Dramatic decline in bat species richness in Singapore, with implications for Southeast Asia

Literature searches and recent surveys of the bat fauna of Singapore indicate that of the 24 species of Microchiroptera and six species of Megachiroptera documented for this small equatorial island just 15 and 5, respectively, are still present. These recorded declines in chiropteran species richness almost certainly understate the true losses as extensive land transformation/habitat loss (>95%) and biota loss occurred early in Singapore’s colonial history before comprehensive surveys of bats were made. In an effort to reconstruct the pre-settlement bat fauna, we inferred an upper bound of pre-settlement species richness using a checklist from a well-known bat assemblage in neighbouring Peninsular Malaysia, and a lower bound based on species common to Peninsular Malaysia, Borneo and Sumatra. The Singapore records were compared with these two species list predictions. Based on this analysis, we infer that between 60 and 72 species would have inhabited Singapore before 1819. We also estimate that between 33% (based on the confirmed inventory) and 72% of the species (based on the upper-bound estimate of species richness) are now locally extinct. For Microchiroptera the data suggest that the documented local extinction rate of 38% may project to between 69% and 75%. Forest-dependant bats are particularly affected and comprise a much lower proportion of the bat fauna than is seen in intact forest in Peninsular Malaysia. All hipposiderids and 40% of the documented rhinolophid taxa have been lost and almost half (6) of the surviving microchiropteran species are locally endangered. Projected local extinction rates for Megachiroptera raise the documented value (17%) to about 60%, with most of the survivors being widespread species known to forage in cultivated or secondary forest habitats or to commute long distances between fragmented resources. The dramatic decline in Singapore bat species richness and a concomitant change in chiropteran guild and trophic structure (Microchiroptera vs. Megachiroptera) reflect patterns of diversity change seen elsewhere in the region in response to loss of forest habitat. In Singapore, the decline in diversity (species richness and abundances) for both mega- and microbats may also relate to urbanisation and deliberate or accidental destruction of bats and their roost sites in a land that has one of the highest human population densities on the planet. Although these losses (actual and inferred) represent a microcosm of mainly local extinctions, a wider geographical extrapolation over the 21st century indicates that heavy deforestation in progress in Southeast Asia might be expected to lead to extinction of many bat taxa, with upper-bound estimates of regional species losses exceeding 40% and global extirpation anticipated for at least 23% of Southeast Asia’s bat fauna by 2100.     

Anthropogenic determinants of primate and carnivore local extinctions in a fragmented forest landscape of southern Amazonia

Habitat fragmentation has been shown to influence the abundance, movements and persistence of many species. Here, we examine the effects of forest patch and landscape metrics, and levels of forest disturbance on the patterns of local extinction of five primate and 14 carnivore species within 129 forest patches in a highly fragmented forest landscape of southern Brazilian Amazonia. Classic habitat area effects were the strongest predictors of species persistence, explaining between 42% and 55% of the overall variation in primate and carnivore species richness. Logistic regression models showed that anthropogenic disturbance, including surface wildfires, timber extraction and hunting pressure, had detrimental effects on the persistence of some species over and above those of fragment size. Different species ranged in their responses from highly sensitive to highly tolerant to forest fragmentation. Patterns of local extinction documented here were by no means chance events, and the nestedness of the overall species-by-site matrix was highly nonrandom in terms of the sets of species extirpated from the most to the least species-rich forest patches.     

Risks of decline and extinction of the endangered Amsterdam albatross and the projected impact of long-line fisheries

The Amsterdam albatross (Diomedea amsterdamensis) is one of the rarest bird species of world avifauna, consisting of a single population in the upland plateau of Amsterdam Island (SE Indian Ocean). All breeding birds of the population are today banded and a monitoring program involving mark-recapture procedures has been carried out continuously over the past 16 years. We present the first estimate of risk of decline for the Amsterdam albatross using a stochastic matrix population model, and evaluate the extent to which the measurement errors in demographic estimates may affect the baseline conservation assessment. We also estimate the potential effect that resumption of long-line fisheries in the vicinity of Amsterdam Island (one the alleged causes for its low numbers in the recent past) may have on the persistence of this population. Our results indicate that, in the absence of any impact of long-line fisheries, the Amsterdam albatross is unlikely to experience a decline larger than 20% of the current population abundance over the next 50 years. Our results point out the difficulty to assess with certainty the extinction risk of small populations despite the availability of long term data on their demography. They suggest that a very cautious approach should be taken for the preservation of small populations of long-lived species that cannot sustain any level of incidental by-catch. Any new long-line fishery resuming in the foraging range of the Amsterdam albatross, but especially close to Amsterdam Island, may rapidly put this species at risk of extinction.     

运用光谱技术改进Beer-Lambert定律的定量化及其应用研究

 运用简便、快捷的无损测试提供的归一化植被指数（normalized difference vegetation index, NDVI）方法，对Beer-Lambert定律进行定量化改进，构建了以NDVI为自变量的LAI预测模型，并采用不同年份、不同株型的玉米数据对其改进结果进行检验。结果表明，当生长55 d时，叶向值（LOV）显著不同的3种株型的NDVI、LAI和消光系数K的差异均最大；披散型（LOV≤30°）NDVI饱和点的出现较中间型和紧凑型为早；利用NDVI改进Beer-Lambert定律的定量预测模型能够敏感反映植株冠层结构参数的动态变化，且最适用于紧凑型品种。随着玉米育种目标更偏向培育偏紧凑型品种，其改进结果在育种栽培实际中更有利用价值。     

小麦株型结构分析法与消光系数分布的基因型间差异

拟定了快速而无需破坏样本的“株型结构分析法”及其计算机程序。调查了小麦冠层结构与消光系数(K值)分布在21个基因型间和同一基因型的不同处理间的差异。对该方法所作的验证表明:采用该法调查结果和分层切片法与Ross法的结果基本一致。此法是可靠的。冠层结构与K值垂直分布在基因型间差异极显著;同一基因型不同密度之间仅达显著程度。K值是比较稳定的遗传性状,广义遗传力为76.9％。总K值对籽粒产量影响不大。由于长江下游地区辐射条件较差,高产群体表现出冠层重心较高,K值分布呈上层大、中层小的特点。说明该地区选育的品种上部叶水平角宜小(倾斜至水平),中部叶宜直立。讨论中提出了以株型结构分析法对K值分布作选样和培育高产品种的可能性。     

Adapting the IUCN Red List criteria for invertebrates

The IUCN Red List is the most useful list of species that are at risk for extinction worldwide, as it relies on a number of objective criteria. Nevertheless, there is a taxonomic bias that excludes species with small body sizes, narrow distribution ranges and low dispersal abilities, which constitute the vast majority of the planet’s biota, particularly local endemics.By evaluating each IUCN criterion separately, we (i) identify the shortcomings for invertebrate applications, (ii) explain how risk categories may be wrongly applied due to inapplicable and/or misleading thresholds, (iii) suggest alternative ways of applying the existing criteria in a more realistic way and (iv) suggest possible new criteria that were not considered in the current evaluation framework but that could allow a more comprehensive and effective assessment of invertebrates.By adapting the criteria to rely more explicitly on the Area of Occupancy and the Extent of Occurrence, their respective trends and by using ecological modelling methods, the criteria’s applicability would be increased. The change in some thresholds or, eventually, the creation of sub-categories would further increase their adequacy. Additionally, co-extinction could be introduced as an explicit part of the classification process.As a case study, we evaluated 48 species of Azorean arthropods and Iberian spiders according to the current criteria. More than one-quarter (27%) of all evaluated species were classified as Critically Endangered, 19% as Endangered, 6% as Vulnerable and 8% as Least Concern. The remaining 40% did not have enough data to reach a classification.     

Global warming, elevational ranges and the vulnerability of tropical biota

Tropical species with narrow elevational ranges may be thermally specialized and vulnerable to global warming. Local studies of distributions along elevational gradients reveal small-scale patterns but do not allow generalizations among geographic regions or taxa. We critically assessed data from 249 studies of species elevational distributions in the American, African, and Asia-Pacific tropics. Of these, 150 had sufficient data quality, sampling intensity, elevational range, and freedom from serious habitat disturbance to permit robust across-study comparisons. We found four main patterns: (1) species classified as elevational specialists (upper- or lower-zone specialists) are relatively more frequent in the American than Asia-Pacific tropics, with African tropics being intermediate; (2) elevational specialists are rare on islands, especially oceanic and smaller continental islands, largely due to a paucity of upper-zone specialists; (3) a relatively high proportion of plants and ectothermic vertebrates (amphibians and reptiles) are upper-zone specialists; and (4) relatively few endothermic vertebrates (birds and mammals) are upper-zone specialists. Understanding these broad-scale trends will help identify taxa and geographic regions vulnerable to global warming and highlight future research priorities.     

Genetic Erosion – Examples from Italy<Superscript>1,2</Superscript>

Italy has been used as a country for estimating genetic erosion in crops. It was possible to compare early surveys (from the 1920s to the 1950s), especially on wheats, with results of later missions in the 1980s and 1990s. In the early years, a relatively high genetic erosion was observed (13.2% p.a.). From the 1950s until the 1980s erosion rates between 0.48 and 4% p.a. were estimated. In the little island of Favignana there was an erosion rate of 12.2% p.a. leading to the extinction of the last wheat landraces of this island. There have been no significant differences in erosion rates between field- and garden-crops though there has been the impression that garden crops are better preserved over the long run. Interestingly extinction rates of wild plants (0.13% in the Mediterranean) come close to the average erosion rates of crop plants in the area. ¹Dedicated to Erna Bennett on the occasion of her 80^th birthday ²Lecture presented during the XVII^th Congress of EUCARPIA in Tulln, Austria, 2004     

Effects of urbanization on California’s fish diversity: Differentiation, homogenization and the influence of spatial scale

Human development of freshwater ecosystems has lead to drastic changes in freshwater fish faunas, including the loss of many native species and the gain of non-natives. Typically conservation ecologists view these two opposing forces as contributing to biological homogenization, and consider homogenization as one of the principle negative consequences of urbanization. However, homogenization is only one outcome out of many that can result from the loss and gain of species. In particular, it is possible for invasions and extinctions to lead to differentiation; a process whereby two (or more) regions become less similar to one another through time. Using the freshwater fishes of California, we show that urbanization is highly positively correlated to both the endangerment of native fish and the invasion of non-native fish within watersheds. Despite this, the fish faunas of California’s watersheds have differentiated from one another through time. Furthermore, the degree of differentiation is positively correlated with measures of urbanization, which is contrary to expectation. We suggest that this result reflects: (1) the haphazard manner in which non-native fishes have been introduced into California watersheds, (2) the difficulty that both native and non-native fishes have in expanding their geographical ranges, and (3) the continued presence of vestiges of formerly distinct regional faunas. This pattern of differentiation among watersheds is likely a matter of scale, as previous work on freshwater fishes has demonstrated homogenization at both larger and smaller spatial scales. In addition the observed pattern is probably a short-term (temporal) phenomena and will disappear with continued invasion and extinction. We suggest that similar patterns may occur for other taxa that have limited natural dispersal abilities and that are idiosyncratically released as non-natives via human activities (e.g. herptiles).     

Surplus killing by introduced predators in Australia—evidence for ineffective anti-predator adaptations in native prey species?

Australian examples of surplus killing by mammalian predators were collated. These included surplus killing of native mammals and birds by foxes (Vulpes vulpes) and stock, native mammals and native birds by dingoes (Canis lupus dingo). We found no examples of surplus killing by feral cats (Felis catus). Incidents collated include historical anecdotes of surplus killing by foxes as they colonised the Australian mainland, recent examples where foxes killed threatened native species at sites despite intensive management to exclude foxes, and recent examples of the killing of native species on formerly fox-free islands to which foxes gained entry. Episodes of surplus killings by foxes, other than predation on captive or closely confined animals, appeared different in kind and frequency to those documented for co-evolved predator-prey systems on the large continental landmasses. They did not appear to be uncommon events associated with synchronised births of prey species, unusual or extreme weather that disadvantaged prey species, or seasonal food caching by a predator. Rather, surplus killing events appeared to reflect ineffective anti-predator defences by prey species when encountering a novel and efficient predator to which they have had no evolutionary exposure. We suggest that surplus killing by foxes may have been a feature of, and major contributor to, the rapid mainland extinction or contraction in range of many native species in Australia. In contrast to foxes, examples of surplus killing by dingoes relate mostly to domestic stock (calves and sheep). The arrival of dingoes to the Australian continent preceded that of foxes by 3500-4000 years, but they appear not to have had the dire impact on native mammals that we attribute to foxes. This may be due to fundamental differences in hunting styles and prey size and to their sparse populations in pre-European Australia. Active persecution of non-commensal dingoes by Aborigines, the lack of free-water, and the absence of European rabbits (Oryctolagus cuniculus) as an alternative food supply would have limited their numbers and their impact on native mammals.