Community Confounding In Joint Species Distribution Models

Joint species distribution models have become ubiquitous for studying species-habitat relationships and dependence among species. Accounting for community structure often improves predictive power, but can also alter inference on species-habitat relationships. Modulated species-habitat relationships are indicative of community confounding: The situation in which interspecies dependence and habitat effects compete to explain species distributions. We discuss community confounding in a case study of mammalian responses to the Colorado bark beetle epidemic in the subalpine forest by comparing the inference from independent single species distribution models and a joint species distribution model. We present a method for measuring community confounding and develop a restricted version of our hierarchical model that orthogonalizes the habitat and species random effects. Our results indicate that variables associated with the severity and duration of the bark beetle epidemic suffer from community confounding. This implies that mammalian responses to the bark beetle epidemic are governed by interconnected habitat and community effects. Disentangling habitat and community effects can improve our understanding of the ecological system and possible management strategies. We evaluate restricted regression as a method for alleviating community confounding and distinguish it from other inferential methods for confounded models.

Palm functional trait responses to local environmental factors in the Colombian Amazon

Functional traits play a key role in driving plant community effects on ecosystem function. We examined nine functional traits in various palm (Arecaceae) species and their relationships with moisture, tree-fall gaps, slope, and forest type at 29 transects (500×5 m) in the northeastern region of the Colombian Amazon. Redundancy analysis of mean trait values of species within a plot weighted by their abundance and Pearson correlations were used to evaluate the relationships between traits and environmental factors. The community trait composition was correlated with local environmental factors, which explained 23% of the trait variance. We detected functional dominance of the tallest palms in soils with high moisture and in floodplain forests (p ≤0.05). Palms with relatively long leaves were dominant in the flooded forests. Acaulescent and small palms were dominant on high slopes, and in terra firme forests, long-petioled palms were dominant in forest gaps. The number of seeds per fruit was not correlated with any environmental variable. Thus, hydrology is one of the main drivers of the functional composition of neotropical palm communities at the local scale, segregating tall palms with competitive and evasive strategies from small understory palms, which are mainly stress tolerant.

A brief history of masting research

Although it has long been recognized that seed production by many forest trees varies greatly from year to year, masting (along with ‘mast fruiting’, ‘mast seeding’ and ‘masting behaviour’) as a concept referring to such variability is a relatively recent development. Here, I provide a brief history of masting research, highlighting some of the early contributions by foresters, zoologists and others that paved the way for the burgeoning number of studies currently being conducted by researchers around the world. Of particular current interest is work attempting to understand the proximate mechanisms, evolutionary drivers and community effects of this important ecological phenomenon as well as the ways that climate change may influence masting behaviour in the future. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants'.

Community Effects of Police-Related Deaths: Associations With Low Birthweight Births and Poverty Among US Counties

Police-related deaths are a public health problem; however, their effects on community-level reproductive health outcomes remain largely unexplored. Among US counties with populations >100,000 (N = 580), we examined the longitudinal association between police-related deaths and rates of low birthweight (LBW) (<2,500 grams) deliveries, with counties stratified by quartiles of poverty. In the two lowest poverty quartiles, two or more police-related deaths were associated with a 5% (incidence rate ratio [IRR]: 1.05, 95% confidence interval [CI]: 1.02, 1.09) and 10% (IRR 1.10, 95% CI: 1.05, 1.15) higher rate of LBW births, respectively. The effect was not significant in the two highest poverty quartiles. No counties are “immune” from the important effects of police-related deaths and therefore the public health importance of police violence is a ubiquitous one regardless of social class or position.

English Teaching Amidst the COVID-19 Pandemic: Teacher Issues and Challenges

The COVID-19 pandemic affected the globe and every strata of community. Effects can be seen in almost all sectors, education being one of the sectors which was greatly impacted. UNICEF cited a number of 1.6 billion children of schooling age affected by the pandemic. Countries all over the world including Malaysia started working on alternatives to ensure that the learning of schooling children continues throughout the COVID-19 pandemic. The approach chosen by the Malaysian Ministry of Education was to disseminate classes and lessons via online platforms otherwise known as the practice of e-learning. With existing issues of access and gaps in achievement between the rural and urban communities it was a point of interest to investigate how teachers in different contexts dealt with the e-learning initiative. In this study, the aim was to measure the attitude of the teacher, their level of technological literacy and the challenges that they face despite of their context. The study was conducted as an online survey involving all the English Teachers in the Limbang district with the total population of English teachers amounting to 103. The return rate of the survey generated 50 responses and the gaps in the research were bridged with a protocoled focus group discussion with 5 teachers. This study echoed the findings of previous studies and highlights pertinent issues which must be dealt with before e-learning can be a strong and viable alternative learning mode for Malaysians.

The paradox of enrichment, spatial heterogeneity, community effects and the phenomenon of apparent disappearance in the marine bacteriophage dynamics

In aquatic microbial systems, high magnitude variations in abundance, such as sudden blooms alternating with comparatively long periods of very low abundance ("apparent disappearance'') are relatively common. The authors suggest that, in order to occur, such variations in abundance in microbial systems and, in particular, the apparent disappearance of species do not require seasonal or periodic forcing of any kind, or external factors of any other nature, and can be caused by internal factors, and in particular by bacteria-phage interaction. Specifically, the authors suggest that the variations in abundance and the apparent disappearance phenomenon can be a result of phage infection and the lysis of infected bacteria. To illustrate this idea, the authors consider a reasonably simple mathematical model of bacteria-phage interaction based on the model suggested by Edoardo Beretta and Yang Kuang, which assumes neither periodic forcing, nor action of other external factors. The model admits a loss of stability via Andronov-Hopf bifurcation and exhibits dynamics which is able to explains the phenomenon. These properties of the model are especially distinctive for spatially non-homogeneous biosystems as well as biosystem with some sorts of cooperation or community effects. doi:10.1017/S1446181120000085