关键词： MULTIPLE SEQUENCE ALIGNMENT   PHYLOGENETIC-RELATIONSHIPS   HISTORICAL BIOGEOGRAPHY   MAXIMUM PARSIMONY   SUPPORT VALUES   FROGS ANURA   PERU   DIVERSIFICATION   SALAMANDERS   BUFONIDAE  

摘要： Wiens (2007, Q. Rev. Biol. 82, 55-56) recently published a severe critique of Frost et al.'s (2006, Bull. Am. Mus. Nat. Hist. 297, 1-370) monographic study of amphibian systematics, concluding that it is "a disaster" and recommending that readers "simply ignore this study". Beyond the hyperbole, Wiens raised four general objections that he regarded as "fatal flaws": (1) the sampling design was insufficient for the generic changes made and taxonomic changes were made without including all type species;(2) the nuclear gene most commonly used in amphibian phylogenetics, RAG-1, was not included, nor were the morphological characters that had justified the older taxonomy;(3) the analytical method employed is questionable because equally weighted parsimony "assumes that all characters are evolving at equal rates";and (4) the results were at times "clearly erroneous", as evidenced by the inferred non-monophyly of marsupial frogs. In this paper we respond to these criticisms. In brief: (1) the study of Frost et al. did not exist in a vacuum and we discussed our evidence and evidence previously obtained by others that documented the non-monophyletic taxa that we corrected. Beyond that, we agree that all type species should ideally be included, but inclusion of all potentially relevant type species is not feasible in a study of the magnitude of Frost et al. and we contend that this should not prevent progress in the formulation of phylogenetic hypotheses or their application outside of systematics. (2) Rhodopsin, a gene included by Frost et al. is the nuclear gene that is most commonly used in amphibian systematics, not RAG-1. Regardless, ignoring a study because of the absence of a single locus strikes us as unsound practice. With respect to previously hypothesized morphological synapomorphies, Frost et al. provided a lengthy review of the published evidence for all groups, and this was used to inform taxonomic decisions. We noted that confirming and reconciling all morpholo

关键词： herbivory   large aninial exclosure   riparian ecotone   sodic area   herbaceous species richness   plant biodiversity  

摘要： Herbivory is a major driver of ecosystem functioning in semi-arid African savannas, yet its impact on herbaceous biomass dynamics has been poorly understood. Using a 72 ha animal exclosure established 3 years prior, we measured the distribution of herbaceous biomass and species composition in the presence and absence of herbivory in a semi-arid savanna toposequence along the Sabie River in Kruger National Park, South Africa. We found that, in the presence of large herbivores in the reference site, the biomass of herbaceous plant species generally increased from the hillcrest to the lower, wetter riparian zone, while species richness did not change. However, after only 2 and 3 years of herbivore exclusion, the annual maximum biomass in the riparian area increased threefold to similar to 600 g m(-2). Simultaneously, plant species richness declined by 55% and 64% from 10.2 to 9.2 species per m(2) in 2004 and 2005, respectively. In the absence of herbivores, fast-growing grasses overtopped and shaded out forbs of lower stature, resulting in a reduction in the richness of herbaceous species. We conclude that large herbivores are essential in reducing herbaceous competition and maintaining species diversity and ecosystem functioning in African savanna ecosystems, especially in riparian corridors. Published by Elsevier Ltd.

关键词： sensors   herds   animal behavior   cattle production   neck   estimation   mathematical models   prediction   geographic information systems   velocity   speed   cattle production   herd   animal behaviour   Sensors   Neck   angle of pitch   sort tree structure  

摘要： An in-depth study of wireless sensor networks applied to the monitoring of animal behaviour in the field is described. Herd motion data, such as the pitch angle of the neck and movement velocity, were monitored by an MTS310 sensor board equipped with a 2-axis accelerometer and received signal strength indicator functionality in a single-hop wireless sensor network. Pitch angle measurements and velocity estimates were transmitted through a wireless sensor network based on the ZigBee communication protocol. After data filtering, the pitch angle measurements together with velocity estimates were used to classify the animal behaviour into two classes;as activity and inactivity. Considering all the advantages and drawbacks of classification trees compared to neural network and fuzzy logic classifiers a general classification tree was preferred. The classification tree was constructed based on the measurements of the pitch angle of the neck and movement velocity of some animals in the herd and was used to predict the behaviour of other animals in the herd. The results showed that there was a large improvement in the classification accuracy if both the pitch angle of the neck and the velocity were employed as predictors when compared to just pitch angle or just velocity employed as a single predictor. The classification results showed the possibility of determining a general decision rule which can classify the behaviour of each individual in a herd of animals. The results were confirmed by manual registration and by GPS measurements. (c) 2008 IAgrE. Published by Elsevier Ltd. All rights reserved.

关键词： biological control   Boreioglycaspis melaleucae   herbivory   Oxyops vitiosa   Paratachardina sp.   Puccinia psidii  

摘要： Invasive plants can respond to injury from natural enemies by altering the quantity and distribution of biomass among woody materials, foliage, fruits, and seeds. Melaleuca, an Australian tree that has naturalized in south Florida, has been reunited with two natural enemies: a weevil introduced during 1997 and a psyllid introduced during 2002. We hypothesized that herbivory from these and other adventive organisms (lobate-lac scale and a leaf-rust fungus) would alter the distribution and allocation of biomass on melaleuca trees. This hypothesis was tested by temporally assessing changes in aboveground biomass components in conjunction with the presence of natural enemies and their damage to melaleuca trees. Melaleuca trees of different diameters representing the range (I to 33 cm diam at 1.3 in height) within study sites were harvested during 1996, prior to the introduction of herbivorous insects, and again during 2003 after extensive tree damage had become apparent. Aboveground biomass, partitioned into several components (woody structures, foliage, fruits, and seeds), was quantified both times in Broward, Miami-Dade, and Palm Beach county sites located in south Florida. The two harvests within each site were performed in closely-matched melaleuca stands, and changes in biomass components were compared between years. Total biomass and woody portions decreased in Broward, whereas they increased in Miami-Dade and Palm Beach sites. Reductions in foliage (on all trees) and seed biomass (among seed-bearing trees) were greatest at Broward and least at Miami-Dade County site. Hence, overall seed and foliage production was severely reduced at the Broward site where both the natural enemy incidence and damage were more abundant compared to other sites. We therefore attribute the reduced foliar biomass and reproductive capability of melaleuca trees to infestations of natural enemies. These findings highlight the role that natural enemies can play in the long-term management

关键词： bird diversity   cattle   indirect effects   Kenya   livestock   megaherbivore  

摘要： Large native mammals are declining dramatically in abundance across Africa, with strong impacts on both plant and animal community dynamics. However, the net effects of this large-scale loss in megafauna are poorly understood because responses by several ecologically important groups have not been assessed. We used a large-scale, replicated exclusion experiment in Kenya to investigate the impacts of different guilds of native and domestic large herbivores on the diversity and abundance of birds over a 2-year period. The exclusion of large herbivorous native mammals, including zebras (Equus burchelli), giraffes (Giraffa camelopardalis), elephants (Loxodonta africana), and buffalos ( Syncerus caffer), increased the diversity of birds by 30%. Most of this effect was attributable to the absence of elephants and giraffes;these mega-herbivores reduced both the canopy area of subdominant woody vegetation and the biomass of ground-dwelling arthropods, and both of these factors were good predictors of the diversity of birds. The canopy area of subdominant trees was positively correlated with the diversity of granivorous birds. The biomass of ground-dwelling arthropods was positively correlated with the diversity of insectivorous birds. Our results suggest that most native large herbivores are compatible with an abundant and diverse bird fauna, as are cattle if they are at a relatively low stocking rate. Future research should focus on determining the spatial arrangements and densities of megaherbivores that will optimize both megaherbivore abundance and bird diversity.

关键词： anti-herbivore defence   dendritic trichome   extrafloral nectary   flavonoids   glandular hair   glycerides   indirect defence   leaf development   morphology   optimal defence hypothesis   Paulownia tomentosa   shoot development  

摘要： Background and Aims Recent studies have shown that small structures on plant surfaces serve ecological functions such as resistance against herbivores. The morphology, distribution, chemical composition and changes during shoot and leaf development of such small structures were examined on Paulownia tomentosa. Methods The morphology and distribution of the structures were studied under light microscopy, and their chemical composition was analysed using thin-layer chromatography and high-performance liquid chromatography. To further investigate the function of these structures, several simple field experiments and observations were also conducted. Key Results Three types of small structures on P. tomentosa were investigated: bowl-shaped organs, glandular hairs and dendritic trichomes. The bowl-shaped organs were densely aggregated on the leaves near flower buds and were determined to be extrafloral nectarines (EFNs) that secrete sugar and attract ants. Nectar production of these organs was increased by artificial damage to the leaves, suggesting an anti-herbivore function through symbiosis with ants. Glandular hairs were found on the surfaces of young and/or reproductive organs. Glandular hairs on leaves, stems and flowers secreted mucilage containing glycerides and trapped small insects. Secretions from glandular hairs on flowers and immature fruits contained flavonoids, which may provide protection against some herbivores. Yellow dendritic trichomes on the adaxial side of leaves also contained flavonoids identical to those secreted by the glandular hairs on fruits and flowers. Three special types of leaves, which differed from the standard leaves in shape, size and identity of small structures, developed near young shoot tips or young flower buds. The density of small structures on these leaf types was higher than on standard leaves, suggesting that these leaf types may be specialized to protect young leaves or reproductive organs. Changes in the small structures d

关键词： trematode infections   treefrogs   malformations   cercariae   Polypedates cruciger  

摘要： Reports on malformations in amphibians due to trematode infections prompted this study on an endemic frog species in Sri Lanka. The effect of an infection with a monostome-type cercaria is reported here. Ten days post-hatch, tadpoles (Gosner stage 27) of the common hourglass treefrog Polypedates cruciger (Anura: Ranidae), were exposed to a monostome-type cercaria, in a dose-dependent manner, under laboratory conditions. Malformations, survival and growth of the tadpoles were monitored for four treatments having different doses of cercariae (control = 0, low = 16, intermediate = 32 and high = 48). The severity and the number of malformations varied depending on the dose of the infection. A higher percentage (90%) of malformations was observed at higher doses of cercariae. Overall, malformations in the limbs, spine and skin pigmentation were common after parasite exposure. Survival declined with increasing doses of parasite infections, declining to 88% in the high treatment group, although not statistically significant. The growth rates of tadpoles as measured by weight and snout to vent length showed that exposed individuals were significantly smaller and had higher variance in growth compared with that of the controls. Thus, this trematode infection significantly affected the growth and induced severe malformations in P. cruciger, under laboratory conditions. Such malformed tadpoles and adults may face high predation under natural conditions. Here, we present the first empirical evidence of the effect of a trematode infection on the development of malformations, growth and survivorship in an endemic amphibian species in Sri Lanka.

关键词： Araucaria   biodiversity   canopy fogging   Chile   Coleoptera   guilds   Nothofagus   S-chao   temperate rain forests  

摘要： Aim To describe the coleopteran fauna occurring in canopies of temperate Gondwanan tree species in terms of their diversity and guild and taxonomic structures, and to test the proposition that this structuring reflects the Gondwanan origins of this fauna. Location The Andes and the coastal cordillera of temperate Chile. Methods Canopy fogging was used to sample beetles from 29 trees. The samples were statistically described using S-chao and the Simpson diversity index D. Cluster analyses and multi-dimensional scaling (MDS) were performed. The taxonomic and guild structures of the Chilean coleopteran fauna were compared quantitatively with those found in other parts of the world using homogeneity chi-square and t-tests. Results A collection of 25,497 beetle specimens was obtained primarily from Nothofagus dombeyi, Nothofagus obliqua and Araucaria araucana. The specimens collected were distributed between 485 morphospecies and included 107 putative, new generic-level taxa and 223 apparently undescribed species. Estimates of the size of the canopy beetle fauna showed that 600+ species were likely to be present. The communities found on a tree species differed markedly between years. MDS plots showed less community divergence between tree species for predators than for phytophages and xylophages. The guild structure was similar to that found on Australian 'Gondwanan' trees but differed significantly from the community structures found on 'Laurasian' tropical and temperate trees in supporting fewer phytophages and saprophages, but more xylophages. The predator guild showed a different pattern, with tropical faunas differing from those of more temperate regions, irrespective of hemisphere, as did the distribution of superfamilies. Main conclusions The beetle fauna found in the canopies of N. dombeyi, N. obliqua and A. araucana was large (600+ species), with about half of the species undescribed. S-chao was found to vary with sample size and to give lower estimates of S th

关键词： Animals   Bayes Theorem   Classification/methods   Computational Biology   Databases, Genetic   Evolution, Molecular   Evolution, Molecular   Expressed Sequence Tags   Gene Library   Humans   Markov Chains   Phylogeny   Phylogeny   Reproducibility of Results   Sample Size   Sensitivity and Specificity  

摘要： Long-held ideas regarding the evolutionary relationships among animals have recently been upended by sometimes controversial hypotheses based largely on insights from molecular data(1,2). These new hypotheses include a clade of moulting animals (Ecdysozoa)(3) and the close relationship of the lophophorates to molluscs and annelids (Lophotrochozoa)(4). Many relationships remain disputed, including those that are required to polarize key features of character evolution, and support for deep nodes is often low. Phylogenomic approaches, which use data from many genes, have shown promise for resolving deep animal relationships, but are hindered by a lack of data from many important groups. Here we report a total of 39.9 Mb of expressed sequence tags from 29 animals belonging to 21 phyla, including 11 phyla previously lacking genomic or expressed-sequence-tag data. Analysed in combination with existing sequences, our data reinforce several previously identified clades that split deeply in the animal tree (including Protostomia, Ecdysozoa and Lophotrochozoa), unambiguously resolve multiple long-standing issues for which there was strong conflicting support in earlier studies with less data (such as velvet worms rather than tardigrades as the sister group of arthropods(5)), and provide molecular support for the monophyly of molluscs, a group long recognized by morphologists. In addition, we find strong support for several new hypotheses. These include a clade that unites annelids (including sipunculans and echiurans) with nemerteans, phoronids and brachiopods, molluscs as sister to that assemblage, and the placement of ctenophores as the earliest diverging extant multicellular animals. A single origin of spiral cleavage (with subsequent losses) is inferred from well-supported nodes. Many relationships between a stable subset of taxa find strong support, and a diminishing number of lineages remain recalcitrant to placement on the tree.

关键词： 中国科学家   动物化石   生物进化   中国地质科学院   地质研究所   学术论文  

摘要： 近日出版的《地质学报》（英文刊）2008年第1期上，来自中国地质科学院地质研究所的两篇学术论文分别对一块5．8亿年前的早期动物化石以及一块1．24亿年前的原始鸟类化石进行了分析和介绍，生物进化树上又增添了两种由中国科学家发现并命名的古代动物。