牛科(哺乳纲:偶蹄目)动物与生境利用有关的适应形态模式

对广义牛科动物颅后骨骼的多元变量分析揭示了牛科生境利用和体型之间的骨学特征。利用逐步分辨分析方法和一个基于机器学习的决策树方法鉴别了每种生境中牛科动物颅后解剖结构的形态特征。从110个广义牛科动物测量了43个指标进行了这项分析。利用所有主要肢骨测量值和以单根肢骨测量为主的测量值获得的分辨函数和决策树可以完美地区分适应开阔生境、森林和山地的牛科动物(在所有分析中得到了100 %正确的再分类)。由于调整的函数仅涉及到很小的颅后骨骼测量集,这些函数可以应用于研究考古学和古生物学发掘物中保存的不完整标本。这些表征生境利用的生态适应函数与那些用颅齿部性状建立、用于推测牛科动物食物选择的函数结合,具有刻画已灭绝的分类类群的古个体生态学和重建古环境的潜力。我们还分析了多元回归是否较单一因子回归表现出较高的预测能力,并提出了从每一种单根主要肢骨测量的颅后形态变量得到的最好代数函数     

安氏薮羚的性二型对采食行为的影响(英文)

安氏薮羚(Tragelaphus angasii)是具有性别体二型的动物,其体型大小的差异可能对采食行为和生境选择有显著影响.利用连续行为取样法检测了雌雄个体在生境和植物利用上的差异,记录采食植物种类和采食高度并进行了性别间比较.在每个采食周期末,采用点中心方形样方法(PCQ)对植被进行一次调查,利用判别函数分析鉴别雌雄个体之间在种类和高度上是否存在差异.雌羚在三类生境中花费的采食时间相似,但雄羚表现出对砂地林的偏好.另外,在同一生境内雄羚利用更多的木本种类且采食较高的部位,而雌羚喜欢采食低层草本植物.安氏薮羚雌雄个体在生境内具有食性(采食种类)和空间(生境斑块)上的分离.我们认为这是由性二型引起的性别间营养与能量需求差异和不同繁殖策略造成的,最终使得精食者动物在具有复杂结构空间异质性的生境内表现为空间性别分离     

黑斑羚粪便中碳同位素揭示的食性变化

利用稳定碳同位素数据(δ13C)分析了南非克鲁格国家公园混食性黑斑羚(Aepyceros melampus)时间和空间尺度上的食性变化,验证了两个假说,即有蹄类食性变化是由生境中木本植物与草本植物的相对配比导致;降雨控制有蹄类生态。结果表明:黑斑羚的食性涵盖了精食者-粗食者采食谱系,且食性中木本与草本比例在不同月间、季节、年度和区域间存在很大变化。栖息于开放性热带稀树草原和草原中的黑斑羚通常采食比生境中更高比例的草本,但在时间尺度上并不恒定。在克鲁格北部的一个区域(Punda Maria) ,黑斑羚采食的草本比克鲁格国家公园中其它任何区域都多。与其它生境相比,在河边的黑斑羚采食草本数量更少,尤其是在食性空间变化更为明显的旱季。因此,我们的数据不支持有蹄类食性组成变化是由生境中木本与草本比例不同造成的假说,食性与降雨量间也无明显的关系。我们的结果支持草本中蛋白含量增加引起黑斑羚采食比例的增加这一模型。粪便中氮含量在时间和空间上的变化很小,揭示在可利用食物中,无论木本还是草本,黑斑羚进行选择采食以保证最好的食物质量。基于这些结果,我们认为更具体的食物选择和可利用性最适采食理论能够更好地解释这种生态学变化。     

香溪河水系大型底栖动物功能摄食类群生态学

2004年7月至2007年6月,通过大型底栖无脊椎动物的量化监测,对三峡水库湖北库区最大河流香溪河大型底栖无脊椎动物功能摄食类群生态学进行研究.结果表明:香溪河大型底栖动物以收集者占绝对优势,其次为刮食者,捕食者、滤食者、撕食者相对丰度较小;各功能摄食类群分布明显受时空资源位的限制;香溪河物质循环能力、两岸物质的输入量和粗有机颗粒/ 细有机颗粒在九冲河明显高于其它河流,在冬季高于其它季节;物质输送能力以高岚河最高,在时间方面以冬季明显高于其它季节.逐步回归分析表明,流速、电导、浊度、总氮、二氧化硅对香溪河河流生态系统物质循环具有指示作用;二氧化硅和化学需氧量对物质输送能力具有指示作用;水温、水深、二氧化硅、总磷可作为沿岸物质输入量的指标;水温、二氧化硅可作为评估河道中粗、细有机颗粒比例的重要指标.     

内蒙古达赉湖地区蒙原羚冬季采食生境选择

蒙原羚是欧亚大陆温带草原生态系统中的特有物种和数量最多的有蹄类动物。2010年11月—2011年1月,在内蒙古达赉湖地区开展了蒙原羚冬季采食生境选择研究。结果表明:蒙原羚冬季选择利用雪深<6cm,地上生物量>50g.m-2,距围栏1000～2000m,植被高度>20cm,植被盖度>40%,隐蔽条件(可视距离)3000～4000m,到居民点距离>2000m,距家畜>2000m,坡度<20°,中上坡位,针茅(Stipa spp.)和羊草(Aneurolepidium chinnenses)等植被类型的生境采食;生境因子综合影响蒙原羚的冬季采食生境选择,依照贡献值的大小依次为到围栏距离、地上生物量、雪深和隐蔽条件。逐步判别分析表明,由这4个变量构成的判别方程在对蒙原羚采食样方进行区分时,正确判别率为82.1%。因此,建立合理的围栏管理制度、提高可利用食物量等是蒙原羚保护的关键。     

激光雷达技术在动物生态学领域的研究进展

激光雷达(light detection and ranging, LiDAR)作为一门新兴的主动遥感技术, 近年来由于在提取和反演森林参数水平上不断提高, 被越来越多地应用于动物生态学研究中。本文通过整理和搜集国内外文献, 对激光雷达的技术特点及其在森林参数提取和动物生境上的研究进展进行综述, 指出当前基于LiDAR的森林参数反演算法主要服务于森林资源调查或林学研究, 缺少对动物生态或生理意义相关的参数量化信息。目前该技术在国内的动物生态学方面的应用较少, 尚未见文章发表。通过总结国外学者的研究, 分别从动物生境选择与三维森林结构的关系、栖息地立体生境制图、生物多样性评估和物种分布模型预测三个方面综述了LiDAR在动物生态学研究中的应用现状。相比传统方法, LiDAR技术提供的高精度三维结构信息, 能够显著提高动物生境质量的评估、生物多样性的监测水平和物种分布模型的评价精度, 有利于从机理上加深对物种生境选择和集群过程的理解。但目前LiDAR技术的应用主要集中在对已知的生态关系研究, 尤其是冠层结构与动物分布的关系, 缺少对林下层生活的动物生境质量和生物多样性的监测和评估, 同时很多有关动物生存和繁衍与立体生境的关系研究有待从LiDAR数据中进一步挖掘分析。未来应加强对森林林下层三维信息的提取, 提高林下层动物生境质量和生物多样性的监测水平, 同时建立适用于动物生态和生理意义相关的参数, 为动物生境质量和生物多样性的评估提供标准的量化指标。     

川西亚高山林牧交错区土壤动物多样性

交错区复杂的生境常常导致相对较高的物种多样性。为探讨牧压条件形成的林牧交错区土壤动物多样性,研究了川西亚高山典型林牧交错区的土壤动物群落结构与多样性。在交错区5种生境下,共获得土壤动物49837只,隶属7门16纲33目126类。从草甸到针叶林的过渡生境中,土壤动物明显受到放牧干扰影响,其个体密度随干扰的减弱呈逐步上升趋势,而类群数则呈单峰型变化趋势;Shannon-Wiener、DG多样性指数都呈现逐步上升趋势;Wilson-Shmida多样性指数表明相邻干扰梯度下土壤动物类群替代率相近。大型土壤动物生物量在草甸最低,阔叶林最高。CCA排序显示凋落物厚度与中小型土壤动物存正相关,pH与其存负相关,不同类群对环境因子响应存在差异。这些结果表明农牧交错区不同干扰梯度下土壤动物群落结构和多样性存在明显差异。     

蒙古野驴的秋季食性分析

2006 年9 月在新疆卡拉麦里山有蹄类野生动物保护区内采集了25 堆蒙古野驴粪便和10 科共29 种植物标本,采用粪便显微组织学分析方法分析了蒙古野驴的秋季食性,并初步探讨了其食性与周围环境的关系。结果表明,蒙古野驴秋季食性广, 共采食8 科26 种植物。这些植物按照其在食物组成中的比例可分为3 大类:主要食物为梭梭、针茅、驼绒藜, 共占食物组成的61.3% ;常采食植物为柽柳、角果藜、蒿、琵琶柴、芨芨草等11种,共占食物组成的33.3%; 少见采食的植物为盐爪爪、獐毛、顶羽菊、黑果枸杞、里海盐爪爪等12 种,共占食物组成的6.7% 。按科别而论,蒙古野驴采食最多的是藜科植物,其次是禾本科植物。从被采食植物的分布区域分析,其采食区域广阔,包括了保护区内所有的生境类型。      

梯级水坝运行对漫湾库区底栖动物群落结构及分布格局的影响

底栖动物是对水生态系统退化和生境条件改变最为敏感的生物类群之一,同时也是开展梯级水坝水生态系统变化和演替研究的指示生物.本研究以国际生物多样性保护及水电梯级开发生态影响研究的热点地区澜沧江中下游为例,以澜沧江干流兴建的第一座水坝漫湾库区为研究区域,分别于2011和2016年开展底栖动物定点采样,并结合其蓄水前(自然河段,1996年)和单级水坝蓄水初期(1997年)的历史调研数据,全面分析了梯级水坝运行前后漫湾库区底栖动物群落的结构、分布格局及演变趋势.结果表明: 漫湾库区底栖动物群落的优势种组成逐渐由寡毛纲和昆虫纲种类演变为软体动物门类占绝对优势;沿库区生境的纵向梯度变化,底栖动物密度和生物量均表现为升高的趋势,而静水区增加更为显著;对底栖动物功能摄食群的分析表明,静水区由掠食者和收集者占优势演变为滤食者类占绝对优势;梯级水坝运行后,采用生物指数评价结果表明,2016年库区综合水质指标明显优于2011年.漫湾库区底栖动物群落的演变与上游梯级小湾水坝的调度运行及库区的水文状况和泥沙淤积情况密切相关,并随着梯级水坝的运行处于动态变化之中.     

海南长臂猿破碎化生境中食物资源可利用性分析

食物种类及其可获得性是动物生存的基本条件,也是生境质量评价的重要指标。2013年1月至2014年7月,对海南长臂猿(Nomascus hainanus) C群生境内食源植物种类、数量、食物可获得性及主要取食植物的径级结构进行调查分析,共记录到64种食源植物(标记胸径≥5 cm的乔木1 484株)。海南长臂猿以高大粗壮的食源植物为主要采食对象。这些乔木型食源植物结果率超过50.0%的有15种,占C群全部乔木型采食植物种数的28.8%;结果率最高的是海南单籽暗罗(Monoon laui, 76.7%),最低的是鹅掌柴(Heptapleurum heptaphyllum, 9.6%)。18种长臂猿主食食源乔木中,白肉榕(Ficus vasculosa)、斜叶榕(Ficus tinctoria)等15种食源植物的植株呈增长型结构。南酸枣(Choerospondias axillaria)、二色波罗蜜(Artocarpus styracifolius)为稳定型结构,而桃榄(Pouteria annamensis)为衰退型结构。提示海南长臂猿食物供应植物仍处于年轻状态,但这些食源植物并非每年结果,...     

Biometric study of ruminant carpal bones and implications for phylogenetic relationships

The mammalian Carpus is a complex of several small bones with multiple interactions during walking. Therefore, it is highly probable that different mammalian families developed distinctive constellations in their Carpi, which could be useful for biometric identification of phylogenetic groupings. The carpal bones of nineteen extant ruminant species (nine bovid, nine cervid, and one moschid) have been investigated to search for biometric traits which are diagnostic for the three families. Additionally, we searched for diverging functional adaptations in the carpal constellations. Therefore, measurements have been taken from the five main carpals, which are carrying the body weight. As a sesamoid bone, Os carpi accessorium was excluded. After transformation of the data into their natural logarithms, multivariate methods of factor analyses and discriminant analyses were performed for each bone. Bivariate plots of the factor scores allowed a clear separation of bovids and cervids. The only one species of the Moschidae (Moschus moschiferus) lies closer to the cervids than to the bovids. The grouping is due to phylogenetic relationships and not due to functional differences in the groups or differing habitat preferences. Generally, the carpals of cervids are more slender and higher in contrast to the bulky and flat carpals in bovids. This approach could be used to assign isolated carpal bones found in fossil sites to their ruminant family.     

Microwear evidence for Plio-Pleistocene bovid diets from Makapansgat Limeworks Cave, South Africa

Makapansgat Limeworks Cave is a well-known Australopithecus africanus bearing locality that has spawned a considerable amount of paleoecological research because of its hominin component. Most recently, the paleoecology of this Plio-Pleistocene site has been studied by determining the diet and habitat of other extinct taxa, particularly the bovids. The diets of seven bovids (Aepyceros sp., Gazella vanhoepeni, Makapania broomi, Parmularius braini, Redunca darti, Tragelaphus sp. aff. T. angasii, and Tragelaphus pricei) have now been classified using taxonomic uniformitarianism, ecomorphology, stable carbon isotopes, and mesowear analysis. Here, dental microwear is applied to the same bovids for additional comparison and to further elucidate the strengths and weaknesses of each method. The different dietary proxy methods noted provide a temporal continuum, with genetic signals such as ecomorphology and taxonomic uniformitarianism indicating behavioral adaptations over geologic time, while nongenetic data such as stable carbon isotopes and mesowear reflect different aspects of average diet over extended portions of an animal's life, and dental microwear provides dietary snapshots.Microwear separated an extant baseline of ten bovid species into expected dietary categories and the Makapansgat bovids clearly fell into two groups with the same degree of separation as between extant grazers and browsers. The results indicate that a multidisciplinary approach produces a more accurate and robust reconstruction of past diets. In sum, the microwear analysis is in-line with the isotope and mesowear results, which suggest a stronger browsing component than either taxonomic uniformitarianism or ecomorphology imply.     

Geometric morphometrics of mandibles for dietary differentiation of Bovidae (Mammalia: Artiodactyla)

The mammalian family Bovidae has been widely studied in ecomorphological research, with important applications to paleoecological and paleohabitat reconstructions. Most studies of bovid craniomandibular features in relation to diet have used linear measurements. In this study, we conduct landmark-based geometric-morphometric analyses to evaluate whether different dietary groups can be distinguished by mandibular morphology. Our analysis includes data for 100 species of extant bovids, covering all bovid tribes and 2 dietary classifications. For the first classification with 3 feeding categories, we found that browsers (including frugivores), mixed feeders, and grazers are moderately well separated using mandibular shape. A finer dietary classification (frugivore, browser, browser–grazer intermediate, generalist, variable grazer, and obligate grazer) proved to be more useful for differentiating dietary extremes (frugivores and obligate grazers) but performed equally or less well for other groups. Notably, frugivorous bovids, which belong in tribe Cephalophini, have a distinct mandibular shape that is readily distinguished from all other dietary groups, yielding a 100% correct classification rate from jackknife cross-validation. The main differences in mandibular shape found among dietary groups are related to the functional needs of species during forage prehension and mastication. Compared with browsers, both frugivores and grazers have mandibles that are adapted for higher biomechanical demand of chewing. Additionally, frugivore mandibles are adapted for selective cropping. Our results call for more work on the feeding ecology and functional morphology of frugivores and offer an approach for reconstructing the diet of extinct bovids.     

Functional differentiation of African grazing ruminants: an example of specialized adaptations to very small changes in diet

We assess whether interspecific differences in craniodental morphology within a single ruminant feeding guild, the grazers, represent anatomical adaptations to subtle differences in diet. Differences in craniodental anatomy follow a distinct taxonomic pattern that is paralleled by dietary niche differentiation recorded in species' stable carbon (δ¹³C) and nitrogen isotope (δ¹⁵N) compositions, strongly supporting a hypothesis for functional divergence within the grazers. We propose that the evolutionary origin of grazers were multifold; at least two and up to four different types of grazing can be discerned within the 11 taxa studied here alone. However, correspondence between craniodental adaptations and isotopic differences across species are not found when only δ¹³C data are considered (i.e. morphological differences do not reflect varying proportions of C₃ browse to C₄ grass consumed). This implies that alternate anatomical adaptations to grazing are not related to differences between variable (part-time browsing) and obligate grazers, as previously predicted. Rather, anatomical differences correlate strongly with changes in δ¹⁵N, which we infer to reflect functional responses to changes in diet quality associated with the degree of feeding selectivity and short-, medium-, or tall-grass grazing.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 755–764.     

Evolution of Craniodental Correlates of Diet in African Bovidae

Establishing the relationship between craniodental morphology and dietary ecology in extant species permits inferences to be made about the ecology and biology of fossil species and the habitats they inhabited. Previous work linking diet and craniodental morphology has historically relied upon categorical classifications of diet and has not considered the phylogenetic signal (i.e., non-independence) of morphology due to shared evolutionary history. Here we use phylogenetic comparative methods to analyze the relationship between diet and eight craniodental indices for 40 species of African Bovidae using both categorical and continuous (stable carbon isotopes of enamel, δ¹³C) classifications of diet. In addition, we examine three modes of evolution that best explain interspecific variation in each of these indices, including: Brownian Motion (BM), Early Burst (EB), and Ornstein-Uhlenbeck (OU). Our results show that the hypsodonty index (HI), the length of the masseteric fossa relative to facial depth (MAS-F), and the length of the diastema relative to the total toothrow length (DIAS-TR) are the best predictors of diet among African bovids. These indices are best explained by either a BM or OU mode of evolution. Our findings have important implications for understanding the evolution of craniodental traits and reconstructing the diet of fossil mammals, especially bovids.     

Analyzing ungulate long bones as a tool for habitat reconstruction

The long bones (humerus, radius, metacarpus, femur, tibia, metatarsus) of 51 extant bovid and 7 equid specimens were measured in order to test the hypothesis that they show adaptations to different habitats. We performed factor analyses (FAs) with principal component extraction method and plotted the extracted factors (Fs) in simple scatterplots. The preferred habitats (grassland, forest, mountainous regions) were labeled in the plots, and our results show three clearly separated clusters for F2 vs. F3. According to our interpretation, F1 reflects the body size of the specimens while F2 is most probably reflecting cursorial adaptations. F3 is largely affected by dimensional bone characteristics adapted to maneuver in the environment, and therefore, F3 is somehow linked to habitat. The investigated equids are plotting within the cluster of bovids preferring grassland habitats, which is surprising because of different constructions of the metapodials in perissodactyls and ruminants. Performed linear discriminant analyses (LDAs) are supporting our FA results. This approach combines biometrics with statistics and presents a tool, which easily can be applied helping to identify the paleo-habitat or the paleo-ecology of extinct bovids with implications on fossil localities.     

Multivariate analysis of neognath skeletal measurements: implications for body mass estimation in Mesozoic birds

The abundant fossils of avian stem taxa unearthed during the last years make it necessary to review and improve the models for estimating body mass used in palaeoecological studies. In this article, single and multiple regression functions based on osteological measurements were obtained from a large data set of extant flying birds for estimating the body mass of 42 Mesozoic specimens from stem taxa Archaeopterygidae, Jeholornithidae, Sapeornithidae, Confuciusornithidae, and Enantiornithes, and basal members of Ornithuromorpha. Traditionally, body mass has been estimated in fossil vertebrates using univariate scaling functions. In contrast, multiple regression functions have been used less frequently. Both predictive methods can be affected by different sources of error from statistics, phylogenetic relationships, ecological adaptations, and bone preservation; however, although some studies have addressed these biases, few have tested them within the context of a single data set. In our data set, we find that the models with greater predictive strength and applicability for new specimens, especially for stem taxa, are those derived from multiple regression analyses. For this reason, we suggest that multiple regression analyses may provide improved predictive strength for stem group specimens. Moreover, the methodology used for selecting variables allowed us to obtain specific sets of predictors for each fossil stem group that presumably minimized the variation resulting from historical contingency (i.e. differences in skeletal morphology arising from phylogeny), locomotor adaptations, and diagenetic compaction. The loss of generalizability in the multiple regression models resulting from collinearity effects was negligible on the body mass estimates derived from our data set. Therefore, the body mass values obtained for Mesozoic specimens are accurate and can be used in future studies in a number of palaeobiological and evolutionary aspects of extinct birds, particularly the first stages of avian flight. © 2015 The Linnean Society of London     

Side steps: the erratic pattern of hominin postcranial change through time

The hominin fossil record reveals brain-size expansion, canine reduction, premolar metaconid development, and numerous other craniodental features that become more human-like through time. In general, the postcranial skeleton also gets more human-like through time, but in some respects it does not. This is particularly apparent in the overall morphology of one of the most frequently preserved elements, the distal humerus. Some of the earliest hominins display quite human-like morphologies, whereas later specimens are quite unusual among extant species of Hominoidea: when described metrically and subjected to multivariate discriminant analyses in the context of large samples of extant hominoid humeri, the shapes of the earliest hominin fossils are more human-like than many of the later specimens. The Mahalanobis distances between many of the 1.5-2Ma hominin humeri and Homo sapiens are remarkably large. Many of the less well-represented postcranial specimens do not follow a linear path through time of increasing hominization either. This is particularly noticeable in the fore-to-hind limb joint-size proportions, ulnar morphology, and pelvic architecture. The hominin postcranial fossil record reveals many side-steps: there appears to be no simple march toward our human bodies, but a pattern better explained as adaptations to proximate conditions and constrained by ontogeny and history.     

Morphometry and allometry of the primate humerus

The primate distal humerus has been used both in phylogenetic reconstruction and in assessing locomotor and postural adaptations. This study uses an allometric approach to predict locomotor patterns of extant primates regardless of phylogenetic position. By showing the relationship between form and function in living primate taxa it will be possible to use this data set to predict locomotor behavior of extinct primates. Several linear measurements were taken from the distal humerus of 71 extant primate species (anthropoids and prosimians). Allometric regressions of each measurement were performed with mandibular M₂ area as a surrogate for body size. These measurements were used to determine if significant differences in distal humerus morphology exist among locomotor groups. The results were then used to test several hypotheses about the relationship between humeral form and function. For example, the hypothesis that suspensory primates have a large medial epicondyle is confirmed; the hypothesis that terrestrial quadrupeds have a deep olecranon fossa could not be confirmed with quantitative data. In addition to this hypothesis testing, the residuals from the allometric regressions of the humeral measurements were used in a discriminant functions analysis to estimate locomotor behavior from distal humerus morphology. The discriminant functions analysis correctly reclassified 64/71 (90%) species.