The importance of physiological ecology in conservation biology

Many of the threats to the persistence of populations of sensitivespecies have physiological or pathological mechanisms, and thosemechanisms are best understood through the inherently integrativediscipline of physiological ecology. The desert tortoise waslisted under the Endangered Species Act largely due to a newlyrecognized upper respiratory disease thought to cause mortalityin individuals and severe declines in populations. Numeroushypotheses about the threats to the persistence of desert tortoisepopulations involve acquisition of nutrients, and its connectionto stress and disease. The nutritional wisdom hypothesis positsthat animals should forage not for particular food items, butinstead, for particular nutrients such as calcium and phosphorusused in building bones. The optimal foraging hypothesis suggeststhat, in circumstances of resource abundance, tortoises shouldforage as dietary specialists as a means of maximizing intakeof resources. The optimal digestion hypothesis suggests thattortoises should process ingesta in ways that regulate assimilationrate. Finally, the cost-of-switching hypothesis suggests thatherbivores, like the desert tortoise, should avoid switchingfood types to avoid negatively affecting the microbe communityresponsible for fermenting plants into energy and nutrients.Combining hypotheses into a resource acquisition theory leadsto novel predictions that are generally supported by data presentedhere. Testing hypotheses, and synthesizing test results intoa theory, provides a robust scientific alternative to the popularuse of untested hypotheses and unanalyzed data to assert theneeds of species. The scientific approach should focus on hypothesesconcerning anthropogenic modifications of the environment thatimpact physiological processes ultimately important to populationphenomena. We show how measurements of such impacts as nutrientstarvation, can cause physiological stress, and that the endocrinemechanisms involved with stress can result in disease. Finally,our new syntheses evince a new hypothesis. Free molecules ofthe stress hormone corticosterone can inhibit immunity, andthe abundance of "free corticosterone" in the blood (thoughtto be the active form of the hormone) is regulated when thecorticosterone molecules combine with binding globulins. Thesex hormone, testosterone, combines with the same binding globulin.High levels of testosterone, naturally occurring in the breedingseason, may be further enhanced in populations at high densities,and the resulting excess testosterone may compete with bindingglobulins, thereby releasing corticosterone and reducing immunityto disease. This sequence could result in physiological andpathological phenomena leading to population cycles with a periodthat would be essentially impossible to observe in desert tortoise.Such cycles could obscure population fluctuations of anthropogenicorigin.     

Survey research in conservation biology

We present systematic arguments for the necessity of field survey in conservation biology. Preservation of biological diversity has become a major challenge in conservation biology, but to comprehend diversity, ecologists have to obtain information on what units the 'diversity' of different parts of the world consists of, where these units are, and how they respond to natural and human-induced environmental change. To reach this end, systematic survey procedures need to be developed that incorporate data collecting, data analysis and conclusions about distributional patterns as well as management recommendations into an iterative process that is corrected as experience accumulates. The appropriate survey design depends on the task and needs to be fixed separately in each case; developing long-term observational systems is no less challenging a task than developing experimental systems in laboratory research, or modeling systems in theoretical research. We conclude the paper with five principles of ecological survey. A common denominator of these principles is the need to make explicit decisions at each step so that errors and insufficiency can be corrected later.     

中国特有植物长苞铁衫的生物学特性及其保护

长苞铁杉（ＴｓｕｇａＩｏｎｇｉｂｒａｃｔｅａｔａ）属松科铁杉属,长苞铁杉组（Ｓｅｃｔ．ＨｅｏｐｅｎｃｅＫｅｎｇｅｔＫｅｎｇｆ．）,为我国特有树种;现正处在濒危状态,已被列为国家三级保护植物。本文比较系统地综述了长苞铁杉的生物学特性,包括其外部形态、内部结构、染色体核型、地理分布、生长特性及材性、生态学和群落特性等。关于长苞铁杉的分类位置,一直争论不休。作者在比较了各种分类观点后,根据上述特性的分析结果,支持建立长苞铁杉属（Ｎｏｔｈｏｔｓｕｇａ）的主张。最后,文章分析了可能引起长苞铁杉濒危的原因,并提出了两点保护措施。     

中国特有植物台湾杉的生物学特性及其保护

本文全面地综述了我国一级国家重点保护植物台湾杉的生物学特性,其中有外部形态特征,内部结构包括苗端、叶片、树皮及木材结构,雌雄配子体与胚胎发育,花粉和染色体。此外还有台湾杉的组织培养、地理分布,生态学与群落学特性等。最后,本文作者还初步分析了台湾杉的濒危原因,并提出了具体保护措施。     

Quantitative genetics in conservation biology

Most of the major genetic concerns in conservation biology, including inbreeding depression, loss of evolutionary potential, genetic adaptation to captivity and outbreeding depression, involve quantitative genetics. Small population size leads to inbreeding and loss of genetic diversity and so increases extinction risk. Captive populations of endangered species are managed to maximize the retention of genetic diversity by minimizing kinship, with subsidiary efforts to minimize inbreeding. There is growing evidence that genetic adaptation to captivity is a major issue in the genetic management of captive populations of endangered species as it reduces reproductive fitness when captive populations are reintroduced into the wild. This problem is not currently addressed, but it can be alleviated by deliberately fragmenting captive populations, with occasional exchange of immigrants to avoid excessive inbreeding. The extent and importance of outbreeding depression is a matter of controversy. Currently, an extremely cautious approach is taken to mixing populations. However, this cannot continue if fragmented populations are to be adequately managed to minimize extinctions. Most genetic management recommendations for endangered species arise directly, or indirectly, from quantitative genetic considerations.     

Genetics and conservation biology

Conservation genetics encompasses genetic management of small populations, resolution of taxonomic uncertainties and management units, and the use of molecular genetic analyses in forensics and to understanding species' biology. The role of genetic factors in extinctions of wild populations has been controversial, but evidence now shows that they make important contributions to extinction risk. Inbreeding has been shown to cause extinctions of wild populations, computer projections indicate that inbreeding depression has important effects on extinction risk, and most threatened species show signs of genetic deterioration. Inappropriate management is likely to result if genetic factors are ignored in threatened species management.     

The notion of homology in current comparative biology

Current notions on homology, and its recognition, causation, and explanation are reviewed in this report. The focus is primarily on concepts because the formulation of precise definitions of homology has contributed little to our understanding of the issue. Different aspects or concepts of homology have been contrasted, currently the most important ones being the distinction between systematic and biological concepts. The systematic concept of homology focuses on common ancestry and on taxa; the biological concept tries to explain patterns of conservatism in evolution by shared developmental constraints. Similarity or correspondence is generally accepted as a primary criterion in the delimitation of homologues, albeit that this criterion is not without practical and theoretical problems. Apart from similarity, the biological concept of homology also stresses developmental individuality of putative homologous structures. Structural and positional aspects of homology can be separated, with positional homology acquiring an independent status. Similarity, topographic relationships, and ontogenetic development cannot be tests of homology. Within the cladistic paradigm, the most decisive test of homology is that of congruence; proponents of the biological-homology concept have been less concerned with test implications. Adopting a hierarchical view of nature suggests that characters have to be homologized at their appropriate level of organization. A taxic or systematic approach to homology has precedence over a transformational or biological approach. Nevertheless, pattern analysis and process explanations are not independent of each other.     

Considering evolutionary processes in conservation biology

Conservation biologists assign population distinctiveness by classifying populations as evolutionarily significant units (ESUs). Historically, this classification has included ecological and genetic data. However, recent ESU concepts, coupled with increasing availability of data on neutral genetic variation, have led to criteria based exclusively on molecular phylogenies. We argue that the earlier definitions of ESUs, which incorporated ecological data and genetic variation of adaptive significance, are more relevant for conservation. Furthermore, this dichotomous summary (ESU or not) of a continuum of population differentiation is not adequate for determining appropriate management actions. We argue for a broader categorization of population distinctiveness based on concepts of ecological and genetic exchangeability (sensu Templeton).     

Field endocrinology and conservation biology

Field endocrinology techniques allow the collection of samples(i.e., blood, urine, feces, tissues) from free-living animalsfor analysis of hormones, receptors, enzymes, etc. These datareveal mechanisms by which individuals respond to environmentalchallenges, breed, migrate and regulate all aspects of theirlife cycles. Field endocrinology techniques can also be usedto address many issues in conservation biology. We briefly reviewpast and current ways in which endocrine methods are used tomonitor threatened species, identify potential stressors andrecord responses to environmental disturbance. We then focuson one important aspect of conservation: how free-living populationsrespond to human disturbance, particularly in relation to ecotourism.Breeding adult Magellanic penguins, Spheniscus magellanicus,appear to habituate well to tourists, and breed in an area whereabout 70,000 people visit during the season. Baseline levelsof corticosterone return to normal after exposure of naïvebirds to humans. However, penguin chicks appear to show a heightenedadrenocortical response to handling stress in nests exposedto tourists, compared to chicks living in areas isolated fromhuman intrusions. Given that developmental exposure to stresscan have profound influences on how individuals cope with stressas adults, this potential effect of tourists on chicks couldhave long-term consequences. This field endocrine approach identifieda stressor not observed through monitoring behavior alone.     

The relevance of time series in molecular ecology and conservation biology

The genetic structure of a species is shaped by the interaction of contemporary and historical factors. Analyses of individuals from the same population sampled at different points in time can help to disentangle the effects of current and historical forces and facilitate the understanding of the forces driving the differentiation of populations. The use of such time series allows for the exploration of changes at the population and intraspecific levels over time. Material from museum collections plays a key role in understanding and evaluating observed population structures, especially if large numbers of individuals have been sampled from the same locations at multiple time points. In these cases, changes in population structure can be assessed empirically. The development of new molecular markers relying on short DNA fragments (such as microsatellites or single nucleotide polymorphisms) allows for the analysis of long‐preserved and partially degraded samples. Recently developed techniques to construct genome libraries with a reduced complexity and next generation sequencing and their associated analysis pipelines have the potential to facilitate marker development and genotyping in non‐model species. In this review, we discuss the problems with sampling and available marker systems for historical specimens and demonstrate that temporal comparative studies are crucial for the estimation of important population genetic parameters and to measure empirically the effects of recent habitat alteration. While many of these analyses can be performed with samples taken at a single point in time, the measurements are more robust if multiple points in time are studied. Furthermore, examining the effects of habitat alteration, population declines, and population bottlenecks is only possible if samples before and after the respective events are included.     

保护生物学中若干术语的理解和辨析(2)

7 Gene Flow（基因流）、Genetic Drift（遗传漂变）和Gene Fixation（基因固定） GeneFlow（基因流,也写作基因流动）,是指由于迁移和杂交等原因导致一个种群的基因进人到另一个种群（同种或不同种）的基因库,使接受者的基因频率发生改变。其他种群基因的流人可以直接改变种群原有的基因频率,影响遗传结构,并使基因交流频繁的种群间在遗传上趋于一致。基因流可以使具有不同等位基因的种群间产生新的遗传组合;不同品种间的基因交流可能形成新种。而且这些新的基因组合也可能具有更强的生存力和适应力,从而在进化上起到很大作用。但事实上,即使种群间有相当多的基因流,由于强有力的选择,种群间仍然会存在一定的遗传分化,并保持各自的属性。     

The Gegenbaur Transformation: a paradigm change in comparative biology

The leading experts in the development of phylogenetic systematics, Walter Zimmermann and Willi Hennig, formulated their research program in opposition to (neo-) idealistic morphology as expounded by authors such as Wilhelm Troll and Adolf Naef. Idealistic morphology was synonymous with systematic morphology for Naef, who wanted it to be strictly kept separate and independent of phylogenetics. Naef conceded, however, that the natural system researched by systematic morphology is to be causally explained by the theory of descent with modification. Naef went on to compile a dictionary that would regulate the translation of the language of systematic morphology into the language of phylogenetics. The switch from idealistic morphology to phylogenetic morphology is paradigmatically exemplified in the two editions (1859, 1870) of Carl Gegenbaur's Grundzüge der vergleichenden Anatomie. This paper traces the development of phylogenetic systematics from Gegenbaur through the work of Adolf Naef to Walter Zimmermann and Willi Hennig. Hennig added to Naef's systematic morphology the dimension of time, which required an ontological replacement: Naef's natural system, a nested hierarchy of intensionally defined sets subject to the membership relation, was replaced by Hennig's phylogenetic system, an enkaptic hierarchy subject to the part-to-whole relation.     

大鲵保护生物学及其研究进展

大鲵（Andrias davidianus)为我国特有的珍稀两栖动物,已列入国家二级保护动物名录,并列入CITES公约附录Ⅰ中。自20世纪50年代起,由于过度收购、非法捕杀和栖息地丧失等原因,大鲵种群数量下降极为严重,湖南、安徽等地的大鲵产量在20世纪50年代至70年代下降超过80％,分布区也极度萎缩,形成了12块岛屿状区域,目前分布于以我国中部山区的长江流域为主的17个省区。部分已建立的大鲵保护区经费短缺,人员不足,管理不力,状况不容乐观。非法捕捉和栖息地丧失仍是威胁大鲵生存的主要因素,保护管理力度还需进一步加强。