关键词： Amphibians   Biotic homogenization   Central Argentina   Exotic   Non-native   Woody invasion  

摘要： Amphibians are declining globally from diverse and complex causes, with one of the most prevalent being alien species invasion. Alien woody invaders, such as the evergreen Ligustrum lucidum, are deeply transforming native ecosystems worldwide. Our aim was to evaluate the effect of Ligustrum lucidum invasion on native anurans in a seasonal semiarid subtropical forest. Sampling was conducted in streams dominated by L. lucidum forest and streams dominated by native forest. Amphibian species richness and diversity, and community and species abundance were recorded. We characterized invaded and non-invaded streams by measuring biotic and abiotic variables. Invaded streams support only three of the seven species present in non-invaded streams. Species richness in non-invaded streams was twice as high as in invaded streams and community abundance was almost five times greater in the former than in the latter. Invasion by L. lucidum triggers profound changes in vegetation physiognomy and composition of this xerophytic seasonal forest, resulting in dark, unsuitable habitats for several native anurans. In agreement with the few studies focused on the effect of alien woody invaders on amphibians, this study supports that woody alien invasion results in a reduction of native anuran richness and the dominance of a generalist anuran species. This is the first report on the disruptive role of L. lucidum invasion in local anurans diversity and community dynamics.

关键词： Anthropization   Cerrado   Ecological networks   Habitat conservation   Plant-animal interactions  

摘要： Human-induced habitat modification can affect species interactions and ecological networks composed of specialized species may be more susceptible to these effects. Immature and adult insect herbivores have different mobility and specificity levels related to their host plants, which can affect their tolerance to anthropic disturbances. In the present study, we compared the structure of plant-herbivore networks composed of adult and immature insects in 16 Neotropical savanna sites under different land-use intensification levels. We compared insect species richness, insect abundance, connectance, specialization, generality, vulnerability, modularity, and nestedness in plant-immature insect and plant-adult insect networks occurring in preserved and non-preserved areas. In total we sampled 328 individuals of 98 species of host plants and 557 individuals of 310 species of insect herbivores (275 individuals of 143 species of immature insects and 479 individuals of 196 species of adult insects). Although the richness of insect species did not differ between the networks, plant-immature insect networks had a lower insect abundance, generality and nestedness than networks of adult insects. On the other hand, connectance was lower for networks of adults than for networks of immature insects. Our results also show that the effects of habitat modification are more pronounced for immature insects than for adults, as network connectance increases and network vulnerability decreases between preserved habitats and disturbed habitats. Our findings support previous warnings that habitat modification can alter plant-herbivore interactions, and advance the understanding of how these effects can be different for assemblages composed of adult and immature insects. Implications for insect conservation Our results indicate more consistent effects of habitat modification on immature insect interactions, which showed more specialized networks in preserved environments. Thus, our results con

关键词： 树鼩   医疗器械生物学评价   遗传毒性试验   体内微核试验  

摘要： 目的:初步探讨建立树鼩体内微核试验体系,将树鼩作为试验动物模型应用于医疗器械生物学评价。方法:将30只树鼩随机分为3组,分别是阴性对照组、样品组(胶原蛋白植入剂)和阳性对照组,样品组按照10 mL/kg两次腹腔注射受试物进行诱导。各组树鼩取股骨骨髓细胞检测微核率,并进行血常规、血生化和电解质检测,计算脾、肝、肾的脏器系数并进行组织病理学检测。同时,用小鼠进行试验,作为体系参考。结果:树鼩和小鼠的微核试验中,阴性对照组、供试样品组的微核率均<5%,供试样品组与阴性对照组间的差异无统计学意义(P>0.05),阳性对照组与阴性对照组间的差异显著(P<0.01),树鼩微核试验结果与小鼠微核试验结果一致。与阴性对照组比较,样品组树鼩血常规、血生化、电解质和组织病理学检测结果均未发现明显异常。与小鼠比较,树鼩的脏器系数更接近于人类。结论:树鼩可以作为模式动物进行微核试验,有可能将其应用于医疗器械的生物安全性评价。

关键词： Austral forests   Taxonomic diversity   Diversity metrics   Habitat variables  

摘要： Standing dead trees are known to house diverse assemblages of vertebrates in temperate forests worldwide. In temperate austral forests of South America, however, the functional role of dead trees has been mostly focused on cavity provision, but other functions remain poorly understood. Thus, we conducted a preliminary study examining the effect of dead trees on the taxonomic diversity of vertebrates in South American temperate forests. Diversity metrics estimated from rarefaction curves and community data augmentation showed that taxonomic diversity of vertebrate species was equal between dead and living trees. Habitat variables equally affected species diversity of vertebrates in dead and living trees. Tree height and elevation had a positive effect while forest cover negatively affected species diversity. The similar diversity and composition of vertebrates found in living and dead trees suggests dead trees are equally valuable for conservation. In austral forests dominated by long-living tree species, the death of a tree is a long process involving the retention of several microhabitats once the tree dies and the enrichment of deadwood structures attracting saproxylic organisms. These findings highlight the need of establishing minimum stocks of dying and senescent trees for achieving ecosystem integrity.

关键词： conservation   fauna   meta‐   analysis   habitat change   tree decline  

摘要： Significant portions of the world's forests have been impacted by severe and large-scale tree declines characterised by gradual but widespread loss of vigour and subsequent death of either single or several tree species. Tree deaths represent a threat for fauna that are dependent on forest habitats for their survival. Although tree declines have received considerable scientific attention, surprisingly, little is known about their impacts on fauna. In total, we calculated 631 effect sizes across 59 studies that quantified the impact of tree declines on animal abundance. Data representing 186 bird species indicated an overall increase in bird abundance in response to tree declines (meta-analysis mean +/- estimation g = 0.172 +/- 0.053 [CI 0.069 to 0.275], P = 0.001);however, there was substantial variability in responses (significant heterogeneity P < 0.001) with a strong influence of diet as well as nesting guild on bird responses. Granivores (especially ground-foraging species, e.g. Passerellidae species), bark-foraging insectivores (e.g. woodpeckers), as well as ground- and cavity-nesting species apparently benefitted from tree declines, while nectarivorous birds [and, although not significant, aerially foraging insectivores (e.g. flycatchers) and leaf-gleaning insectivores (canopy-feeding)] were less common in the presence of tree declines. Data representing 33 mammal species indicate a tendency for detrimental effects of tree declines on mammals that use trees as refuges, while aerial foragers (i.e. bats) may benefit from opening up the canopy. Overall the average effect for mammals was neutral (meta-analysis mean estimation g = -0.150 +/- 0.145 [-0.433 to 0.134], P = 0.302). Data representing 20 reptile species showed an insufficient range of responses to determine any diet or foraging effect on their responses. Data for 28 arthropod taxa should be considered with caution, as we could not adequately separate taxa according to their specialisations and reliance o

关键词： Scatter-hoarding   Pilferage   PIT tagging   Plant-animal interaction   Seed-rodent interaction  

摘要： Seed hoarding by rodents plays a significant role in shaping mutualistic or predatory interactions between tree and rodent species in forest ecosystems. However, it is still challenging to identify the seed-rodent interaction at individual level so as to reveal the differences in mutualistic or predatory interactions between seeds and rodents due to lack of efficient methods of tracking seed hoarding behaviour and seed fate. Here, by using the double-duplex passive integrated transponder tagging technique, we investigated seed hoarding behaviour of two rodent species (Niviventer confucianus with larger body size;Apodemus draco with smaller body size) on seeds of two tree species (Quercus variabilis with larger seeds, thicker seed coat, higher tannin and starch contents;Camellia oleifera with smaller seeds, thinner seed coat, and lower tannin but higher fat contents) in a subtropical forest of China. We found N. confucianus preferably consumed and scatterhoarded seeds of Q. variabilis. In contrast, A. draco preferably consumed and scatterhoarded seeds of C. oleifera. Our study showed significant difference in mutualistic or predatory interactions between trees and rodent species, which is likely to be associated with the functional traits of seeds and rodents. Our results suggest that the double-duplex passive integrated transponder tagging technique is useful in quantifying mutualistic or predatory interactions between multiple tree and rodent species.

关键词： Tree cavities   Mammal decline   Motion-activated cameras   Threatened species  

摘要： Tree hollows are a critical resource for many arboreal vertebrates, including many threatened species. In northern Australia's vast tropical savannas, arboreal mammals are of particular conservation concern, as many have exhibited rapid population declines in recent decades. To understand the extent to which arboreal vertebrates compete for tree hollows in these savannas, we used motion-activated cameras to estimate rates of hollow visitation (i.e. individuals seen at the hollow entrance) and hollow use (i.e. individuals seen entering or exiting a hollow) by all vertebrate species at 29 hollows over a nine-month wet season period in the tropical savanna of Melville Island, Australia. We assessed the frequency of interactions between vertebrate species at the tree hollows. We recorded 21 vertebrate species visiting hollows, with larger hollows most frequently visited: 84% with entrance diameter > 10 cm. Larger-bodied mammal species were more likely to use larger hollows, in larger trees, at greater heights. However, smaller-bodies species also visited and used large hollows. The brush-tailed rabbit-rat (Conilurus penicillatus) used relatively shallow hollows close to the ground, and these hollows were most frequently visited by monitors (Varanus spp.) and snakes. This arboreal rodent has declined severely in recent decades, most likely due to predation by feral cats, and it is noteworthy that their hollow selection behaviour may be associated with increased predation risk. Our study highlights the importance of large tree hollows for a range of taxa in the tropical savannas of northern Australia and the potential impact of reductions in the density of large hollows on hollow-dependent species. Frequent, intense fires are a threat to large hollow-bearing trees, with appropriate fire management needed to conserve this resource and help to stem mammal declines.

关键词： ant   disturbance   Gopher frog   historical legacies   Ornate chorus frog   wiregrass  

摘要： Longleaf pine savannas historically supported abundant ground cover maintained by frequent fire but little other disturbance. Ground cover creates microclimates with lower temperatures, higher humidity, and increased soil moisture that may benefit wildlife, particularly small vertebrates such as amphibians. Today, most historical pine savannas have had extensive soil disturbance and altered fire regimes resulting in reduced ground cover and altered soil fauna communities including predatory invertebrates. We used a factorial terrestrial cage study to test the effects of native wiregrass (Aristida spp.) cover and the exclusion of a native predatory ant (Dorymyrmex smithi) on the survival of post-metamorphic Ornate chorus frogs (Pseudacris ornata) and Gopher frogs (Rana capito). Although we were unable to achieve full ant exclusion, ant reduction in exclusion treatments and plant cover had an interactive effect on metamorph survival. Ant exclusion tended to increase Gopher frog survival and this effect was more pronounced when wiregrass was present. Within ant treatments, survival of Gopher frogs increased slightly with increasing wiregrass cover. Ornate chorus frogs had a high probability of survival (>95%) in all ant exclusion treatments regardless of wiregrass cover;however, in treatments without ant exclusion, survival increased with increasing wiregrass cover. Our results demonstrate that high abundances of a native ant species and low coverage of native wiregrass, which are legacies of historical soil disturbance and altered fire regimes, interact to elevate mortality of juvenile amphibians. Minimizing soil disturbance and restoring native ground cover are likely important for amphibian habitat management within historical southeastern pine savannas.

关键词： Bivalvia   Arca boucardi   byssus morphology   reattachment   attachment strength  

摘要： We observed the behavior of the bivalve mollusk Arca boucardi during reattachment of the mollusk to plexiglass. According to our observations, after 0.5-4 h of active movement in search of a suitable place, the mollusks began to form a byssus and secreted a transparent discharge. After 9-10 h a new byssus formed, which did not fundamentally differ from the old one. It was shown that the byssus is a monolithic relatively elastic green band with an adhesive sole in the distal part and a system of septa in the proximal cavity that serves for attaching the muscles responsible for the byssus function. Field studies to evaluate the adhesion strength of mollusks to the substrate have shown that the strength varies from a few hundred grams to 23.5 kg, depending on the size of mollusk. The data are discussed in terms of the functional morphology and peculiarities of the spatial distribution of A. boucardi in the upper subintertidal zone.