Distinguishing between dispersal and vicariance: A novel approach using anti‐tropical taxa across the fish Tree of Life

Abstract

Aim: Anti-tropical taxa are species split by the tropics into disjunct northern and southern populations. These distributions occur throughout the Tree of Life, but the mechanisms proposed to drive this pattern are debated and generally fit into two categories: dispersal and vicariance. Here, we quantitatively test the prevalence of dispersal and vicariance as plausible drivers of anti-tropical marine distributions using intraspecific anti-tropical marine fishes as a model system. Location: Primarily Indo-Pacific. Taxon: Marine fishes. Methods: To test between dispersal and vicariance in latitudinally disjunct marine fishes, we used an ecological niche modelling framework to predict the spatio-temporal suitability of tropical habitats during contemporary and glacial time periods.

Missing in the Middle: A Review of Equatorially Disjunct Marine Taxa

“…Critical thermal maximum temperature studies, while limited in number for anti-tropical species, have also supported the notion that many of these taxa are near their critical temperature thresholds at their lowest latitudes, and therefore would experience thermal stress in tropical waters (Walther et al, 2013;Payne et al, 2016). Additionally, using ecological niche models across 29 anti-tropical fishes, Ludt and Myers (2021) found that some species lack current suitable abiotic habitat in the tropics, but that suitable habitat and dispersal corridors between hemispheres were available for some species during the LGM despite only minor tropical temperature shifts during this time period. Together, these studies provide compelling evidence that glacial dispersal is one mechanism that produced antitropical distributions.…”

“…Another direction that studies have taken is ecological niche modeling to examine the suitability of habitats in the Pleistocene (Waltari and Hickerson, 2013;Ludt and Myers, 2021). This approach has the potential to distinguish between some of the hypotheses that are notoriously hard to test.…”

“…This approach has the potential to distinguish between some of the hypotheses that are notoriously hard to test. Ludt and Myers (2021) used niche modeling to distinguish between glacial dispersal and biotic exclusion in intra-specific anti-tropical marine fishes by examining the amount of suitable abiotic habitat in the tropics for both the LGM and contemporary time periods, and found potential support for both hypotheses in different species. However, these approaches are more informative if combined with other sources of data.…”

“…While these broad patterns may not strictly apply to all temperate taxa, ancestral area reconstructions focusing specifically on antitropical fishes like sawtail surgeonfishes and stripeys, and also herbivorous sea chubs that are a mix of temperate and tropical species, have suggested species origination in temperate areas, not tropical ones Knudsen et al, 2019;Tea et al, 2019). While this runs counter to one of the assumptions of the biotic exclusion hypothesis, suggesting that it might not apply to all anti-tropical taxa, the occurrence of contemporary suitable abiotic habitat in the tropics across a wide diversity of anti-tropical fishes suggests that biotic exclusion may be a plausible explanation for some taxa (Ludt and Myers, 2021; see discussion below).…”

Genetic diversity of the Southern Black Drum Pogonias courbina (Teleostei: Sciaenidae) from Río de la Plata and Atlantic Ocean coasts

“…However, during glacial maxima, the decrease in sea surface temperature could have allowed the dispersal from one hemisphere to the other of currently antitropical species (Ludt 2021). Ludt & Myers (2021) using ecological niche models could demonstrate that several anti-tropical species do not have a suitable abiotic habitat in the tropics, however, during the Last Glacial Maximum they found dispersal corridors between hemispheres. For instance, Tea et al (2019) proposed that the species Microcanthus strigatus in the Northern Hemisphere has had originated as a result of equatorial crossing during Pleistocene climate changes.…”