Paleocene Malvaceae from northern South America and their biogeographical implications

Abstract

The leaf compressions, the oldest fossils for Eumalvoideae, indicate a minimum divergence time of 58-60 Ma, older than existing estimates from molecular analyses of living species. The abundance of eumalvoid leaves and of bombacoid pollen in the midlate Paleocene of Colombia suggests that the Malvatheca group (Malvoideae + Bombacoideae) was already a common element in neotropical forests and does not support an Australasian origin for Eumalvoideae.

Paleocene wind-dispersed fruits and seeds from Colombia and their implications for early Neotropical rainforests

“…13-16%; Prance 1978, Mori & Brown 1994, where wind-dispersed fruits are typical of canopy emergent and lianescent species. The low percentage of wind-dispersed taxa may suggest that the forest canopies represented by the Paleocene Cerrejón and Bogotá floras were already multistratal, as has been suggested before based on floristic analogs (Doria et al 2008, Herrera et al 2011, Stull et al 2012. Ulmoidicarpum and Aerofructus show resemblance to fin-winged fruits of Holopte lea (Ulmaceae) and Cavanillesia (Malvaceae), respectively.…”

“…At least sixty fruit and seed morphotypes are recognizable from ca 300 specimens collected from the combined Cerrejón and Bogotá floras (see online appendix of Wing et al 2009, Herrera et al 2011), but only six are interpreted as wind-dispersed. Four are conspicuously winged: Ulmoidicarpum, Pl.…”

“…9). D i s c u s s i o n. Aerofructus dillhoffii augments pollen and leaf data, indicating the presence of the Malvaceae in Paleocene Neotropical floras (Jaramillo et al 2007, Carvalho et al 2011. Leaves of Malvaciphyllum macondicus and abundant pollen grains of Bombacacidites annae found in the Cerrejón flora indicate the Paleocene occurrence of members of the Eumalvoideae and Bombacoideae clades respectively.…”

“…2). The phylogenetic position of these genera (Baum et al 2004, Nyffeler et al 2005, Carvalho et al 2011 suggests that fin-winged fruits have evolved multiple times in the family. Burre tiodendron differs from Aerofructus (Pl.…”

Repeated polyploidization of Gossypium genomes and the evolution of spinnable cotton fibres

“…New insight into Gossypium biology is offered by a genome sequence of G. Shortly after its divergence from an ancestor shared with Theobroma cacao at least 60 Myr ago 6 , the cotton lineage experienced an abrupt five-to sixfold ploidy increase. Individual grape chromosome segments resembling ancestral eudicot genome structure, or corresponding cacao chromosome segments, generally have five (infrequently six) best-matching G. raimondii regions and secondary matches resulting from pan-eudicot hexaploidy 7,8 (Fig.…”