Skull size and shape variation in Psammomys spp. (Rodentia,Gerbillinae) from Tunisia,with emphasis on the impact of allometric variation on species recognition

In Tunisia both Psammomys obesus and P. vexillaris are found. These taxa have been the subject of taxonomic controversy for some time, due to variability in the classical morphological characters used for taxonomic recognition. In this study we investigated skull size and shape variation in the genus Psammomys by using geometric morphometrics to evaluate the extent of intra- and interspecific shape variation and explicitly tested for the impact of allometric shape variation on species discrimination. Eleven populations of the two species from 10 localities in Tunisia were studied. Statistical analyses of size and shape showed large size variation within P. obesus, but no shape differences were revealed among populations of this species. Interspecific analysis revealed that P. vexillaris had the smallest skull. Principal component analysis and Procrustes distances showed good discrimination between the two species after removal of the allometric component of shape variation. The results obtained show that allometric-related shape variation could mask discrimination between the two Psammomys species. This finding might explain the uncertainty in classification of these species in the past. The interspecific allometric-free phenotypic differences observed may be associated with adaptive processes linked to the different environmental and trophic preferences of the two species.     

Host evolution in Mastomys natalensis (Rodentia: Muridae): An integrative approach using geometric morphometrics and genetics

The commensal rodent Mastomys natalensis is the natural reservoir of Lassa arenavirus (LASV), which causes hemorrhagic fever in West Africa. To study a possible effect of the virus on phenotypic and genotypic variation of its persistently infected host, we compared LASV‐positive and non‐infected wild‐caught M. natalensis. The LASV effects on the phenotypic variation were explored using standard external morphometric measurements, geometric morphometric analyses of the cranial size and shape, and brain case volume. The genetic variability of M. natalensis specimens was assessed using 9 polymorphic microsatellite markers. Independent of sex and age, LASV‐infected animals had smaller external body measurements, reproductive organs, skull size and brain case volume. Cranial shape differences between the 2 groups are represented by a lateral constriction of the entire skull. The genetic variability revealed consanguinity only among the LASV‐positive rodents. We hypothesize that growth impairment may result in a selective disadvantage for LASV‐infected M. natalensis, leading to a preferably commensal lifestyle in areas where the LAVS is endemic and, thereby, increasing the risk of LASV transmission to humans.     

Morphological variation in the short-tailed fruit bat (Carollia) in Ecuador,with comments on the practical and philosophical aspects of boundaries among species

The mechanisms for the morphological delimitation of species in Carollia remain poorly understood. This is the first study to assess variation in size and shape from strictly geometric terms. Both factors are assessed by statistical perspectives of distribution, overlap and relative distances. Despite its overlap, the size of the skull seems to be the most influential character for the discrimination of species, with shape playing a much smaller role. The smallest species seems to be the most distinct in shape, not only in terms of distance among centroids in morphometric space, but also in the overall trend and direction of variation. Contrary to previous studies, sexual dimorphism is not given by size but by distinct shapes of the skull. Characters such as the shape of the maxilla, previously described qualitatively as discrete with sharp boundaries, appear to be truly continuous with fuzzy borders among species. Because morphometric space is a gamut of continuous variation and overlap, the taxonomic error rate for size characters seems to be substantial for the medium-sized species (Carollia brevicauda Schinz, 1821), with approximately 30–40% of individuals erroneously assigned to a different species after a jackknifed discriminant function. This taxonomic error is higher for shape characters. Morphological, systematic and ecological consequences of the observed patterns of shape and size variation are commented within the context of previously proposed arguments and hypotheses.     

Effects of Sagebrush Restoration and Conifer Encroachment on Small Mammal Diversity in Sagebrush Ecosystem

Conifer encroachment in sagebrush ecosystems reduces habitat heterogeneity, niche space, and resource availability, all of which negatively affect many wildlife populations. Sagebrush restoration is recommended as a management action to mitigate conifer encroachment and restore wildlife across millions of hectares in the Great Basin. Despite this recommendation, the effects of conifer encroachment and sagebrush restoration are unknown for most wildlife species. Small nonvolant mammal communities include keystone species, consumers and prey; facilitate energy flow and ecological function; and provide important ecological goods and services. We assessed causal relationships between conifer encroachment and sagebrush restoration (conifer removal and seeding native plants) on small mammal communities over 11 yr using a Before-After-Control–Impact design. Sagebrush habitat supported an additional small mammal species, twice the biomass, and nearly three times higher densities than conifer-encroached habitat. Sagebrush restoration increased shrub cover, decreased tree cover, and density but failed to increase native herbaceous plant density. Restoration caused a large increase in the non-native, invasive annual cheatgrass (Bromus tectorum L.). Counter to prediction, small mammal diversity did not increase in response to sagebrush restoration, but restoration maintained small mammal density in the face of ongoing conifer encroachment. Piñon mice (Peromyscus truei), woodland specialists with highest densities in conifer-encroached habitat, were negatively affected by sagebrush restoration. Increasing cheatgrass due to sagebrush restoration may not negatively impact small mammal diversity, provided cheatgrass density and cover do not progress to a monoculture and native vegetation is maintained. The consequences of conifer encroachment, a long-term, slow-acting impact, far outweigh the impacts of sagebrush restoration, a short-term, high-intensity impact, on small mammal diversity. Given the ecological importance of small mammals, maintenance of small mammal density is a desirable outcome for sagebrush restoration.     

A Landmark Analysis-Based Approach to Age and Sex Classification of the Skull of the Mediterranean Monk Seal (Monachus monachus) (Hermann, 1779)

This work aimed at applying geometric morphometric analysis techniques to the skull of the Mediterranean monk seal ( Monachus monachus , Hermann, 1779). Inferential analyses were performed using a non-parameteric permutation framework based on a series of skulls of different age classes belonging to individuals of both sexes. Our goal was to establish whether a statistical approach based on osteometric measurements and surface analysis of photographs of the left lateral plane of the skull may lead to a different and scientifically sound method of age and sex classification in this critically endangered marine mammal. Our data indicate that non-parametric combination methodology enables the researcher to give local assessment using a combination with domains. Developing geometric morphometric techniques in a non-parametric permutation framework could be useful in solving high dimensional and small sample size problems as well as classification problems, including zoological classification of specimens within a specific population. The Mediterranean monk seal is believed to be the world's rarest pinniped and one of the most endangered mammals of the world, with fewer than 600 individuals currently surviving. The use of shape analysis would allow new insights into the biological characteristics of the monk seal by simply extracting potentially new information on age and size from museal specimens.     

Variation in mammal species richness and relative abundance in the Karoo§

Understanding how climate change and land transformation may impact the distribution and diversity of wildlife species requires landscape-level foundational biodiversity surveys. The Karoo BioGaps Project aims to provide such data and to support the scientific assessment for shale gas development projects in the Karoo basin. In this paper we present the findings of the BioGaps mammal survey, which recorded medium and large mammals across twenty-five 1 km × 1 km sampling sites within the proposed fracking footprint using camera trapping techniques. We use sample rarefaction curves, non-parametric species richness estimators and non-metric multidimensional scaling plots to explore both species richness and community structure. We also used a generalised linear model to investigate how species diversity varies with both site-specific and landscape-level predictors. A total of 38 species were recorded at the majority of sites. Longitude (z = 4.018, p = 0.0005) emerged as the best predictor of species diversity across the study area, which we suggest is linked to the clear east–west aridity gradient. Together these results reveal the cosmopolitan distribution of the mammal taxa in the Karoo and could be used to inform decision-making linked to mining activities in the area.     

Is neutral genetic diversity related to quantitative variation in semen traits in bulls?

Conservation decisions based on neutral genetic diversity have been observed to promote retention of useful quantitative variation in biological populations. An experiment was undertaken to determine the association between microsatellite marker polymorphisms and phenotypic variation in semen production and cryosurvival traits in bulls. Thirty-five ejaculates were collected from ten bulls of two breeds and evaluated before and after cryopreservation for several semen traits. The bulls were also genotyped using a set of sixteen bovine-specific microsatellite marker loci. Fixation indices (F_ST), heterozygosity and Nei's genetic distance measures were computed from allele frequency data for each of the bulls. Molecular and phenotypic data were used to compute tri-distance matrices for the ten bulls and correlated using Mantel's test in GenAIEx 6.5. The study revealed extensive heterogeneity in semen traits, heterozygosity and F_ST values among the bulls. Large pairwise phenotypic and genetic distances were also observed. Correlation between pairwise genetic distances and phenotypic distances was significant and highly positive for sperm viability (r = .61, p < .001) and moderately positive for sperm motility (r = .40–42, p < .05) variables. For sperm morphology, ejaculate volume and sperm concentration, correlation with genetic distances was positive, low and not significantly different from zero (p > .05). A tendency for a triangular-shaped relationship between genetic and phenotypic distances for post-thaw motility and viability traits was also observed. Accordingly, association with neutral genetic diversity was absent for semen production traits and moderate to highly positive for sperm cryosurvival traits. Given these findings, conservation decisions based on neutral genetic diversity may capture variation in some adaptive traits, but not others.     

无尾鸡骨骼发育关键信号通路研究进展

骨骼系统对机体的生命活动至关重要，它为生物体提供了造血微环境、机械支撑、保护脏器等功能，同时也是钙和其他矿物质等的储存库。家鸡尾骨的表型多样性是研究骨骼系统发育及形成机制的良好资源。Notch、Wnt信号通路的靶基因及其相互作用可以形成周期性表达的特点，是调节体节形成及尾部骨骼终止延伸的分子通路。为了解无尾鸡骨骼发育终止的分子机制，作者分别总结了骨骼发育、无尾鸡骨骼研究进展，并重点讨论影响无尾性状的关键信号通路Notch、Wnt及其在无尾鸡研究中的进展。但是，受体和配体之间相互作用的精确调节以及信号通路中的核心元素仍不清楚，需要通过更多的功能基因组和蛋白质组等方法进行深入研究。     

Unraveling the morphological patterns of a subantarctic eelpout: a geometric morphometric approach

Phenotypic variation in organisms depends on the genotype and the environmental constraints of the habitat that they exploit. Therefore, for marine species inhabiting contrasting aquatic conditions, it is expected to find covariation between the shape and its spatial distribution. We studied the morphology of the head and cephalic sensory canals of the eelpout Austrolycus depressiceps (4.5–22.5 cm TL) across its latitudinal distribution in South Pacific (45°S–55°S). Geometric morphometric analyses show that the shape varied from individuals with larger snout and an extended suborbital canal to individuals with shorter snouts and frontally compressed suborbital canal. There was size variation across the sampled populations, but that size does not have a clear latitudinal gradient. Only 8% of the shape variation relates to this size variation (allometry), represented by a decrease in the relative size of the eye, and a depression of the posterior margin of the head. There were spatial differences in the shape of the head, but these differences were probably caused by allometric effects. Additionally, 2 of the canals of the cephalic lateralis pores and the head shape showed modularity in its development. This study shows that the morphology of marine fish with a shallow distribution varies across distances of hundreds of kilometers (i.e., phenotypic modulation).     

Testing the effectiveness of conservation management within biosphere reserves: the case of the Mexican deer mouse (Peromyscus mexicanus) as a bioindicator

Biosphere reserves are protected areas whose purpose is to combine conservation and sustainable development. However, their effectiveness has not been tested sufficiently, especially from an ecological and genetic approach. In this sense, the Peromyscus genus represents an excellent bioindicator to address these questions, due to its short life and high evolutionary rate and fecundity. For conservation managers, genetic structure can increase the rate of loss of genetic diversity because alleles exclusive of a subpopulation are more likely to disappear as a consequence of genetic drift in comparison with a panmictic population. Here we analyzed the abundance, movement distances, morphology/morphometry and genetic structure of 3 populations of Mexican deer mouse (Peromyscus mexicanus) located in different protected zones of La Tigra National Park (Honduras). Our results are consistent among the 3 approaches and showed the highest values of abundance, morphometry and genetic diversity in the population located at the core zone, whereas non‐statistically significant differences were found between buffer and transition zone populations, suggesting suitable effectiveness of conservation management in the core zone but a lack of ecological buffering function of the other zones. In addition, the low movement distances and high genetic structure among the studied populations provide evidence of poor conservation management in the buffer and transition zone. Thus, we discuss the utility of the novel methodology used in this work, combining morphometry, abundance and genetics, in testing the effectiveness of conservation strategies in biosphere reserves, and the value of the Peromyscus genus as a bioindicator.     

黄土丘陵区天然群落的植物组成、植物多样性及其与环境因子的关系

选择陕北黄土丘陵区不同立地条件下的4个典型群落,进行群落调查与土壤水分和养分的测定,探索天然群落自然恢复过程中群落的结构组成、植物多样性与环境因子的关系,为该地区的植被恢复提供指导。结果表明:植物群落组成主要集中在菊科、禾本科、豆科和蔷薇科,这4大科植物在该区具有较强的生态适应性;研究区天然群落组成较为简单;铁杆蒿(Artemisia sacrorum)在各立地均有分布,且重要值相对较大,为各个群落的优势种或者亚优势种;植物的生活型中多年生草本植物占优势,其次是半灌木,再其次是一、二年生草本植物,灌木植物所占的比例最少;相同坡向不同坡位的群落较为相似;不同立地条件下群落多样性指数的大小与各立地的水分条件关系密切。植被盖度、坡度、海拔高度和坡向对多样性产生影响,主要是通过直接影响土壤含水量实现的。土壤含水量是影响植物群落组成和多样性最为关键的生态因子,是黄土高原植被恢复和重建的关键性因子。     

Size and Shape Variability in the Skull of the Bottlenose Dolphin,Tursiops truncatus (Montagu, 1821)

The bottlenose dolphin (Tursiops truncatus) is a widely spread cetacean species. We present a quantitative analysis of age dimorphism variation in the skull of T. truncatus assessed by geometric morphometrics (GM) methods. Differences in size and shape of skulls were investigated using eight landmarks plotted on 2‐D images of ventral views of 14 museum specimens. The results of GM revealed differences in size, but not in shape. The left side appears more variable, which is probably an effect of telescoping.     

Integrating small mammal community variables into aircraft–wildlife collision management plans at Namibian airports

Understanding ecosystems within and around airports can help to determine the causes and possible mitigation measures for collisions between aircraft and wildlife. Small mammal communities are an important component of the semi‐arid savanna ecosystems of Namibia, its productivity and its ecosystem integrity. They are also a major direct attractant for raptors at airports. The present study compared the abundance and diversity of small mammals between Namibia's 2 main airport properties (Hosea Kutako International Airport and Eros Airport), and among areas of land used for various purposes surrounding the airports. A total of 2150 small mammals (3 orders, 11 species) were captured over 4 trapping seasons. Small mammal abundance was significantly higher at the end of the growing season than during the non‐growing season. The grass mowing regimen in current management plans at the airports resulted in a significant reduction of small mammal abundance at Hosea Kutako during the non‐growing season only, thus indicating that annual mowing is effective but insufficient to reduce the overall abundance of mammal prey species for raptors. Small mammal numbers were significantly higher at Hosea Kutako Airport compared to the cattle and game farming land surrounding the airport, while no differences in small mammal densities or diversity were found for areas with different land uses at and surrounding Eros. The study suggests that the fence around Hosea Kutako provides a refuge for small mammals, resulting in higher densities. It also indicates that different surrounding land use practices result in altered ecosystem function and productivity, an important consideration when identifying wildlife attractants at airports.     

桑子叶表型多样性初探

子叶形状和数量是桑树的重要形态特征。通过对83个杂交组合桑树的幼苗观测,发现桑子叶表现出丰富的表型多样性。子叶形状不仅有圆形、椭圆形、卵圆形、纺锤形等,还观察到了几种畸形子叶。桑树幼苗一般具有2片子叶,但在20个杂交组合中观察到了3片子叶、4片子叶等多子叶现象,多子叶出现的概率因组合而异。     

广西省芒野生居群表型多样性研究

通过方差、聚类和相关分析等方法对分布在我国广西省芒的13个野生居群的18个叶片、茎秆、花序和小穗的表型性状进行居群内和居群间的遗传多样性研究。结果表明,18个表型性状在居群内和居群间均存在极显著差异,说明芒种群内表型性状变异较丰富且遗传多样性较高。表型分化系数的变幅为17.99%～47.21%,其中,叶片、茎秆、花序和小穗性状分别为38.01%,29.80%,32.84%和27.14%,所有性状均值为32.05%,说明芒表型性状的变异主要来源于居群内。UPGMA聚类结果表明,在阈值5.388处可以将13个居群分为4个类群,聚类结果表明,聚成一类的居群在地理位置上并不靠近。表型性状与地理因子的相关性分析表明,部分表型性状的变化与地理因子呈显著或极显著相关性。本研究结果为我国芒属能源植物在遗传改良以及野生资源的保护与利用等方面提供了可参考的理论依据。     

野豌豆属种子形态多样性与种子分类鉴定方法的研究

本研究以48份野豌豆属的14个种为研究对象,以17个种子表型性状来揭示野豌豆属表型性状的遗传多样性,并对其进行分类鉴定。结果表明：种子表型性状种间变异较大,数量性状中百粒重变异系数最大,为81.92%,种形指数的Shannon多样性信息指数最大,为1.94;质量性状中种脐颜色的变异系数最大,为75.12%,其Shannon多样性信息指数也最大,为1.56;主成分分析表明前6个主成分累计贡献率达86.09%;相关性分析表明种子长、种子宽、种子厚和百粒重相互之间呈极显著正相关关系（P<0.01）;在相似性系数为0.79时可将试验材料分为5大类群。本研究中百粒重、种脐颜色、种皮颜色、种皮纹理、种脐长/种子长、子叶颜色、胚根基部斑纹、种脐形状、胚根宽/胚根长可作为该14种野豌豆属植物种间分类鉴定依据,并据此制作相应检索表,为野豌豆属的鉴定提供依据。     

Oviparity in Two South African Skinks of the Genus Mabuya,With Notes on Hatching

This study was conducted as part of the interdisciplinary biodiversity project BIOTA and describes small mammal communities on two differently managed farmlands (cattle and game farm) in Namibia over the course of one year. Species diversity, density and activity are discussed and compared to data on vegetation parameters, and on grazing and trampling effects by large herbivores. Small mammal abundance was related to vegetation cover on both farm areas. Species composition differed between the cattle and the game farm. These differences and the dominance structure are discussed in the view of different grazing techniques of cattle and wild ungulates.     

Ecotourist trail-use affects the taxonomic,functional and phylogenetic diversity of mammals in a protected area: lessons for conservation management

Ecotourism, by definition, aims to engage peoples’ interest in wildlife and the environment. The use of tourist roads and trails to access sites within protected areas (PAs) can detrimentally affect the behavior and distribution of species. The way mammals respond to anthropogenic pressures may differ across taxonomic, functional, and phylogenetic groups; nevertheless, how ecotourist trail-use affects these different diversity remains under-investigated. Here, we assessed 6 metrics of taxonomic, phylogenetic, and functional diversity for a mammal community in a PA in central China, recording how Trail use (using Trail type as a proxy) and habitat variables affected sightings and signs of mammals across 60 replicate 0.5 km transects. We then examined how Trail use affected the taxonomic, functional, and phylogenetic diversity indices of species (>1 kg). Using generalized liner mixed modeling, we identified that more used trail types had a greater adverse effect on all diversity richness indices than did less used trail types. Consequently, tourist pressure was associated with a general tendency to homogenize the site's mammal community. In contrast, the effects of Trail Types on all diversity evenness indices were non-significant. Furthermore, more developed and more heavily used trail types had a greater, significant negative effect on taxonomic, functional, and phylogenetic richness, whereas these richness indices were unaffected by minor trail types, used less intensively. As a general principle, lower biodiversity indices reduce ecosystem resilience, and so it is vital to better understand these responses to balance public access against biodiversity management in PAs.     

黄土丘陵沟壑区植被恢复过程中物种组成及多样性

通过小流域内不同生境条件下的植被调查,研究了半干旱黄土丘陵沟壑区植被恢复过程中的物种组成和植物多样性。结果表明:各植物种占总数比例为多年生草本一年生草本灌木乔木;阳坡灌木作用较大,半阳坡和半阴坡乔木树种与灌木树种作用相近,阴坡明显以乔木树种作用占优势;不同人工林类型之间植物多样性不存在显著差异,而立地条件是影响植物多样性的主要因素,人们对退耕地的经营活动,不利于生物多样性恢复。     

Marker-based estimates of between and within population kinships for the conservation of genetic diversity

In this article coefficients of kinship between and within populations are proposed as a tool to assess genetic diversity for conservation of genetic variation. However, pedigree-based kinships are often not available, especially between populations. A method of estimation of kinship from genetic marker data was applied to simulated data from random breeding populations in order to study the suitability of this method for livestock conservation plans. Average coefficients of kinship between populations can be estimated with low Mean Square Error of Prediction, although a bias will occur from alleles that are alike in state in the founder population. The bias is similar for all populations, so the ranking of populations will not be affected. Possible ways of diminishing this bias are discussed. The estimation of kinships between individuals is imprecise unless the number of marker loci is large (> 200). However, it allows distinction between highly related animals (full sibs, half sibs and equivalent relations) and animals that are not directly related if about 30–50 polymorphic marker genes are used. The marker-based estimates of kinship coefficients yielded higher correlations than genetic distance measures with pedigree-based kinships and thus to this measure of genetic diversity, although correlations were high overall. The relation between coefficients of kinship and genetic distances are discussed. Kinship-based diversity measures conserve the founder population allele frequencies, whereas genetic distances will conserve populations in which allele frequencies are the most different. Marker-based kinship estimates can be used for the selection of breeds and individuals as contributors to a genetic conservation programme.