Variation in abundance across a species' range predicts climate change responses in the range interior will exceed those at the edge: a case study with North American beaver

The absence of information about how abundance varies across species' ranges restricts most modeling and monitoring of climate change responses to the range edge. We examine spatial variation in abundance across the northeastern range of North American beaver ( Castor canadensis ), evaluate the extent to which climate and nonclimate variables explain this variation, and use a species–climate envelope model that includes spatial variation in abundance to predict beaver abundance responses to projected climate change. The density of beaver colonies across Québec follows a roughly logistic pattern, with high but variable density across the southern portion of the province, a sharp decline in density at about 49°N, and a long tail of low density extending as far as 58°N. Several climate and nonclimate variables were strong predictors of variation in beaver density, but 97% of the variation explained by nonclimate variables could be accounted for by climate variables. Because of the peak and tail density pattern, beaver climate sensitivity (change in density per unit change in climate) was greatest in the interior and lowest at the edge of the range. Combining our best density–climate models with projections from general circulation models (GCM) predicts a relatively modest expansion of the species' northern range limit by 2055, but density increases in the range interior that far exceed those at the range edge. Thus, some of the most dramatic responses to climate change may be occurring in the core of species' ranges, far away from the edge-of-the-range focus of most current modeling and monitoring efforts.     

Mainland size variation informs predictive models of exceptional insular body size change in rodents

The tendency for island populations of mammalian taxa to diverge in body size from their mainland counterparts consistently in particular directions is both impressive for its regularity and, especially among rodents, troublesome for its exceptions. However, previous studies have largely ignored mainland body size variation, treating size differences of any magnitude as equally noteworthy. Here, we use distributions of mainland population body sizes to identify island populations as ‘extremely’ big or small, and we compare traits of extreme populations and their islands with those of island populations more typical in body size. We find that although insular rodents vary in the directions of body size change, ‘extreme’ populations tend towards gigantism. With classification tree methods, we develop a predictive model, which points to resource limitations as major drivers in the few cases of insular dwarfism. Highly successful in classifying our dataset, our model also successfully predicts change in untested cases.     

Is Marine Mammal Health Deteriorating? Trends in the Global Reporting of Marine Mammal Disease

A recent rise in the reporting of diseases in marine organisms has raised concerns that ocean health is deteriorating. The goal of this study was to determine whether or not there has been a recent deterioration in marine mammal health by investigating the trends in disease reports over the past 40 years (categorized by the method of study, the species affected, and the etiology of the disease) and by exploring the changes in frequency of mass mortality events among marine mammals reported in the United States since 1978. The number of papers on marine mammal disease published each year has increased since 1966, although the annual publication rate appears to have stabilized since ∼1992. Those published in the 1960s and 1970s were largely about helminth and bacterial disease, those investigating viruses emerged in the late 1970s and increased in the 1980s and 1990s, whereas protozoal diseases and harmful algal toxins were largely not reported until the 1990s. The annual number of mass mortality events in the U.S. approximately doubled between 1980 and 1990 but since 2000 has been between seven and eight events per year. Causes of mass mortality events have included biotoxins, viruses, bacteria, parasites, human interactions, oil spills, and changes in oceanographic conditions. Events due to biotoxins appear to be increasing, but the change in the frequency of mass mortality events from other causes over the past 40 years cannot be determined from the available published literature due to changes in marine mammal abundance, inconsistencies in effort and extent of resources for pathological investigation, and advances in technology that have allowed improved detection of pathogens and toxins in more recent years. To ensure future information on the true incidence of marine diseases and their underlying causes is more reliable, specific and directed marine health monitoring programs, well-equipped stranding networks, and dedicated diagnostic laboratories are needed.     

西藏农区鼠害调查初报

2007年4月和6月在西藏山南、日喀则地区及拉萨市农区进行鼠密度和鼠种调查.采用铗夜法,共捕鼠169只,隶属2科4属5种,分别为小家鼠、黄胸鼠、白尾松田鼠、藏仓鼠和长尾仓鼠.白尾松田鼠为该区农田优势种,其组成比例为93.44%;黄胸鼠为山南地区农舍区的优势种,组成比例为82.35%.在日喀则农舍区则只捕获有小家鼠.山南和日喀则地区4月农田的平均捕获率分别为2.06%和7.43%;农舍区的平均捕获率分别为9.77%和9.15%.6月山南地区农田的平均捕获率为5.37%,显著高于该地4月的捕获率.西藏农区的白尾松田鼠在4月开始进入繁殖期.     

Accelerated molecular evolution in Microtus (Rodentia) as assessed via complete mitochondrial genome sequences

Microtus is one of the most taxonomically diverse mammalian genera, including over 60 extant species. These rodents have evolved rapidly, as the genus originated less than 2 million years ago. If these numbers are taken at face value, then an average of 30 microtine speciation events have occurred every million years. One explanation for the rapid rate of cladogenesis in Microtus could be the karyotypic differentiation exhibited across the genus: diploid numbers range from 17 to 64. Despite the striking chromosomal variability within Microtus, phenotypic variation is unremarkable. To determine whether nucleotide substitution rates are also elevated in voles, we sequenced the entire mitochondrial DNA (mtDNA) genome of the Eurasian sibling vole (Microtus rossiaemeridionalis). We compared this genome to another previously sequenced vole mtDNA genome (Microtus kikuchii) and performed pairwise sequence comparisons with the mtDNA genomes of ten additional mammalian genera. We found that microtine mtDNA genomes are evolving more rapidly than any other mammalian lineage we sampled, as gauged by the rate of nucleotide substitution across the entire mtDNA genome as well as at each individual protein-coding gene. Additionally, we compared substitution rates within the cytochrome b gene to seven other rodent genera and found that Microtus mtDNA is evolving fastest. The root cause of accelerated evolution in Microtus remains uncertain, but merits further investigation. The mitochondrial genome sequence from this article has been deposited with the GenBank database under accession number DQ015676.     

Rats dying for mice: Modelling the competitor release effect

Abstract Introduced vertebrate predators are one of the most important threats to endemic species throughout a range of ecosystems, in particular on islands in biodiversity hot spots. Consequently, the reduction of predator numbers is considered a key conservation action in the management of many native vertebrates vulnerable to predators. It is now established that control attempts may affect non‐target species through trophic interactions, but little is known concerning their consequences on competitive relationships. We study a mathematical model mimicking the effects of controlling introduced species in the presence of their competitors. We used two competing rodents to illustrate our study: black rats, Rattus rattus, and mice, Mus musculus. Analyses of the model show that control of only one introduced species logically results in the dramatic increase of the overlooked competitor. We present empirical data that confirm our theoretical predictions. Less intuitively, this process, which we term ‘the competitor release effect’, may also occur when both introduced competitors are simultaneously controlled. In our setting, controlling both predators can promote their coexistence. This occurs as soon as the inferior competitor benefits from the differential effect of the simultaneous control of both competitors, that is, when the indirect positive effect of control (the removal of their competitors) exceeds its direct negative effect (their own removal). Both control levels and target specificity have a direct influence on the extent of this process: counter‐intuitively, the stronger and more specific the control, the greater the effect. The theoretical validation of the competitor release effect has important implications in conservation, especially for control management.     

浅谈野生动物保护与流行疫病防控

保护野生动物对维持生物多样性和促进国计民生具有重要意义,而近年来新冠肺炎的全球大流行使得人们进一步重视野生动物保护与疫情防控的关联性。野生动物生存于复杂开放的自然环境,容易被各种病原微生物侵袭,而社会经济的高速发展和人们生活水平的提高使得野生动物与人类活动轨迹的重合度越来越高,且交流日渐频繁。因此,野生动物所携带的病原体有机会通过多种途径进入人类社会并造成潜在的疫病威胁。本文结合我国野生动物保护现状,探讨了野生动物感染性疾病现状及成因、野生动物感染性疾病与人类健康,并提出了通过进一步提升生物安全意识,加强野生动物疾控相关人才培养,提高野生动物疾病防治技能,建设野生动物疾病相关新发、突发病原体防控体系四方面来遏制野生动物疫病的对策,以期为野生动物保护内容和方向提供参考。     

我国濒危哺乳动物保护生物学研究进展

本文简要论述了2010-1015年间,我国濒危哺乳动物（主要是食肉类、灵长类、有蹄类和鲸类) 保护生物学的研究进展,涉及进化保护生物学、保护生态学、保护行为学、保护生理学、保护遗传学、保护基因组学与宏基因组学和保护政策建议与实践等诸多领域。以大熊猫和金丝猴为代表的濒危动物保护生物学研究成绩显著。各项研究结果表明,大熊猫并非是一个已走到“进化尽头”的物种,仍具进化潜力。虽然大熊猫仍然面临栖息地破碎等环境问题,总的来看其种群数量在逐渐增长,栖息地面积在逐渐扩大,已走出困境并脱离“濒危”的状态,可降为“易危”。我国大熊猫的保护为世界生物多样性保护树立了成功的范例。根据国内研究进展和国际发展动态,该文还对未来保护生物学的研究提出了一些建议,包括加强长期定点监测与系统性的研究工作,加强新理论、新方法和新技术的研发及应用,加强宏微观研究手段的结合从机制上揭示科学问题,加强动物对食物、高原极端环境和水生生态环境的适应性进化分子机制的揭示,加强理论与实践相结合积极推动研究成果的应用,为濒危动物的有效保护保驾护航。     

Genetic Characterization and Epidemiology of Helicobacters in Non‐domestic Animals

Background: Novel helicobacter infections and associated disease are being recognized with increasing frequency in animals and people. Yet, the pervasiveness of infection in distantly related animal taxa, genetic diversity of helicobacters, and their transmissability are not known. Aim: To better understand the ecology of helicobacters, we did a PCR survey and epidemiologic analysis of 154 captive or wild vertebrate taxa originating from 6 continents. Materials and Methods: One hundred twenty nine helicobacter 16s rRNA gene segments were amplified by PCR and sequenced from ninety‐three mammalian, reptilian, avian, or amphibian host species. Prevalence estimates were generated, and univariate logistic regression analyses were used to explore relationships between infection status and the health and characteristics of the 220 individual animals. Results: One hundred and nineteen novel helicobacter DNA sequences were found. No significant relationship between infection and host health was found; however, multi‐infection or infections with particular genotypes were associated with mild clinical signs. Phylogenetic and genetic comparisons of helicobacters suggested prolonged co‐adaptation and niche‐associated divergence as well as periodic inter‐species transmission. Conclusion: The genus Helicobacter should accordingly be viewed as a collection of hundreds of organisms that have colonized most tetrapod taxa and have the potential to expand into new hosts as contact among animals and between animals and people increases.