生物多样性事业需要科学、可操作的物种概念

物种概念(species concept)是生物学家们持续关注的中心问题。物种概念决定物种划分, 而物种划分的合理性关系到生物多样性的研究、保护和可持续利用。本文把现有较流行的物种概念分为6类, 并对它们予以述评后指出: 虽然生物学物种概念、遗传学物种概念、进化物种概念、系统发生物种概念等从不同方面认识了物种的客观真实性和物种的本质, 但在实践中都难以操作。绝大多数物种是由分类学家划分的, 但目前所有的分类学物种概念都包含有不同程度的主观因素, 从而造成物种划分的人为性, 对生物多样性研究造成负面影响。因此, 生物多样性事业需要科学、可操作的物种概念。本文在吸收了生物学物种概念、遗传学物种概念、进化物种概念以及系统发生物种概念等的长处, 也分析了它们的不足和问题的基础上提出一个新的物种概念, 即形态-生物学物种概念。最后, 以芍药属(Paeonia)几个物种的处理为例, 说明这一新的物种概念是可操作的, 划分的物种在形态上区别分明, 易于鉴别。更重要的是, 其结果得到基于25或26个单拷贝或寡拷贝核基因DNA序列所作的系统发生分析的强有力支持。各个物种在系统发生树上形成单系和独立的谱系, 表明其间各自形成独立的基因库, 没有基因交换, 它们独立进化, 有各自的生态位和独立的分布区。因此, 利用这一新的物种概念能够达到预期目标。     

Reclassification of the serows and gorals: the end of a neverending story?

1. Taxonomy is partly a subjective matter, but it is instrumental for ecological, behavioural and especially conservation studies. According to the International Union for Conservation of Nature, goat‐antelopes (Bovidae: Rupicaprini tribe) number 13 species, 62% of which are ‘Threatened’ or ‘Near Threatened’ with extinction. During recent decades, the number of extant species of goat‐antelopes – especially in endemic Asian genera (goral: six species Naemorhedus spp.; serow: seven species Capricornis spp.) – has been inflated.
2. We have revised the taxonomy and phylogeny of the gorals and serows, for the first time using the total mitochondrial genome of all taxa.
3. We confirm the existence of three goral and four serow species. We can find no justification for the existence of Naemorhedus griseus (Chinese goral), Naemorhedus bedfordi (Himalayan goral) and Naemorhedus evansi (Burmese goral), which should be pooled together within Naemorhedus goral (brown goral). Two species of mainland serow are also recognised: Capricornis rubidus (red serow) and Capricornis sumatraensis (Sumatran serow). Capricornis rubidus and Naemorhedus baileyi (red goral) are the forms more closely related to the common Pliocenic, still‐unknown ancestor. Among serows, Capricornis crispus is sister to all remaining species. Capricornis rubidus and Capricornis swinhoei (Formosan serow) are sister species, probably the remnants of an older radiation of mainland serows.

     

The What,Why and How of Primate Taxonomy

Taxonomy has a well-defined role, which is much more than simply stamp-collecting and pigeon-holing. Species are the units of classification, biogeography and conservation; as such they must be defined as objectively as possible. The biological species concept, still widely used in biology, though predominantly by non-taxonomists and all too often misunderstood, is a process-based concept, which offers no criterion for the classification of allopatric populations beyond inference and hypothesis. The phylogenetic species concept—a pattern-based concept—is as nearly objective as we are likely to get. Amount of difference is not a criterion for recognizing species. It is not possible to insist on monophyly at the specific level, but it is mandatory for the higher categories (genus, family, etc.). The rank we assign to a given supraspecific category should be determined by its time depth.     

浅析物种概念的演变历史

本文是一篇关于物种概念演变的简述。生物学家用不同的方法或标准划分物种, 就形成了不同的物种概念, 如生物学物种、形态学物种、生态学物种、进化物种、系统发生或支序物种, 或它们的组合, 等等。它们都揭示了物种属性的特定侧面, 都是不同物种客观存在的真实反映, 但都无法令所有人满意。对真核生物来说, 无论它们在形态上的差别有多大, 生殖隔离(不能产生可育的后代)应该是两个群体能否真正分化成不同物种的关键, 这种隔离机制可以是地理的、行为的或其他方式; 而生殖隔离总会伴随着一些形态或遗传上的变化, 虽然这些特征可能与生殖隔离本身并无多大关系, 但往往成为分类学家或分子进化生物学家区分种的依据,对已经灭绝的化石物种来说, 生殖隔离的物种划分方式就无能为力了。如何准确定义一个物种依然充满着矛盾, 因为基于生殖隔离的物种概念不实用, 而实用的物种概念(如形态学物种)又被认为是人为的。     

An update on the diversity of Wolbachia in Spalangia spp. (Hymenoptera: Pteromalidae)

Results from 13 additional host populations improves resolution on the diversity of Wolbachia bacteria in Spalangia spp. (Hymenoptera: Pteromalidae). These bacteria are of interest because they can profoundly affect their host's reproduction. Manipulating Wolbachia infections may provide a method to improve the efficacy of biocontrol agents including Spalangia spp.     

The genic view of the process of speciation

The unit of adaptation is usually thought to be a gene or set of interacting genes, rather than the whole genome, and this may be true of species differentiation. Defining species on the basis of reproductive isolation (RI), on the other hand, is a concept best applied to the entire genome. The biological species concept (BSC; 84 ) stresses the isolation aspect of speciation on the basis of two fundamental genetic assumptions – the number of loci underlying species differentiation is large and the whole genome behaves as a cohesive, or coadapted genetic unit. Under these tenets, the exchange of any part of the genomes between diverging groups is thought to destroy their integrity. Hence, the maintenance of each species’ genome cohesiveness by isolating mechanisms has become the central concept of species. In contrast, the Darwinian view of speciation is about differential adaptation to different natural or sexual environments. RI is viewed as an important by product of differential adaptation and complete RI across the whole genome need not be considered as the most central criterion of speciation. The emphasis on natural and sexual selection thus makes the Darwinian view compatible with the modern genic concept of evolution. Genetic and molecular analyses of speciation in the last decade have yielded surprisingly strong support for the neo‐Darwinian view of extensive genetic differentiation and epistasis during speciation. However, the extent falls short of what BSC requires in order to achieve whole‐genome ‘cohesiveness’. Empirical observations suggest that the gene is the unit of species differentiation. Significantly, the genetic architecture underlying RI, the patterns of species hybridization and the molecular signature of speciation genes all appear to support the view that RI is one of the manifestations of differential adaptation, as 34 , Chap. 8) suggested. The nature of this adaptation may be as much the result of sexual selection as natural selection. In the light of studies since its early days, BSC may now need a major revision by shifting the emphasis from isolation at the level of whole genome to differential adaptation at the genic level. With this revision, BSC would in fact be close to Darwin’s original concept of speciation.     

The subspecies concept in butterflies: has its application in taxonomy and conservation biology outlived its usefulness?

Subspecies lie at the interface between systematics and population genetics, and represent a unit of biological organization in zoology that is widely used in the disciplines of taxonomy and conservation biology. In this review, we explore the utility of subspecies in relation to their application in systematics and biodiversity conservation, and briefly summarize species concepts and criteria for their diagnosis, particularly from an invertebrate perspective. The subspecies concept was originally conceived as a formal means of documenting geographical variation within species based on morphological characters; however, the utility of subspecies is hampered by inconsistencies by which they are defined conceptually, a lack of objective criteria or properties that serve to delimit their boundaries, and their frequent failure to reflect distinct evolutionary units according to population genetic structure. Moreover, the concept has been applied to populations largely comprising different components of genetic diversity reflecting contrasting evolutionary processes. We recommend that, under the general lineage (unified) species concept, the definition of subspecies be restricted to extant animal groups that comprise evolving populations representing partially isolated lineages of a species that are allopatric, phenotypically distinct, and have at least one fixed diagnosable character state, and that these character differences are (or are assumed to be) correlated with evolutionary independence according to population genetic structure. Phenotypic character types include colour pattern, morphology, and behaviour or ecology. Under these criteria, allopatric subspecies are a type of evolutionarily significant unit within species in that they show both neutral divergence through the effects of genetic drift and adaptive divergence under natural selection, and provide an historical context for identifying biodiversity units for conservation. Conservation of the adaptedness and adaptability of gene pools, however, may require additional approaches. Recent studies of Australian butterflies exemplify these points. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

The lesser wanderer butterfly, Danaus petilia (Stoll 1790) stat. rev. (Lepidoptera: Danainae), reinstated as a species

Abstract  The lesser wanderer butterfly, Danaus ( Anosia ) chrysippus petilia (Stoll) (Lepidoptera: Danainae), has been treated as a subspecies for the last 100 years. New mitochondrial DNA sequence data for D. petilia , in conjunction with allozyme, structural, morphometric and pattern characters, constitute a compelling case for its specific rank. The holotype of D. petilia has never been located and, as the type location is uncertain, a neotype is designated. Fresh material was collected and examined for this project. Danaus petilia and D. chrysippus have been separated at Lydekker's Line for an estimated 1.1 million years, and they remain interfertile. However, as an allopatric taxon, diagnosable from D. chrysippus , D. petilia merits specific status under the phylogenetic species concept. The following pairs of D. chrysippus subspecies are considered to be synonyms, the first member of each pair having priority: chrysippus  +  aegyptius (subspecies), klugii  +  infumata (hybrid phenotypes) and orientis  + liboria (subspecies).