Speciation in Freshwater Fishes

Abstract

The extraordinary species richness of freshwater fishes has attracted much research on mechanisms and modes of speciation. We here review research on speciation in freshwater fishes in light of speciation theory, and place this in a context of broad-scale diversity patterns in freshwater fishes. We discuss several major repeated themes in freshwater fish speciation and the speciation mechanisms they are frequently associated with. These include transitions between marine and freshwater habitats, transitions between discrete freshwater habitats, and ecological transitions within habitats, as well as speciation without distinct niche shifts. Major research directions in the years to come include understanding the transition from extrinsic environment-dependent to intrinsic reproductive isolation and its influences on species persistence and understanding the extrinsic and intrinsic constraints to speciation and how these relate to broad-scale diversification patterns through time. 621 Annu. Rev. Ecol. Evol. Syst. 2014.45:621-651. Downloaded from www.annualreviews.org Access provided by University of California -San Francisco UCSF on 12/04/14. For personal use only.

Phylogenomics of pike cichlids (Cichlidae: Crenicichla): the rapid ecological speciation of an incipient species flock

“…Seehausen () discussed several factors that might explain the paucity of such adaptive radiations in rivers, including physical differences between lakes and rivers that might influence the ecological opportunities and therefore evolutionary results in each ecosystem. The obvious spatial disparity between rivers and lakes is the depth dimension offered by lakes, which is hypothesized to play a major role during diversification of lake‐dwelling cichlids (Seehausen & Magalhaes, ) and fishes in general (Seehausen & Wagner, ). Secondly, rocky shorelines and reefs associated with many of the East African Great Lakes may provide sufficient conditions for primary producer‐associated trophic roles (e.g.…”

Diabolical survival in Death Valley: recent pupfish colonization, gene flow and genetic assimilation in the smallest species range on earth

“…For example, current models assume that the accumulation of postzygotic intrinsic isolation takes millions of years due to substantial work in many groups [80,81], including pupfishes [82,83]. Nearly all studies of rapid speciation in fishes report no intrinsic incompatibilities in hybrid crosses [84][85][86][87], most notably in East African cichlid clades diversifying over millions of years [88]. These assumptions have inspired recent models of diversification, such as ephemeral speciation [89] and the million-year-waiting-time for macroevolutionary bursts [90].…”

Distinct colonization waves underlie the diversification of the freshwater sculpin (Cottus gobio) in the Central European Alpine region

“…Although sculpins are known to occur in either environment (Kontula & Vainola, ; Kottelat & Freyhof, ; Goto et al ., ), such a lake‐stream differentiation within a drainage was unknown for Cottus gobio (Hänfling & Brandl, ,b; Vonlanthen et al ., ; Neuenschwander et al ., ; Seehausen & Wagner, ; Goto et al ., ). Habitat‐dependent ecotype formation along a lake‐stream axis is well known in some other freshwater fishes where it occurs with some regularity (Seehausen & Wagner, ). This is likely because lake and stream environments often require adaptation to different physical (flow, light, temperature) and biotic conditions (predation regimes, parasite communities, food resources; Seehausen & Wagner, ).…”

“…Factors that promote or impede adaptive radiation are best studied at early stages of the process where phenotypic and genotypic segregation is likely to be incomplete (Yoder et al ., ). The relevance of adaptive radiations for the generation of biodiversity has been highlighted for fishes in insular freshwater habitats, like deep lakes in the tropics or temperate zones (Seehausen & Wagner, ). Post‐glacial diversification among the latter may occur between distinct habitats, such as lakes and streams as well as within the same macrohabitat, where for example species within lakes segregate according to water depth and/or trophic niches (Hendry, ; Seehausen & Wagner, ).…”

“…Few examples are known in other temperate fish taxa (Seehausen & Wagner, ). To understand the extent to which lineage‐specific traits facilitate or constrain post‐glacial diversification, additional taxa in similar and unimpacted environments need to be investigated (Seehausen & Wagner, ).…”