Caught in the Act: Incipient Speciation at the Southern Limit of Viburnum in the Central Andes.

A fundamental objective of evolutionary biology is to understand the origin of independently evolving species. Phylogenetic studies of species radiations rarely are able to document ongoing speciation; instead, modes of speciation, entailing geographic separation and/or ecological differentiation, are posited retrospectively. The Oreinotinus clade of Viburnum has radiated recently from north to south through the cloud forests of Mexico and Central America to the Central Andes. Our analyses support a hypothesis of incipient speciation in Oreinotinus at the southern edge of its geographic range, from central Peru to northern Argentina. Although several species and infraspecific taxa have been recognized in this area, multiple lines of evidence and analytical approaches (including analyses of phylogenetic relationships, genetic structure, leaf morphology, and climatic envelopes) favor the recognition of just a single species, V. seemenii. We show that what has previously been recognized as V. seemenii f. minor has recently occupied the drier Tucuman-Bolivian forest region from Samaipata in Bolivia to Salta in northern Argentina. Plants in these populations form a well-supported clade with a distinctive genetic signature and they have evolved smaller, narrower leaves. We interpret this as the beginning of a within-species divergence process that has elsewhere in the neotropics resulted repeatedly in Viburnum species with a particular set of leaf ecomorphs. Specifically, the southern populations are in the process of evolving the small, glabrous, and entire leaf ecomorph that has evolved in four other montane areas of endemism. As predicted based on our studies of leaf ecomorphs in Chiapas, Mexico, these southern populations experience generally drier conditions, with large diurnal temperature fluctuations. In a central portion of the range of V. seemenii, characterized by wetter climatic conditions, we also document what may be the initial differentiation of the leaf ecomorph with larger, pubescent, and toothy leaves. The emergence of these ecomorphs thus appears to be driven by adaptation to subtly different climatic conditions in separate geographic regions, as opposed to parapatric differentiation along elevational gradients as suggested by Viburnum species distributions in other parts of the neotropics.

Replicated radiation of a plant clade along a cloud forest archipelago.

Replicated radiations, in which sets of similar forms evolve repeatedly within different regions, can provide powerful insights into parallel evolution and the assembly of functional diversity within communities. Several cases have been described in animals, but in plants we lack well-documented cases of replicated radiation that combine comprehensive phylogenetic and biogeographic analyses, the delimitation of geographic areas within which a set of 'ecomorphs' evolved independently and the identification of potential underlying mechanisms. Here we document the repeated evolution of a set of leaf ecomorphs in a group of neotropical plants. The Oreinotinus lineage within the angiosperm clade Viburnum spread from Mexico to Argentina through disjunct cloud forest environments. In 9 of 11 areas of endemism, species with similar sets of leaf forms evolved in parallel. We reject gene-flow-mediated evolution of similar leaves and show, instead, that species with disparate leaf forms differ in their climatic niches, supporting ecological adaptation as the driver of parallelism. Our identification of a case of replicated radiation in plants sets the stage for comparative analyses of such phenomena across the tree of life.

ColectoR, a digital field notebook for voucher specimen collection for smartphones.

PREMISE OF THE STUDY: ColectoR was developed to aid botanists in the collection of data for voucher specimens using smartphones, accelerating the process of data capture in situ and its subsequent organization. METHODS AND RESULTS: ColectoR features a minimalist design that uses an intuitive iconic interface. The integration of external application programming interfaces (APIs) and an automated spreadsheet extends its functionality and increases the information and tools available to the user. This app is currently supported by any Android device. CONCLUSIONS: ColectoR provides an efficient method for capturing data in the field while also serving to organize the information into a coherent database, thereby greatly reducing the time required for postcapture data organization and label printing.