Abstract
The Brazilian subterranean ichthyofauna is distinguished worldwide by high taxonomic and phylogenetic diversity, involving at least 30 exclusively subterranean (troglobitic) lineages. This may be explained by high native epigean diversty, allied to opportunities for colonization and genetic isolation in the subterranean biotope, thence originating troglobites. An updated list of Brazilian troglobitic lineages and a review of previous hypotheses on modes of colonization and differentiation in subterranean habitats are presented with fresh data and models. Colonization of and isolation in the subterranean biotope are independent processes, usually separate over time. Access to subterranean habitats varies from the (sub)horizontal through sinkholes and resurgences of base-level streams and vadose tributaries to the vertical by shallow and deep phreatic waters through the hyporheic zone. Phenotypic differentiation of subterranean populations originating troglobites may be achieved by various, non-mutually exclusive modes of genetic isolation, e.g., directly in base-level streams and upper tributaries through the extinction of epigean populations, due to drainage discontinuation in dry paleoclimatic phases (or by other causes), by topographic isolation due to a lowering of the regional base level and karst catchments or by parapatric differentiation. Differentiation may also be a consequence of transition from lotic to lentic waters in flooded caves, and from shallow to deep phreatic habitats.
Subject
Nature and Landscape Conservation,Agricultural and Biological Sciences (miscellaneous),Ecological Modeling,Ecology
Cited by
3 articles.
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