Abstract Detail

Molecular Ecology and Evolution

Hernández, Rebeca [1], Magallón, Susana [2].

Diversification of Bombacoideae (Malvaceae s.l.) associated to pollination.

The great diversity of angiosperms in the Neotropics can be understood by means of macroevolutionary processes that have promoted diversification. One of these processes is the selective pressure that pollinators cause on floral evolution and lead to speciation events. Subfamily Bombacoideae (Malvaceae) is a group of tropical trees with an interesting floral diversity as the androecium has undergone substantial modifications, and the resulting distinctive structural and morphological modifications are probably a response to pollinators. Two main types of androecium organization are distinguished within Bombacoideae, one with sessile, elongated, sometimes convoluted anthers, and the other with stalked, monothecate stamens that conform the characteristic brush-flower of most bombacoids. Bat pollination is well known in Bombacoideae, but there are also many species pollinated by birds, hawkmoths and butterflies. The aim of this work is to document the diversification dynamics within Bombacoideae, and to investigate the effects that pollinators may have had on it. We used sequence data of three plastid regions (ndhF, trnK-matK and trnL-F) and one of the nuclear marker (ITS) to estimate the phylogenetic relationships within Bombacoideae, including representatives of Malvoideae, and of all other subfamilies of Malvaceae. We obtained a phylogenetic hypothesis from which we estimated the divergence times (using BEAST), and conducted a diversification analysis to identify major rate shifts (using MEDUSA). For Bombacoideae and outgroups we obtained data of pollinators from the literature. Since there is no data for all the species included here, we made three categories to give our analyses a range of error based on the accuracy of the data: (1) strict pollination studies, (2) studies that only mention the visitors and (3) inferences based on floral syndrome. We subsequently conducted ancestral state reconstructions of pollinator type implementing Maximum Likelihood and Bayesian frameworks to evaluate whether there is a correlation between shifts of pollinator and shifts in diversification rates. The results confirm that Bombacoideae is monophyletic, it is characterized by palmately compound leaves and is sister to Malvoideae. The ancestral pollination type in Bombacoideae is likely to have been by bats. However, the age that we estimated for Bombacoideae is older than independent estimates for the age of bats. The possibility of an early transition from some vertebrate pollinator, different from bat, leading to widespread bat pollination especially associated with the diversification of the Adansonieae clade is discussed.

1 - Instituto de Biología, Botanica, Tercer Circuito S/N, Ciudad Universitaria, Mexico, D. F., 04510, México
2 - Instituto De Biologia, Universidad Nacional Autonoma De Mexico, 3er Circuito De Ciudad Universitaria, Del. Coyoacan, A.P. 70-233, Mexico City, Mexico D.F., N/A, 04510, Mexico

Keywords:
diversification
pollination
Bombacoideae
molecular dating
character reconstruction.

Presentation Type: Oral Paper:Papers for Topics
Session: 11
Location: Firs North/Boise Centre
Date: Monday, July 28th, 2014
Time: 3:45 PM
Number: 11009
Abstract ID:269
Candidate for Awards:Margaret Menzel Award