Autopodial skeletal diversity in hystricognath rodents: Functional and phylogenetic aspects

Metapodials and phalanges of the second to fourth digital ray were measured for the hands and feet of 214 specimens belonging to 45 extant species of hystricognath rodents, encompassing members of all major clades of the radiation. Principal components analysis (PCA), the phalangeal index of the third digital ray in the hands and feet, and the relationship between second and fourth digital ray were used to investigate intrinsic autopodial proportions as well as to provide a base for comparisons between hands and feet. PCA separated cursorial Hystricognathi from arboreal ones, but lead to little distinction in other locomotory modes. Cursors have longer metapodials and shorter phalanges, particularly in their hind limb, while arboreal species have relatively longer manual and pedal phalanges. Terrestrial, scansorial, fossorial, and semi-aquatic species were not clearly distinguished, but there is a tendency towards elongated manual digits and relatively short feet in most fossorial species. Closely related species with similar locomotory habits tend to group together in PCA morphospace, and also have similar phalangeal indices. The results are in agreement with current hypotheses on locomotory adaptations of the hand and foot, and concur with many previous findings on autopodial proportions in arboreal, cursorial, and fossorial species. They also highlight the limited use of autopodial proportions for inferring systematic affinities. The lack of distinction in the majority of species is likely related to the lack of highly specialized locomotory types in Hystricognathi.     

鸟类跗跖骨远端形态的两种模式及其栖息行为

通过对大量现生鸟类的跗跖骨进行对比研究,得出鸟类的跗跖骨远端特征可以被用来作为判断鸟类栖息习性的依据。地栖性鸟类的跗跖骨远端由第Ⅱ、第Ⅲ、第Ⅳ跖骨滑车组成典型的“三角”模式,而树栖性鸟类的跗跖骨远端则是由位于同一平面位置的第Ⅱ、第Ⅲ、第Ⅳ跖骨滑车组成典型的“滚轴”模式。由此还尝试对中生代鸟类的栖息习性和功能作了检验和判定,依此鉴定与借助其他依据识别的结果比较一致。鸟类跗跖骨远端形态结构的观察与研究,对评判古鸟的栖息习性以及鸟类的栖息演化历史都具有重要意义。     

Circumventing the polydactyly 'constraint': the mole's 'thumb'

Talpid moles across all northern continents exhibit a remarkably large, sickle-like radial sesamoid bone anterior to their five digits, always coupled with a smaller tibial sesamoid bone. A possible developmental mechanism behind this phenomenon was revealed using molecular markers during limb development in the Iberian mole (Talpa occidentalis) and a shrew (Cryptotis parva), as shrews represent the closest relatives of moles but do not show these conspicuous elements. The mole's radial sesamoid develops later than true digits, as shown by Sox9, and extends into the digit area, developing in relation to an Msx2-domain at the anterior border of the digital plate. Fgf8 expression, marking the apical ectodermal ridge, is comparable in both species. Developmental peculiarities facilitated the inclusion of the mole's radial sesamoid into the digit series; talpid moles circumvent the almost universal pentadactyly constraint by recruiting wrist sesamoids into their digital region using a novel developmental pathway and timing.     

长掌义县龙(兽脚类:恐龙)及其在手盗龙类进化和热河动物群生态学研究中的意义

重新研究了产于辽西义县组下部的带羽毛小型兽脚类恐龙长掌义县龙(Yixianosaurus longimanus)的不完整骨架.系统发育分析得出义县龙属于手盗龙类基干类群,与阿尔瓦雷斯龙(Alvarezsaurus)、镰刀龙类、除阿尔瓦雷斯龙之外的其他阿尔瓦雷斯龙类以及由窃蛋龙类和副鸟龙类等进步手盗龙类组成的一个类群形成多分支状态.义县龙既有原始特征,如臂指数低,第三指强壮;也有进步特征,如乌喙骨近长方形,表明在手盗龙类当中,前肢演化呈现出比以前认为的更加复杂的镶嵌现象.强壮的前肢骨骼以及厚重、弯曲而尖利的手爪表明义县龙是捕食者,尽管这一认识尚待该属种更完整化石的发现来证实.义县龙在手盗龙类系统发育中的基部位置暗示,在虚骨龙类演化的这一节点上,前肢形态的变异范围更大.在许多方面,义县龙强壮的前肢和过度增大的弯曲爪子与长臂猎龙(Tanycolagreus)和虚骨龙(Coelurus)的相似,可能代表了这些属种与基干镰刀龙类和窃蛋龙类之间的过渡形态.义县龙保存了大的片状体羽,表明这些皮肤衍生物在虚骨龙类中的起源可能比以前报道的要早.最后,强壮而伸长的前肢暗示了其生态功能与根据同一区域的其他小型兽脚类推测的不同,支持了热河生物群的小型非鸟兽脚类中存在小生境划分的观点.     

The socioecology of the black mangabey (Cercocebus aterrimus) near Lake Tumba,Zaire

Socioecological data were gathered in a two-year study of black mangabey monkeys in a secondary forest on the west bank of Lake Tumba, Zaire. The mangabeys of the study area lived in multi-male, multi-female groups numbering between 14 and 19 individuals. They were completely arboreal, fed mostly on fruit and nuts, and frequently were associated with other species of arboreal monkeys. Their predators were human hunters and the crowned hawk-eagle. The primary vocalizations of black mangabeys were analyzed and their social contexts compared with those of closely related gray-cheeked mangabeys, to which they were found to be very similar.     

Activity patterns and feeding behaviour of the tree hyrax, Dendrohyrax arboreus, in the Parc National des Volcans, Rwanda

Activity patterns of Dendrohyrax arboreus were investigated by direct observation of a habituated population in the Parc National des Volcans, Rwanda. Of seventeen animals caught, four were males and thirteen were females. Of the population, 17% were juveniles. Population estimates from transects indicated a biomass of 23.3 kg/ha. Radio-tracking of ten individuals showed bimodal activity patterns, with peaks after dusk and later in the night for males and during the day in females. Hyrax were active 16% of the time. Feeding was the dominant activity and mature leaves of Hagenia abyssinica were the most important food. Travelling within and between trees occupied 4% of the time and occurred predominantly during daylight hours. Calling behaviour was markedly seasonal, being most pronounced in the dry season when hyrax called regularly in the early evening, and often a second time late at night. During the rains, calls were infrequent and unpredictable, tending to occur in the second half of the night. There was no correlation between weather or lunar conditions and calling behaviour. The ecological strategy of tree hyrax in terms of metabolic rate, thermoregulation and energy conservation is discussed in the light of their activity and feeding behaviour.     

Global comparisons of beta diversity among mammals, birds, reptiles, and amphibians across spatial scales and taxonomic ranks

Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates （mammals, birds, reptiles, and amphibians） at both regional （biogeographic realm） and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa （birds and mammals） than for the two ectothermic taxa （reptiles and amphibians） in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000-99,999 km^2 than for ecoregions of 100,000-5,000,000 km^2.     

Evolution of nest-weaving behaviour in arboreal nesting ants of the genus Polyrhachis Fr. Smith (Hymenoptera: Formicidae)

Abstract  Polyrhachis ants represent one of the most taxonomically and ecologically diverse ant genera, with over 500 described species organised into 12 subgenera. Nesting habits range from subterranean localities to arboreal nests incorporating silk produced by the ants' own larvae (nest weaving). In this article, we combine scanning electron microscopy and gross observations of the nests of 35 species representing nine subgenera thought to contain individuals that nest above the ground (Cyrtomyrma, Hagiomyrma, Hedomyrma, Hemioptica, Myrma, Myrmatopa, Myrmhopla, Myrmothrinax, Polyrhachis) to revaluate the relationship between nest locale, the type of nest material used and the use of larval silk for nest construction. Nesting habits are highly diverse, ranging from truly arboreal nests on or between leaves and branches, to lignicolous nests inside hollow stems or bamboo internodes and lithocolous nests on the sides of rock walls. Flat sheets of larval silk are used only by arboreal nesting species within the subgenera Cyrtomyrma , Hemioptica , Myrma , Myrmatopa , Myrmothrinax and Polyrhachis . Lignicolous nesting habits were demonstrated predominantly by Hedomyrma spp., but these habits also occur in Myrma and Myrmhopla . Lithicolous nesting habits occur within Hagiomyrma and Hedomyrma , though the actual nesting material used can be either carton or dense masses of spider silk. Based on existing phylogenetic hypotheses, the use of larval silk for nest construction has evolved independently within the genus, and has evolved independently of the construction of silk nests per se . Further examination of the exact type of silk found in the colonies of 'nest-weaving' Polyrhachis is warranted.