Divergent habitat use of two urban lizard species

Faunal responses to anthropogenic habitat modification represent an important aspect of global change. In Puerto Rico, two species of arboreal lizard, Anolis cristatellus and A. stratulus, are commonly encountered in urban areas, yet seem to use the urban habitat in different ways. In this study, we quantified differences in habitat use between these two species in an urban setting. For each species, we measured habitat use and preference, and the niche space of each taxon, with respect to manmade features of the urban environment. To measure niche space of these species in an urban environment, we collected data from a total of six urban sites across four different municipalities on the island of Puerto Rico. We quantified relative abundance of both species, their habitat use, and the available habitat in the environment to measure both microhabitat preference in an urban setting, as well as niche partitioning between the two different lizards. Overall, we found that the two species utilize different portions of the urban habitat. Anolis stratulus tends to use more “natural” portions of the urban environment (i.e., trees and other cultivated vegetation), whereas A. cristatellus more frequently uses anthropogenic structures. We also found that aspects of habitat discrimination in urban areas mirror a pattern measured in prior studies for forested sites in which A. stratulus was found to perch higher than A. cristatellus and preferred lower temperatures and greater canopy cover. In our study, we found that the multivariate niche space occupied by A. stratulus did not differ from the available niche space in natural portions of the urban environment and in turn represented a subset of the niche space occupied by A. cristatellus. The unique niche space occupied by A. cristatellus corresponds to manmade aspects of the urban environment generally not utilized by A. stratulus. Our results demonstrate that some species are merely tolerant of urbanization while others utilize urban habitats in novel ways. This finding has implications for long‐term persistence in urban habitats and suggests that loss of natural habitat elements may lead to nonrandom species extirpations as urbanization intensifies.     

Sampling scale can cause bias in positive assortative mating estimates: evidence from two intertidal snails

Assortative mating in the wild is commonly estimated by correlating between traits in mating pairs (e.g. the size of males and females). Unfortunately, such an approach may suffer from considerable sampling bias when the distribution of different expressions of a trait in the wild is nonrandom (e.g. when segregation of different size classes of individuals occurs in different microhabitats or areas). Consequently, any observed trait correlation in the wild can be an artefact of pooling heterogeneous samples of mating pairs from different microhabitats or areas rather than true nonrandom matings. This bias in estimating trait correlations as a result of sampling scale is termed the scale‐of‐choice effect (SCE). In the present study, we use two intertidal littorinid species from Hong Kong to show how the SCE can bias size‐assortative mating estimates from mating pairs captured in the wild, empirically demonstrating the influence of this effect on measures of positive assortative mating. This finding cautions that studies overlooking the SCE may have misinterpreted the magnitude and the cause of assortative mating, and we provide a new analytical approach for protecting against this potential bias in future studies.     

Ecological specialization and morphological diversification in Greater Antillean boas

Colonization of islands can dramatically influence the evolutionary trajectories of organisms, with both deterministic and stochastic processes driving adaptation and diversification. Some island colonists evolve extremely large or small body sizes, presumably in response to unique ecological circumstances present on islands. One example of this phenomenon, the Greater Antillean boas, includes both small (<90 cm) and large (4 m) species occurring on the Greater Antilles and Bahamas, with some islands supporting pairs or trios of body‐size divergent species. These boas have been shown to comprise a monophyletic radiation arising from a Miocene dispersal event to the Greater Antilles, though it is not known whether co‐occurrence of small and large species is a result of dispersal or in situ evolution. Here, we provide the first comprehensive species phylogeny for this clade combined with morphometric and ecological data to show that small body size evolved repeatedly on separate islands in association with specialization in substrate use. Our results further suggest that microhabitat specialization is linked to increased rates of head shape diversification among specialists. Our findings show that ecological specialization following island colonization promotes morphological diversity through deterministic body size evolution and cranial morphological diversification that is contingent on island‐ and species‐specific factors.     

Costing Alternative Birth Settings for Women at Low Risk of Complications: A Systematic Review

Background

There is demand from women for alternatives to giving birth in a standard hospital setting however access to these services is limited. This systematic review examines the literature relating to the economic evaluations of birth setting for women at low risk of complications.

Methods

Searches of the literature to identify economic evaluations of different birth settings of the following electronic databases: MEDLINE, CINAHL, EconLit, Business Source Complete and Maternity and Infant care. Relevant English language publications were chosen using keywords and MeSH terms between 1995 and 2015. Inclusion criteria included studies focussing on the comparison of birth setting. Data were extracted with respect to study design, perspective, PICO principles, and resource use and cost data.

Results

Eleven studies were included from Australia, Canada, the Netherlands, Norway, the USA, and the UK. Four studies compared costs between homebirth and the hospital setting and the remaining seven focussed on the cost of birth centre care and the hospital setting. Six studies used a cost-effectiveness analysis and the remaining five studies used cost analysis and cost comparison methods. Eight of the 11 studies found a cost saving in the alternative settings. Two found no difference in the cost of the alternative settings and one found an increase in birth centre care.

Conclusions

There are few studies that compare the cost of birth setting. The variation in the results may be attributable to the cost data collection processes, difference in health systems and differences in which costs were included. A better understanding of the cost of birth setting is needed to inform policy makers and service providers.     

The Chilliwack Respiratory Survey, 1963: Part IV. The Effect of Tobacco Smoking on the Prevalence of Respiratory Disease

Chronic non-specific respiratory disease was found by a survey at Chilliwack, B.C., to affect 29.3% of men and 18.0% of women between the ages of 25 and 74. The habit of current cigarette smoking was found to be the most important single factor associated with respiratory disease, and was found to be related to changes in simple measures of lung function. The authors were unable to confirm the existence of a threshold in lifetime cigarette smoking before respiratory disease occurred.Comparisons were made with a population previously studied at Berlin, New Hampshire, U.S.A., in 1961. At Berlin, where pollution by SO₂ and dust-fall had been thoroughly documented, the comparable prevalence rates for respiratory disease were 40.0% for men and 21.6% for women. When differences between the two populations as to age and number of cigarettes smoked daily were taken into account, the disease rates in these two communities were found to be quite similar. The Chilliwack sample did, however, have significantly higher values for the lung function tests.     

Peripheral Vγ9Vδ2 T Cells Are a Novel Reservoir of Latent HIV Infection

Eradication of HIV infection will require the identification of all cellular reservoirs that harbor latent infection. Despite low or lack of CD4 receptor expression on Vδ2 T cells, infection of these cells has previously been reported. We found that upregulation of the CD4 receptor may render primary Vδ2 cells target for HIV infection in vitro and we propose that HIV-induced immune activation may allow infection of γδ T cells in vivo. We assessed the presence of latent HIV infection by measurements of DNA and outgrowth assays within Vδ2 cells in 18 aviremic patients on long-standing antiretroviral therapy. In 14 patients we recovered latent but replication-competent HIV from highly purified Vδ2 cells demonstrating that peripheral Vδ2 T cells are a previously unrecognized reservoir in which latent HIV infection is unexpectedly frequent.     

Climate Change-related Health Impacts in the Hindu Kush–Himalayas

Our goal was to identify the climate change-related health risks and vulnerable populations specific to the mountainous regions of the Hindu Kush–Himalayas. We reviewed published information of the likely health consequences of climate change in mountain regions, especially the findings of a workshop for countries in the Hindu Kush–Himalaya region, organized by the World Health Organization, World Meteorological Organization, United Nations Environment Programme, and United Nations Development Programme. The main climate-related risks in the Hindu Kush–Himalaya region include the expansion of vector-borne diseases as pathogens take advantage of new habitats in altitudes that were formerly unsuitable. Diarrheal diseases could become more prevalent with changes in freshwater quality and availability. More extreme rainfall events are likely to increase the number of floods and landslides with consequent death and injuries. A unique risk is sudden floods from high glacier lakes, which cause substantial destruction and loss of life. Because glaciers are the main source of freshwater for upland regions and downstream countries, the long-term reduction in annual glacier snowmelt is expected to heighten existing water insecurity in these areas. Climate change also is bringing some benefits to mountain populations, including milder winters and longer growing seasons. Populations in mountain regions have unique combinations of vulnerabilities to climate change. The extent of the health impacts experienced will depend on the effectiveness of public health efforts to identify and implement low-cost preparedness and response measures, and on the speed at which emissions of greenhouse gas emissions can be reduced.