Effects of ecogeographic variables on genetic variation in montane mammals: implications for conservation in a global warming scenario

Aim Evolutionary theory predicts that levels of genetic variation in island populations will be positively correlated with island area and negatively correlated with island isolation. These patterns have been empirically established for oceanic islands, but little is known about the determinants of variation on habitat islands. The goals of this study were twofold. Our first aim was to test whether published patterns of genetic variation in mammals occurring on montane habitat islands in the American Southwest conformed to expectations based on evolutionary theory. The second aim of this research was to develop simple heuristic models to predict changes in genetic variation that may occur in these populations as a result of reductions in available mountaintop habitat in response to global warming. Location Habitat islands of conifer forest on mountaintops in the American Southwest. Methods Relationships between island area and isolation with measures of allozyme variation in four species of small mammal, namely the least chipmunk (Tamias minimus), Colorado chipmunk (Tamias quadrivittatus), red squirrel (Tamiasciurus hudsonicus), and Mexican woodrat (Neotoma mexicana), were determined using correlation and regression techniques. Significant relationships between island area and genetic variation were used to develop three distinct statistical models with which to predict changes in genetic variation following reduction in insular habitat area arising from global warming. Results Patterns of genetic variation in each species conformed to evolutionary predictions. In general, island area was the most important determinant of heterozygosity, while island isolation was the most important determinant of polymorphism and allelic diversity. The heuristic models predicted widespread reductions in genetic variation, the extent of which depended on the population and model considered. Main conclusions The results support a generalized pattern of genetic variation for any species with an insular distribution, with reduced variation in smaller, more isolated populations. We predict widespread reductions in genetic variation in isolated populations of montane small mammals in the American Southwest as a result of global warming. We conclude that climate‐induced reductions in the various dimensions of genetic variation may increase the probability of population extinction in both the short and long term.     

放牧压力条件下荒漠草原小型哺乳动物群落多样性的空间格局

在植物生长期 ,采用夹日法对放牧扰动下的祁连山北坡山地荒漠草地小型哺乳动物群落多样性空间分布格局进行测度 ,结果表明 :在不同的放牧强度条件下 ,小型哺乳动物群落物种组成、结构和多样性指数受相应影响 ,物种丰富度和多样性指数随放牧压力增加而减小 ,经 Whittaker的相似性指数的聚类分析 ,在相似性指数大于 0 .4的水平上 ,可把研究区小型哺乳动物群落分为被家畜啃食和未被家畜啃食 2个类群。研究结果进一步验证了大型食草动物放牧干扰对改变小型哺乳动物群落结构具有重要作用的假设     

Spatial heterogeneity of tree diversity response to climate warming in montane forests

Many studies reported biotic change along a continental warming gradient. However, the temporal and spatial change of tree diversity and their sensitivity to climate warming might differ from region to region. Understanding of the variation among studies with regard to the magnitude of such biotic changes is minimal, especially in montane ecosystems. Our aim is to better understand changes in spatial heterogeneity and temporal dynamics of mountain tree communities under climate warming over the past four decades. In 2017, we resurveyed and recorded all tree species from 107 long‐term monitoring plots that were first studied between 1974 and 1976. These plots were located in montane forests in the Giant Panda National Park (GPNP), China. Our results showed that spatial differences were found in tree species diversity changes response to mean annual temperature change over the past four decades. Tree species richness increased significantly under climate warming in Minshan (MS) and Xiaoxiangling (XXL) with higher warming rate than Qionglai (QLS) and Liangshan (LS). The trees species diversity in MS and XXL were more sensitive to climatic warming. MS and XXL should receive priority protection in the next conservation plan of the GPNP. The GPNP should avoid taking a “one‐size‐fits‐all” approach for diversity conservation due to spatial heterogeneity in plant community dynamics.     

Ecological niche modelling of montane mammals in the Great Basin, North America: examining past and present connectivity of species across basins and ranges

Aim The goal of this study was to determine the extent of suitable habitats across the basins and ranges of the Great Basin for 13 montane mammals in the present and during the Last Glacial Maximum (LGM). For all these mammal species, we test whether: (1) more suitable habitat was available in basin areas during the LGM; (2) suitable habitat shifted upwards in elevation between the LGM and the present; (3) more ranges have suitable habitat than are currently occupied; and (4) these species are currently restricted to suitable habitats at higher‐elevation range areas. We also examine whether and how much distributional response varies among these montane mammal species. Location The Great Basin of western North America. Methods We re‐examine the past and present distributions of 13 Great Basin montane mammals using ecological niche modelling techniques that utilize now widely available species occurrence data and new, fine‐scale past climatological GIS layers in the present and at the LGM. These methods provide an objective, repeatable means for visual comparison of past and present modelled distributions for species examined in previous biogeographical studies. Results Our results indicate greater areal and lower elevational suitable habitat in the LGM than at present for nearly all montane mammals, and that there is more suitable habitat at present than is currently occupied. Our results also show that lowland areas provide suitable dispersal routes between ranges for most of the montane mammals both at the LGM and at present. However, three of the 13 species have little to no predicted suitable habitat in the LGM near currently occupied ranges, in contrast to the pattern for the other 10. For these species, the model results support more recent long‐distance colonization. Main conclusions Our finding of suitable lowland dispersal routes in the present for most species supports and greatly extends similar findings from single‐species studies. Our results also provide a visually striking confirmation that changes in species distribution and colonization histories of Great Basin montane mammals vary in a fashion related to the tolerances and requirements of each of these species; this has previously been hypothesized but not rigorously tested for multiple montane mammals in the region.     

海南五指山热带山地雨林植物物种多样性研究

王指山热带山地雨林的物种种类十分丰富,在１ｈｍ＾２样地中共出现５４个科,１００个属的乔木树种１７７种,１３３７个个体。区系地理分析表明属的分布区类型以热带分布型成分占优,为８９．０％,充分体现了五指山山地雨林的热带性质。多样性指数分析结果为：样地１Ｍａｒｇａｌｅｆ指数１７．８２２,Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数５．６２１,均匀度０．８２３,Ｓｉｍｐｓｏｎ指数０．０５０,均匀度６．７７５,表明五指     

Gap-phase regeneration in a tropical montane forest: the effects of gap structure and bamboo species

To study the influence of gap structure and bamboo species on the regrowth of montane Atlantic forest, colonization by plants was characterized in 30 treefall gaps (30.3–500.5 m²). The study was conducted at Santa Virgínia (45°30 W, 23°17 S), a 4970-ha reserve of Atlantic montane forest in southeastern Brazil. Area covered by bamboos ranged from 0% to 100% of gap area. Average height of surrounding canopies ranged from 12 to 30 m. As gap are covered by bamboo and average height of surrounding canopies increased, both density and richness of pioneer woody species decreased. Density and richness of shade-tolerant species were negatively influenced by gap area. Low-light-demanding species of Miconia, Leandra and Rapanea accounted for the majority of both pioneer species and individuals sampled, whereas high-light demanding pioneers of Cecropia, Alchornea and Tibouchina were poorly represented. We suggest that in the Atlantic montane forest bamboo species compete for gaps, excluding other light-demanding pioneers. This results in an overall reduction of pioneer species richness in the Atlantic forest.     

Relationship between host diversity and parasite diversity: flea assemblages on small mammals

Aim We examined the relationship between host species richness and parasite species richness using simultaneously collected data on small mammals (Insectivora, Rodentia and Lagomorpha) and their flea parasites. Location The study used previously published data on small mammals and their fleas from 37 different regions. All the world's main geographical regions other than Australasia and Wallacea were represented in the study, i.e. neotropical, nearctic, palaearctic, oriental and afrotropical realms. Methods We controlled the data for the area sampled and sampling effort and then tested this relationship using both cross‐region conventional analysis and the independent contrasts method (to control for the effects of biogeographic historical relationships among different regions). Brooks parsimony analysis was used to construct a region cladogram based on the presence/absence of a host species and host phylogeny. Results Both cross‐region and independent contrasts analyses showed a positive correlation between host species richness and flea species richness. Conventional cross‐region regression under‐ or overestimated fleas species richness in the majority of regions. Main conclusions When the regression derived by the independent contrasts method was mapped onto the original tip data space, points that deviated significantly from the regression originated from Kenya, Mississippi and southern California (lower than expected flea richness) and Chile, Idaho, south‐western California and Kyrgyzstan (higher than expected flea richness). These deviations can be explained by the environmental mediation of host–flea relationships and by a degree of environmental variety in sampled areas.     

Elevational diversity gradients, biogeography and the structure of montane mammal communities in the intermountain region of North America

1  Distribution data were assembled for non-volant small mammals along elevational gradients on mountain ranges in the western U.S.A. Elevational distributions in the species-rich Uinta Mountains were compared to those on smaller mountain ranges with varying degrees of historical isolation from the Uintas.
2  For mountain ranges supporting the richest faunas, species richness is highest over a broad low- to mid-elevation zone and declines at both lower and higher elevations. Patterns on other mountain ranges are similar but reflect lower overall species richness.
3  A basic relationship between elevational and geographical distribution is apparent in the occurrence patterns of mammals on regional mountains. Faunas on mountains that have had low levels of historical isolation appear to be influenced by immigration rather than extinction. Species restricted to high elevations in the Uintas are poorly represented on historically isolated mountains and form a portion of local faunas shaped by extinction. Species occurring at lower elevations in the Uintas have better representation on isolated mountains and apparently maintain populations through immigration.
4  Several widespread species show substantial variation in maximum elevation records on different mountain ranges. This involves (1) an upward shift in habitat zones on small, isolated mountain ranges, allowing greater access by low-elevation species, and (2) expansion of certain low- and mid-elevation species into habitats normally occupied by absent high-elevation taxa.
5  Results indicate that montane mammal faunas of the intermountain region have been shaped by broad-scale historical processes, unique regional geography and local ecological dynamics. Parallel examples among mammals of the Philippine Islands suggest that such patterns may characterize many insular faunas.     

Lethal effects of experimental warming approximating a future climate scenario on southern African quartz-field succulents: a pilot study

Here we examine the response of succulents in a global biodiversity hot spot to experimental warming consistent with a future African climate scenario. Passive daytime warming (averaging 5.5 degrees C above ambient) of the natural vegetation was achieved with 18 transparent hexagonal open-top chamber arrays randomized in three different quartz-field communities. After 4-months summer treatment, the specialized-dwarf and shrubby succulents displayed between 2.1 and 4.9 times greater plant and canopy mortalities in the open-top chambers than in the control plots. Those surviving in cooler ventilated areas and shaded refuges in the chambers had lower starch concentrations and water contents; the shrubby succulents also exhibited diminished chlorophyll concentrations. It is concluded that current thermal regimes are likely to be closely proximate to tolerable extremes for many endemic succulents in the region, and that anthropogenic warming could significantly exceed their thermal thresholds. Further investigation is required to elucidate the importance of associated moisture deficits in these warming experiments, a potential consequence of supplementary (fog and dew) precipitation interception by open-top chambers and higher evaporation therein, on plant mortalities.     

Species richness, rarity and endemicity of European mammals: a biogeographical approach

This paper investigates the distribution of species richness, rarity and endemicity of European land mammals (bats and introduced species excluded). The highest level of species richness was in Central Europe, while Southern areas had the highest rarity and endemicity scores. The distribution of richness was affected by the location of sampling points in islands and peninsulas. After excluding these sampling points, richness continued to decrease Westward suggesting the existence of a large-scale peninsular effect on mammal distribution. These patterns of continental distribution of richness, rarity and endemicity could be the result of the distribution of refuge areas in the southern Mediterranean peninsulas, and the Pleistocene advances and retreats of mammals throughout the Western Palearctic. Thus, European mammal distribution can be interpreted on the basis of two different patterns of abundance distribution in which Palearctic species reduce their abundance from central-Europe outwards, while endemic, rare species show a similar depletion in the North. It should be useful to evaluate the role of the different regions in Europe in conserving the demographic interactions between central and peripheral populations of mammal species. Given the restricted distribution and potential small size of population, these endemic species are most likely to be susceptible to anthropogenic environmental degradation.     

Spatially heterogeneous impact of climate change on small mammals of montane California

Resurveys of historical collecting localities have revealed range shifts, primarily leading edge expansions, which have been attributed to global warming. However, there have been few spatially replicated community-scale resurveys testing whether species'' responses are spatially consistent. Here we repeated early twentieth century surveys of small mammals along elevational gradients in northern, central and southern regions of montane California. Of the 34 species we analysed, 25 shifted their ranges upslope or downslope in at least one region. However, two-thirds of ranges in the three regions remained stable at one or both elevational limits and none of the 22 species found in all three regions shifted both their upper and lower limits in the same direction in all regions. When shifts occurred, high-elevation species typically contracted their lower limits upslope, whereas low-elevation species had heterogeneous responses. For high-elevation species, site-specific change in temperature better predicted the direction of shifts than change in precipitation, whereas the direction of shifts by low-elevation species was unpredictable by temperature or precipitation. While our results support previous findings of primarily upslope shifts in montane species, they also highlight the degree to which the responses of individual species vary across geographically replicated landscapes.     

Comparative biogeography of mammals on islands

Insular faunas of terrestrial mammals and bats are examined on a worldwide basis to test the adequacy of equilibrium and historical legacy models as explanations for species-area relationships. Species numbers of bats on islands conform to predictions from equilibrium theory, whereby recurrent immigrations and extinctions influence species richness. By contrast, species numbers of terrestrial mammals on islands result from a historical legacy of very low immigration rates on oceanic islands (the faunas are colonization-limited) and by the fragmentation of once contiguous continental faunas to form relictual populations, which subsequently undergo extinctions, on landbridge islands (the faunas are extinction-limited). This explanation is supported by several lines of evidence: (1) z values (slopes of species-area curves) are lower for non-volant mammals on oceanic islands than for those on landbridge islands, but are the opposite for bats; (2) z values for non-volant mammals are lower than those for bats on oceanic islands, but are higher than those for bats on landbridge islands; and (3) landbridge island faunas are attenuated mainland faunas, whereas those on oceanic islands are ecologically incomplete. No support is found for alternative hypotheses to explain low species-area slopes for terrestrial mammals on oceanic islands.     

Rarity, commonness, and patterns of species richness: the mammals of Mexico

Aim To determine whether rare or common species contribute most to overall patterns of spatial variation in extant species richness. Location Mexico. Methods Using data on the distribution of mammal species across Mexico at a quarter degree resolution, we ranked species from the most widespread to the most restricted (common‐to‐rare) within the study area, and from the most restricted to the most widespread (rare‐to‐common), and generated a sequence of patterns of species richness for increasing numbers of species. At each stage along both series of richness patterns, we correlated the species richness pattern for the subassemblage with that of the full assemblage. This allows comparison of subassemblages of the n most common with the n most rare species, in terms of how well they match the full assemblage richness pattern. Further analyses examined the effects on these patterns of correlation of the amount of raw information contained in the distributions of given numbers of rare and common species. Results For the mammals of Mexico the more widely distributed species contribute disproportionately to patterns of species richness compared with more restricted species, particularly for non‐volant species and endemic species. This is not simply a consequence of differences in the volumes of information contained in the distributions of rare and common species, with the disproportionate contribution of common species if anything being sharpened when these differences are taken into account. The pattern is most clearly demonstrated by endemic species, suggesting that the contribution of common species is clearest when the causes of rarity and commonness are limited to those genuinely resulting in narrow and widespread geographical ranges, respectively, rather than artificial (e.g. geopolitical) boundaries to the extents of study regions. Conclusions Perhaps surprisingly, an understanding of the determinants of overall patterns of species richness may gain most from consideration of why common species occur in some areas and are absent from others, rather than consideration of the distributions of rare species.     

中国哺乳动物形态、生活史和生态学特征数据集

物种特征是生物对生存环境适应和响应的表现, 反映了物种的生态位、适合度和生态功能。特征数据库的建立和共享是研究生物多样性维持与丧失、物种进化与适应、生态过程与生态系统功能、物种对气候变化和人类干扰响应、种内与种间关系等的基础。中国是世界哺乳动物物种数最多的国家之一, 然而目前中国还没有包含哺乳动物形态、生活史、生态学和地理分布等物种特征的数据库。我们系统查阅了文献和各种数据资料, 共收集整理出中国有分布记录的754种哺乳动物(包括近些年野外绝灭种、分布存疑种)的体重、脑容量、体长、尾长、前臂长(翼手目)、后足长、耳长、性成熟时间、妊娠期、窝崽数、年窝数、世代长度、食性、活动模式、是否特有种、濒危等级、海拔范围、栖息地类型、栖息地宽度、动物地理界、生物群系、分布型、动物地理区划和分布省份或水域等24个生态特征数据。在这些特征中, 除了分布省份或水域及是否特有种外, 其余特征数据均存在不同程度的缺失, 数据的完整度为30%‒100%。本数据库收录的哺乳动物种数为目前中国哺乳动物种数的上限, 为中国哺乳动物研究提供了基础数据, 推进中国哺乳动物多样性信息共享和深度挖掘。     

物种多度和径级尺度对于评价群落系统发育结构的影响: 以尖峰岭热带山地雨林为例

研究不同径级尺度群落系统发育多样性有助于了解不同年龄模式下物种的亲缘关系及其群落系统发育结构; 但是关于物种多度对群落系统发育结构影响的研究较少。以海南尖峰岭热带山地雨林群落为例, 首先在不同径级尺度比较物种多度加权与否分别对4个广泛采用的系统发育指数的影响, 继而利用其中2个经过标准化处理的系统发育多样性指数: 净种间亲缘关系指数(net relatedness index, NRI)和净最近种间亲缘关系指数(nearest taxon index, NTI), 结合群落的生境类型来量度不同局域生境条件下不同径级尺度木本植物系统发育关系。结果发现: (1)未考虑物种多度加权的系统发育平均成对距离(mean pairwise distance, MPD)指数比考虑物种多度加权的MPD指数显著地高估了群落整体系统发育多样性, 且这种现象在小径级尺度(1 cm≤DBH<5 cm)最为明显。因此, 在森林监测样地中对于中、小径级群落系统发育结构研究中建议考虑物种多度信息。(2) 从群落组成整体系统发育结构来看, 尖峰岭热带山地雨林在几乎所有径级尺度和生境下均倾向于系统发育发散, 且随着径级的递增发散程度趋于明显(NRI<0)。(3)从群落组成局部系统发育结构来看, 尖峰岭热带山地雨林在中、小径级倾向于系统发育聚集(NTI>0), 而在大径级(DBH≥15 cm)则倾向于系统发育发散(NTI<0)。总之, 研究群落系统发育结构时应考虑物种多度的影响以及径级尺度效应。     

Traits,trees and taxa: global dimensions of biodiversity in mammals

Measures of biodiversity encompass variation along several dimensions such as species richness (SR), phylogenetic diversity (PD) and functional/trait diversity (TD). At the global scale, it is widely recognized that SR and PD are strongly correlated, but the extent to which either tends to capture variation in TD is unclear. Here, we assess relationships among PD, SR and TD for a number of traits both across clades and regional assemblages of mammals. We also contrast results using two different measures of TD, trait variance and a new measure we refer to as trait bin filling (the number of orders of magnitude of variation that contain at least one species). When TD is defined as trait variance, PD is a much stronger correlate of TD than SR across clades, consistent with hypotheses about the conservation value of PD. However, when TD is defined as bin filling, PD and SR show similar correlations with TD across clades and space. We also investigate potential losses of SR, PD and TD if species that are currently threatened were to go extinct, and find that threatened PD is often a similar predictor of threatened TD as SR.     

Community structure and diversity of tropical forest mammals: data from a global camera trap network

Terrestrial mammals are a key component of tropical forest communities as indicators of ecosystem health and providers of important ecosystem services. However, there is little quantitative information about how they change with local, regional and global threats. In this paper, the first standardized pantropical forest terrestrial mammal community study, we examine several aspects of terrestrial mammal species and community diversity (species richness, species diversity, evenness, dominance, functional diversity and community structure) at seven sites around the globe using a single standardized camera trapping methodology approach. The sites-located in Uganda, Tanzania, Indonesia, Lao PDR, Suriname, Brazil and Costa Rica-are surrounded by different landscape configurations, from continuous forests to highly fragmented forests. We obtained more than 51 000 images and detected 105 species of mammals with a total sampling effort of 12 687 camera trap days. We find that mammal communities from highly fragmented sites have lower species richness, species diversity, functional diversity and higher dominance when compared with sites in partially fragmented and continuous forest. We emphasize the importance of standardized camera trapping approaches for obtaining baselines for monitoring forest mammal communities so as to adequately understand the effect of global, regional and local threats and appropriately inform conservation actions.     

海南尖峰岭国家级自然保护区森林动态监测样地鸟类和兽类多样性

2016年8月至2019年2月,我们利用红外相机对海南尖峰岭60 ha森林动态监测样地的鸟类和兽类进行了调查.共在79个位点上布设了红外相机,累积27,848个相机日,获得可鉴定到物种的独立有效照片15,320张.经鉴定,共拍摄到46种野生动物,包括16种兽类(隶属于6目11科)和30种鸟类(隶属于8目16科).其中,...