Out of the Andes: patterns of diversification in clearwing butterflies

Abstract

Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene-Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.

Diversification patterns in the North Andean Block: a perspective from biogeographical hypotheses

“…Andean uplift and the asynchronous Andean formation (Case et al, 1990;Hoorn et al, 1995;Gómez et al, 2003) are the major events involved in taxa separation between lowlands and highlands, as seen in our area relationships, and between southern and northern latitudes (Elias et al, 2009;Doan, 2003). Authors such as Chaves et al (2011) and García-Moreno and Fjeldså (2000), suggest that the North Andean taxa are Central Andes, Central America, and the Amazonian region support the previous idea.…”

“…Apart from the affirmation above, mountain-building could influence the diversification of different groups acting as a barrier or as a dispersal corridor (Ribas et al, 2007;Elias et al, 2009) and it might generate a single or multiple patterns over time (Fig. 3).…”

Diversification of clearwing butterflies with the rise of the Andes

“…Indeed, forest productivity is higher on nutrient‐rich western Amazonian soils, in contrast to the nutrient‐poor soils of the eastern Amazon (Hoorn et al ., 2010). Further diversification within the monotypic O. aegle group in eastern Amazonia and the Guianas may also have been limited by the availability of larval host plants as has been noted with other ithomiine genera in this region (Elias et al ., 2009). Several instances of sympatric onega group sister species within western Amazonia suggests that fine‐scale ecological adaptation, such as specialization on different but related host plant species (Willmott & Mallet, 2004), might have been important in the diversification of this clade.…”

“…In summary, our results reveal that the Andean orogeny instigated and had a profound influence on the diversification of the Oleriina, in agreement with the ithomiine genera Napeogenes and Ithomia (Elias et al ., 2009), and other butterfly groups such as Morpho (Blandin & Purser, 2013), Taygetis (Matos‐Maraví et al ., 2013) and Lymanopoda (Casner & Pyrcz, 2010). The evolution of the Oleriina occurred when the Central Andes had attained at least 1000‐1500 m (Garzione et al ., 2008).…”

“…However, mounting evidence suggests that the Andean orogeny and geologically dynamic areas, in general, (Hoorn et al ., 2013) have also promoted diversification through allopatric speciation while also presenting new opportunities for ecological adaptation (Gentry, 1982; Kattan et al ., 2004; Elias et al ., 2009; Santos et al ., 2009). …”