Biogeographic regions and events of isolation and diversification of the endemic biota of the tropical Andes

Abstract

Understanding the spatial and temporal evolution of biota in the tropical Andes is a major challenge, given the region's topographic complexity and high beta diversity. We used a network approach to find biogeographic regions (bioregions) based on high-resolution species distribution models for 151 endemic bird taxa. Then, we used dated molecular phylogenies of 14 genera to reconstruct the area history through a sequence of allopatric speciation processes. We identified 15 biogeographical regions and found 26 events of isolation and diversification within their boundaries that are independently confirmed with disjunct distributions of sister taxa. Furthermore, these events are spatially congruent with six geographical barriers related to warm and/or dry river valleys, discontinuities in elevation, and high peaks separating fauna from different range slopes. The most important barrier is the Marañon River Valley, which limits the boundaries of four bioregions and is congruent with eight phylogenetic distribution breaks, separating the Central and Northern Andes, where the most bioregions are found. We also show that many bioregions have diffuse and overlapping structures, with contact and transition zones that challenge previous conceptions of biogeographical regions as spatially simple in structure. This study found evidence that the drivers of our identified bioregions were processes of Andean uplift and mountain dispersal facilitated by temperature oscillations of the Pleistocene. Therefore, Andean bioregions were not formed from one simple biogeographical event in a certain time frame, but from a combination of vicariance and dispersal events, which occurred in different time periods.

The flickering connectivity system of the north Andean páramos

“…Several insightful schematic representations of Pleistocene diversification models in the Neotropics have been developed in recent years (Flantua & Hooghiemstra, ; Hazzi, Moreno, Ortiz‐Movliav, & Palacio, ; Ramírez‐Barahona & Eguiarte, ; Rull, ). Phylogeographical and phylogenetic synthesis work within and among páramo taxa is currently still largely lacking (see for instance Yu et al., for the Qinghai‐Tibet Plateau), inhibiting the direct testing of these models.…”

Divergence of tropical pitvipers promoted by independent colonization events of dry montane Andean habitats

“…Antonelli et al (), for example, found extensive rates of biotic interchange across different taxonomic groups and between major Neotropical regions – Amazonia being the primary source of diversity. Similarly, Hazzi et al () found that patterns of spatial and temporal evolution in birds from the Tropical Andes were explained by a combination of vicariance driven by mountain uplift and downslope dispersal events using river valley habitats. We complement these findings by identifying a fine‐scale case occurring in an ecologically distinct group of animals (i.e.…”

“…His 22‐month‐long expedition along the northern Andes in the early 19th century certainly constituted a pivotal time for the establishment of his revolutionary ideas about the natural world. Although great advances have been made in how biodiversity is generated in the Neotropics, an understanding of the origin and maintenance of Andean diversity is still incomplete (Hazzi, Moreno, Ortiz‐Movliav, & Palacio, ). In South America, the uplift of the Andes mountain range undoubtedly played an important role in the diversification of several taxonomic groups (Antonelli et al, ; Esquerré, Brennan, Catullo, Torres‐Pérez, & Keogh, ; Hoorn et al, ; Lagomarsino, Condamine, Antonelli, Mulch, & Davis, ).…”

Quaternary Highlights (July–September 2018)

“…For further relevant readings, see Caley et al [7], Hazzi et al [8], Hildebrand et al [9], Maier et al [10], Nogués-Bravo et al [11], Nolan et al [12], Scerri et al [13], and Taylor et al [14].…”