Comparative genetic analyses of historical and contemporary collections highlight contrasting demographic histories for the bumble bees Bombus pensylvanicus and B. impatiens in Illinois

Direct comparison of genetic patterns between museum specimens and contemporary collections can be a powerful approach for detecting recent demographic changes. Using microsatellite markers, we examined historical and contemporary genetic variation from an apparently declining bumble bee species, Bombus pensylvanicus , and from a stable species, Bombus impatiens , in central Illinois. For each species, we genotyped specimens from the Illinois Natural History Survey collected from three populations between 1969–1972 and from a resurvey of the same areas conducted in 2008. Population structure in B . pensylvanicus increased markedly over the last four decades (from θ_ST = 0.001 to 0.027) while no structure was detected in B . impatiens for either time period (θ_ST = –0.006 to –0.003). Changes in genetic diversity were not significant for either species, although small reductions were observed for B . pensylvanicus in all three populations. Coalescent simulations incorporating both contemporary and historical samples suggest that this small change is not surprising for recent population declines, as large reductions in genetic diversity were only apparent under the most severe bottleneck scenarios. These results demonstrate how comparisons of genetic patterns between temporal periods and species can help elucidate potential threats to population health and suggest several strategies that might be useful in the conservation of B . pensylvanicus in the Midwestern USA.     

Genetic variation in Holocene bowhead whales from Svalbard

Bowhead whales (Balaena mysticetus) are distributed in the Arctic in five putative stocks. All stocks have been heavily depleted due to centuries of exploitation. In the present study, nucleotide sequence variation of the mitochondrial control region was determined from bone remains of 99 bowhead whales. The bones, 14C dated from recent to more than 50,000 bp, were collected on Svalbard (Spitsbergen) and are expected to relate to ancestors of the today nearly extinct Spitsbergen stock. Fifty-eight haplotypes were found, a few being frequent but many only found in one individual. The most abundant haplotypes of the Spitsbergen stock are the same as those most abundant in the extant Bering-Chukchi-Beaufort (BCB) Seas stock of bowhead whales. Although F(ST) indicates a slight but statistically significant genetic differentiation between the Spitsbergen and the BCB stocks this was not considered informative due to the very high levels of genetic diversity of mitochondrial DNA haplotypes in both bowhead whale stocks. Other measures such as K(ST) also indicated very low genetic differentiation between the two populations. Nucleotide diversity and haplotype diversity showed only minor differences between the Spitsbergen and BCB stocks. The data suggest that the historic Spitsbergen stock--before the severe bottleneck caused by whaling--did not have substantially more genetic variation than the extant BCB stock. The similar haplotypes of the Holocene Svalbard samples and the current BCB stock indicate significant migration between these two stocks and question the current designation of five distinct stocks of bowhead whales in the Arctic.     

The data void in modeling current and future distributions of tropical species

Conserving biodiversity in the face of climate change requires a predictive ecology of species distributions. Nowhere is this need more acute than in the tropics, which harbor the majority of Earth's species and face rapid and large climate and land‐use changes. However, the study of species distributions and their responses to climate change in high diversity tropical regions is potentially crippled by a lack of basic data. We analyzed a database representing more than 800 000 unique geo‐referenced natural history collections to determine what fraction of tropical plant species has sufficient numbers of available collections for use in the habitat or niche models commonly used to predict species responses to climate change. We found that more than nine out of 10 species from the three principle tropical realms are so poorly collected (n < 20 records) that they are essentially invisible to modern modeling and conservation tools. In order to predict the impact of climate change on tropical species, efforts must be made to increase the amount of data available from tropical countries through a combination of collecting new specimens and digitizing existing records.     

The Eclipse of Species Ranges

This paper distinguishes four recognisably different geographical processes in principle causing species to die out. One of these processes, the one we dub “range eclipse”, holds that one range expands at the expense of another one, thereby usurping it. Channell and Lomolino (2000a, Journal of Biogeography 27: 169–179; 2000b, Nature 403: 84–87; see also Lomolino and Channell, 1995, Journal of Mammalogy 76: 335–347) measured the course of this process in terms of the proportion of the total range remaining in its original centre, thereby essentially assuming a homogeneous distribution of animals over the range. However, part of their measure seems mistaken. By giving a general, analytical formulation of eclipsing ranges, we estimate the exact course of this process. Also, our formulation does not partition a range into two spatially equal parts, its core and its edge, but it assumes continuity. For applying this model to data on the time evolution of species, individual time series should be available for each of them. For practical purposes we give an alternative way of plotting and interpreting such time series. Our approach, being more sensitive than Channell and Lomolino’s, gives a less optimistic indication of range eclipses than theirs once these have started.     

Two decades of interaction between the MacArthur-Wilson model and the complexities of mammalian distributions

More than two decades after its publication, MacArthur and Wilson's equilibrium model of insular biogeography continues to provide the conceptual foundation for investigating the distribution of species on islands and the composition of insular biotas. During this period, studies of the distributions of mammals among insular habitats have tested, modified, and extended MacArthur and Wilson's simple formalism to enhance greatly our understanding of the complexities of biogeographic patterns and processes. The papers in this symposium summarize many of the past contributions of mammalian biogeographers and introduce important new data and ideas. The diversity of biological characteristics and associated distributional patterns exhibited by mammals has facilitated this endeavour. Some insular mammalian faunas appear to represent approximate equilibria between opposing rates of contemporary colonization and extinction. Other faunas are currently decreasing in diversity because of extinctions, owing either to natural habitat fragmentation that has occurred since the Pleistocene or to human activities within the last few centuries. Still other faunas have been increasing in diversity (at least until recent human impacts) because limiting rates of origination, both colonization and speciation, have been extremely low. The questions and analyses of island biogeography can also be applied to continents with comparable overall results: the distributions of continental faunas reflect the consequences of similar processes of colonization, speciation and extinction. Analyses of insular distributions show unequivocally that probabilities of extinction, colonization and speciation are highly deterministic and vary in predictable ways among different taxa and archipelagos. These findings have important implications for applying the theory and data of insular biogeography to the pressing practical problems of designing natural reserves to preserve native species.     

Museum genomics: low-cost and high-accuracy genetic data from historical specimens

Natural history collections are unparalleled repositories of geographical and temporal variation in faunal conditions. Molecular studies offer an opportunity to uncover much of this variation; however, genetic studies of historical museum specimens typically rely on extracting highly degraded and chemically modified DNA samples from skins, skulls or other dried samples. Despite this limitation, obtaining short fragments of DNA sequences using traditional PCR amplification of DNA has been the primary method for genetic study of historical specimens. Few laboratories have succeeded in obtaining genome-scale sequences from historical specimens and then only with considerable effort and cost. Here, we describe a low-cost approach using high-throughput next-generation sequencing to obtain reliable genome-scale sequence data from a traditionally preserved mammal skin and skull using a simple extraction protocol. We show that single-nucleotide polymorphisms (SNPs) from the genome sequences obtained independently from the skin and from the skull are highly repeatable compared to a reference genome.     

数字植物标本在科学研究中的应用: 进展及挑战

全球自然历史博物馆中保存着约3.9亿份植物标本,这些标本为科学研究提供了重要支撑。近20年来,随着标本数字化的发展,数字植物标本在科学研究中的应用日益广泛。数字植物标本不仅为标本传统的用途提供了便利,而且衍生出了新的研究主题和方向。鉴于目前中文文献中缺乏数字植物标本在科学研究中的应用概述及所面临挑战的分析,该文概述了全球植物标本数字化的现状,并对数字标本在生物地理学、入侵生物学、气候变化和保护生物学等领域中的应用情况进行了综述。主要集中在以下5个方面:(1)生物地理学研究中物种分布格局及其成因;(2)编制入侵植物名录、重建入侵历史和预测入侵风险;(3)气候变化情景下植物分布格局的变迁机制;(4)生物多样性编目和保护区规划;(5)其他相关应用(如农业和民族药物学等)。最后,针对数字植物标本应用中存在的问题进行了讨论,并提出了应对策略,同时提出开发将数字标本与其他学科大数据进行整合分析的新理论、新方法和新工具,为植物学及相关学科提供参考。     

岛屿生物地理学与集合种群理论的本质与渊源

岛屿生物地理学和集合种群理论是目前生物多样性保育所依赖的主要生态学理论。人们通常强调这两种理论的区别,对它们之间的关联却很少注意到。事实上,这两种理论是同根同源的。以经典集合种群理论的创始者R．Levim对他与岛屿生物地理学的创始者R．H．MaeArthur的合作过程以及岛屿生物地理学对他提出集合种群理论的影响的回顾为基础,分析比较了岛屿生物地理学、经典集合种群理论、以Hanski为代表的现代集合种群理论的基本假设、研究范式和核心思想的异同,简要介绍了多物种集合种群与集合群落研究的差异,最后分析了岛屿生物地理学和集合种群理论在生物多样性保育实践中的应用和存在问题。     

Metapopulation dynamics: brief history and conceptual domain

We review the early development of metapopulation ideas, which culminated in the well-known model by Levins in 1969. We present a survey of metapopulation terminology and outline the kinds of studies that have been conducted on single-species and multispecies metapopulations. Metapopulation studies have important conceptual links with the equilibrium theory of island biogeography and with studies on the dynamics of species living in patchy environments. Metapopulation ideas play an increasingly important role in landscape ecology and conservation biology.