Does Counting Different Life Stages Impact Estimates for Extinction Probabilities for Tsetse (Glossina spp)?

As insect populations decline, due to climate change and other environmental disruptions, there has been an increased interest in understanding extinction probabilities. Generally, the life cycle of insects occurs in well-defined stages: when counting insects, questions naturally arise about which life stage to count. Using tsetse flies (vectors of trypanosomiasis) as a case study, we develop a model that works when different life stages are counted. Previous branching process models for tsetse populations only explicitly represent newly emerged adult female tsetse and use that subpopulation to keep track of population growth/decline. Here, we directly model other life stages. We analyse reproduction numbers and extinction probabilities and show that several previous models used for estimating extinction probabilities for tsetse populations are special cases of the current model. We confirm that the reproduction number is the same regardless of which life stage is counted, and show how the extinction probability depends on which life stage we start from. We demonstrate, and provide a biological explanation for, a simple relationship between extinction probabilities for the different life stages, based on the probability of recruitment between stages. These results offer insights into insect population dynamics and provide tools that will help with more detailed models of tsetse populations. Population dynamics studies of insects should be clear about life stages and counting points.

Reappearance of Dhole Cuon alpinus (Mammalia: Carnivora: Canidae) in Gujarat after 70 years

The Dhole Cuon alpinus used to be the meso carnivore of the forests throughout Indian subcontinent; however, habitat loss, low prey biomass, and human disturbance exterminated the species from India’s 60% historic range, and the numbers are less than 1,500 individuals in wild. Following the same shrinking trend, Dholes were extirpated from Gujarat. A few doubtful sightings and inevident reportings generated ambiguity of Dhole presence in Gujarat. We conducted a study in Vansda National Park with 15,660 trap nights at 30 trap locations, and have confirmed the rediscovery of Dholes in Gujarat after 70 years. We estimated the Dhole’s minimum home range as 13.7km2 and also analyzed relative abundance index of other mammals. The future retention of Dholes requires detailed range, diet, and adaption studies along with conservational efforts to reduce re-extinction probabilities.

A dynamic occupancy model for interacting species with two spatial scales

1AbstractOccupancy models have been developed independently to account for multiple spatial scales and species interactions in a dynamic setting. However, as interacting species (e.g., predators and prey) often operate at different spatial scales, including nested spatial structure might be especially relevant in models of interacting species. Here we bridge these two model frameworks by developing a multi-scale two-species occupancy model. The model is dynamic, i.e. it estimates initial occupancy, colonization and extinction probabilities - including probabilities conditional to the other species’ presence. With a simulation study, we demonstrate that the model is able to estimate parameters without bias under low, medium and high average occupancy probabilities, as well as low, medium and high detection probabilities. We further show the model’s ability to deal with sparse field data by applying it to a multi-scale camera trapping dataset on a mustelid-rodent predator-prey system. The field study illustrates that the model allows estimation of species interaction effects on colonization and extinction probabilities at two spatial scales. This creates opportunities to explicitly account for the spatial structure found in many spatially nested study designs, and to study interacting species that have contrasted movement ranges with camera traps.

The Properties of Generalized Collision Branching Processes

We consider basic properties regarding uniqueness, extinction, and explosivity for the Generalized Collision Branching Processes (GCBP). Firstly, we investigate some important properties of the generating functions for GCB q-matrix in detail. Then for any given GCB q-matrix, we prove that there always exists exactly one GCBP. Next, we devote to the study of extinction behavior and hitting times. Some elegant and important results regarding extinction probabilities, the mean extinction times, and the conditional mean extinction times are presented. Moreover, the explosivity is also investigated and an explicit expression for mean explosion time is established.

Positive correlations in species functional contributions drive the response of multifunctionality to biodiversity loss

Changes in biodiversity can severely affect ecosystem functioning, but the impacts of species loss on an ecosystem's ability to sustain multiple functions remain unclear. When considering individual functions, the impacts of biodiversity loss depend on correlations between species functional contributions and their extinction probabilities. When considering multiple functions, the impacts of biodiversity loss depend on correlations between species contributions to individual functions. However, how correlations between extinction probabilities and functional contributions determine the impact of biodiversity loss on multifunctionality (MF) is not well understood. Here, we use biodiversity loss simulations to examine the influence of correlations among multiple functions and extinction probabilities on the diversity–MF relationship. In contrast with random extinction, we find that the response of MF to biodiversity loss is influenced by the absence of positive correlations between species functional contributions, rather than by negative correlations. Communities with a high number of pairwise positive correlations in functional contributions achieve higher levels of MF, but are also less resilient to extinction. This work implies that understanding how species extinction probabilities correlate with their contribution to MF can help identify the degree to which MF will change with ongoing biodiversity loss and target conservation efforts to maximize MF resiliency.

Genetic analyses reveal population structure and recent decline in leopards (Panthera pardus fusca) across the Indian subcontinent

Background Large carnivores maintain the stability and functioning of ecosystems. Currently, many carnivore species face declining population sizes due to natural and anthropogenic pressures. The leopard, Panthera pardus, is probably the most widely distributed and highly adaptable large felid globally, still persisting in most of its historic range. However, we lack subspecies-level data on country or regional scale on population trends, as ecological monitoring approaches are difficult to apply on such wide-ranging species. We used genetic data from leopards sampled across the Indian subcontinent to investigate population structure and patterns of demographic decline. Methods We collected faecal samples from the Terai-Arc landscape of northern India and identified 56 unique individuals using a panel of 13 microsatellite markers. We merged this data with already available 143 leopard individuals and assessed genetic structure at country scale. Subsequently, we investigated the demographic history of each identified subpopulations and compared genetic decline analyses with countrywide local extinction probabilities. Results Our genetic analyses revealed four distinct subpopulations corresponding to Western Ghats, Deccan Plateau-Semi Arid, Shivalik and Terai region of the north Indian landscape, each with high genetic variation. Coalescent simulations with microsatellite loci revealed a possibly human-induced 75–90% population decline between ∼120–200 years ago across India. Population-specific estimates of genetic decline are in concordance with ecological estimates of local extinction probabilities in these subpopulations obtained from occupancy modeling of the historic and current distribution of leopards in India. Conclusions Our results confirm the population decline of a widely distributed, adaptable large carnivore. We re-iterate the relevance of indirect genetic methods for such species in conjunction with occupancy assessment and recommend that detailed, landscape-level ecological studies on leopard populations are critical to future conservation efforts. Our approaches and inference are relevant to other widely distributed, seemingly unaffected carnivores such as the leopard.