Historical Biogeography of the New-World Pupfish Genus Cyprinodon (Teleostei: Cyprinodontidae)

Abstract

Analysis of mtDNA sequence variation (2,548 bp from ND2, cytb, and part of the control region) indicates that the genus Cyprinodon began diverging in the Late Miocene from a common ancestor with Megupsilon, a monotypic genus on the Mesa del Norte of Mexico. The geographic pattern of mtDNA variation, with estimates of divergence time, suggests that by the end of the Miocene Cyprinodon occurred from the Atlantic Coast and West Indies to near the western margin of North America via ancestral Rio Grande and Colorado River systems. Phylogeographic structure within the major mtDNA complexes supports a variety of hypotheses from geology and previous phylogenetic analyses for Late Neogene connections among basins in southwestern North America now separated by formidable barriers to dispersal. Comparison of the mtDNA tree with previous phylogenetic inferences from allozymes indicates that reticulate evolution involving divergent lineages probably was important in the history of Cyprinodon.El análisis de variació n de secuencias de ADNmt (ND2, cytb, y parte de la región reguladora; 2,548 pb) indica que el género Cyprinodon empezó a divergir en el mioceno tardío de un antepasado comú n con Megupsilon, un género monotípico de la Mesa del Norte de México. El patró n geográfico de la variació n de ADNmt, con estimadas de los tiempos divergencias, sugiere que al llegar al fin del mioceno Cyprinodon ocurrió desde la costa Atlántica y las Antillas hasta casi el margen oeste de Norteamérica por los sistemas pluviales antiguos del río Bravo y del río Colorado. La estructura filogeográfica entre los grupos principales de ADNmt apoya a una variedad de hipó tesis de la geología y de los análisis filogenéticos anteriores para conexiones del neogeno tardío entre cuencas del suroeste de Norteamérica que ahora están separadas por barreras imponentes contra la dispersió n. La comparació n del árbol de ADNmt con deducciones filogenéticos anteriores de alozimas indica que la evolució n reticulada que incluye líneas divergentes probablemente fue importante en la historia del Cyprinodon.

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

“…Similarly, molecular estimates for the age of polar bears spanned 600 kyr-5 Myr ago using conventional demographic modelling approaches, but were revised to 400 kyr ago, consistent with the fossil evidence, by modelling with dadi [70]. Second, many studies calibrate with distantly related outgroup fossils or ancient vicariance events, such as the breakup of Gondwanaland, assuming no subsequent dispersal was possible [30,32,77]. For example, the age of the modern bowhead whale was revised from 1.1 Myr ago to 150 kyr ago (1 order of magnitude, similar to this study) when calibrating with radiocarbon dates for ancient DNA samples rather than outgroup fossils [36].…”

“…Geological evidence strongly indicates that Devils Hole opened to the surface only 60 000 years ago based on the abrupt cessation of mammillary calcite deposition [34], which places an upper bound on the isolation of diabolis within this extreme habitat. Previous studies attributed overestimation of species divergence times to incomplete lineage sorting [30,31]; however, this cannot account for such a large discrepancy [35,36]. Instead, this conflict appears to be caused by 11 Myr priors placed on the root age of Cyprinodon þ Megupsilon þ Cualac [30,31] based on the assumption that pupfish populations were isolated by the formation of ancient land barriers [32].…”

Ancient vicariance and recent dispersal of springsnails (Hydrobiidae: Pyrgulopsis) in the Death Valley system, California-Nevada

“…3). This relationship also implies an old divergence event, as any prior hydrographic connection between these two areas surely preceded establishment of the present course of the lower Colorado River after 6 Ma (Howard and Bohannon, 2004;Lucchitta and Jeanne, 2004), and it is paralleled by molecular phylogenetic evidence of middle Pliocene vicariance between pupfishes of the Death Valley system and the lower Colorado River region (Echelle et al, 2005).…”

“…Subsequent investigators have instead emphasized the role of middle to late Tertiary rearrangements of topography and drainage in shaping the biogeographic history of Death Valley system aquatic fauna (e.g., Taylor, 1985;Minckley et al, 1986;Polhemus and Polhemus, 2002). Recent molecular phylogenetic studies of cyprinodontid pupfishes iCyprinodon) (Echelle and Dowling, 1992;Echelle et al, 2005) and cochhopid gastropods (Tryonid) (Hershler et al, 1999a(Hershler et al, , 1999b have documented deeply divergent Death Valley system hneages consistent with ancient origins; however, most of the regional fauna has yet to be studied phylogenetically. The hydrobiid gastropod genus Pyrgulopsis (= Fontelicella of authors) is one of the most ubiquitous and diverse elements (14 species; Fig.…”

Rangewide microsatellite phylogeography of the endangered tidewater goby, Eucyclogobius newberryi (Teleostei: Gobiidae), a genetically subdivided coastal fish with limited marine dispersal

“…It was one of the taxa initially used to justify the Endangered Species Act, and most authors concur that drying from glacial pluvials during the last 20,000 years played a significant role in isolation of C. diabolis (e.g., Echelle et al 2005). Mitochondrial sequence based tree topology indicates that the C. diabolis is not reciprocally monophyletic relative to other species, but falls within the named subspecies C. nevadensis nevadensis (Duvernell and Turner 1998).…”