming. It is argued that if there was interspecific diversification due to simultaneous vicariance then, within extant species, there are three predictions on current population structure. First, lowland areas, even those connected by streams, would be barriers to contemporary dispersal. Second, there would be contemporary dispersal between catchments covered by mesic rainforests. Third, there would have been recent Pleistocene intraspecific vicariant events. The population structure of E. robertsi, E. fleckeri, E. hystricosus and E. sulcatus was investigated with mtDNA and allozymes and it was found that the intraspecific data were consistent with these predictions. Furthermore, the Euastacus underwent limited range expansions during the cooler Pleistocene glacial cycles, and it is hypothesised that during cooler glacial periods, lowlands were still effective barriers to dispersal because of increased Pleistocene aridity.

Looking through glassfish: marine genetic structure in an estuarine species

“…Additionally, dispersal in adults, juveniles and larvae is relatively unimpeded by physical barriers, allowing for the free transfer of genes from population to population (Ward and Elliot 2001). In contrast, genetic structure in freshwater organisms tends to be dominated by gene frequencies that can often be quite distinct from neighbouring populations (Cook et al 2006;Ponniah and Hughes 2006). Hydrological connectivity in Australian freshwater systems in particular is often highly variable, with periods of low flow often disconnecting pools and reducing opportunities for gene flow (Huey et al 2006).…”

Small‐scale population‐genetic differentiation in the New Zealand caddisflyOrthopsyche fimbriataand the crayfishParanephrops planifrons

“…Streams separated by <10 km, but in different catchments (e.g., sites T2/W3 and K4/O2), were characterised by catchment-specific haplotypes, leading to higher nucleotide diversities among catchments than found in O. fimbriata. These observations indicate, as might be expected for a weak disperser, that there is little or no inter-catchment dispersal in P. planifrons, and contrast with northern Queensland E. hystricosus where shared haplotypes among neighbouring upland streams are indicative of contemporary or recent overland movement among neighbouring streams in different catchments (Ponniah & Hughes 2006). Specimens of P. planifrons collected from the two northern catchments, Oparau and Mangaora (K3, K4, O1, O2; Fig 1) did have haplotypes in common, and these populations may have recently diverged.…”

“…For obligate freshwater taxa, the stream hierarchical architecture is the major constraint to movement (see Meffe & Vrijenhoek 1988;Hughes 2007), but patterns of genetic differentiation detected with molecular tools differ among taxa. For example, in mountain crayfish Euastacus hystricosus in northern Queensland, Australia, shared haplotypes among neighbouring upland streams are indicative of contemporary or recent overland movement among neighbouring streams in different catchments that enter the ocean hundreds of kilometres apart (Ponniah & Hughes 2006). In contrast, for E. fleckeri there does not appear to be any pattern to the haplotype distribution with some connected streams characterised by fixed differences and some unconnected streams with shared haplotypes (Ponniah & Hughes 2006).…”

“…These streams drain into the shallow Kawhia Harbour and would have been connected during the late Pleistocene when sea levels were up to 50 m lower than present day (Stevens 1980). Alternatively, P. planifrons may be capable of limited inter-catchment dispersal through headwater seepages and pools that provide connectivity pathways in areas of continuous forest cover, as suggested for E. hystricosus (Ponniah & Hughes 2006). Paranephrops planifrons have occasionally been reported from isolated ephemeral pools in forested headwaters (Collier & Smith 2005).…”

“…For example, in mountain crayfish Euastacus hystricosus in northern Queensland, Australia, shared haplotypes among neighbouring upland streams are indicative of contemporary or recent overland movement among neighbouring streams in different catchments that enter the ocean hundreds of kilometres apart (Ponniah & Hughes 2006). In contrast, for E. fleckeri there does not appear to be any pattern to the haplotype distribution with some connected streams characterised by fixed differences and some unconnected streams with shared haplotypes (Ponniah & Hughes 2006). Populations of the euryhaline shrimp Parataya australiensis showed little genetic differentiation between streams within sub-catchments, presumably because of extensive in-stream movement (Hurwood et al 2003).…”