Abstract Detail

Plant life in Neotropical rocky outcrops

Alcantara, Suzana [1].

Morphological and ecological divergence in Neotropical Velloziaceae.

Rocky outcrops in Eastern South America occur mainly as granitic formations in the peaks of the coastal Atlantic rainforest, i.e., campos de altitude-CA, and as quartzite soils on the Espinhaço Range, i.e., campos rupestres-CR, newly recognized as the biogeographic region holding the highest plant endemism in Brazil. The monocot family Velloziaceae is one of the clades able to thrive in both areas, with species diversity and dominance in CR markedly higher than in CA. Previous results indicated that both genera of Velloziaceae, Barbacenia and Vellozia, suffered diversification rate shifts toward faster diversification, which was associated with CR endemism. In addition, Vellozia shows a decreasing diversification rate toward the present, corroborating previous hypothesis of adaptive radiation in the CR. On the other hand, Barbacenia shows a pattern of young diversification affected by the present pool of species, which has been hypothesized to be caused by increasing specialization to rocky outcrops. Here, I focus on morphological disparification of vegetative and ecophysiological traits in Barbacenia and Vellozia, and also on microhabitat specialization in order to better understand the causes of plant diversity in the CR. As expected, Vellozia displays higher morphological diversification than Barbacenia, with growth forms diverging early in the genus and being conserved among the extant species. However, the multivariate variation of individual traits have been highly convergent in Vellozia, with species from different clades occupying close positions in the phylomorphospace. The most diverse clade within Vellozia in terms of species number and morphological variation is also the most recently diverged and highly restricted to the South Espinhaço province. When microhabitat specialization to outcrops was considered, generalist lineages in Barbacenia and Vellozia did show higher diversification rates than the specialists, rejecting the initial hypothesis that outcrop specialization drove diversification in Barbacenia. Although morphological divergence in Barbacenia is less pronounced among extant species, it shows a much more marked disparification than Vellozia, starting around 4My toward the present. Vellozia also shows a small increase in disparification around the same time, although its morphological divergence started earlier and accumulated over mostly constant rates. In both genera, morphological disparification occurred  much later than diversification rate shifts. This time slice of higher disparification coincides with the period in which many CR endemic lineages display highest diversification rates, reinforcing the importance of late Pliocene/Pleistocene events to the assemblage of the CR flora.

Related Links:

1 - UFSC-Universidade Federal De Santa Catarina, Depto De Botanica, Campus Universitário Trindade, Bairro Trindade, Florianopolis, SC, 88040-900, Brazil

ecological strategy
adaptive radiation.

Presentation Type: Colloquium Presentations
Session: COL08, Plant life in Neotropical rocky outcrops
Location: Virtual/Virtual
Date: Friday, July 31st, 2020
Time: 11:00 AM
Number: COL08004
Abstract ID:262
Candidate for Awards:None

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