Vicariance, dispersal and scale in the aquatic subterranean fauna of karst regions

Abstract

SUMMARY1. The causes of distribution patterns of stygobionts (obligate subterranean-dwelling aquatic species) were examined with special emphasis on vicariance and dispersal. 2. Dispersal was investigated on the premise that if migration is important, then migration at small scales should predict patterns at larger scales. Data on the copepod fauna of epikarst in Slovenia were especially useful for the study of migration, because data on habitat occupancy could be collected at scales of individual drips located metres apart to the scale of individual caves to entire karst regions. Occupancy of drips in one cave was a remarkably good predictor of occupancy of caves in a region, although not of the overall range of a given species. These results were also supported by occupancy patterns of the general stygobiotic fauna of West Virginia caves, compared at different scales. 3. Vicariance was investigated by noting that proximity to marine embayments increases the likelihood of vicariant speciation. In the U.S.A., only the fauna of the Edwards Aquifer of Texas has a significant component of marine-derived species. Differences in shape of the relationship between species number and number of caves in a county indicated that the marine-derived component represented an addition to rather than a replacement of the other stygobiotic species. 4. Thus, we found evidence for the importance of both vicariance and dispersal. The techniques employed could be used to study these patterns more generally, as more data become available.

Assessing and conserving groundwater biodiversity: synthesis and perspectives

“…For example, the composition of the rich stygofauna of Slovenia appears to result from its proximity to the Mediterranean Sea (Sket, 1999). Increased probability of vicariant events following marine recession may have increased diversity of this fauna, as apparently is also the case for the Edwards Aquifer of Texas (Culver et al. , 2009).…”

“…However, well studied sites outside of Europe rarely have richness levels that even approach those of European hotspots (Culver & Sket, 2000; Deharveng, 2005). Seven of the 10 most stygobiotic species‐rich karst sites of the world are located in Europe (Culver, Pipan & Schneider, 2009). These findings suggest that sampling bias alone is an insufficient explanation for the large differences in groundwater species richness observed among continents.…”

Early Pliocene range expansion of a clade of subterranean Pyrenean beetles

“…The possibility that subterranean terrestrial species could expand their ranges and diversify once fully adapted to the subterranean environment is rarely contemplated, and usually only for closely related species at a reduced geographical scale (e.g. Barr, ; Crouau‐Roy, ; Holsinger, ; Culver et al ., ). Only recently have large‐scale diversifications within the subterranean environment been advocated for ancient (i.e.…”

“…Recently, the application of molecular methods has allowed for the first time tests of some of the traditional hypotheses on the origin and distribution of the subterranean fauna (Juan et al ., ). There are, however, many questions that remain open, especially regarding the possibility of geographical expansion and diversification of species adapted to the subterranean environment (Culver et al ., ; Juan et al ., ; Ribera et al ., ).…”

At the confluence of vicariance and dispersal: Phylogeography of cavernicolous springtails (Collembola: Arrhopalitidae, Tomoceridae) codistributed across a geologically complex karst landscape in Illinois and Missouri

“…Genetic isolation is a primary driver of molecular divergence and ultimately speciation, but determining the factors that promote or constrain genetic diversity remains a significant challenge in evolutionary biology. Patterns of diversity in caves are often attributed to vicariance or dispersal, but the relative influence these processes have on the evolution and contemporary distributions of cave fauna has been widely debated (see Culver, Pipan, & Schneider, ; Porter, ). However, it is generally accepted that patterns of diversity in caves are likely shaped by a complex interaction of intrinsic factors (e.g., species‐specific differences in ecology, life history, or biology) that can influence dispersal capacity and extrinsic factors (e.g., geographic barriers or climate change) that can enhance or limit dispersal opportunity (Juan et al., ; Porter, ).…”