Competitive effects and responses of the invasive grass Eragrostis plana in Río de la Plata grasslands

The ability of an invasive species to establish is mostly determined by its biotic interactions with native species from the recipient community. Here, we evaluate the competitive effects and responses of the invasive Eragrostis plana when interacting with native species, in order to identify possible mechanisms driving invasion in Río de la Plata grasslands. A pairwise competition experiment was performed consisting of treatments that varied in the identity of neighbour plant species: (i) control (no interaction); (ii) intraspecific interaction; (iii) interspecific interaction between native and invasive species; and (iv) interspecific interaction between two co‐occurring native species. Data analysis was separated into the effect of E. plana on the performance of three native perennial grasses (target species: Aristida laevis, Eragrostis neesii and Paspalum notatum) and the response of E. plana to natives (target species: E. plana). Separately for each target species, components of plant performance were compared between neighbouring species treatments. We found that the strength of competitive interactions depended on both target and neighbour species identity. Regarding natives, interspecific competition was stronger than intraspecific. Native species showed distinctive responses to whether the neighbour was the invasive or a co‐occurring native (Eragrostis lugens). Competition between E. plana and native species was stronger than between co‐occurring natives. We demonstrated E. plana had a greater negative effect on native's species performance than the native congener E. lugens. Regarding E. plana, intraspecific competition was stronger than interspecific, and its response was positive or neutral when interacting with natives, suggesting its high tolerance to grow in competition with neighbours. We conclude E. plana's negative effects on native species performance, and its positive or neutral responses to neighbouring native plants demonstrate its strong competitive ability in the recipient community. This may explain its invasion success in southern Brazil and in the encompassing Río de la Plata grasslands. Abstract in Spanish is available with online material.     

Perceived challenges in the informed consent process: Mismatches between enrollers and researchers at a South African clinical research site

Enrollers play a critical yet often overlooked role in clinical research, particularly in informed consent processes. Study retention may depend in part on how complex information is conveyed to potential participants. This qualitative study aimed to assess communicative barriers during consent and enrolment in two South African TB/HIV clinical studies. In particular, we compared our own perceptions of potential challenges to consent with that of thirteen enrollers, gained via reflective journaling and focus group discussions. Some overlap of identified challenges was evident, including terminology, jargon and consent document format. However there were mismatches to identified challenges. Enrollers provided further insights into potential challenges to consent, in particular, blood withdrawal, discussion of sexual issues and misunderstanding of study participation. Enrollers also reported feeling ill‐equipped to provide counselling when participants became distressed. We offer several recommendations for strengthening the inclusion of enrollers in the development of clinical research protocols and consent documents.     

Effects of fragmentation and landscape matrix on the nesting success of grassland birds in the Pampas grasslands of Argentina

The loss of grasslands in southeastern South America has negatively affected grassland birds, leading to marked declines in their populations. However, the extent to which habitat transformation impacts on their reproductive performance, and whether the magnitude of these effects may be modulated by landscape matrices, is unknown. We assessed the effect of fragmentation on grassland bird reproduction by comparing the combined influence of fragmentation and landscape matrix on nesting success, brood parasitism and productivity of the Spectacled Tyrant Hymenops perspicillatus and the Brown‐and‐yellow Marshbird Pseudoleistes virescens. Surveys were undertaken in small grassland patches embedded within different landscape matrices (urban and agro‐ecosystem) and in a large patch within a reserve. Reproductive performance was adversely affected by fragmentation. However, these effects were conditioned by matrix type, and the response was not the same for the two species. For Brown‐and‐yellow Marshbird, fragmentation resulted in higher rates of brood parasitism and lower productivity regardless of the matrix type, whereas for Spectacled Tyrant, we found a negative effect only in an agricultural matrix. The lack of extensive grasslands makes small patches important; however, knowing the effects of different matrix types is critical to predicting the conservation value of grassland patches, and the response of different species is not uniform.     

Palaeoecology of microconchids from microbialites near the Permian–Triassic boundary in South China

Abundant isolated specimens of microconchid tubes have been extracted from a microbialite deposit near the Permian–Triassic boundary (PTB) in the Dajiang section, southern Guizhou Province, South China. They are assignable to Microconchus aff. utahensis, M. aff. aberrans and Helicoconchus aff. elongatus, all of which possess micro‐lamellar tube walls. Quantitative analysis of bulk samples indicates that most microconchids occur in the upper part of the PTB microbialite deposit and show substrate selectivity for bioclastic grainstone–packstones. In contrast, very few microconchids were found in the rocks bearing well‐developed microbialite structures. Both stratigraphical and substrate preferences indicate proliferation of microconchids coincided with an ebb of microbialite development. Microconchids therefore only proliferated in local niches in which microbial activities were not very active within the PTB microbialite ecosystem. The presence of abundant microconchids further strengthens the impression that PTB microbialite metazoans are much more diverse than previously thought. The end‐Permian mass extinction is calibrated to the base of microbialite deposit in South China. Thus, abundant microbialite metazoans, such as ostracods, lingulid brachiopods, microgastropods and microconchids, together with the considerable, temporarily surviving faunas reported from non‐microbialite PTB sections in South China, indicate that metazoans diversified immediately after the first episode of the end‐Permian mass extinction, supporting the scenario that marine ecosystems underwent episodic collapses during the devastating biocrisis over the Permian–Triassic transition.     

Oral health of the Paleoamericans of Lagoa Santa,central Brazil

The peopling, origins, and early prehistory of the Americas are topics of intense debate. However, few studies have used human remains to document and interpret patterns of health and lifestyle of Paleoamericans. This study provides the first investigation to characterize oral health in a series of early Holocene skeletal remains from Lagoa Santa, Brazil, a locality containing the remains of some of the earliest inhabitants of South America (10,000–7,000 BP). The sample is composed of 949 teeth and 1925 alveoli from an estimated 113 individuals excavated from 17 archaeological sites located in the State of Minas Gerais. We compare dental caries and abscess prevalence at Lagoa Santa to a large sample of human skeletons from the Western Hemisphere Project (WHP) database using both individual and tooth/alveolus count methods. In addition, antemortem tooth loss and tooth wear were analyzed in Lagoa Santa by sex and age. The results show that Lagoa Santa dental caries and abscess prevalence are significantly higher than observed among other hunter–gatherers included in the WHP database, except when abscess prevalence is considered by individual count. Adult females have less tooth wear coupled with higher prevalence of dental caries and antemortem tooth loss than adult males. These results point to an unexpected record of poor oral health at Lagoa Santa, especially among females. A diet based on a highly cariogenic combination of wild tubers and fruits is suggested as an explanation for the elevated rate, characterizing an early adaptation to a tropical environment in South America. Am J Phys Anthropol 154:11–26, 2014. © 2014 Wiley Periodicals, Inc.     

Comparative morphology of pond,stream and phytotelm‐dwelling tadpoles of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus)

We present a comprehensive review of larval morphology in the Neotropical toad genus Melanophryniscus. The taxa studied included 23 species with representatives of recognized phenetic groups and different larval ecomorphological guilds: pond, stream, and phytotelm‐dwelling tadpoles. Their external morphology variation is congruent with current phenetic arrangement based on adult features, but also reflects the habitat where larvae develop. Lotic tadpoles (i.e. M. tumifrons group and M. krauczuki) in general exhibit a more depressed body, a longer tail with lower fins, and larger oral discs than lentic forms (i.e. M. stelzneri group, M. moreirae, M. sanmartini, and M. langonei). Despite their peculiar, confined microhabitat, phytotelm larvae do not diverge markedly from non‐arboreal species. The distinctive features of all species are the presence of a pineal end organ and the placement of the intestinal reversal point at the left of the abdomen in typical larval stages. The buccal cavity and musculoskeletal anatomy are quite conserved between species, yet some characteristics differ from those of other bufonids. The presence of one pair of subhyoid muscles is apparently an exclusive trait of Melanophryniscus among Bufonidae. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 417–441.     

Gelsemiaceae (Gentianales) expanded to include the enigmatic Asian genus Pteleocarpa

The enigmatic South‐East Asian monotypic genus Pteleocarpa has been considered as a genus incertae sedis among the eudicots for a long time. Molecular data (plastid and nuclear ribosomal regions) from 44 widely sampled species across Lamiidae and phylogenetic analyses have finally clarified its familial relationships, and it is here included in Gelsemiaceae (order Gentianales). Its morphological characteristics support a placement in this family and order as a result of the presence of potential synapomorphies, such as imbricate and commonly yellow corollas, latrorse anther dehiscence, divided styles and compressed seeds. Unique characters for Pteleocarpa in Gelsemiaceae are alternate leaves and indehiscent samaras. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 482–496.