Biotic regionalization of freshwater fishes in Northern Middle America highlights high beta diversity created by prominent biogeographic barriers

Abstract

Highlights• Seven distinct and geographically coherent bioregions were detected in Northern Middle America based on obligate freshwater fishes.• Biotic regionalization of Northern Middle America is greatly influenced by the presence of three biogeographic barriers: (1) the Sea of Cortés and Sierra de Juárez-Cerro Gordo highlands;(2) the Trans-Mexican Volcanic Belt, Sierra Madre del Sur, and Sierra Madre de Chiapas highlands; and (3) the Río Grande Rift, Sierra Madre Occidental, and Mesa Central highlands.• Species richness across bioregions in Middle America vary from two species in Baja California to 187 in the Grande-Pánuco. Dissimilarity among bioregions ranged from 0.92 to 0.98%, excluding the Baja California bioregion which was 100% different from all other bioregions. Such levels of faunal distinctiveness suggest the presence of strong, longstanding geographical barriers enhanced by aridity in the North.• Our results suggest that the northern boundary of Middle America is not delimited by the political border between the USA and Mexico. Instead, the biological northern border of Middle America extends into the USA drainages in California, the Colorado River basin and the headwaters of the Río Grande in the Southern Rocky Mountains.

Historical biogeography of New World Killifishes (Cyprinodontiformes: Funduloidea) recapitulates geographical history in the Gulf of México watershed

“…1). The boundary between realms was the Trans-Mexican Volcanic Belt (Rico et al ., 2022). We used sample-size corrected Akaike weights (AIC c ) to compare fitness among models (Garcia-R & Matzke, 2021).…”

“…Map depicting the distribution of Funduloidea between North and northern South America. The boundary between realms is the Trans-Mexican Volcanic Belt (TMVB; Rico et al, 2022). The red line depicts the boundary between the coastal plain physiographic province and continental uplands.…”

Biogeography of Greater Antillean freshwater fishes, with a review of competing hypotheses

“…2) indicates that the NSA and NGM bioregions each have <10% cyprinodontiforms, with proportions increasing further away from either continent, reaching 50% in the MT bioregion. Non-cyprinodontiform families from North America are diminished in the WGM and MT bioregions because deserts and mountains limit southward immigrations (Miller et al, 2005;Rico et al, 2022). Non-cyprinodontiform families from South America are diminished in the CB and MT bioregions due to barrier effects of the Isthmus of Panam a and former Central American Seaway (Matamoros et al, 2015;Bagley et al, 2018).…”

Biogeography of Greater Antillean freshwater fishes, with a review of competing hypotheses

“…Additional examples are available. The Baja Peninsula has existed for >6 Ma (Umhoefer et al, 2018), twice as long as proposed for GAARlandia, but harbours no primary freshwater species (Miller, Minckley, & Norris, 2005; Rico et al, 2022). This is partly attributable to aridity, but also reflects limited riverine connectivity along the peninsula and across the narrow continental shelf (Dolby et al, 2018).…”

“…2) indicates NSA and NGM bioregions have <10% cyprinodontiforms, with proportions increasing moving away from either continent, reaching 50% in the MT bioregion. Non-cyprinodontiform families from North America are diminished in the WGM and MT bioregions because deserts and mountains limit southward immigrations (Miller et al, 2005; Rico et al, 2022). Non-cyprinodontiform families from South America are diminished in the CB and MT bioregions due to barrier effects of the Isthmus of Panamá and former Central American Seaway (Matamoros et al, 2015; Bagley et al, 2018).…”