Monday, May 22, 2017

[Entomology • 2017] Phylogeny and Diversification of the Cloud Forest Morpho sulkowskyi Group (Lepidoptera, Nymphalidae) in the Evolving Andes


The monophyletic Morpho sulkowskyi butterfly group, endemic of Andean cloud forests, was studied to test the respective contributions of Mio-Pliocene intense uplift period and Pleistocene glacial cycles on Andean biodiversity. We sampled nine taxa covering the whole geographical range of the group. Two mitochondrial and two nuclear genes were analysed using a Bayesian method. We established a dated phylogeny of the group using a relaxed clock method and a wide-outgroup approach. To discriminate between two hypotheses, we used a biogeographical probabilistic method. Results suggest that the ancestor of the M. sulkowskyi group originated during the Middle–Late Miocene uplift of the Eastern Cordillera in northern Peru. Biogeographical inference suggests that the M. sulkowskyi and Morpho lympharis clades diverged in the northern Peruvian Andes. The subsequent divergences, from the Late Miocene to the Late Pliocene, should have resulted from a dispersal towards the Northern Andes (M. sulkowskyi clade), after the closure of the West Andean Portal separating the Central and Northern Andes, and a southwards dispersal along the Peruvian and Bolivian Eastern Cordilleras (M. lympharis clade). Only a few divergences occurred at the very end of the Pliocene or during the Pleistocene, a period when the more recent uplifts interfered with Pleistocene glacial cycles.

Figure 1.  Map of the region where field studies were carried out, with habitus of the taxa calderoni, zachi and nieva (m: male; f: female; f1 and f2: female morphs within the calderoni population). N1 and N2: sampling areas along the upper Río Nieva. Other localities where specimens were collected: AP: Abra Patricia; EF: El Afluente; OP: Oso Perdido; PM: Abra Pardo Miguel; V: Venceremos. Two specimens of nieva were also collected at Santa Cruz del Mirador (M), at ca. 20 km ESE from El Afluente. 

Simple relationships between Andean uplift and the diversification of various plant and animal groups, implying pre-Pleistocene driving processes, have been supposed by various authors. Doan (2003), for example, proposed the south-to-north speciation hypothesis, where the process of speciation should be related to the south-to-north progression of uplift throughout the Andes. Other authors emphasized the possible role of a rapid uplift that occurred during the Late Miocene and Early Pliocene, but often without establishing clear links between dated divergences and local geologic events (e.g. Casner & Pyrcz 2010; Mulch et al. 2010; Matos-Maraví et al. 2013; Lagomarsino et al. 2016). From a geological point of view, the concept of a progressive, general south-to-north uplift is an oversimplified view of a much more complex reality (Sempere et al. 2008). In the Central Andes, palaeo-elevation histories differ not only between the south and the north, but also between the western and the eastern cordilleras, notably in northern Peru (Picard et al. 2008; Eude et al. 2015; Margirier et al. 2015). The idea that the Northern Andes, as a whole, uplifted later than the Central Andes, as suggested by Doan (2003), and often admitted by other authors, is not supported by geological studies that also demonstrate that the timing of palaeo-elevation differed between the three Colombian Cordilleras (Restrepo- Moreno et al. 2009). Consistent with many other examples, notably the clearwing Oleriina butterflies (De-Silva et al. 2016), the M. sulkowskyi group illustrates the diversity of diversification histories throughout the Andes. It also demonstrates that Mio-Pliocene orogenic and Pleistocene climatic diversification drivers should not be opposed.

Romain Nattier, Claire Capdevielle-Dulac, Catherine Cassildé, Arnaud Couloux, Corinne Cruaud, Gilbert Lachaume, Gerardo Lamas, Jean-François Silvain and Patrick Blandin. 2017. Phylogeny and Diversification of the Cloud Forest Morpho sulkowskyi Group (Lepidoptera, Nymphalidae) in the Evolving Andes.  Zoologica Scripta.  DOI: 10.1111/zsc.12226