共查询到20条相似文献,搜索用时 15 毫秒
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《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2012,43(4):751-757
Michael Devitt, 2008, Devitt, 2010 has argued that species have intrinsic essences. This paper rebuts Devitt’s arguments, but in so doing it shores up the anti-essentialist consensus in two ways that have more general interest. First, species membership can be explanatory even when species have no essences; that is, Tamsin’s membership of the tiger species can explain her stripyness, without this committing us to any further claim about essential properties of tigers. Second, even the views of species that appear most congenial to essentialism—namely phenetic and genotypic cluster accounts—do not entail strong forms of intrinsic essentialism. 相似文献
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Meiotic Chromosome Behavior in Species,Species Hybrids,Haploids, and Induced Polyploids of Gossypium 总被引:5,自引:0,他引:5
Beasley JO 《Genetics》1942,27(1):25-54
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Species concepts,individuality, and objectivity 总被引:2,自引:0,他引:2
《Biology & philosophy》1987,2(2):127-143
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A. Turner 《Human Evolution》1986,1(5):419-430
Human evolution is considered from the perspective of the recognition concept of species, which views species as an epiphenomenon
of shared fertilisation systems in sexually reproducing organisms. It is argued that this concept predicts the controversial
pattern of punctuated equilibrium, and offers an understanding of the hominid fossil evidence in line with that pattern. Changes
in the nature of the fertilization system in the human lineage over time are discussed in relation to the pattern of morphological
continuity between proposed species. 相似文献
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Reed GB 《Journal of bacteriology》1945,49(5):503-505
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Phylogenetic Species, Nested Hierarchies, and Character Fixation 总被引:1,自引:0,他引:1
Paul Z. Goldstein Rob DeSalle† 《Cladistics : the international journal of the Willi Hennig Society》2000,16(4):364-384
Cladistic mechanics and ramifications of various species concepts rooted in phylogenetic theory are explored. Published discussions of the phylogenetic species concept (PSC) have been hampered by persistent misconceptions surrounding its ontology and applicability, and by confusion of various incompatible versions of species concepts claiming to follow from Hennig's (1966), Phylogenetic Systematics, Univ. of Illinois Press, Urbana work. Especially problematic are topology- or tree-based versions of species diagnosis, which render diagnoses dependent on relationships depicted as hierarchically structured regardless of any lack of underlying hierarchy. Because the applicability of concepts such as monophyly, paraphyly, and polyphyly rests ultimately on the underlying hierarchical distribution of characters, representations of tokogenetic or reticulating systems as nested hierarchies are necessarily inaccurate. And since hierarchical representations—even if accurate—of nonrecombining genetic elements need not coincide with the organisms that bear them, tree-based diagnoses are further hampered, except potentially as retrospective tools. The relationship between tree-based species delineations and the criterion of character fixation is explored. Fixation of characters by which one identifies phylogenetic species is further distinguished from the fixation of character state differences, and the implications of that distinction are explored with reference to the interpretation of speciation events. It is demonstrated that character fixation in alternative species need not coincide with the achievement of reciprocal monophyly. While the PSC retains shortcomings, some of the more frequently criticized aspects of the PSC are functions of sampling that are no more problematic than for any basic systematic endeavor. 相似文献
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Species Dynamics During Early Secondary Forest Succession: Recruitment, Mortality and Species Turnover 总被引:2,自引:0,他引:2
The "Initial Floristic Composition" hypothesis is applied to secondary tropical rain forest succession in abandoned agricultural fields with light previous land-use and close to seed sources. This hypothesis predicts that both pioneer and shade-tolerant species colonize a site directly after abandonment, and as the canopy closes, the recruitment of pioneers sharply declines, while recruitment of shade-tolerant species continues. It also predicts higher mortality among pioneers. Consequently, recruited and dead trees are expected to differ in species composition, with highest species richness for the recruits. During 18 mo, we monitored recruitment and mortality of trees with height ≥ 1.5 m in eight plots in abandoned cornfields with initial fallow age of 1–5 yr, in SE Mexico. Shade-tolerant species established in the first years of succession, albeit in low numbers. As predicted, recruited and dead trees differed in species richness and composition, and in shade-tolerant frequency. In contrast to our expectations, over 50 percent of recruits were from pioneer species, as high stand-level mortality opened new opportunities for continued pioneer colonization. Species turnover starts very early in succession but is not always a gradual and continuous process, complicating prevailing succession models. The strong spatial and temporal variability of succession emphasizes the need to monitor these dynamics in permanent plots across a range of initial stand ages, with multiple plots in a given age class. 相似文献
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Fourteen morphologically putative populations of X. krugi were clearly separated into four different profiles by RFLP analysis (Alu I and Hinf I), sequencing of the ITS-1 region, and subsequent Maximum Likelihood phylogenetic analyses. These four profiles were further supported by a principal component analysis of morphometric characters that yielded four taxonomic clusters matching those produced by the molecular data. Sequence homology was greater amongst populations that represented the same RFLP profile than between profiles and similar both between representative populations of the RFLP profiles and putative closely related Xiphinema species. This study suggests that X. krugi is a potential species complex comprised of at least four distinct genotypes. 相似文献
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SARAH SAMADI ANOUK BARBEROUSSE 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(1):217-222
Velasco recently criticized our formal definition of the species concept, arguing for its inappropriateness both in fundamental and practical aspects [Velasco JD (2008) Biological Journal of the Linnean Society , 93 , 865–869]. Here, we clarify some misunderstandings that are at the basis of Velasco's paper. First, we show why and how the definition of the species concept can be grounded in the theory of evolution and what that implies. Then, we explain why Velasco's formal criticisms are unjustified. Finally, we point out the practical and methodological consequences of a rigorous conceptual framework for species study, and we show that today's development of species delimitation methods fully agrees with our proposal. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 217–222. 相似文献
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线粒体,活性氧和细胞凋亡 总被引:56,自引:1,他引:56
在能量代谢和自由基代谢中,线粒体均占据着十分重要的地位.通过呼吸链电子漏途径,线粒体产生大量超氧阴离子,并通过链式反应形成对机体有损伤作用的活性氧.通过呼吸链电子漏,氧化磷酸化解偶联,线粒体内膜产生通透性转变孔道(PTP)及Box-和/或PTP-介导的细胞色素c向胞质的转移等种种因素,线粒体参与一般抗氧化防御及细胞凋亡等重要生理过程的调控.在与线粒体相关的细胞凋亡中,活性氧的信号作用是十分明显的. 相似文献
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Although many studies have debated the theoretical links between physiology, ecological niches and species distribution, few
studies have provided evidence for a tight empirical coupling between these concepts at a macroecological scale. We used an
ecophysiological model to assess the fundamental niche of a key-structural marine species. We found a close relationship between
its fundamental and realized niche. The relationship remains constant at both biogeographical and decadal scales, showing
that changes in environmental forcing propagate from the physiological to the macroecological level. A substantial shift in
the spatial distribution is detected in the North Atlantic and projections of range shift using IPCC scenarios suggest a poleward
movement of the species of one degree of latitude per decade for the 21st century. The shift in the spatial distribution of
this species reveals a pronounced alteration of polar pelagic ecosystems with likely implications for lower and upper trophic
levels and some biogeochemical cycles. 相似文献