Abstract Detail

Macroevolution

López Martínez, Andrea Monserrath [1], Sauquet, Hervé [2], Magallon, Susana [3].

Evolution of floral groundplan in the transition to Pentapetalae (eudicots, angiosperms) through total-evidence analysis of extant and fossil species.

Phylogenetic results have consistently identified a grade of independent lineages at the onset of eudicot diversification, corresponding to Ranunculales, Proteales, Trochodendrales, Buxales, and Gunnerales, which are successive sister taxa to the species-rich, Pentapetalae clade. The early-diverging eudicots include a small to moderate number of species (i.e. two species in Trochodendrales and ~4510 species for Ranunculales), and encompass substantial diversity in their floral organization, including changes in perianth differentiation and arrangement and number of floral parts (phyllotaxy and merosity). In contrast, Pentapetalae clade contains ~73% of all angiosperm species and is mostly characterized by a generalized floral groundplan with whorled phyllotaxy, a pentamerous (or tetramerous) perianth and androecium, and a perianth differentiated into calyx and corolla. Here, we investigate floral groundplan evolution in the transition from the early-diverging eudicot grade to Pentapetalae. To conduct this study, we constructed a total-evidence phylogenetic framework with data from 68 extant species and 15 well-preserved fossil flowers, using parametric methods. We estimated the temporal context of floral evolution using node dating, tip dating and the Fossilized Birth-Death Process with total-evidence. Based on the total-evidence timetrees we conducted ancestral state reconstruction of perianth differentiation, phyllotaxy and floral merosity characters. Our results confirm previous systematic relationships of most fossil with only few exceptions. We found that the distinctive elements of the Pentapetalae groundplan were established by Early Cretaceous. We show that integrating fossils and extant taxa to elucidate morphological evolution provides results that were not evident based on extant taxa alone, for example, the emergence of pentamery in early branches of eudicot evolution.

1 - Universidad Nacional Autónoma de México, Botany, Cto. Zona Deportiva S/N, México City, México City, 04510, México
2 - Royal Botanic Gardens and Domain Trust, National Herbarium of New South Wales (NSW), Mrs Macquaries Rd, Sydney, Sydney, NSW 2000, Australia
3 - Universidad Nacional Autonoma De Mexico, Instituto De Biologia, 3er Circuito De Ciudad Universitaria, Del. Coyoacan, A.p. 70-233, Mexico City, Mexico D.F., DIF, 04510, Mexico

Keywords:
fossil flowers
Total Evidence Dating
Merosity
Basal eudicots.

Presentation Type: Oral Paper
Session: MACRO1, Macroevolution I
Location: Tucson B/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 8:15 AM
Number: MACRO1002
Abstract ID:406
Candidate for Awards:None