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ECOLOGÍA EVOLUTIVA  |
In evolutionary time, species come and go. In ecological time-anything from days to decades or even centuries-most species, in most places, persist. They do so in complex networks of local communities and extended metacommunities, within and between which even similar and closely related species may vary greatly in abundance. And while processes such as invasion and succession sometimes bring about a rapid reordering of the biological status quo for a particular site or region, species more typically maintain themselves in fairly constant numbers, neither taking over everything, like kudzu, nor dwindling to nothing, like the dodo. BioScience, Vol. 53, No. 2:. 124–129. |
In the study of sociocultural and memetic evolution, approaches modelled on population genetics and on systematics and taxonomy have been prominent but the influence of evolutionary ecology has been slight. The cultural evolution indicates the application of some principles of evolutionary ecology to the scientific process. Effects of density, scale, frequency and heterogeneity on various strategies of research and teaching in science are considered. Journal of Memetics - Evolutionary Models of Information Transmission: Vol. 7, No.1, p35, 18p. |
Behavioral Drive versus Behavioral Inertia in Evolution: a null model approach Raymond B. Huey, Paul E. Hertz and B. Sinervo Develops a null model that quantifies the impact of regulatory behaviors on body temperature and on performance of ectotherms. Overview of the phenomenon called the Bogert effect; Contradiction to the classical view that behavior is invariably the driving force in evolution; Diverse effects of behavior on the directions and rates at which other traits evolve. American Naturalist, Vol. 161, No.3: 357-366 . |
The Naturalist in a World of Genomics Stearns, Stephen C. and Magwene, Paul Reports on the significance of functional genomics to address issues of fundamental interest in evolutionary biology. Ability to study biological processes from a whole genome perspective; Impact on evolutionary biology and ecology; Discussion of how genomewide gene expression studies can be used to reformulate questions about pleiotropy. American Naturalist, Vol. 161, No.2: 171-180. |
Phylogeny and Ecological Radiation of New World Thistles (Cirsium, Cardueae – Compositae) based on ITS and ETS rDNA Sequence Data. Kelch, Dean G., and Baldwin, Bruce G. Sequence data from a portion of the external transcribed spacer (ETS) and internal transcribed spacers (ITS-1 and ITS-2) of 18S-26S nuclear ribosomal DNA were used to resolve historical biogeography and ecology of true thistles (Cirsium, Cardueae, Compositae) in the New World. The 650 base-pair, 3 ' portion of the ETS examined here showed a level of variation across taxa similar to that of the ITS sequences included. A maximum-likelihood tree based on combined ETS and ITS sequences leads us to suggest that the New World species of true thistles constitute a major lineage, which in turn comprises several smaller lineages. A western North American lineage shows weak quartet-puzzling support, but includes a well-supported lineage of species endemic to the California Floristic Province. Comparisons of this Californian lineage with other neoendemic angiosperm groups of the region show that the Californian Cirsium lineage exhibits unusually high ecological diversity for a group displaying such low levels of rDNA sequence divergence across taxa. Similarly low levels of sequence divergence were found throughout the New World Cirsium lineage. These results indicate either that Cirsium underwent a rapid ecological radiation in North America, or that rDNA evolution in North American Cirsium has been highly conservative. Molecular Ecology (enero): Vol. 12, No.1: 141-151. |
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Looking over the last four back decades, I can see several eras in evolutionary biology. The use of protein electrophoresis from the 1960s onward exposed all species to genetic analysis and initiated a long-running controversy over whether most alleles are subject to selection. Then in the 1970s, evolutionary biologists adopted DNA sequencing techniques, which fueled the growth of molecular systematics. More recently, markers from mitochondrial DNA and then chloroplast DNA have provided the data for phylogeography, geographic analyses of phylogenetic lineages that make inferences about glacial refugia and other important features of species' evolutionary history. A paper published in "Ecology" by Whitham et al in 2003 may herald a new era in evolutionary biology: the elaboration of community and ecosystem genetics.If this comes about, evolutionary biology and ecology will be more tightly linked than ever before. As a population geneticist who usually focuses on single-locus studies of variation within species, the sound of community and ecosystem genetics initially made me fidgety. But community genetics is introduced here with well-documented empirical studies of genetic variation that produces not only phenotypic variation within a species but also changes in interactions among species that are profound in effect and widespread in a community. Community genetics relies on genes with extended phenotypes and on community heritability. The basis of community genetics is intraspecific genetic variation with major effects that trigger a cascade of interactions with other species in the community. Because the genetic variation underlying the extended phenotype conforms to normal patterns of inheritance, the extended phenotypes--the interactions with other species--are heritable.Community genetics is a new form of ecological genetics, in which the genes not only respond to the environment but also change physical and biotic components of the environment. Bioscience, Vol. 53, No.3, p208, 2p.
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Population-genetic studies have been remarkably productive and successful in the last decade following the invention of PCR technology and the introduction of mitochondrial and microsatellite DNA markers. While mitochondrial DNA has proven powerful for genealogical and evolutionary studies of animal populations, and microsatellite sequences are the most revealing DNA markers available so far for inferring population structure and dynamics, they both have important and unavoidable limitations. To obtain a fuller picture of the history and evolutionary potential of populations, genealogical data from nuclear loci are essential, and the inclusion of other nuclear markers, i.e. single copy nuclear polymorphic (scnp) sequences, is clearly needed. Four major uncertainties for nuclear DNA analyses of populations have been facing us, i.e. the availability of scnp markers for carrying out such analysis, technical laboratory hurdles for resolving haplotypes, difficulty in data analysis because of recombination, low divergence levels and intraspecific multifurcation evolution, and the utility of scnp markers for addressing population-genetic questions. In this review, we discuss the availability of highly polymorphic single copy DNA in the nuclear genome, describe patterns and rate of evolution of nuclear sequences, summarize past empirical and theoretical efforts to recover and analyse data from scnp markers, and examine the difficulties, challenges and opportunities faced in such studies. We show that although challenges still exist, the above-mentioned obstacles are now being removed. Recent advances in technology and increases in statistical power provide the prospect of nuclear DNA analyses becoming routine practice, allowing allele-discriminating characterization of scnp loci and microsatellite loci. This certainly will increase our ability to address more complex questions, and thereby the sophistication of genetic analyses of populations. Molecular Ecology, Vol. 12, No. 3, p563, 22p. |
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Phenotypic Integration: studying the ecology and evolution of complex phenotypes Pigliucci, Massimo Phenotypic integration refers to the study of complex patterns of covariation among functionally related traits in a given organism. It has been investigated throughout the 20th century, but has only recently risen to the forefront of evolutionary ecological research. In this essay, I identify the reasons for this late flourishing of studies on integration, and discuss some of the major areas of current endeavour: the interplay of adaptation and constraints, the genetic and molecular bases of integration, the role of phenotypic plasticity, macroevolutionary studies of integration, and statistical and conceptual issues in the study of the evolution of complex phenotypes. I then conclude with a brief discussion of what I see as the major future directions of research on phenotypic integration and how they relate to our more general quest for the understanding of phenotypic evolution within the neo-Darwinian framework. I suggest that studying integration provides a particularly stimulating and truly interdisciplinary convergence of researchers from fields as disparate as molecular genetics, developmental biology, evolutionary ecology, palaeontology and even philosophy of science. Ecology Letters, Vol. 6, No. 3, p265, 8p. |
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I reconstructed a phylogeny of 66 species and varieties of Bursera and 9 outgroup species using sequences of the internal transcribed spacer region (ITS), the 5S non-transcribed region (5S-NTS), and the external transcribed region (ETS) of nuclear ribosomal DNA. This study extends a previously proposed parsimony-based phylogenetic study that used the ITS sequences of 57 Bursera species and five outgroups. Parsimony and maximum likelihood methods were used to infer the phylogeny in this new study. Analyses of the combined data sets largely confirmed the phylogenetic relationships proposed by the previous molecular study but generated a considerably more robust topology. The new phylogenies corroborate the monophyly of the genus, and its division into the two monophyletic subgenera or sections, Bursera and Bullockia. The current analyses also identify four main groups of species in section Bursera, and two in section Bullockia, confirming some of the previously proposed groups based on fruit, flower, and leaf morphology. One previously problematic species B. sarcopoda, which has sometimes been placed in Commiphora, is shown to belong in Bursera. Another controversial species, Commiphora leptophloeos, which was thought to belong to Bursera, falls within Commiphora. Molecular Phylogenetics & Evolution, Vol. 26, No.2, p300, 10p. |
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