关键词： American chestnut   browse   Castanea dentata   matrix model   plant population and community dynamics   post-dispersal seed predation   pre-dispersal seed predation   transient analysis  

摘要： Both seed predators and herbivores can have profound effects on individual plant growth, reproduction and survival, but their population-level effects are less well understood. While most plants interact with a suite of seed predators and herbivores over their life cycle, few studies incorporate the effects of multiple interacting partners and multiple life stages on plant population growth. We constructed a matrix model using 6years of data from a rare, seed-producing population of American chestnut (Castanea dentata). We combined field demographic data with published experimental results on the effects of pre-dispersal seed predators (weevils) and post-dispersal seed predators (scatter-hoarding vertebrates) and incorporated the effect of vertebrate herbivores estimated from the field data. We explored the impact of these three different animal interactions for short-term (transient) and long-term (asymptotic) tree population growth. In addition, we used the model to explore the conditions under which scatter hoarding would function as a mutualism. Seed predators had greater effect on both short- and long-term population growth than herbivores. Although weevil infestation can greatly reduce the probability of germination, pre-dispersal seed predators had smaller effects on both short- or long-term population growth than post-dispersal predators. The elasticities of weevil-related parameters were also small. The effect of browsers on both the short- and long-term population growth rate were the smallest of the effects studied. Post-dispersal seed predation affected population growth the most in the interactions studied. The probability of seed removal was among the largest elasticities, similar in magnitude to survival of large ***. Our results indicate that neither weevils nor the intensity of browse damage observed at our study site are likely to hinder tree regeneration or reintroduction, although both reduced population growth. Although researchers a

关键词： Bayesian hierarchical abundance model   Bush encroachment   Camera trapping   Mammals   Savanna systems   Swaziland  

摘要： In grasslands across the world, woody species are replacing grass cover. This bush encroachment can alter available food, cover, and space resources for most mammalian species;however, the specific responses of mammals to bush encroachment in African savannas remain largely unknown. We examined the fine-scale response of mammals across a gradient of bush encroachment using camera traps and a Bayesian hierarchical multi-species abundance model that estimates local relative abundance and species richness while accounting for imperfect detection. Additionally, we simulated species-specific relative abundances and species richness responses to differing bush encroachment management actions. Contrary to our expectations, the relative abundance of only one species showed a negative relationship to shrub cover and another to tree cover. However, the relative abundance of eight out of twenty-one species showed a positive association with grass cover. Mammal species richness increased with grass cover, decreased with shrub cover, and showed no clear pattern with increasing tree cover. Furthermore, our simulations suggest reducing and increasing shrub and grass cover respectively by 50% would increase species richness and local abundances for the mammal community of the area. Our results indicate grass cover exerts a strong influence on habitat use, relative abundances and species richness in bush encroached areas. Our study shows that mammal's positive response to grass cover is more important than potential negative impacts of increasing shrub cover. Consequently, recovering and maintaining adequate grass cover in savannas subject to bush encroachment is an indispensable condition to maximize mammalian diversity and abundances.

关键词： body mass   carbonate   collagen   hair   pleistocene  

摘要： Predator-prey size relationships are among the most important patterns underlying the structure and function of ecological ***,these relationships have already been shown to be important for understanding patterns of macroevolution and differential extinction in the terrestrial vertebrate fossil *** isotope analysis(SIA)is a powerful remote approach to examining animal diets and *** approach is based on the principle that isotope compositions of consumer tissues reflect those of their *** systems where resource isotope compositions are distributed along a body size gradient,SIA could be used to reconstruct predator-prey size *** analyzed stable carbon isotope distributions amongst mammalian herbivores in extant and Plio-Pleistocene African savanna assemblages,and show that the range ofδ^(13)C values among mammalian prey species(herbivores and rodents)increases with body mass(BM),because C_(4) plant feeding(essentially grazing)is more common among larger ***,δ^(13)C values of mammalian carnivores in these systems are related to species’BM,reflecting a higher average C_(4) prey component in the diets of larger-bodied *** pattern likely emerges because only the largest carnivores in these systems have regular access to the C_(4) prey base,whereas smaller carnivores do ***δ^(13)C-BM relationship observed in mammalian carnivores is a potentially powerful approach for reconstructing and parameterizing predator-prey size relationships in contemporary and fossil savanna assemblages,and for interpreting how various behavioral,ecological and environmental factors influence prey size selection.

关键词： Antilles   Dispersal   Eulipotyphla   Nesophontes   Solenodon   Vicariance  

摘要： The mammalian order Eulipotyphla includes four extant families of insectivorans: Solenodontidae (solenodons);Talpidae (moles);Soricidae (shrews);and Erinaceidae (hedgehogs). Of these, Solenodontidae includes only two extant species, which are endemic to the largest islands of the Greater Antilles: Cuba and Hispaniola. Most molecular studies suggest that eulipotyphlan families diverged from each other across several million years, with the basal split between Solenodontidae and other families occurring in the Late Cretaceous. By contrast, Sato et al. (2016) suggest that eulipotyphlan families diverged from each other in a polytomy similar to 58.6 million years ago (Mya). This more recent divergence estimate for Solenodontidae versus other extant eulipotyphlans suggests that solenodons must have arrived in the Greater Antilles via overwater dispersal rather than vicariance. Here, we show that the young timetree estimates for eulipotyphlan families and the polytomy are due to an inverted ingroup-outgroup arrangement of the tree, the result of using Tracer rather than TreeAnnotator to compile interfamilial divergence times, and of not enforcing the monophly of well-established clades such as Laurasiatheria and Eulipotyphla. Finally, Sato et al.'s (2016) timetree includes several zombie lineages where estimated divergence times are much younger than minimum ages that are implied by the fossil record. We reanalyzed Sato et al.' s (2016) original data with enforced monophyly for well-established clades and updated fossil calibrations that eliminate the inference of zombie lineages. Our resulting timetrees, which were compiled with TreeAnnotator rather than Tracer, produce dates that are in good agreement with other recent studies and place the basal split between Solenodontidae and other eulipotyphlans in the Late Cretaceous.

关键词： Bats   birds   conservation   fire   fire management   INLA   mammals   protected areas  

摘要： Fire is a fundamental process in savannas and is widely used for management. Pyrodiversity, variation in local fire characteristics, has been proposed as a driver of biodiversity although empirical evidence is equivocal. Using a new measure of pyrodiversity (Hempson etal.), we undertook the first continent-wide assessment of how pyrodiversity affects biodiversity in protected areas across African savannas. The influence of pyrodiversity on bird and mammal species richness varied with rainfall: strongest support for a positive effect occurred in wet savannas (> 650 mm/year), where species richness increased by 27% for mammals and 40% for birds in the most pyrodiverse regions. Range-restricted birds were most increased by pyrodiversity, suggesting the diversity of fire regimes increases the availability of rare niches. Our findings are significant because they explain the conflicting results found in previous studies of savannas. We argue that managing savanna landscapes to increase pyrodiversity is especially important in wet savannas.

关键词： archaeomalacology   shell midden   human impacts   Pacific Islands archaeology   intertidal ecosystems   archeomalacologie   restes de mollusques   impacts humaine   archeologie du Iles Pacifique   ecosystemes marins intertidaux  

摘要： Small, remote islands, such as low coral atolls, with nutrient-poor, biogenic soils for food crops and vulnerability to extreme weather, have long been considered marginal environments for human habitation. Yet, four decades of archaeological research in the atoll archipelago of the Marshall Islands, eastern Micronesia have demonstrated sustained human occupation there for over two millennia. Here, we present a fine-grained analysis of mollusc remains from four recently excavated archaeological sites (4476 total MNI / 14843 total NISP) combined with mapping and analysis of extant benthic habitats, on Ebon Atoll, Marshall Islands. We examine spatial and temporal variability in mollusc foraging practices from prehistoric village sites and ephemeral camp sites across the windward-leeward exposure gradient. Our analysis demonstrates that foragers targeted a rich assemblage of taxa from different habitats, reflecting a foraging strategy that was adapted to local environmental conditions. Human foraging over 2000 years documented no observable human impacts to molluscs or nearshore intertidal marine ecosystems, challenging previous notions of atolls as marginal, exceptionally difficult settings for human habitation. RESUME Les petites iles reculees, comme les atolls coralliens de faible altitude aux sols biogeniques pauvres en elements nutritifs pour les cultures alimentaires et exposes a des conditions climatiques extremes, ont longtemps ete considerees comme des environnements marginaux pour l'habitat humain. Pourtant, quatre decennies de recherches archeologiques dans l'archipel d'atolls des iles Marshall a l'est de la Micronesie y ont demontre une occupation humaine soutenue pendant plus de deux millenaires. Nous presentons ici une analyse nuancee de restes de mollusques provenant de quatre sites recents de fouilles archeologiques (NMI total 4476 / NISP total 14843) combines a une cartographie et une analyse d'habitats benthiques subsistants sur l'atoll d'Ebon dans le

关键词： 生物群   哺乳动物   新型式   侏罗纪   结构   中耳   滑翔   晚侏罗世  

摘要： 中国科学院古脊椎动物与古人类研究所研究人员与中美数家研究机构,于2017年11月13日在英国《自然》（Nature）期刊联合发表了关于晚侏罗世早期燕辽生物群树贼兽一个新种——阿霍氏树贼兽的研究成果。新种标本产于河北省青龙县干沟镇髫髻山组,时代为晚侏罗世早期（距今约164～159百万年前）,属于燕辽生物群。

关键词： feeding behavior   Hemideina thoracica   insect   lipids   nutrition   protein   selective foraging  

摘要： Insects are important but overlooked components of forest ecosystems in New Zealand. For many insect species, information on foraging patterns and trophic relationships is lacking. We examined diet composition and selectivity in a large-bodied insect, the Auckland tree wet Hemideina thoracica, in three habitat zones in a lowland New Zealand forest. We asked whether *** selectively forage from available plant food sources, and whether these choices were lipid-rich compared to nonpreferred available plants. We also identified the proportion of invertebrates in their frass as a proxy for omnivory. From reconnaissance plot sampling, together with fecal fragment analysis, we report that more than 93% of individual tree wet had eaten invertebrates before capture. Additionally, wet in the highest elevation hillslope habitat zone consumed significantly fewer species of plants on average than wet on the low-elevation terrace habitat. Upper hillslope wet also had the highest average number of invertebrate fragments in their frass, significantly more than wet in the low-elevation terrace habitat zone. Wet showed high variability in the consumption of fruit and seeds across all habitat zones. Generally, we did not observe diet differences between the sexes (although it appears that male wet in the mid-hillslope habitat ate fruits and seeds more voraciously than females), suggesting that the sexes have similar niche breadths and display similar degrees of omnivorous behavior. Extraction of leaf lipids demonstrated a range of lipid content values in available plants, and Ivlev's Electivity Index indicated that plant species which demonstrated high electivity tended to have higher concentrations of lipids in their leaves. Our findings indicate that *** forage omnivorously and selectively, and hence play multiple roles in native ecosystems and food webs.

摘要： Information on amphibian diversity in Neotropical savannas and in protected areas in the Caribbean is lacking. We evaluated amphibian diversity and species composition in the Aripo Savannas Scientific Reserve in Trinidad, in relation to the two major habitat types, savanna and marsh forest. Thirty 200-m-long transects were sampled visually and aurally in 4 periods (total 120 samples), with 10 transects in savanna, and 20 in marsh forest (10 along trails and 10 off trails), at night in the wet season from June to December 2015. We recorded 895 individuals representing 16 species, 11 genera, and 7 families, with greater counts and diversity of amphibians in marsh forest compared to savanna. The three species recorded in savanna (Leptodactylus fuscus, Scinax ruber, and Rhinella beebei) were also found in marsh forest, with no separate savanna amphibian community. Audio detection was more effective at sampling most species, and there were greater counts along trails compared to transects off trails.

关键词： Canopy trees   Functional traits   Leaf economics   Plant defense   Tropical forests  

摘要： Trade-offs among plant functional traits indicate diversity in plant strategies of growth and survival. The leaf economics spectrum (LES) reflects a trade-off between short-term carbon gain and long-term leaf persistence. A related trade-off, between foliar growth and anti-herbivore defense, occurs among plants growing in contrasting resource regimes, but it is unclear whether this trade-off is maintained within plant communities, where resource gradients are minimized. The LES and the growth-defense trade-off involve related traits, but the extent to which these trade-off dimensions are correlated is poorly understood. We assessed the relationship between leaf economic and anti-herbivore defense traits among sunlit foliage of 345 canopy trees in 83 species on Barro Colorado Island, Panama. We quantified ten traits related to resource allocation and defense, and identified patterns of trait co-variation using multivariate ordination. We tested whether traits and ordination axes were correlated with patterns of phylogenetic relatedness, juvenile demographic trade-offs, or topo-edaphic variation. Two independent axes described similar to 60% of the variation among canopy trees. Axis 1 revealed a trade-off between leaf nutritional and structural investment, consistent with the LES. Physical defense traits were largely oriented along this axis. Axis 2 revealed a trade-off between investments in phenolic defenses versus other foliar defenses, which we term the leaf defense spectrum. Phylogenetic relationships and topo-edaphic variation largely did not explain trait co-variation. Our results suggest that some trade-offs among the growth and defense traits of outer-canopy trees may be captured by the LES, while others may occur along additional resource allocation dimensions.