Multiple drainage reversal episodes and glacial refugia in a Patagonian fish revealed by sequenced microsatellites

Abstract

The rise of the southern Andes and the Quaternary glacial cycles influenced the landscape of Patagonia, affecting the phylogeographic and biogeographic patterns of its flora and fauna. Here, we examine the phylogeography of the freshwater fish, Percichthys trucha, using 53 sequenced microsatellite DNA markers . Fish ( n = 835) were collected from 16 river systems (46 locations) spanning the species range on both sides of the Andes. Eleven watersheds drain to the Pacific, five of which are trans-Andean (headwaters east of Andes). The remaining five drainages empty into the Atlantic. Three analytical approaches (neighbour-joining tree, hierarchical AMOVAs, S tructure ) revealed evidence of historic drainage reversals: fish from four of the five trans-Andean systems (Puelo, Futalaufquen/Yelcho, Baker, Pascua) exhibited greater genetic similarity with Atlantic draining systems than with Pacific systems with headwaters west of Andes. Present-day drainage (Pacific versus Atlantic) explained only 5% of total genetic variance, while ancestral drainage explained nearly 27% of total variance. Thus, the phylogeographic structure of P. trucha is consistent with episodes of drainage reversal in multiple systems and suggests a major role for deglaciation in the genetic and indeed the geographical distribution of P. trucha in Patagonia. The study emphasizes the significant role of historical processes in the current pattern of genetic diversity and differentiation in a fish from a southern temperate region.

Historical and Contemporary Diversity of Galaxiids in South America: Biogeographic and Phylogenetic Perspectives

“…The temporal pattern of colonization likely varied with latitude and the particular characteristics of the focal system. For instance, a study using microsatellites to estimate divergence time and changes in migration patterns revealed that mountain lakes in northwestern Patagonia west of the Andes (San Pedro River, Valdivia River watershed) appear to have been colonized only during the late Holocene (720-2040 years BP); Figure 3A; [39];) following drainage reversals that took place when glaciers, which previously had acted as barriers to western dispersal, began melting (similar episodes of drainage reversals were documented for other species as well using DNA sequences and microsatellite markers, see [52,60]). Further south, in central Andean Patagonia, studies using microsatellite markers and DNA sequences suggest that G. platei populations likely also survived the Pleistocene glaciations in areas east of the Andes, and colonized western Andean systems during the Holocene [22,34]; Figure 3B).…”

“…Although orogeny and glaciations played a major role in extant patterns of genetic diversity in galaxiid and other native Patagonian fishes [50,60,67,68], more recent processes, such as the introduction of invasive species (e.g., salmonid species) and the construction of dams for hydroelectric power generation, have likely had a greater influence on the genetic patterns of galaxiid fishes from South America than has been recognized thus far. Some authors have found a slight negative correlation between salmonid abundance and microsatellite diversity (heterozygosity and allelic richness) in Aplochiton zebra, but have not find a correlation between salmonid abundance and mtDNA diversity [52].…”

Genetic Diversity and Demographic History of the Shaggy Soft-Haired Mouse Abrothrix hirta (Cricetidae; Abrotrichini)

“…Since the footprints get erased with time and with the occurrence of subsequent events, such inferences have limitations ( Avise, 2009 ). The body of literature accumulated on the phylogeography of the biota from southern South America, including plants (e.g., Premoli et al, 2010 ; Achimón et al, 2018 ; Biersma et al, 2018 ; Nicola et al, 2019 ), reptiles (e.g., Victoriano et al, 2008 ; Femenias et al, 2020 ), amphibians (e.g., Nuñez et al, 2011 ), fishes (e.g., Ruzzante et al, 2006 ; Zemlak et al, 2008 ; Ruzzante et al, 2020 ), birds ( Norambuena et al, 2018 ), and mammals (e.g., Lessa et al, 2010 ; Palma et al, 2012 ), reveals that the responses to Quaternary dynamics were varied and mostly species-specific (e.g., Lessa et al, 2010 ; Sersic et al, 2011 ). Two general patterns were described by Lessa et al (2010) for Patagonian sigmodontine rodents.…”

Genomic data support management of anadromous Arctic Char fisheries in Nunavik by highlighting neutral and putatively adaptive genetic variation

“…with diversity and differentiation decreasing in populations far from the Iberic glacial refugia (Mateus et al, 2016), and in Scottish populations of Atlantic Salmon, where Dalton et al (2020), is represented by shades of gray for 6000-12,000 years before present (YBP) genetic diversity was lower in more recently deglaciated regions (Cauwelier et al, 2018). Following the initial recolonization of rivers in Nunavik by Arctic Char, processes such as isostatic rebound and the formation of proglacial lakes considerably modified the drainage basins (Dubé-Loubert et al, 2018;Jansson, 2003), which could have contributed to gene flow between regions (e.g., Ruzzante et al, 2020).…”