Abstract Detail

Macroevolution

Dellinger, Agnes [1], Lagomarsino, Laura [2], Smith, Stacey [3].

Colonization of the Andes triggered pollinator shifts and a burst in speciation rate in Neotropical Merianieae (Melastomataceae).

Andean cloud forests are among the most species rich habitats on our planet, and their dynamic geological history is regarded as major driver of angiosperm diversification. Many Andean plant radiations feature prominent shifts in life history traits (i.e., shifts in growth form or pollinators), but our understanding of the relative contribution of functional traits, biotic interactions and changeable historic processes in driving lineage diversification remains fragmentary. We here use the tribe Merianieae (Melastomataceae) as a model to test the role of Andean uplift, paleoclimatic fluctuations, biogeography, abiotic niche evolution, vegetative traits and pollinator shifts in shaping the diversification history of the group. Merianieae are widely distributed across the Neotropics, occur from lowland rainforests to high-elevation cloud forests, and show a diversity of growth forms (i.e., herbs, lianas, shrubs, trees) and pollination strategies (buzz-bee pollination and vertebrate pollination). Using birth-death models and biogeographic reconstructions, we show that a single colonization of the Northern Andes approximately 12 million years ago resulted in a pulse of speciation in the tribe. Lineages which remained in the lowlands of the Amazon basin, the Guyana shield or the Venezuelan Highlands did not undergo comparable rate shifts. The evolution into Andean environments was accompanied by increased rates of flower morphological evolution, which allowed for adaptation to larger-sized mountain-adapted bees. The cold montane environment further drove repeated shifts from bee to vertebrate pollination, but vertebrate pollination was no pre-condition for Andean colonization. We did not find comparable rate shifts in vegetative traits in association with montane environments, albeit a trend of herbs and lianas occurring mostly outside of the Andes. Overall, our results add to the increasing evidence that in situ diversification, accompanied with increased floral diversification associated with pollination, is the dominant evolutionary process in the Andes.

1 - University Of Colorado Boulder, Ecology And Evolutionary Biology, 1800 Colorado Avenue, Ramaley Biology, Boulder, CO, 80309, United States
2 - Louisiana State University, Dept Of Biological Sciences, 103 Life Sciences Building, Baton Rouge, LA, 70803, United States
3 - University Of Colorado-Boulder, EBIO Department, Campus Box 0334, Boulder, CO, 80309, United States

Keywords:
plant-pollinator interactions
Diversification
Neotropical biogeography
vegetative traits
Climatic niche
morphospace
disparity
Andean uplift.

Presentation Type: Oral Paper
Number: MACRO I003
Abstract ID:217
Candidate for Awards:None