Vicariance and dispersal in southern hemisphere freshwater fish clades: a palaeontological perspective

Abstract

Widespread fish clades that occur mainly or exclusively in fresh water represent a key target of biogeographical investigation due to limited potential for crossing marine barriers. Timescales for the origin and diversification of these groups are crucial tests of vicariant scenarios in which continental break‐ups shaped modern geographic distributions. Evolutionary chronologies are commonly estimated through node‐based palaeontological calibration of molecular phylogenies, but this approach ignores most of the temporal information encoded in the known fossil record of a given taxon. Here, we review the fossil record of freshwater fish clades with a distribution encompassing disjunct landmasses in the southern hemisphere. Palaeontologically derived temporal and geographic data were used to infer the plausible biogeographic processes that shaped the distribution of these clades. For seven extant clades with a relatively well‐known fossil record, we used the stratigraphic distribution of their fossils to estimate confidence intervals on their times of origin. To do this, we employed a Bayesian framework that considers non‐uniform preservation potential of freshwater fish fossils through time, as well as uncertainty in the absolute age of fossil horizons. We provide the following estimates for the origin times of these clades: Lepidosireniformes [125–95 million years ago (Ma)]; total‐group Osteoglossomorpha (207–167 Ma); Characiformes (120–95 Ma; a younger estimate of 97–75 Ma when controversial Cenomanian fossils are excluded); Galaxiidae (235–21 Ma); Cyprinodontiformes (80–67 Ma); Channidae (79–43 Ma); Percichthyidae (127–69 Ma). These dates are mostly congruent with published molecular timetree estimates, despite the use of semi‐independent data. Our reassessment of the biogeographic history of southern hemisphere freshwater fishes shows that long‐distance dispersals and regional extinctions can confound and erode pre‐existing vicariance‐driven patterns. It is probable that disjunct distributions in many extant groups result from complex biogeographic processes that took place during the Late Cretaceous and Cenozoic. Although long‐distance dispersals likely shaped the distributions of several freshwater fish clades, their exact mechanisms and their impact on broader macroevolutionary and ecological dynamics are still unclear and require further investigation.

Phenotypic and genetic differentiation between diadromous and landlocked puyen Galaxias maculatus

“…Although the fossil record is low (restricted to Miocene deposits from New Zealand), galaxiids are estimated to have originated in Oceania during the Mesozoic–Cenozoic (235–21.2 Ma) and migrated to South America through the Antarctic Circumpolar Current (Berra et al ., ; Burridge et al ., ; Capobianco & Friedman, ; McDowall, ; Waters et al ., ; Waters & Burridge, ). Before the last glaciation, about 20 kyr bp , and the retreat of the glaciers, about 13.5 kyr bp , G. maculatus individuals would have established in the south of Tierra del Fuego.…”

“…Although the fossil record is low (restricted to Miocene deposits from New Zealand), galaxiids are estimated to have originated in Oceania during the Mesozoic-Cenozoic (235-21.2 Ma) and migrated to South America through the Antarctic Circumpolar Current (Berra et al, 1996;Burridge et al, 2012;Capobianco & Friedman, 2018;McDowall, 1970;Waters et al, 2000;Waters & Burridge, 1999) generating the distribution observed today. Furthermore, the only connection between the two sites (the AN stream) is a shallow stream with small but several waterfalls and beaver dams, which could lead to physical isolation, because it has been observed, experimentally, that a fall height of 20 cm is sufficient to restrict G. maculatus (Baker, 2003).…”

Global biogeographical regions of freshwater fish species

“…O. bengalense lives in estuaries and is tolerant to brackish waters, and thus may have dispersed through Wallacea (e.g. Capobianco & Friedman, ). On the other hand, the distributions of the other two species are more surprising, and the absence of data in all islands of Wallacea makes hypotheses highly speculative.…”

“…Terrestrial boundaries and salt waters represent strong barriers to dispersal, hence drainage basins have been considered as “island‐like” systems for strictly freshwater organisms (Dias et al, ; Hugueny, Oberdorff, & Tedesco, ; Rahel, ; Tedesco et al, ). Dispersal can occur actively or passively via underground waters, stream captures, exceptional floods, glacier melting causing stream overflow, confluence during sea‐level lowering and displacement by other organisms or typhoons (see also discussion in Capobianco & Friedman, ). However, such dispersal events are rare, therefore, immigration and speciation presumably occur on similar time‐scales (Oberdorff et al, ).…”

Global biogeographical regions of freshwater fish species

“…Terrestrial boundaries and salt waters represent strong barriers to dispersal, hence drainage basins have been considered as ‘island-like’ systems for strictly freshwater organisms (Rahel, 2007; Hugueny, Oberdorff, & Tedesco, 2010; Tedesco et al, 2012; Dias et al, 2014). Dispersal can occur actively or passively via underground waters, stream captures, exceptional floods, glacier melting causing stream overflow, confluence during sea-level lowering, and displacement by other organisms or typhoons (see also discussion in Capobianco & Friedman, 2018). However, such dispersal events are rare, therefore immigration and speciation presumably occur on similar time-scales (Oberdorff et al, 2011).…”