Metabolic Rate and Climatic Fluctuations Shape Continental Wide Pattern of Genetic Divergence and Biodiversity in Fishes

Abstract

Taxonomically exhaustive and continent wide patterns of genetic divergence within and between species have rarely been described and the underlying evolutionary causes shaping biodiversity distribution remain contentious. Here, we show that geographic patterns of intraspecific and interspecific genetic divergence among nearly all of the North American freshwater fish species (>750 species) support a dual role involving both the late Pliocene-Pleistocene climatic fluctuations and metabolic rate in determining latitudinal gradients of genetic divergence and very likely influencing speciation rates. Results indicate that the recurrent glacial cycles caused global reduction in intraspecific diversity, interspecific genetic divergence, and species richness at higher latitudes. At the opposite, longer geographic isolation, higher metabolic rate increasing substitution rate and possibly the rapid accumulation of genetic incompatibilities, led to an increasing biodiversity towards lower latitudes. This indicates that both intrinsic and extrinsic factors similarly affect micro and macro evolutionary processes shaping global patterns of biodiversity distribution. These results also indicate that factors favouring allopatric speciation are the main drivers underlying the diversification of North American freshwater fishes.

Correlations between broad‐scale taxonomic and genetic differentiations suggest a dominant imprint of historical processes on beta diversities

“…For fish species, it is well known that historical dispersal influences genetic structure across basins (Carvalho, ), especially for zones that were subject to intense postglacial recolonization such as our study area. Multispecies comparisons at large spatial scales in Europe (Seifertová, Bryja, Vyskočilová, Martínková, & Šimková, ) and in North America (April, Hanner, Mayden, & Bernatchez, ) have shown that the climatic fluctuations that caused glacial cycles during the Pleistocene had a generalized effect on the patterns of fish genetic divergence. In addition, three other, non‐exclusive hypotheses may explain the independent β‐SGDC we observed.…”

Patterns of Evolutionary Speed: In Search of a Causal Mechanism

“…They presented empirical data in support of this model using marine foraminifera. There is also empirical support for such a relationship among North American fresh water fish [57,58]; whereas, studies using large data sets have found no support for a relationship between BMR and rates of genetic evolution in animals [34,56].…”

Speciation in fishes

“…For example, glacial cycles in North America created pockets of allopatry that produced large numbers of freshwater fish species and were characterized as ‘speciation pumps’ (April et al . ,b). Another classic example is the rise and fall over geological times of the water level in Lake Tanganyika that resulted in almost complete physical separation of smaller bodies of water within the lake, eventually leading to allopatric genetic divergence for populations of cichlids trapped in those isolated pools.…”