Adriana Sanchez

Phylogenetics of Polygonaceae with an Emphasis on the Evolution of Eriogonoideae

Abstract Polygonaceae has long been recognized as a monophyletic family but the circumscription of groups within it has been in constant flux. Two groups currently recognized are the subfamilies Eriogonoideae and Polygonoideae. An analysis using three chloroplast regions (rbcL, matK, and ndhF) and increased taxon sampling of Eriogonoideae does not support this delimitation. The second intron and portions of the flanking exons of the nuclear gene LEAFY, were used to explore phylogenetic utility in Polygonaceae. The intron showed high levels of variability and was useful at low taxonomic levels, but not alignable outside of Eriogonum and allied genera. Phylogenetic analysis of data from the flanking exons of the second intron of LEAFY generally supports the major groupings found in the chloroplast analysis. A new definition of the subfamilies is proposed. Polygonoideae is restricted to what has been recognized as tribes Persicarieae, Rumiceae, and Polygoneae, with the addition of Muehlenbeckia. Eriogonoideae now includes Antigonon, Brunichia, Coccoloba, Ruprechtia, Triplaris, and Eriogonum and allied genera. The genera Eriogonum and Chorizanthe are nonmonophyletic.

A Large‐Scale Phylogeny of Polygonaceae Based on Molecular Data

Few studies have addressed the evolutionary relationships within Polygonaceae from a global perspective. The convoluted taxonomic history of Polygonaceae is a major barrier to understanding evolution in this group, and only portions of it have been included in systematic treatments. Phylogenetic studies have been limited in both taxon sampling and amount of data. Our objective is to identify clades within Polygonaceae and to provide a global estimate of phylogenetic relationships in this morphologically diverse and geographically widespread group. We include a total of 75 species representing approximately 40 of the 55 named genera in the family. We use three chloroplast regions (rbcL, matK, and ndhF) and the ribosomal internal transcribed spacer to understand the phylogenetic relationships in Polygonaceae. Maximum parsimony and maximum likelihood are used to analyze the data. Symmeria is the sister group to remaining Polygonaceae sampled, and there is strong support for this placement. Afrobrunnichia branches next but has only moderate support. Two large clades comprise Polygonaceae, generally corresponding to those found in previous molecular analyses. Circumscription of most of the currently recognized subgroups within Polygonaceae did not agree with clades identified in the total data analyses, with the exception of Rumiceae Dum.

Placing the woody tropical genera of Polygonaceae: A hypothesis of character evolution and phylogeny

UNLABELLED PREMISE OF THE STUDY Taxonomic groups have often been recognized on the basis of geographic distinctions rather than accurately representing evolutionary relationships. This has been particularly true for temperate and tropical members from the same family. Polygonaceae exemplifies this problem, wherein the woody tropical genera were segregated from temperate members of the family and placed in the subfamily Polygonoideae as two tribes: Triplarideae and Coccolobeae. Modern phylogenetic studies, especially when inferred from many lines of evidence, can elucidate more probable hypotheses of relationships. This study builds on previous work in the family and aims to test the traditional classification of the tropical woody taxa, which have been understudied and undersampled compared to their temperate relatives. • METHODS A phylogenetic study was undertaken with expanded sampling of the tropical genera with data from five plastid markers (psbA-trnH, psaI-accD, matK, ndhF, and rbcL), nuclear ribosomal DNA (ITS) and morphology. • KEY RESULTS Results support the placement of nine of 12 genera of the Triplarideae and Coccolobeae within Eriogonoideae, in which these genera form a paraphyletic assemblage giving rise to Eriogoneae. The remaining woody tropical genera excluded from Eriogonoideae occur in the paleotropics. • CONCLUSIONS Traditional characters used to delimit Coccolobeae and Triplarideae are not useful for defining monophyletic groups. The six-tepal condition is derived from the five-tepal condition, and unisexual flowers have arisen multiple times in different sexual systems. Ruminate endosperm has arisen multiple times in the family, suggesting this character is highly plastic.

Isolation of Cryptococcus gattii molecular type VGIII, from Corymbia ficifolia detritus in Colombia

An environmental sampling survey was carried out in different areas of Bogotá, Colombia, to obtain isolates of members of the Cryptococcus neoformans/C. gattii species complex from Corymbia ficifolia trees. During a 6-month period in 2007, 128 samples consisting of bark, soil around trunk bases, detritus, seeds and flowers were collected from 91 trees and processed according to standard procedures. The molecular type was determined using URA5 restriction fragment length polymorphism (RFLP) analysis and the mating type was established by PCR using specific primers for Mfalpha and Mfa C. gattii was isolated from 15 of the 128 (11.7%) samples, of which three (20%) were recovered from the red flower extract and the remaining 12 from C. ficifolia detritus. URA5 RFLP analysis revealed that all 15 isolates belonged to the molecular type VGIII and mating type specific PCR revealed that all were mating type a. The isolation of C. gattii from C. ficifolia represents an important finding since this is the first report revealing C. ficifolia as a habitat for C. gattii and adds additional information to the ever growing spectrum of tree species from which C. gattii can be recovered.

Dynamic Cloud Regimes, Incident Sunlight, and Leaf Temperatures in Espeletia grandiflora and Chusquea tessellata, Two Representative Species of the Andean Páramo, Colombia

Abstract The alpine páramo of Chingaza National Park, Colombia, has a highly variable cloud regime typical of many tropical alpine areas. Yet, little information is available regarding the effects of such dynamic sunlight regimes on alpine temperatures. A close association between changes in incident sunlight and corresponding air (Ta) and leaf (Tl) temperatures occurred in two dominant species with strongly contrasting leaf form and whole-plant architecture. Spikes in sunlight incidence of >3000 &mgr;mol m-2 s-1 occurred during cloud cover and corresponded to increases in Tl of 4–5 °C in a 1-min-interval in both species. Although Tl was predominately above Ta, during the day, depressions below Ta of over 6 °C occurred during cloudy conditions when photosynthetic photon flux density (PFDs) was <400 &mgr;mol m-2 s-1. The greatest frequency (69%) of changes in incident sunlight (PFDs; over 2-min intervals) was less than 100 &mgr;mol m-2 s-1, although changes >1000 &mgr;mol m-2 s-1 occurred for 2.4% of the day, including a maximum change of 1512 &mgr;mol m-2 s-1. These data may be valuable for predicting the ecophysiological impact of climate warming and associated changes in future cloud regimes experienced by tropical alpine species.

Colombia: Dealing in conservation

Colombias decades-long Civil conflict, which resulted in more than 8 million victims ([ 1 ][1]), has never been so close to an end. The recently signed peace agreement ([ 2 ][2]) between the government and The Revolutionary Armed Forces of Colombia (FARC) covers a number of key areas, including

Revised subfamily classification for Polygonaceae, with a tribal classification for Eriogonoideae

Recent phylogenetic studies have provided a revised hypothesis of the evolutionary relationships within Polygonaceae, particularly regarding placement of certain tropical taxa. Based on phylogenetic data, we recognize three subfamilies: Eriogonoideae, Polygonoideae, and Symmerioideae. Within the Eriogonoideae we accept six tribes, two of which, Leptogoneae and Gymnopodieae, are new.

Fidelity and Promiscuity in an Ant-Plant Mutualism: A Case Study of Triplaris and Pseudomyrmex

The association between the myrmecophyte Triplaris and ants of the genus Pseudomyrmex is an often-reported example of mutualism but no molecular studies have examined this association to date. In this study, the interspecific relationships of Triplaris were reconstructed using five molecular markers (two chloroplast and three nuclear), and the relationships of the associated Pseudomyrmex using two molecular regions (one mitochondrial and one nuclear). A data set including all known collections of plant hosts and resident ants was also compiled. The pattern of distribution of both organisms reveals that there are varying degrees of host specificity; most ants show broader host usage (promiscuous) but one species (P. dendroicus) is faithful to a single species of Triplaris. In most ant-plant interactions, host usage is not specific at the species level and preferences may result from geographical or ecological sorting. The specificity of P. dendroicus could be based on chemical recognition of the host they were raised on.

Establishing an ant-plant mutualism: foundress queen mortality and acquiring the third partner

In the Neotropics, colonies of the ant Pseudomyrmex dendroicus are found in the hollow stems of Triplaris americana. The ants are obligate inhabitants of the ant-plant and they nest and reproduce exclusively in this myrmecophyte. However, this mutualistic association often involves a third partner, scale insects (Coccoidea, Hemiptera). Established colonies of this ant are always associated with scale insects and ants appear to be dependent on the honeydew excretions of their trophobionts. Acquisition of scale insects is therefore an important step in the successful establishment of a new colony. Domatia of juvenile host-plants were dissected to determine (1) how colonies are founded, (2) if there was evidence of co-dispersal between trophobionts and foundress queens. Colony foundation is claustral. Founding queens of Pseudomyrmex chew their entrance holes at the prostoma and then close the hole with debris. 104 queens were located with few or no workers. Of the 104 foundresses, 69 were found dead and only 32 had at least a single trophobiont. Although the association with trophobionts may prove vital to the establishment of the colony, these results indicate that scale insects do not seem to co-disperse with the foundress queens.

Protection against herbivory in the mutualism between Pseudomyrmex dendroicus (Formicidae) and Triplaris americana (Polygonaceae)

Herbivory significantly impacts the growth and reproduction of plants. Many plants have developed ways to defend against herbivores and one common strategy is to associate with ants. In many ant-plant interactions, ants are known to protect their host. However, in the Neotropical ant-plant genus Triplaris, the benefits provided by associated ants have never been tested. Many Pseudomyrmex spp. ants are obligate inhabitants of Triplaris spp. trees. In this study, Triplaris americana was studied in association with Pseudomyrmex dendroicus, an ant highly specific to its host (it has not been collected from any other species of Triplaris). Ant exclusion experiments were carried out to assess the protective effect of ants. In addition, ant behavior was monitored in control plants to study the mechanisms by which ants might confer protection against herbivory. Ant removal led to a more than 15-fold increase in herbivory. Pseudomyrmex dendroicus are active at all times of day and night and aggressively and efficiently remove insect herbivores from their host.