Stream fish assemblages in relation to environmental factors on a montane plateau (Nyika Plateau,Malawi)

Few studies have examined river fishes of Malawi. This study is one of the first to examine the stream fish assemblages on the Nyika Plateau in northern Malawi. Twenty four sites were sampled over three different periods in two river systems of the plateau. Eighteen species were collected and among these was Hippopotamyrus ansorgii, the first collection of this species in the Lake Malawi catchment. Three species, including a non-native trout, were common in the two systems studied. Correspondence analysis (CA) suggested gradients in species composition related to altitude and river type. Species succession, from a trout dominated upstream to a downstream dominated by indigenous species, was shown on the first CA axis. The second CA axis showed the assemblage of the plateau separated by river type. A direct gradient analysis method, canonical correspondence analysis (CCA), showed the importance of two stream position metrics (stream order and c-link), depth, water temperature and substrate type in determining species composition. According to variation partitioning in CCA, the spatial and temporal components respectively explained 46% and 3.6% variation in assemblage composition based on the all species data matrix, and 48.7% and 2.6% variation in assemblage composition based on the native species data matrix. The species collected were also discussed in relation to the morphological adaptations in their body forms to the environmental conditions of the streams studied.     

Amassing diversity in an ancient lake: evolution of a morphologically diverse parthenogenetic gastropod assemblage in Lake Malawi

Exceptional ecological niche diversity, clear waters and unique divergent selection pressures have often been invoked to explain high morphological and genetic diversity of taxa within ancient lakes. However, it is possible that in some ancient lake taxa high diversity has arisen because these historically stable environments have allowed accumulation of lineages over evolutionary timescales, a process impossible in neighbouring aquatic habitats undergoing desiccation and reflooding. Here we examined the evolution of a unique morphologically diverse assemblage of thiarid gastropods belonging to the Melanoides polymorpha'complex' in Lake Malawi. Using mitochondrial DNA sequences, we found this Lake Malawi complex was not monophyletic, instead sharing common ancestry with Melanoides anomala and Melanoides mweruensis from the Congo Basin. Fossil calibrations of molecular divergence placed the origins of this complex to within the last 4 million years. Nuclear amplified fragment length polymorphism markers revealed sympatric M. polymorpha morphs to be strongly genetically differentiated lineages, and males were absent from our samples indicating that reproduction is predominantly parthenogenetic. These results imply the presence of Lake Malawi as a standing water body over the last million years or more has facilitated accumulation of clonal morphological diversity, a process that has not taken place in more transient freshwater habitats. As such, the historical stability of aquatic environments may have been critical in determining present spatial distributions of biodiversity.     

Implications of an early land plant spore assemblage for the late Silurian age of the Si Ka Formation,northern Vietnam

The first plant microfossil assemblage from the Si Ka Formation of the Song Cau Group, northern Vietnam is reported. It is composed of cryptospores in dyads and tetrads, trilete spores, tubular remains consisting of an association of smooth, banded, and externally thickened tubes, and cuticle-like fragments. The biostratigraphic assemblage of sporomorphs indicates a late Silurian (late Ludfordian) to Early Devonian (early Lochkovian) age. Further comparison with coeval reports using the characteristic features of the assemblage confines their age to the late Ludlow (late Ludfordian) to early Přídolí. This report presents the oldest spore assemblage from Vietnam and contributes to a broader understanding of its paleo-landscape during the late Silurian.     

峙峪遗址碎骨的研究

本文对峙峪遗址出土的近七百件碎骨进行了研究,结果表明这些碎骨主要是由于人工打击和动物啃咬造成的。在有人工打击痕迹的碎骨中,存在着打制骨器。在个别碎骨的局部表面有磨光的现象,推测是人类使用的结果。     

Axes of differentiation in the bower-building cichlids of Lake Malawi

The 500-1000 cichlid species endemic to Lake Malawi constitute one of the most rapid and extensive radiations of vertebrates known. There is a growing debate over the role natural and sexual selection have played in creating this remarkable assemblage of species. Phylogenetic analysis of the Lake Malawi species flock has been confounded by the lack of appropriate morphological characters and an exceptional rate of speciation, which has allowed ancestral molecular polymorphisms to persist within species. To overcome this problem we used amplified fragment length polymorphism (AFLP) to reconstruct the evolution of species within three genera of Lake Malawi sand-dwelling cichlids that construct elaborate male display platforms, or bowers. Sister taxa with distinct bower morphologies, and that exist in discrete leks separated by only 1-2 m of depth, are divergent in both sexually selected and ecological traits. Our phylogeny suggests that the forces of sexual and ecological selection are intertwined during the speciation of this group and that specific bower characteristics and trophic morphologies have evolved repeatedly. These results suggest that trophic morphology and bower form may be inappropriate characters for delineating taxonomic lineages. Specifically the morphological characters used to describe the genera Lethrinops and Tramitichromis do not define monophyletic clades. Using a combination of behavioural and genetic characters, we were able to identify several cryptic cichlid species on a single beach, which suggests that sand dweller species richness has been severely underestimated.     

Mitochondrial phylogeny of the endemic mouthbrooding lineages of cichlid fishes from Lake Tanganyika in eastern Africa

Of the three cichlid species flocks in eastern Africa, Lake Tanganyika harbors the oldest species assemblage, which is also the most diverse morphologically and behaviorally. For 12 species (20 individuals) of 12 genera of the tribe Ectodini, 852 bp from two segments (cytochrome b and control region) of the mitochondrial genome were sequenced. In addition, orthologous sequences were obtained from eight species (11 individuals) representing other mouthbrooding lineages from Lake Tanganyika. Comparisons of sequence divergences revealed that the single Tanganyikan tribe Ectodini appears to be approximately five times older than the whole Lake Malawi cichlid species flock, suggesting that the radiation of the Tanganyikan mouthbrooding lineages took place long before the species flocks of Lakes Malawi and Victoria evolved. Seven of nine surveyed tribes of Tanganyikan cichlids appear to be approximately equally divergent, and this seems to corroborate the hypothesis of a rapid simultaneous formation of lineages at an early stage in the history of the Lake Tanganyika species flock. The close genetic relationship between the endemic Tropheus lineage and a nonendemic "Haplochromine," Astatotilapia burtoni, indicates that members of the tribe Tropheini may be the sister group of the cichlid flocks of Lakes Malawi and Victoria. The phylogenetic analyses demonstrate the monophyly of the Ectodini and identify the Cyprichromini as their sister group among the Tanganyikan cichlids. Within the tribe Ectodini the molecular data suggest both a branching pattern different than that previously proposed and a subdivision of the Ectodini into four clades, instead of the two originally described. The previously postulated model of morphological transformations believed to be responsible for the drastically different types of ecological specialization found among the Ectodini might therefore be in need of reinterpretation. Characters immediately related to foraging and nutrition seem to be particularly prone to homoplasy, even among members of a single lineage of cichlid fishes.      

Pterosaur remains from the Cretaceous of Morocco

New pterosaur remains consisting of jaw fragments of toothless taxa and isolated teeth are described from the red beds of the Kern Kern region of southern Morocco. The stratigraphic position of those red beds is discussed and it is concluded that they are in all likelihood early Cenomanian in age. At least four taxa of pterodactyloid pterosaurs are present. The toothless jaw fragments are referred to the families ?Pteranodontidae, ?Azhdarchidae and Tapejaridae. Four different morphotypes can be distinguished among the isolated teeth. They are tentatively referred to the Ornithocheiridae. This assemblage reveals a high diversity of pterosaurs in Africa during the early Upper Cretaceous. The possible occurrence of tapejarids and anhanguerids indicates relationships with the somewhat older pterosaur assemblage from the Santana Formation (Aptian/Albian) of Brazil. If confirmed, the presence of azhdarchids and pteranodontids in the early Cenomanian suggests an early differentiation of these essentially late Late Cretaceous groups of large pterosaurs.     

Beta diversity of rock-restricted cichlid fishes in Lake Malawi: importance of environmental and spatial factors

The rock-restricted cichlid fish assemblages of Lake Malawi exhibit high spatial diversity in their species composition and relative abundance. However the extent to which this is due to the effects of local environmental differences, dispersal limitation of constituent taxa, and the assignment of allopatric populations to species is uncertain. We examined the factors associated with diversity within an assemblage from the north-western shores, encompassing a spatial scale of 170 km. For both the whole assemblage, and all constituent species-complexes, spatial variance in community structure was significantly dependent upon both geographic distances between locations and local habitat variables. Pronounced effects of distance indicate limited dispersal, but our results also show that that the spatial variance explained by geographic distance alone was strongly linked to proportion of allopatric populations within a species-complex with species status. Thus, the taxonomic status of allopatric populations underlies, at least partially, the biogeographical structure of this assemblage. Substrate composition and habitat depth were also significant determinants of community structure, although spatial variance attributed to these variables was less than that associated with distance alone. Substantial unexplained variance may be a consequence of the effects of unmeasured habitat variables, high ecological similarity between co-occurring species, stochastic influences on population abundance, and the effects of local adaptation. Despite low spatial variance explained by the assessed environmental variables, significant environmental influence on cichlid assemblage structure across a wide spatial scale indicates that even slight future environmental changes may have the capacity to significantly alter species composition.     

湖北郧县肖沟旧石器时代遗址发掘简报

肖沟遗址位于湖北省郧阳区安阳镇钟家河村,埋藏于丹江口库区汉江左岸第二级堆积阶地,遗址所在地三面环水,北靠低山。2010年10月-12月对该地点进行抢救性发掘,揭露面积近1500 m~2,出土石制品413件。石制品类型包括石器、石核、石片、断块断片和碎块碎片等。古人类利用河流砾石,就地取材加工石制品;硬锤锤击是主要剥片方法;石制品总体以小型居多,石器主要以石片为毛坯,边刮器为主要类型。石制品特点显示石片工业特点。石制品类型以石片类和断块类为主体,石制品拼合率近10%,是一处原地埋藏的古人类遗址。通过与丹江口库区相关旧石器遗址的比较,结合地貌地层特点,推测该遗址形成于旧石器时代晚期。     

Population structure on breeding grounds of Lake Malawi’s ‘twilight zone’ cichlid fishes

Aim Free‐ranging benthopelagic fishes often have large population sizes and high rates of dispersal. These traits can act to homogenize population structure across the distributional range of a species and to reduce the likelihood of allopatric speciation. The apparent absence of any barriers to gene flow among populations, together with prior molecular evidence for panmixia across the ranges of three species, has resulted in Diplotaxodon, a genus of benthopelagic cichlid fishes of Lake Malawi, being proposed as a candidate case of sympatric speciation. Our aim was to further investigate this possibility by testing for intraspecific genetic subdivision among breeding populations, and intraspecific differences in breeding habitat. Location Lake Malawi, central‐east Africa. Methods We analysed eight microsatellite DNA loci to test for spatial genetic differences among populations on breeding grounds of eight Diplotaxodon species. We also tested for temporal population genetic differences within breeding grounds of three species. Records of ripe Diplotaxodon encountered during sampling were analysed to test if spatial variation in assemblage structure was linked to nearshore water depth and geographic proximity of sampling sites. Results Consistent with previous molecular evidence, within four of the eight species tested we found no evidence of spatial genetic structuring among breeding populations. However, within the other four species we found slight yet significant spatial genetic differences, indicating restricted gene flow among breeding grounds. There was no evidence of temporal genetic differences within sites. Analyses of the distributions of ripe Diplotaxodon revealed differences in assemblage structure linked to nearshore water depth. Main conclusions Together, these results demonstrate both the evolution of fidelity to deep‐water breeding locations in some Diplotaxodon species, and differences in breeding habitat among species. These findings are consistent with a role for divergence of breeding habitat in speciation of these cichlids, possibly promoted by dispersal limitation among geographically segregated spawning aggregations.     

Amphibian Diversity and Threatened Species in a Severely Transformed Neotropical Region in Mexico

Many regions around the world concentrate a large number of highly endangered species that have very restricted distributions. The mountainous region of central Veracruz, Mexico, is considered a priority area for amphibian conservation because of its high level of endemism and the number of threatened species. The original tropical montane cloud forest in the region has been dramatically reduced and fragmented and is now mainly confined to ravines and hillsides. We evaluated the current situation of amphibian diversity in the cloud forest fragments of this region by analyzing species richness and abundance, comparing assemblage structure and species composition, examining the distribution and abundance of threatened species, and identifying the local and landscape variables associated with the observed amphibian diversity. From June to October 2012 we sampled ten forest fragments, investing 944 person-hours of sampling effort. A total of 895 amphibians belonging to 16 species were recorded. Notable differences in species richness, abundance, and assemblage structure between forest fragments were observed. Species composition between pairs of fragments differed by an average of 53%, with the majority (58%) resulting from species replacement and the rest (42%) explained by differences in species richness. Half of the species detected are under threat of extinction according to the International Union for Conservation of Nature, and although their distribution and abundance varied markedly, there were also ubiquitous and abundant species, along with rare species of restricted distribution. The evident heterogeneity of the ten study sites indicates that to conserve amphibians in a mountainous region such as this one it is necessary to protect groups of fragments which represent the variability of the system. Both individually and together cloud forest fragments are very important to conservation because each remnant is inhabited by several threatened species, some of them at imminent risk of extinction.     

Early Cretaceous Ferns From Lacustrine Limestones At Las Hoyas, Cuenca Province, Spain

A brief outline is presented of the geological conditions prevailing in the hard-water lake that produced the Las Hoyas fossiliferous site in the Serranía de Cuenca (north-east central Spain). The corresponding Barremian laminated limestones contain varied fossil remains including plants. The fern component of the assemblage is described in the present paper. Ten taxa are referable to the families Matoniaceae, Dicksoniaceae and Schizaeaceae, whilst eight are unclassified. A new species of Dicksoniaceae is described: Coniopteris laciniata. Three species, Pelletixia valdensis, Cladophlebis albertsii, and Sphenopteris fontainei, are recorded here for the first time outside the English Wealden; one species, Acrostichopteris foliosa, is new to the Barremian of Europe. The fern assemblage from the Las Hoyas site is most similar to that of the English Wealden. The xeromorph character of some species is noted.   Although the specimens from Las Hoyas are generally small, even tiny, most are still identifiable leaf fragments preserved as imprints on platy limestone. Epidermal detail has been obtained from a few impressions. Some rather delicate remains, such as indusia, a crozier with pinnules, and fragments of Pelletixia valdensis occur, thus suggesting limited residence time in water.     

The Lower Palaeolithic assemblage of Layers 15–18 (Unit G) at Hummal. An exemplary case addressing the problems placing undated,archaic-looking stone tool assemblages in the Early and Lower Palaeolithic record by techno-typological classification

The site of Hummal is situated in the region of El Kowm in central Syria. The site comprises an archaeological sequence covering the entire Pleistocene epoch, and encompasses all major Palaeolithic complexes currently known in the Middle East. At the base of the site, 14 m below today's ground level, several layers with a lithic assemblage attributed to the Lower Palaeolithic have been excavated over the past years. At present, the collection recovered from this lowest succession at Hummal contains more than 700 stone artefacts and more than 3000 bone fragments. The lithic assemblage is characterized by a simple flaking technique and the presence of different pebble tools, such as choppers, hammerstones and sphaeroids. Additionally four handaxes were recovered, which have a symmetric shape, are clearly bifacial and rather flat. The lithic assemblage from the lowermost layers of the Hummal excavation largely resembles an Archaic, Lower Palaeolithic assemblage, belonging to the so-called Oldowan or Mode 1 stage. However, the presence of well-shaped and symmetric handaxes sheds doubt on the validity of this attribution to a Mode 1, Oldowan or the Early Acheulean Stage. It can, therefore, be debated, whether the common classifications of lithic industries are adequate for describing the archaeological record from the period in question in the Middle East.     

Differences in stable isotope composition within and among zooplanktivorous Utaka cichlid populations from Lake Malawi

Stable isotope analysis was used to determine whether five sympatric zooplanktivorous cichlids of the Utaka assemblage from Lake Malawi vary in isotopic signature as an indication of possible differences in food resource composition. The isotopic composition of the Utaka in combination with literature data about diet composition suggests that these species exploit a narrow range of zooplanktonic prey types. At five sampling locations, significant differences in δ¹³C and δ¹⁵N were detected among species but a consistent pattern across locations was absent. Significant intraspecific differences between locations were found. These differences were relatively low in view of the large geographic distances between the populations and there was no consistent spatial pattern among the species. The observed differences may be indicative of local variations in diet composition, which may help in reducing niche overlap among these zooplanktivores.     

Geographical ancestry of Lake Malawi's cichlid fish diversity

The Lake Malawi haplochromine cichlid flock is one of the largest vertebrate adaptive radiations. The geographical source of the radiation has been assumed to be rivers to the south and east of Lake Malawi, where extant representatives of the flock are now present. Here, we provide mitochondrial DNA evidence suggesting the sister taxon to the Lake Malawi radiation is within the Great Ruaha river in Tanzania, north of Lake Malawi. Estimates of the time of divergence between the Lake Malawi flock and this riverine sister taxon range from 2.13 to 6.76 Ma, prior to origins of the current radiation 1.20–4.06 Ma. These results are congruent with evaluations of 2–3.75 Ma fossil material that suggest past faunal connections between Lake Malawi and the Ruaha. We propose that ancestors of the Malawi radiation became isolated within the catchment during Pliocene rifting that formed both Lake Malawi and the Kipengere/Livingstone mountain range, before colonizing rivers to the south and east of the lake region and radiating within the lake basin. Identification of this sister taxon allows tests of whether standing genetic diversity has predisposed Lake Malawi cichlids to rapid speciation and adaptive radiation.     

Singular taphonomic record of a wildfire event from middle Albian deposits of Escucha Formation in northeastern of Spain

A fossil plant assemblage composed of a great amount of macro, meso and microscopical charcoalifed remains occur in a single layer in Albian deposits of the Escucha Formation in northeastern Spain. This assemblage consists fundamentally of fragments of pinnae and pinnules corresponding to the Matoniaceous ferns Weichselia reticulata and Phlebopteris dunkeri also with some gymnosperm wood remains. The features of both the fossil plants and the deposit itself indicate accurate paleoenvironmental conditions related to the action of wildfires over the vegetation growing in freshwater swamp plains during Albian in Southwestern Eurasia.     

African swine fever virus encodes a gene with extensive homology to type II DNA topoisomerases.

Nucleotide sequencing of a virulent African swine fever virus (ASFV) isolate (Malawi LIL20/1) identified an open reading frame of 1191 amino acid residues encoding a protein of 134.9 kDa. This gene mapped to the SalI i and j restriction endonuclease fragments of the ASFV genome. The predicted polypeptide was found to share 21.1% identity over a 1077 amino acid region with the human type II DNA topoisomerase. The sequence is compared to other type II DNA topoisomerases and the possible roles in ASFV replication are discussed.     

Viability of ecological processes in small Afromontane forest patches in South Africa

Abstract The conservation of biodiversity is dependent on protecting ecosystem‐level processes. We investigated the effects of fragment size and habitat edge on the relative functioning of three ecological processes – decomposition, predation and regeneration of trees – in small Afromontane forests in KwaZulu‐Natal, South Africa. Ten sampling stations were placed in each of four forest categories: the interior of three large indigenous forest fragments (100 m from the edge), the edges of these large fragments, 10 small indigenous fragments (<1 ha) and 10 small exotic woodlands (<0.5 ha). Fragment size and edge effects did not affect the abundance of the amphipod Talitriator africana, a litter decomposer, and overall dung beetle abundance and species richness significantly. Bird egg predation was marginally greater at large patch edges compared with the other forest categories, while seed predation did not differ among forest categories. Tree seedling assemblage composition did not differ significantly among large patch interiors and edges, and small indigenous fragments. Sapling and canopy assemblage composition each differed significantly among these three indigenous forest categories. Thus, while tree recruitment was not negatively affected by patch size or distance from the edge, conditions in small fragments and at edges appear to affect the composition of advanced tree regeneration. These ecological processes in Afromontane forests appear to be resilient to fragmentation effects. We speculate that this is because the organisms in these forests have evolved under fragmented conditions. Repeated extreme changes in climate and vegetation over the Pleistocene have acted as significant distribution and ecological extinction filters on these southern hemisphere forest biota, resulting in fauna and flora that are potentially resilient to contemporary fragmentation effects. We argue that because small patches and habitat edges appear to be ecologically viable they should be included in future conservation decisions.     

Functional composition and phenology of fruit-feeding butterflies in a fragmented landscape: variation of seasonality between habitat specialists

For butterflies, tolerance to the matrix may be an important criterion of habitat occurrence in fragmented landscapes. Here we examine the relative effects of habitat fragmentation and the surrounding agricultural matrix on the functional composition of fruit-feeding butterflies of the Atlantic rain forest in southeastern Brazil. Generalized linear models were used to detect the effects of landscape metrics on butterfly richness and abundance of the total assemblage and functional groups. Circular statistics were used to analyze the patterns of monthly abundance of the total assemblage and functional groups in the forest remnants and the surrounding matrices. In total, 650 butterflies representing 57 species were captured; species composition differed significantly between the forest fragments and the surrounding matrices. We recorded 22 forest specialists, 18 matrix specialists, 11 common species with matrix preference and six common species with forest preference. Forest connectivity favored the richness of forest specialists, while habitat fragmentation enhances the richness and abundance of matrix-tolerant species. Circular analysis revealed that forest specialists were more abundant in the rainy season while matrix-tolerant species proliferated in the dry season. Although maintaining connectivity of forest fragments may increase the mobility and dispersion of forest species, our results showed that landscape fragmentation modify butterfly assemblage by promoting an increase of matrix tolerant species with detriment of forest specialists.