Giant panda (Ailuropoda melanoleuca) population dynamics and bamboo (subfamily Bambusoideae) life history: a structured population approach to examining carrying capacity when the prey are semelparous

Spatial models of giant pandas under current and future conditions reveal extinction risks

In addition to habitat loss and fragmentation, demographic processes-the vagaries of births, deaths and sex ratio fluctuations-pose substantial threats to wild giant panda populations. Additionally, climate change and plans for the Giant Panda National Park may influence (in opposing directions) the extinction risk for wild giant pandas. The Fourth National Giant Panda Census showed pandas living in 33 isolated populations. An estimated 259 animals live in 25 of these groups, ~14% of the total population. We used individual-based models to simulate time series of these small populations for 100 years. We analysed the spatial pattern of their risk of extinction under current conditions and multiple climate change models. Furthermore, we consider the impact of the proposed Giant Panda National Park. Results showed that 15 populations face a risk >90%, and for 3 other populations the risk is >50%. Of the 15 most at-risk populations, national parks can protect only 3. Under the Representative Concentration Pathway 8.5 climate change scenario, the 33 populations will probably further divide into 56 populations. Some 41 of them will face a risk >50% and 35 face a risk >90%. Although national parks will probably connect some fragmented habitats, 26 populations will be outside national park planning. Our study gives practical advice for conservation policies and management and has implications for the conservation of other species in the world that live in isolated, fragmented habitats.

A first report of Thelazia callipaeda infection in Phortica okadai and wildlife in national nature reserves in China

Background

Thelazia callipaeda is a zoonotic parasitic nematode of the family Thelaziidae, with Phortica okadai as its intermediate host and only confirmed vector in China. China has the largest number of human cases of thelaziosis in the world. It is generally believed that infected domestic animals (dogs and cats) are the most important reservoir hosts of T. callipaeda, and thus pose a direct threat to humans. At present, there is little research or attention focused on the role of wildlife in the transmission cycle of thelaziosis in nature reserves.

Methods

We selected locations in four national nature reserves across China to monitor P. okadai and wildlife. We used a fly-trap method to monitor P. okadai density. Morphological analysis of the parasites collected from the conjunctival sac of the infected wildlife was undertaken as the first step in species identification, and polymerase chain reaction (PCR) was used for species confirmation.

Results

In 2019, the density of P. okadai in Foping National Nature Reserve in China increased sharply, and infected P. okadai were newly found in the reserve. Giant panda, wild boar, leopard cat, and black bear were found to be newly infected with T. callipaeda (one individual of each species). A total of four worms were collected, one from each species of wildlife. The four worms were identified as T. callipaeda by their morphological characteristics; species identification was confirmed by PCR amplification.

Conclusions

To the best of our knowledge, this is the first report of T. callipaeda infection in P. okadai as well as in a variety of wildlife, including giant panda, in nature reserves in China. These results indicate that there is a transmission cycle of T. callipaeda among wildlife in these nature reserves. The increasing number of case reports of thelaziosis in wildlife suggest a likely risk of T. callipaeda infection for the inhabitants of villages situated around nature reserves.

Canine distemper viral infection threatens the giant panda population in China

We evaluated exposure to canine distemper virus (CDV) in eight wild giant pandas (Ailuropoda melanoleuca) and 125 unvaccinated domestic dogs living in and around Foping National Nature Reserve (FNNR), China. Seventy-two percent of unvaccinated domestic dogs (mixed breed) had neutralizing antibodies for CDV due to exposure to the disease. The eight wild giant pandas were naïve to CDV and carried no positive antibody titer. RT-PCR assays for hemagglutinin (H) gene confirmed the presence of CDV in 31 clinically ill dogs from several areas near FNNR. Genomic sequence analysis showed that the 21 canine CDV were highly homologous to each other and belonged to the Asian-1 genotype. They showed high homology with the GP01 strain sequenced from a fatally infected giant panda, suggesting cross-species infection. Observational and GPS tracking data revealed home range overlap in pandas and dogs around FNNR. This study shows that CDV is endemic in domestic dogs near FNNR and that cross-species CDV infection threatens the wild giant panda population.

Carnivora population dynamics are as slow and as fast as those of other mammals: implications for their conservation

Of the 285 species of Carnivora 71 are threatened, while many of these species fulfill important ecological roles in their ecosystems as top or meso-predators. Population transition matrices make it possible to study how age-specific survival and fecundity affect population growth, extinction risks, and responses to management strategies. Here we review 38 matrix models from 35 studies on 27 Carnivora taxa, covering 11% of the threatened Carnivora species. We show that the elasticity patterns (i.e. distribution over fecundity, juvenile survival and adult survival) in Carnivora cover the same range in triangular elasticity plots as those of other mammal species, despite the specific place of Carnivora in the food chain. Furthermore, reproductive loop elasticity analysis shows that the studied species spread out evenly over a slow-fast continuum, but also quantifies the large variation in the duration of important life cycles and their contributions to population growth rate. These general elasticity patterns among species, and their correlation with simple life history characteristics like body mass, age of first reproduction and life span, enables the extrapolation of population dynamical properties to unstudied species. With several examples we discuss how this slow-fast continuum, and related patterns of variation in reproductive loop elasticity, can be used in the formulation of tentative management plans for threatened species that cannot wait for the results of thorough demographic studies. We argue, however, that such management programs should explicitly include a plan for learning about the key demographic rates and how these are affected by environmental drivers and threats.

Effects of elevated CO₂ and temperature on photosynthesis and leaf traits of an understory dwarf bamboo in subalpine forest zone, China

The dwarf bamboo (Fargesia rufa Yi), growing understory in subalpine dark coniferous forest, is one of the main foods for giant panda, and it influences the regeneration of subalpine coniferous forests in southwestern China. To investigate the effects of elevated CO₂, temperature and their combination, the dwarf bamboo plantlets were exposed to two CO₂ regimes (ambient and double ambient CO₂ concentration) and two temperatures (ambient and +2.2°C) in growth chambers. Gas exchange, leaf traits and carbohydrates concentration were measured after the 150-day experiment. Elevated CO₂ significantly increased the net photosynthetic rate (Anet ), intrinsic water-use efficiency (WUEi ) and carbon isotope composition (δ¹³C) and decreased stomatal conductance (g(s)) and total chlorophyll concentration based on mass (Chl(m)) and area (Chl(a)). On the other hand, elevated CO₂ decreased specific leaf area (SLA), which was increased by elevated temperature. Elevated CO₂ also increased foliar carbon concentration based on mass (C(m)) and area (C(a)), nitrogen concentration based on area (N(a)), carbohydrates concentration (i.e. sucrose, sugar, starch and non-structural carbohydrates) and the slope of the A(net)-N(a) relationship. However, elevated temperature decreased C(m), C(a) and N(a). The combination of elevated CO₂ and temperature hardly affected SLA, C(m), C(a), N(m), N(a), Chl(m) and Chl(a). Variables Anet and Na had positive linear relationships in all treatments. Our results showed that photosynthetic acclimation did not occur in dwarf bamboo at elevated CO₂ and it could adjust physiology and morphology to enable the capture of more light, to increase WUE and improve nutritional conditions.

A MODEL FOR TWO SPECIES WITH STAGE STRUCTURE AND FEEDBACK CONTROL

This paper studies a periodic coefficients predator-prey delay system with mixed functional response, in which the prey has a history that takes them through two stages, immature and mature. Also, the total toxic action on the predator population expressed by an integral term is considered in our system. Furthermore, the feedback control is considered in our system. Sufficient conditions which guarantee the permanence and extinction of the system are obtained. Finally, we give a brief discussion of our results. From a biological point of view, our results can be used to help protect beneficial animals.

Survivorship patterns in captive mammalian populations: implications for estimating population growth rates

For species of conservation concern, ecologists often need to estimate potential population growth rates with minimal life history data. We use a survivorship database for captive mammals to show that, although survivorship scale (i.e., longevity) varies widely across mammals, survivorship shape (i.e., the age-specific pattern of mortality once survivorship has been scaled to maximum longevity) varies little. Consequently, reasonable estimates of population growth rate can be achieved for diverse taxa using a model of survivorship shape along with an estimate of longevity. In addition, we find that the parameters of survivorship shape are related to taxonomic group, a fact that may be used to further improve estimates of survivorship when full life history data are unavailable. Finally, we compare survivorship shape in captive and wild populations of the same species and find higher adult survivorship in captive populations but no corresponding increase in juvenile survivorship. These differences likely reflect a convolution of true differences in captive vs. wild survivorship and the difficulty of observing juvenile mortality in field studies.

Discrete three-stage population model: persistence and global stability results

A general three-stage discrete-time population model is studied. The inherent net reproductive number for this model is derived. Global stability of the origin is established provided that the inherent net reproductive number is less than one. If it is larger than one the existence of a unique positive fixed point is proved and the persistence of the system is established. Finally, for certain parameter ranges global stability of the positive fixed point is proved.

Reproduce and die! Why aging? Part I

In multi-cellular organisms--and hence also in man--aging and dying is the fate of the soma, i.e., the body proper; germ cells are--at least in principle--immortal. As the soma can be considered to be the "service compartment" of the germ cells, it loses its function once a species' phase of reproduction is over. Hence, there is an intimate relationship between reproduction and aging, and therefore also between a species' reproductive strategy and aging: there has been no selection for maintenance of the soma beyond the reproductive phase of life (when there is no reproduction, there is also no natural selection). As a consequence, mechanisms, important for maintenance of the soma during the reproductive phase, increasingly begin to fail once this phase is over, resulting in an accumulation of all kinds of pathology and genetic errors, rendering an individual increasingly more prone to a variety of (internal and external) attacks. In the end, the soma collapses, be it due to organ failure, a neoplasm or to a final external push, e.g., an infection.

Equivalence relationships between stage-structured population models

Matrix population models are widely applied in conservation ecology to help predict future population trends and guide conservation effort. Researchers must decide upon an appropriate level of model complexity, yet there is little theoretical work to guide such decisions. In this paper we present an analysis of a stage-structured model, and prove that the model's structure can be simplified and parameterised in such a way that the long-term growth rate, the stable-stage distribution and the generation time are all invariant to the simplification. We further show that for certain structures of model the simplified models require less effort in data collection. We also discuss features of the models which are not invariant to the simplification and the implications of our results for the selection of an appropriate model. We illustrate the ideas using a population model for short-tailed shearwaters (Puffinus tenuirostris). In this example, model simplification can increase parameter elasticity, indicating that an intermediate level of complexity is likely to be preferred.