Spatial Ecology of an Arboreal Iguana (Oplurus cyclurus) in a Treeless Landscape

Understanding the spatial ecology of species has important implications for conservation, as it helps identify suitable habitats and minimum requirements for biodiversity monitoring and management. The spiny-tailed lizard Oplurus cyclurus is a widespread endemic iguanid occurring in dry areas of southern and western Madagascar. While the species is known to be mostly arboreal, populations of the Isalo sandstone massif suggest local adaptation to a less forested savannah and a more exposed habitat. We radio-tracked 19 spiny-tailed lizards to investigate the species’ rock-dwelling behaviour and spatial ecology at Isalo National Park. Tracked individuals showed high site and burrow fidelity, and a basking behaviour mostly tied to the accessibility of their burrow, the time of day, and their life stage. Activity peaked during the sunniest hours, while juveniles were more active than adults with unfavourable weather conditions. Despite high burrow fidelity, lizards used shelters non-exclusively, regularly changing (approx. once a week) with neighbouring burrows (average distance between burrows = 13.6 m). However, there was no obvious relation between lizards’ body and/or tail size and the width and depth of selected burrows. Dynamic Brownian Bridge Movement Models estimated frequented areas over 247.8 m2 (95% isopleth), where territorial overlap is common. Our results challenge the notion that burrow-site fidelity is the sole driving factor behind space utilization in the studied population. We argue that the apparently unusual saxicolous habits imposed by habitat features (the absence of trees) may lead to local behavioural adjustments influencing antipredatory and foraging strategies, as well as intraspecific interactions.info:eu-repo/semantics/publishedVersio

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria

For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd) has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, including amphibians. Little is known, however, about the cutaneous bacterial residents of Malagasy amphibians and the functional capacity they have against Bd. We cultured 3179 skin bacterial isolates from over 90 frog species across Madagascar, identified them via Sanger sequencing of approximately 700 bp of the 16S rRNA gene, and characterized their functional capacity against Bd. A subset of isolates was also tested against multiple Bd genotypes. In addition, we applied the concept of herd immunity to estimate Bd-associated risk for amphibian communities across Madagascar based on bacterial antifungal activity. We found that multiple bacterial isolates (39% of all isolates) cultured from the skin of Malagasy frogs were able to inhibit Bd. Mean inhibition was weakly correlated with bacterial phylogeny, and certain taxonomic groups appear to have a high proportion of inhibitory isolates, such as the Enterobacteriaceae, Pseudomonadaceae, and Xanthamonadaceae (84, 80, and 75% respectively). Functional capacity of bacteria against Bd varied among Bd genotypes; however, there were some bacteria that showed broad spectrum inhibition against all tested Bd genotypes, suggesting that these bacteria would be good candidates for probiotic therapies. We estimated Bd-associated risk for sampled amphibian communities based on the concept of herd immunity. Multiple amphibian communities, including those in the amphibian diversity hotspots, Andasibe and Ranomafana, were estimated to be below the 80% herd immunity threshold, suggesting they may be at higher risk to chytridiomycosis if a lethal Bd genotype emerges in Madagascar. While this predictive approach rests on multiple assumptions, and incorporates only one component of hosts' defense against Bd, their culturable cutaneous bacterial defense, it can serve as a foundation for continued research on Bd-associated risk for the endemic frogs of Madagascar

Tracing a toad invasion: lack of mitochondrial DNA variation, haplotype origins, and potential distribution of introduced Duttaphrynus melanostictus in Madagascar

The black-spined toad, Duttaphrynus melanostictus, is widespread in South and South-East (SE) Asia, although recent molecular analyses have revealed that it represents a species complex (here called the D. melanostictus complex). Invasive populations of this toad have been detected in Madagascar since, at least, 2014. We here trace the origin of this introduction based on mitochondrial DNA sequences of 340 samples. All 102 specimens from Madagascar have identical sequences pointing to a single introduction event. Their haplotype corresponds to a lineage occurring in Cambodia, China, Laos, Thailand, Vietnam, and some locations of eastern Myanmar and northern Malaysia, here named the SE Asian lineage. Within this lineage, specimens from one location in Cambodia and three locations in Vietnam have the same haplotype as found in Madagascar. This includes Ho Chi Minh City, which has a major seaport and might have been the source for the introduction. Species distribution models suggest that the current range of the Madagascan invasive population is within the bioclimatic space occupied by the SE Asian lineage in its native range. The potential invasion zone in Madagascar is narrower than suggested by models from localities representing the full range of the D. melanostictus complex. Thus, an accurate taxonomy is essential for such inferences, but it remains uncertain if the toad might be able to spread beyond the potential suitable range because (1) knowledge on species-delimitation of the complex is insufficient, and (2) the native range in SE Asia might be influenced by historical biogeography or competition

The Role of Geography in Human Adaptation

Various observations argue for a role of adaptation in recent human evolution, including results from genome-wide studies and analyses of selection signals at candidate genes. Here, we use genome-wide SNP data from the HapMap and CEPH-Human Genome Diversity Panel samples to study the geographic distributions of putatively selected alleles at a range of geographic scales. We find that the average allele frequency divergence is highly predictive of the most extreme FST values across the whole genome. On a broad scale, the geographic distribution of putatively selected alleles almost invariably conforms to population clusters identified using randomly chosen genetic markers. Given this structure, there are surprisingly few fixed or nearly fixed differences between human populations. Among the nearly fixed differences that do exist, nearly all are due to fixation events that occurred outside of Africa, and most appear in East Asia. These patterns suggest that selection is often weak enough that neutral processes—especially population history, migration, and drift—exert powerful influences over the fate and geographic distribution of selected alleles

The Last Turtle in the Prairie

There are over 300 kinds of turtles and tortoises. More than half are threatened with extinction. They sit at the forefront of a biodiversity crisis; their habitat is plowed, bulldozed, and drained. They are collected for food and for pets. Because turtles and tortoises take more than a decade to mature, their populations are slow to recover. Most baby turtles never survive to adults. I studied a few of the last Ornate Box Turtle strongholds in Illinois. The tiny parcels of sand prairie they inhabit are few and far between. The baby turtle in the photo is one of only a handful of hatchlings I found in three years of searching. How many Ornate Box Turtles are left in Illinois? How long will their small and isolated populations persist? What can we do to ensure their future

Figure 2 in Year-round activity patterns in a hyperdiverse community of rainforest amphibians in Madagascar

Figure 2. Annual variation of relative abundance in eight species with more than 100 individual observations along the study transect. Note different activity patterns displayed by the species, some active year round (M. grandidieri), some restricted to the warm/rainy season (A. madagascariensis, B. pyrrhus), some active year round but with a clear peak in the late cold/dry season (B. viridis) or early dry season (Heterixalus spp.), and P. palmata showing an extremely seasonal, explosive breeding activity. The asterisk in the plot for P. palmata indicates the massive breeding of the species when the number of individuals was uncountable and estimated as 100.Published as part of Heinermann, Janosch, Rodríguez, Ariel, Segev, Ori, Edmonds, Devin, Dolch, Rainer & Vences, Miguel, 2015, Year-round activity patterns in a hyperdiverse community of rainforest amphibians in Madagascar, pp. 2213-2231 in Journal of Natural History 49 (33) on page 2220, DOI: 10.1080/00222933.2015.1009513, http://zenodo.org/record/400179

Figure 4 in Year-round activity patterns in a hyperdiverse community of rainforest amphibians in Madagascar

Figure 4. Canonical correspondence biplot relating amphibian species abundance along the study transect and five environmental predictors (italics, labelled as in Figure 3). Circles identify the sampling units (days) and crosses identify species. Species occurring more frequently at extreme environmental conditions are labelled using the codes presented in Table 1.Published as part of Heinermann, Janosch, Rodríguez, Ariel, Segev, Ori, Edmonds, Devin, Dolch, Rainer & Vences, Miguel, 2015, Year-round activity patterns in a hyperdiverse community of rainforest amphibians in Madagascar, pp. 2213-2231 in Journal of Natural History 49 (33) on page 2225, DOI: 10.1080/00222933.2015.1009513, http://zenodo.org/record/400179

Appendix A. Strengths of intra- and interspecific competition (C) and competition coefficients (A) for all four response variables (mass, length, developmental stage, and survival).

Strengths of intra- and interspecific competition (C) and competition coefficients (A) for all four response variables (mass, length, developmental stage, and survival)

Supplement 1. Competition experiment data set and R code for model 1 (individual level), model 2 (basin level), and model 3 (basin level accounting for heteroscedasticity).

<h2>File List</h2><div> <p><a href="Competition_Model_Code.txt">Competition_Model_Code.txt</a> (MD5: 70506b9d3752928cbc45b020488d6c33)</p> <p><a href="Tadpole_Competition_Data.txt">Tadpole_Competition_Data.txt</a> (MD5: 1dfe519a33a7f7bfd54ba2ae682e4a66)</p> </div><h2>Description</h2><div> <p>Tadpole_Competition_Data.txt: This is tab-delimited data from tadpole competition experiments. Column descriptions below:</p> <ul> <li>Block = categorical A, B, C, or D corresponding to temporal block (date) </li> <li>Start = Start date of experiment </li> <li>End = End date of experiment</li> <li>Species = categorical F, M, or P corresponding to one of the three species of the focal individual</li> <li>Basin = categorical basin code corresponding to one of the 36 basins used in experiment</li> <li>Trt = categorical F, M, P, or C corresponding to competition treatment (C = low density / 60 individuals of focal species)</li> <ul> <li>Examples: </li> <ul> <li>Species = F, Trt = F → high density F treatment</li> <li>Species = F, Trt = P → F individual in P treatment</li> </ul> </ul> <li>Stage = response variable Gosner developmental stage (ranging from 25 to 46 or NA if the individual did not survive)</li> <li>Mass = response variable final weight (g) (NA if individual did not survive)</li> <li>Length = Body length (mm) (NA if individual did not survive)</li> <li>Survival = 1 if individual survived; 0 if individual did not survive until the end of the experiment.</li> </ul> <p>Competition_Model_Code.txt: This file contains R code to perform the following:</p> <ul> <li>Analyze the tadpole competition data with the three models described in the main text of the manuscript</li> </ul> </div