Integrating population size analysis into habitat suitability assessment: implications for giant panda conservation in the Minshan Mountains, China

Giant Panda Microhabitat Study in the Daxiangling Niba Mountain Corridor

Habitat reduction and increased fragmentation are urgent issues for the survival and recovery of the giant panda (Ailuropoda melanoleuca). However, changes in the distribution and microhabitat selection of giant panda habitats in different seasons in the same region have rarely been assessed. To further understand giant panda habitat requirements, this study analyzed the giant panda habitat selection characteristics and differences using the sample data of the giant panda occurrence sites collected during 2020-2022. The results showed that the giant panda in both seasons selected medium altitudes (2000-2400 m), southeastern slopes, slopes less than 15°, taller tree layers (8-15 m) with a larger diameter at breast height (17-25 cm) and medium density (25-55%), shorter shrub layers (<4 m) with sparse density (<30%), and taller bamboo (>2 m) with high density (>35%). The giant panda microhabitat survey in the Niba Mountain corridor clarified the characteristics of suitable habitat selection for the giant panda in the corridor. The findings of the study can provide scientific references for the development of practical habitat conservation and management measures for giant pandas in the study area.

Characteristics and impacts of solid waste on giant panda habitat in Wanglang Nature Reserve

Systematic research on solid waste pollution in giant panda habitat is lacking. To fill in this gap in the literature, a survey for solid waste was conducted in Wanglang Nature Reserve in July and August of 2018 and 2019. A total of 16 transects, 16 giant panda habitat plots, 16 livestock habitat plots, and 16 common habitat plots were surveyed. We analyzed the type and distribution of solid waste and the possible impacts of typical solid waste. Results showed that 133 solid waste samples from the five categories (livestock feces, plastic waste, metal waste, construction waste, and paper waste) were detected. Livestock feces accounted for the highest proportion of solid waste at 82.7%, while the remaining types of waste accounted for only 17.3% of the solid waste observed. Livestock feces were distributed relatively evenly within 400 m from roads, while 69.6% of non-livestock fecal waste were distributed 0-100 m away from roads. Giant panda habitat and common habitat (shared by giant pandas and livestock) did not significantly differ in habitat characteristics, but livestock habitat was significantly different from them in the number of trees and the height of bamboo. Specifically, livestock habitat had more trees and shorter bamboo. Based on the short bamboo located in livestock habitat, we predicted that bamboo in the common habitat has a high probability of being damaged by livestock. To limit solid waste pollution, livestock should be forbidden from entering giant panda habitat. In addition, tourism and infrastructure construction activities should be strictly controlled. To ensure the effectiveness of conservation, the needs and possible contributions of residents in surrounding communities should be taken into account in the giant panda conservation plan, and routine monitoring of solid waste should be performed.

Integrating priority areas and ecological corridors into national network for conservation planning in China

Considering that urban expansion and increase of human activities represent important threats to biodiversity and ecological processes in short and long term, developing protected area (PA) network with high connectivity is considered as a valuable conservation strategy. However, conservation planning associated with the large-scale network in China involves important information loopholes about the land cover and landscape connectivity. In this paper, we made an integrative analysis for the identification of conservation priority areas and least-cost ecological corridors (ECs) in order to promote a more representative, connected and efficient ecological PA network for this country. First, we used Zonation, a spatial prioritization software, to achieve a hierarchical mask and selected the top priority conservation areas. Second, we identified optimal linkages between two patches as corridors based on least-cost path algorithm. Finally, we proposed a new framework of China's PA network composed of conservation priority and ECs in consideration of high connectivity between areas. We observed that priority areas identified here cover 12.9% of the region, distributed mainly in mountainous and plateau areas, and only reflect a spatial mismatch of 19% with the current China's nature reserves locations. From the perspective of conservation, our result provide the need to consider new PA categories, specially located in the south (e.g., the middle-lower Yangtze River area, Nanling and Min-Zhe-Gan Mountains) and north regions (e.g., Changbai Mountains), in order to construct an optimal and connected national network in China. This information allows us better opportunities to identify the relative high-quality patches and draft the best conservation plan for the China's biodiversity in the long-term run.

Excess of genomic defects in a woolly mammoth on Wrangel island

Woolly mammoths (Mammuthus primigenius) populated Siberia, Beringia, and North America during the Pleistocene and early Holocene. Recent breakthroughs in ancient DNA sequencing have allowed for complete genome sequencing for two specimens of woolly mammoths (Palkopoulou et al. 2015). One mammoth specimen is from a mainland population 45,000 years ago when mammoths were plentiful. The second, a 4300 yr old specimen, is derived from an isolated population on Wrangel island where mammoths subsisted with small effective population size more than 43-fold lower than previous populations. These extreme differences in effective population size offer a rare opportunity to test nearly neutral models of genome architecture evolution within a single species. Using these previously published mammoth sequences, we identify deletions, retrogenes, and non-functionalizing point mutations. In the Wrangel island mammoth, we identify a greater number of deletions, a larger proportion of deletions affecting gene sequences, a greater number of candidate retrogenes, and an increased number of premature stop codons. This accumulation of detrimental mutations is consistent with genomic meltdown in response to low effective population sizes in the dwindling mammoth population on Wrangel island. In addition, we observe high rates of loss of olfactory receptors and urinary proteins, either because these loci are non-essential or because they were favored by divergent selective pressures in island environments. Finally, at the locus of FOXQ1 we observe two independent loss-of-function mutations, which would confer a satin coat phenotype in this island woolly mammoth.

We observe an excess of detrimental mutations, consistent with genomic meltdown in woolly mammoths on Wrangel Island just prior to extinction. We observe an excess of deletions, an increase in the proportion of deletions affecting gene sequences, and an excess of premature stop codons in response to evolution under low effective population sizes. Large numbers of olfactory receptors appear to have loss of function mutations in the island mammoth. These results offer genetic support within a single species for nearly-neutral theories of genome evolution. We also observe two independent loss of function mutations at the FOXQ1 locus, likely conferring a satin coat in this unusual woolly mammoth.

The minimum area requirements (MAR) for giant panda: an empirical study

Habitat fragmentation can reduce population viability, especially for area-sensitive species. The Minimum Area Requirements (MAR) of a population is the area required for the population's long-term persistence. In this study, the response of occupancy probability of giant pandas against habitat patch size was studied in five of the six mountain ranges inhabited by giant panda, which cover over 78% of the global distribution of giant panda habitat. The probability of giant panda occurrence was positively associated with habitat patch area, and the observed increase in occupancy probability with patch size was higher than that due to passive sampling alone. These results suggest that the giant panda is an area-sensitive species. The MAR for giant panda was estimated to be 114.7 km² based on analysis of its occupancy probability. Giant panda habitats appear more fragmented in the three southern mountain ranges, while they are large and more continuous in the other two. Establishing corridors among habitat patches can mitigate habitat fragmentation, but expanding habitat patch sizes is necessary in mountain ranges where fragmentation is most intensive.

Evaluating landscape options for corridor restoration between giant panda reserves

The establishment of corridors can offset the negative effects of habitat fragmentation by connecting isolated habitat patches. However, the practical value of corridor planning is minimal if corridor identification is not based on reliable quantitative information about species-environment relationships. An example of this need for quantitative information is planning for giant panda conservation. Although the species has been the focus of intense conservation efforts for decades, most corridor projects remain hypothetical due to the lack of reliable quantitative researches at an appropriate spatial scale. In this paper, we evaluated a framework for giant panda forest corridor planning. We linked our field survey data with satellite imagery, and conducted species occupancy modelling to examine the habitat use of giant panda within the potential corridor area. We then conducted least-cost and circuit models to identify potential paths of dispersal across the landscape, and compared the predicted cost under current conditions and alternative conservation management options considered during corridor planning. We found that due to giant panda's association with areas of low elevation and flat terrain, human infrastructures in the same area have resulted in corridor fragmentation. We then identified areas with high potential to function as movement corridors, and our analysis of alternative conservation scenarios showed that both forest/bamboo restoration and automobile tunnel construction would significantly improve the effectiveness of corridor, while residence relocation would not significantly improve corridor effectiveness in comparison with the current condition. The framework has general value in any conservation activities that anticipate improving habitat connectivity in human modified landscapes. Specifically, our study suggested that, in this landscape, automobile tunnels are the best means to remove current barriers to giant panda movements caused by anthropogenic interferences.

Phylogenetic analysis of conservation priorities for aquatic mammals and their terrestrial relatives, with a comparison of methods

BACKGROUND

Habitat loss and overexploitation are among the primary factors threatening populations of many mammal species. Recently, aquatic mammals have been highlighted as particularly vulnerable. Here we test (1) if aquatic mammals emerge as more phylogenetically urgent conservation priorities than their terrestrial relatives, and (2) if high priority species are receiving sufficient conservation effort. We also compare results among some phylogenetic conservation methods.

METHODOLOGY/PRINCIPAL FINDINGS

A phylogenetic analysis of conservation priorities for all 620 species of Cetartiodactyla and Carnivora, including most aquatic mammals. Conservation priority ranking of aquatic versus terrestrial species is approximately proportional to their diversity. However, nearly all obligated freshwater cetartiodactylans are among the top conservation priority species. Further, ∼74% and 40% of fully aquatic cetartiodactylans and carnivores, respectively, are either threatened or data deficient, more so than their terrestrial relatives. Strikingly, only 3% of all 'high priority' species are thought to be stable. An overwhelming 97% of these species thus either show decreasing population trends (87%) or are insufficiently known (10%). Furthermore, a disproportional number of highly evolutionarily distinct species are experiencing population decline, thus, such species should be closely monitored even if not currently threatened. Comparison among methods reveals that exact species ranking differs considerably among methods, nevertheless, most top priority species consistently rank high under any method. While we here favor one approach, we also suggest that a consensus approach may be useful when methods disagree.

CONCLUSIONS/SIGNIFICANCE

These results reinforce prior findings, suggesting there is an urgent need to gather basic conservation data for aquatic mammals, and special conservation focus is needed on those confined to freshwater. That evolutionarily distinct--and thus 'biodiverse'--species are faring relatively poorly is alarming and requires further study. Our results offer a detailed guide to phylogeny-based conservation prioritization for these two orders.