关键词： testudines   Trachemys scripta elegans   tetrapod phylogeny   molecular evolution   alpha-crystallin  

摘要： The phylogenetic relationships among the major groups of amniote vertebrates remain a matter of controversy. Various alternatives for the position of the turtles have been proposed, branching off either before or after the mammals. To discover the phylogenetic position of turtles in relation to mammals and birds, we have determined cDNA sequences for the eye lens proteins alpha A- and alpha B-crystallin of the red-eared slider turtle (Trachemys scripta elegans). In addition, databases were searched for turtle protein sequences, for which mammalian, avian, and outgroup orthologs were available. All sequences were analyzed by three phylogenetic tree reconstruction methods (neighbor-joining, maximum parsimony, and maximum likelihood). Including the alpha-crystallins, 7 out of 12 proteins support a sister-group relation of turtles and birds with all 3 methods. For each of the other five proteins no topology was consistently preferred by the three approaches. Analyses of the combined amino acid data (1,695 aligned sites) also give extremely strong evidence that turtles are nearer to birds, indicating that mammals branched off before the divergence between turtles and birds occurred.

关键词： Tadpoles   Snakes   Predators   Swimming   Garters   Amphibians   Phenotypic traits   Ecological competition   Predator prey relationships  

摘要： Two experimental approaches were used to determine if burst swimming speed in Pseudacris regilla tadpoles is subject to selection by predatory garter snakes, Thamnophis sirtalis. In eight our of 10 experiments in seminatural arenas, fast tadpoles survived snake predation more often than expected (P < 0.01). In videotaped encounters, tadpoles that escaped attacks swam 1.68 times as fast (P < 0.0001) and nearly four times as evasively (P < 0.05) as those that were captured. Burst swimming speed is clearly important to success at escaping snakes In experimental arenas and, given widespread snake predation on tadpoles is probably subject to predator-mediated selection in nature.

关键词： airways, branching geometry   mammals, dog, hamster, humans, rat   model, branching airways (4 mammals)  

摘要： A diameter-based classification technique, which we have previously used to analyse human bronchial geometry (Phillips et al., Respir. Physiol. 98: 193-217, 1994) is applied also to the partial measurements of the dimensions of dog, rat and hamster conducting airways, made by Raabe et al. (Tracheobronchial Geometry: Human, Dog, Rat, Hamster, 1976). The local branching patterns are characterised by means of three parameters, which reflect the asymmetry and the degree of expansion at each bifurcation, and the ratio of the length of each branch to its diameter. The mean values of these parameters as functions of diameter, calculated from the raw morphometric data, are shown for the four species. A statistical reconstruction technique is then used to estimate from the incomplete measurements of Raabe and coworkers some geometrical properties of the whole system of conducting airways, which are likely to influence transport processes in the lung. These include the distribution of the total airway volume between branches of different diameters, the mean and variance of the total lengths of different pathways through the bronchial tree, and a simple model for the variation of now velocity with airway diameter. Our results show significant differences between the branching structures of all four species. In particular, the human differs from the others in branching much more symmetrically, and in that branches of a given diameter are typically much longer than in the other species;together, these observations imply that the human bronchial tree is geometrically very different from those of the other species.

关键词： Old growth forests   Salamanders   Forest habitats   Forest stands   Habitat conservation   Soil water   Agricultural management  

摘要： There is a lack of research on the effects of logging on Canadian amphibians. We compared the abundance of terrestrial salamanders in old-growth forests with that in young and mature post-harvest stands. We also measured habitat features of amphibians and contrasted these with old-growth and harvested stands to assess the effects of forest harvest. Quadrat searches demonstrated that clearcut harvesting reduces terrestrial amphibian populations by up to 70% in coastal old-growth forests. We suggest that this reduction results from a decrease in availability of moist microhabitats. Salamander densities within 10 meters of streams in managed stands were similar to those near and away from streams in old growth. We recommend that forest managers recognize the needs of terrestrial amphibians and help maintain amphibian populations by preserving cool, moist habitats. This can be accomplished within cutblocks by (1) maintaining an even distribution of logs and snags as stable, moist microhabitats;(2) retaining some understory as sources of shade;and (3) preserving streamside buffers. Managers must also ensure some level of landscape connectivity to enable climate-sensitive amphibians to disperse and recolonize marginal habitats.

关键词： CARBON-NUTRIENT BALANCE   DELAYED INDUCIBLE RESISTANCE   FERTILIZATION   INDUCTION   INSECT GUILDS   LEAF DAMAGE   NUTRIENT AVAILABILITY   PLANT DEFENSES   QUERCUS   TANNINS  

摘要： Previous work has shown that fertilization can mitigate across-year induced resistance among individual Alaska paper birch, supporting the hypothesis that induction results from nutrient deficiency rather than active defense. The present study suggests that fertilization can prevent induction responses in oak within one season, and among leaves within individual trees. Saplings of two oak species, divided among fertilizer treatments within a plantation, were defoliated to varying degrees by a gypsy moth outbreak during spring. We monitored foliage chemistry and insect herbivore distributions during summer and fall of the same year. Damaged leaves within unfertilized Quercus prinus saplings showed increases in foliar astringency and proanthocyanidins. Within fertilized trees, damage did not induce increases in either astringency or proanthocyanidins. Defoliation also induced increases in proanthocyanidins and astringency within Q. rubra saplings, but induction was unaffected by fertilization. On both tree species, the distributions of certain insect guilds were skewed away from damaged leaves on unfertilized trees, but independent of damage on fertilized trees. We suggest that the effects of fertilization on induction can vary among tree species, and can occur at more than one spatial and temporal scale. Our data support the view that nutrient availability may affect phytochemical induction and herbivore responses.

关键词： Bones   Scavenging   Hyenas   Lions   Carnivores   Savannas   Fossils   Habitat preferences   Lakes  

摘要： Modern East African savannas serve as the primary model for the paleoenvironments of early hominids. However, throughout the Neogene there have been cooling and drying trends through time and fluctuations in seasonality. As a result, many modern East African savannas are drier, with more severe dry seasons, than during some periods in the Plio/Pleistocene in which early hominids lived. Our understanding of these moister and less seasonal periods is crucial for reconstructing early hominid lifeways. This paper presents a study of the ecology and bone taphonomy of a savanna less dry and less seasonal than the East African ones, the Central African savanna in Parc National des Virunga, Zaire. The natural bone distributions across the landscape of Parc National des Virunga contain information about the spatial distribution of scavenging opportunities and the effects on bone deposition of ecological variables such as large-herbivore biomass, proximity to water, and tree density. This information is a significant for taphonomic interpretation of fossil distributions in paleosols and the paleoecology of hominid scavenging. My results indicate that the Central African savanna differs in bone distributions and scavenging opportunities from the savannas of East Africa. Bone deposition is higher in open grasslands than in wooded areas near rivers, and there is no dry-season glut of carcasses. There is also no evidence for increased bone deposition near permanent water or ephemeral water holes. These differences are ultimately the result of the less seasonal rainfall pattern. For early periods in human evolution, Central African savannas may be a useful analog, and the implications for site formation and the ecology of scavenging are profound.

关键词： HOMINOID EVOLUTION   MITOCHONDRIAL DNA DIVERSITY   CYTOCHROME OXIDASE SUBUNIT II GENE  

摘要： Here we present a DNA sequence study that incorporates intraspecific variation from all five genera of hominoids (apes and humans). Recently it has been claimed that using single individuals to analyze species' relationships might be misleading if within-species variation is great. Our results indicate that despite high intraspecific variation in mitochondrial cytochrome oxidase subunit II gene sequences of some hominoids, humans and chimpanzees are nonetheless significantly most closely related. We also report the observation that variation within the gorilla species exceeds that between common and pygmy chimpanzee species, a finding with implications for conservation. In contrast, humans are less mitochondrially diverse than lowland gorillas inhabiting western Africa.

关键词： ECHINOIDEA   CASSIDULOIDA   NEOLAMPADOIDA   OLIGOPYGOIDA   CLYPEASTEROIDA   PHYLOGENETIC ANALYSIS   HOMLOPLASY   STRATIGRAPHIC DEPT  

摘要： The Neognathostomata (comprising the orders Clypeasteroida, Oligopygoida, Neolampadoida, and the paraphyletic Cassiduloida) form one of the three major clades of irregular echinoids. Despite the group's apparent success since the Jurassic and impressive peak diversity in the mid-Cretaceous, most included clades are now severely reduced. A phylogeny is essential for reconstructing the taxonomic, environmental and biogeographic patterns of this decline, and understanding the causal processes responsible for them. I examined the distribution of qualitative morphological characters (including those defining genera) for 97 species from 77 non-clypeasteroid genera and the three clypeasteroid suborders. Following preliminary analyses, I reduced the data to 40 characters (having 60 apomorphic states) and 71 representative genera. Goloboff's data decisiveness, the skewness of tree length distributions, and permutation tests all reveal significant phylogenetic structure in the data. Heuristic searches conducted with PAUP found more than 72 500 trees of 217 steps (CI = 0.276), but only the first 30 000 were evaluated. These exhibit considerable instability in the relationships among taxa. Successive approximations weightings did not reduce the numbers of favoured trees. Analyses using only less homoplasious characters failed to improve the resolution. Fisher's stratigraphic debt provides an objective means of selecting a very few of the morphologically most-parsimonious trees. Most nodes are supported by only one to three character changes, and these are generally reversed or paralleled elsewhere. The results suggest some cassiduloid families can not be separated, and support the reassignment of several genera. Despite the high levels of homoplasy, the most-parsimonious trees require fewer changes than had been previously suggested for evolutionary trends in several characters. Whether the rampant homoplasy present in the data reflects incorrect character analysis, limited str

关键词： Integrated pest management   Mite fauna, phytoseiid   Orchard tree, apple   Pest control, biological   Vegetation effect, surrounding  

摘要： Predaceous phytoseiid mites were collected from 14 apple orchards and from nearby deciduous trees and bushes in southern Finland. Phytoseiids were rare in insecticide-treated orchards bordered by just a few suitable host plants, whereas they were more abundant in other sprayed orchards that were surrounded by many suitable host plants. Phytoseius macropilis was the dominant phytoseiid species on unsprayed apple trees, but Euseius finlandicus was more common in sprayed orchards. In a 2 ha orchard surrounded by deciduous trees and bushes, the mean phytoseiid mite density was high only 15 days after a dimethoate treatment. Phytoseiid mites, primarily E. finlandicus, were encountered in the vicinity on the following trees: bird cherry (0.3 mites per leaf), hazel (9.8 per leaf), honeysuckle (2.7 per leaf), lime (2.4 per leaf), oak (1.2 per leaf) and great sallow (0.8 per leaf). Phytoseiid densities on adjacent vegetation had a noticeable effect on phytoseiid densities and species composition on apple orchard trees. Tall trees, such as oak and lime, are probably more important than low bushes as natural sources of phytoseiids for aerial dispersal into orchards. The migration of E. finlandicus into orchards from surrounding vegetation is concluded to be faster than that of Phytoseius macropilis.

关键词： SYSTEMATICS   PHYLOGENY   INTRASPECIFIC VARIATION   HUMANS   APES   DNA SEQUENCES  

摘要： Molecular evolutionary processes modify DNA over time, creating both newly derived substitutions shared by related descendant lineages (phylogenetic signal) and ''false'' similarities which confound phylogenetic reconstruction (homoplasy). However, some types of DNA regions, for example those containing tandem duplicate repeats, are preferentially subject to homoplasy-inducing processes such as sporadically occurring concerted evolution and DNA insertion/deletion. This added level of homoplasic ''noise'' can make DNA regions with repeats less reliable in phylogenetic reconstruction than those without repeats. Most molecular datasets which distinguish among African hominoids support a human-chimpanzee clade;the most notable exception is from the involucrin gene. However, phylogenetic resolution supporting a chimpanzee-gorilla clade is based entirely on involucrin DNA repeat regions. This is problematic because (1) involucrin repeats are difficult to align, and published alignments are contradictory;(2) involucrin repeats are subject to DNA insertion/deletion;(3) gorillas are polymorphic in that some do not have repeats reported to be synapomorphies linking chimpanzees and gorillas. Gene tree/species tree conflicts can occur due to the sorting of ancestrally polymorphic alleles during speciation. Because hominoid females transfer between groups, mitochondrial and nuclear gene flow occur to the same extent, and the probability of conflict between mitochondrial and nuclear gene trees is theoretically low. When hominoid intraspecific mitochondrial variability is taken into account [based on cytochrome oxidase subunit II (COII) gene sequences], humans and chimpanzees are most closely related, showing the same relative degree of separation from gorillas as when single individuals representing species are analyzed. Conflicting molecular phylogenies can be explained in terms of molecular evolutionary processes and sorting of ancient polymorphisms. This perspective can enhanc