Timing the diversification of the Amazonian biota: butterfly divergences are consistent with Pleistocene refugia

Abstract

Rejection of the Pleistocene refugium hypothesis (PRH) as an explanation for the high biodiversity of Neotropical forest is based in part on the assertion that biotic elements of these forests evolved during the Neogene. That argument is justified, in turn, by the ages of crown groups (the age of the most recent common ancestor of extant species of a clade). We consider the use of crown ages as a metric to reject the PRH to be an unfair test, because the circumscription of crown groups of interest is arbitrary, and their ages represent overestimates of the time of species formation. We present divergence times between pairs of sister species (131 pairs), and among pairs of sister species and their closest relative (56 triplets), from 35 genera of Neotropical butterflies. Our aim is to refocus the discussion about the timing of diversification of the Neotropical biota on the time of the formation of extant species, a metric that is consistent and comparable across taxa. Our results show that 72% of speciation events leading to the formation of butterfly sister species occurred within the last 2.6 Myr, a result consistent with the temporal predictions of the PRH, suggesting that the PRH cannot be completely discarded as a driver of Neotropical diversification.

Pleistocene speciation is not refuge speciation

“…Garzón‐Orduña et al . (, p. 1631) found that ‘…72% of speciation events leading to the formation of butterfly sister species occurred within the last 2.6 Myr [the Pleistocene]…’ and concluded that ‘…the PRH [Pleistocene refuge hypothesis] cannot be completely discarded as a driver of Neotropical diversification’. In their analysis, Garzón‐Orduña et al .…”

“…Garzón‐Orduña et al . () used DNA molecular phylogenies to estimate the age of speciation of Neotropical butterflies in their contribution to the debate about the timing and causes of Neotropical diversification. These authors addressed the problem using species dating (estimating the age of divergence of sister species) instead of crown dating (estimating the age of the initial diversification of supra‐specific clades), as it has been suggested that, in general, crown dating tends to overestimate the chronological origin of diversity (Rull, ,b).…”

Model-based analysis supports interglacial refugia over long-dispersal events in the diversification of two South American cactus species

“…The paucity of data for South American species, particularly for those adapted to open and/or dry habitat types, has greatly hindered the understanding about diversification mechanisms in the continent (Hughes et al, 2013;Turchetto-Zolet et al, 2013). Despite the controversy about Haffer's (1969) forest refuge hypothesis (for example, Hoorn et al, 2010;Rull 2011), many species associated with mesic vegetation display similar patterns (Turchetto-Zolet et al, 2013;Garzón-Orduña et al, 2014) that are consistent with the tropical refugial hypothesis. This is not true for species occurring in xeric and open environments as the rocky savanna habitats in Eastern South America, which show more idiosyncratic patterns (Turchetto-Zolet et al, 2013).…”

“…The investigation into the effect of historical climatic changes on the distribution and population dynamics of species has been a major focus of phylogeography (Hewitt, 1996;Avise et al, 1998;Taberlet et al, 1998;Soltis et al, 2006;Garzón-Orduña et al, 2014). Most of these studies focused in the Northern Hemisphere (Beheregaray, 2008), and tried to identify putative species refugia by locating regions of the species' range that contain high levels of genetic diversity and were also ice-free during glaciation (Keppel et al, 2012).…”

North Andean origin and diversification of the largest ithomiine butterfly genus

“…12) or the Pebas system, a large network of shallow lakes and wetlands, which occupied the upper Amazon region, may have constrained dispersal and promoted local diversification until its drainage around 10-7 million years ago1314. It is also suggested that climatic instability during the Pleistocene drove the diversification of extant Neotropical species, but the importance of this mechanism remains controversial9151617181920.…”