Página 1 dos resultados de 5827 itens digitais encontrados em 0.116 segundos

‣ Rapid Evolution of H5N1 Influenza Viruses in Chickens in Hong Kong

Zhou, Nan Nan; Shortridge, Kennedy F.; Claas, Eric C. J.; Krauss, Scott L.; Webster, Robert G.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/1999 Português
Relevância na Pesquisa
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The H5N1 avian influenza virus that killed 6 of 18 persons infected in Hong Kong in 1997 was transmitted directly from poultry to humans. Viral isolates from this outbreak may provide molecular clues to zoonotic transfer. Here we demonstrate that the H5N1 viruses circulating in poultry comprised two distinguishable phylogenetic lineages in all genes that were in very rapid evolution. When introduced into new hosts, influenza viruses usually undergo rapid alteration of their surface glycoproteins, especially in the hemagglutinin (HA). Surprisingly, these H5N1 isolates had a large proportion of amino acid changes in all gene products except in the HA. These viruses maybe reassortants each of whose HA gene is well adapted to domestic poultry while the rest of the genome arises from a different source. The consensus amino acid sequences of “internal” virion proteins reveal amino acids previously found in human strains. These human-specific amino acids may be important factors in zoonotic transmission.

‣ Rapid evolution of reproductive proteins in abalone and Drosophila

Panhuis, Tami M; Clark, Nathaniel L; Swanson, Willie J
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
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Observations from different taxa, including plants, protozoa, insects and mammals, indicate that proteins involved in reproduction evolve rapidly. Several models of adaptive evolution have been proposed to explain this phenomenon, such as sexual conflict, sexual selection, self versus non-self recognition and pathogen resistance. Here we discuss the potential role of sexual conflict in the rapid evolution of reproductive genes in two different animal systems, abalone (Haliotis) and Drosophila. In abalone, we reveal how specific interacting sperm–egg proteins were identified and discuss this identification in the light of models for rapid protein evolution and speciation. For Drosophila, we describe the genomic approaches taken to identify male accessory gland proteins and female reproductive tract proteins. Patterns of protein evolution from both abalone and Drosophila support the predicted patterns of rapid protein evolution driven by sexual conflict. We stress however that other selective pressures may contribute to the rapid evolution that is observed. We conclude that the key to distinguishing between sexual conflict and other mechanisms of protein evolution will be an integration of genetic, experimental and theoretical data.

‣ Rapid evolution of an X-linked microRNA cluster in primates

Zhang, Rui; Peng, Yi; Wang, Wen; Su, Bing
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /05/2007 Português
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MicroRNAs (miRNAs) are a growing class of small RNAs (about 22 nt) that play crucial regulatory roles in the genome by targeting mRNAs for cleavage or translational repression. Most of the identified miRNAs are highly conserved among species, indicating strong functional constraint on miRNA evolution. However, nonconserved miRNAs may contribute to functional novelties during evolution. Recently, an X-linked miRNA cluster was reported with multiple copies in primates but not in rodents or dog. Here we sequenced and compared this miRNA cluster in major primate lineages including human, great ape, lesser ape, Old World monkey, and New World monkey. Our data indicate rapid evolution of this cluster in primates including frequent tandem duplications and nucleotide substitutions. In addition, lineage-specific substitutions were observed in human and chimpanzee, leading to the emergence of potential novel mature miRNAs. The expression analysis in rhesus monkeys revealed a strong correlation between miRNA expression changes and male sexual maturation, suggesting regulatory roles of this miRNA cluster in testis development and spermatogenesis. We propose that, like protein-coding genes, miRNA genes involved in male reproduction are subject to rapid adaptive changes that may contribute to functional novelties during evolution.

‣ Cryptic Population Dynamics: Rapid Evolution Masks Trophic Interactions

Yoshida, Takehito; Ellner, Stephen P; Jones, Laura E; Bohannan, Brendan J. M; Lenski, Richard E; Hairston, Nelson G
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
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Trophic relationships, such as those between predator and prey or between pathogen and host, are key interactions linking species in ecological food webs. The structure of these links and their strengths have major consequences for the dynamics and stability of food webs. The existence and strength of particular trophic links has often been assessed using observational data on changes in species abundance through time. Here we show that very strong links can be completely missed by these kinds of analyses when changes in population abundance are accompanied by contemporaneous rapid evolution in the prey or host species. Experimental observations, in rotifer-alga and phage-bacteria chemostats, show that the predator or pathogen can exhibit large-amplitude cycles while the abundance of the prey or host remains essentially constant. We know that the species are tightly linked in these experimental microcosms, but without this knowledge, we would infer from observed patterns in abundance that the species are weakly or not at all linked. Mathematical modeling shows that this kind of cryptic dynamics occurs when there is rapid prey or host evolution for traits conferring defense against attack, and the cost of defense (in terms of tradeoffs with other fitness components) is low. Several predictions of the theory that we developed to explain the rotifer-alga experiments are confirmed in the phage-bacteria experiments...

‣ Evolutionary Genomics Reveals Lineage-Specific Gene Loss and Rapid Evolution of a Sperm-Specific Ion Channel Complex: CatSpers and CatSperβ

Cai, Xinjiang; Clapham, David E.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/10/2008 Português
Relevância na Pesquisa
46.84562%
The mammalian CatSper ion channel family consists of four sperm-specific voltage-gated Ca2+ channels that are crucial for sperm hyperactivation and male fertility. All four CatSper subunits are believed to assemble into a heteromultimeric channel complex, together with an auxiliary subunit, CatSperβ. Here, we report a comprehensive comparative genomics study and evolutionary analysis of CatSpers and CatSperβ, with important correlation to physiological significance of molecular evolution of the CatSper channel complex. The development of the CatSper channel complex with four CatSpers and CatSperβ originated as early as primitive metazoans such as the Cnidarian Nematostella vectensis. Comparative genomics revealed extensive lineage-specific gene loss of all four CatSpers and CatSperβ through metazoan evolution, especially in vertebrates. The CatSper channel complex underwent rapid evolution and functional divergence, while distinct evolutionary constraints appear to have acted on different domains and specific sites of the four CatSper genes. These results reveal unique evolutionary characteristics of sperm-specific Ca2+ channels and their adaptation to sperm biology through metazoan evolution.

‣ Is Speciation Accompanied by Rapid Evolution? Insights from Comparing Reproductive and Nonreproductive Transcriptomes in Drosophila

Jagadeeshan, Santosh; Haerty, Wilfried; Singh, Rama S.
Fonte: SAGE-Hindawi Access to Research Publicador: SAGE-Hindawi Access to Research
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.17025%
The tempo and mode of evolutionary change during speciation have remained contentious until recently. While much of the evidence claiming speciation is an abrupt and rapid process comes from fossil data, recent molecular phylogenetics show that the background of gradual evolution is often broken by accelerated rates of molecular evolution during speciation. However, what kinds of genes affect or are affected by speciation remains unexplored. Our analysis of 4843 protein-coding genes in five species of the Drosophila melanogaster subgroup shows that while ~70% of genes follow clock-like evolution, between 17–19.67% of loci show signatures of accelerated rates of evolution in recently formed species. These genes show 2-3-fold higher rates of substitution in recently diverged species compared to older species. This fraction of loci affects a diverse range of functions. Only a small proportion of reproductive genes experience speciation-related accelerated changes but many sex-and -reproduction related genes show an interesting pattern of persistent rapid evolution suggesting that sex-and-reproduction related genes are under constant selective pressures. The identification of loci associated with accelerated evolution allows us to address the mechanisms of rapid evolution and speciation...

‣ Rapid evolution in a plant-pathogen interaction and the consequences for introduced host species

Gilbert, Gregory S; Parker, Ingrid M
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em /03/2010 Português
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46.85319%
Plant species introduced into new regions can both leave behind co-evolved pathogens and acquire new ones. Traits important to infection and virulence are subject to rapid evolutionary change in both plant and pathogen. Using Stemphylium solani, a native foliar necrotroph on clovers (Trifolium and Medicago) in California, USA, we explore how plant-fungal interactions may change in an invasion context. After four generations of experimental serial passage through multiple hosts, Stemphylium consistently showed increased infection rates but no consistent change in damage to the host. In a historical opportunity study, we compared infection and virulence across four groups of clover hosts: California natives, European clovers not found in California, and both California and European genotypes of species naturalized in California. There was significant variation among hosts, but no pattern across the four groups. However, in direct comparisons of familiar California genotypes to unfamiliar European genotypes of the same naturalized species, Stemphylium consistently infected familiar hosts more frequently, while causing less damage on them. This pattern is consistent with the hypothesis of adaptive evolution in both the pathogen (ability to infect) and the host (tolerance of infection). Together these results suggest the potential for rapid evolution to alter interactions between plant invaders and their natural enemies.

‣ Comparative genomics of chemosensory protein genes reveals rapid evolution and positive selection in ant-specific duplicates

Kulmuni, J; Wurm, Y; Pamilo, P
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
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Gene duplications can have a major role in adaptation, and gene families underlying chemosensation are particularly interesting due to their essential role in chemical recognition of mates, predators and food resources. Social insects add yet another dimension to the study of chemosensory genomics, as the key components of their social life rely on chemical communication. Still, chemosensory gene families are little studied in social insects. Here we annotated chemosensory protein (CSP) genes from seven ant genomes and studied their evolution. The number of functional CSP genes ranges from 11 to 21 depending on species, and the estimated rates of gene birth and death indicate high turnover of genes. Ant CSP genes include seven conservative orthologous groups present in all the ants, and a group of genes that has expanded independently in different ant lineages. Interestingly, the expanded group of genes has a differing mode of evolution from the orthologous groups. The expanded group shows rapid evolution as indicated by a high dN/dS (nonsynonymous to synonymous changes) ratio, several sites under positive selection and many pseudogenes, whereas the genes in the seven orthologous groups evolve slowly under purifying selection and include only one pseudogene. These results show that adaptive changes have played a role in ant CSP evolution. The expanded group of ant-specific genes is phylogenetically close to a conservative orthologous group CSP7...

‣ Probing the Boundaries of Orthology: The Unanticipated Rapid Evolution of Drosophila centrosomin

Eisman, Robert C.; Kaufman, Thomas C.
Fonte: Genetics Society of America Publicador: Genetics Society of America
Tipo: Artigo de Revista Científica
Publicado em /08/2013 Português
Relevância na Pesquisa
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The rapid evolution of essential developmental genes and their protein products is both intriguing and problematic. The rapid evolution of gene products with simple protein folds and a lack of well-characterized functional domains typically result in a low discovery rate of orthologous genes. Additionally, in the absence of orthologs it is difficult to study the processes and mechanisms underlying rapid evolution. In this study, we have investigated the rapid evolution of centrosomin (cnn), an essential gene encoding centrosomal protein isoforms required during syncytial development in Drosophila melanogaster. Until recently the rapid divergence of cnn made identification of orthologs difficult and questionable because Cnn violates many of the assumptions underlying models for protein evolution. To overcome these limitations, we have identified a group of insect orthologs and present conserved features likely to be required for the functions attributed to cnn in D. melanogaster. We also show that the rapid divergence of Cnn isoforms is apparently due to frequent coding sequence indels and an accelerated rate of intronic additions and eliminations. These changes appear to be buffered by multi-exon and multi-reading frame maximum potential ORFs...

‣ Rapid evolution of quantitative traits: theoretical perspectives

Kopp, Michael; Matuszewski, Sebastian
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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An increasing number of studies demonstrate phenotypic and genetic changes in natural populations that are subject to climate change, and there is hope that some of these changes will contribute to avoiding species extinctions (‘evolutionary rescue’). Here, we review theoretical models of rapid evolution in quantitative traits that can shed light on the potential for adaptation to a changing climate. Our focus is on quantitative-genetic models with selection for a moving phenotypic optimum. We point out that there is no one-to-one relationship between the rate of adaptation and population survival, because the former depends on relative fitness and the latter on absolute fitness. Nevertheless, previous estimates that sustainable rates of genetically based change usually do not exceed 0.1 haldanes (i.e., phenotypic standard deviations per generation) are probably correct. Survival can be greatly facilitated by phenotypic plasticity, and heritable variation in plasticity can further speed up genetic evolution. Multivariate selection and genetic correlations are frequently assumed to constrain adaptation, but this is not necessarily the case and depends on the geometric relationship between the fitness landscape and the structure of genetic variation. Similar conclusions hold for adaptation to shifting spatial gradients. Recent models of adaptation in multispecies communities indicate that the potential for rapid evolution is strongly influenced by interspecific competition.

‣ Rapid evolution of binding specificities and expression patterns of inhibitory CD33-related Siglecs in primates

Padler-Karavani, Vered; Hurtado-Ziola, Nancy; Chang, Yung-Chi; Sonnenburg, Justin L.; Ronaghy, Arash; Yu, Hai; Verhagen, Andrea; Nizet, Victor; Chen, Xi; Varki, Nissi; Varki, Ajit; Angata, Takashi
Fonte: Federation of American Societies for Experimental Biology Publicador: Federation of American Societies for Experimental Biology
Tipo: Artigo de Revista Científica
Publicado em /03/2014 Português
Relevância na Pesquisa
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Siglecs are sialic acid-binding Ig-like lectins that recognize sialoglycans via amino-terminal V-set domains. CD33-related Siglecs (CD33rSiglecs) on innate immune cells recognize endogenous sialoglycans as “self-associated molecular patterns” (SAMPs), dampening immune responses via cytosolic immunoreceptor tyrosine-based inhibition motifs that recruit tyrosine phosphatases. However, sialic acid-expressing pathogens subvert this mechanism through molecular mimicry. Meanwhile, endogenous host SAMPs must continually evolve to evade other pathogens that exploit sialic acids as invasion targets. We hypothesized that these opposing selection forces have accelerated CD33rSiglec evolution. We address this by comparative analysis of major CD33rSiglec (Siglec-3, Siglec-5, and Siglec-9) orthologs in humans, chimpanzees, and baboons. Recombinant soluble molecules displaying ligand-binding domains show marked quantitative and qualitative interspecies differences in interactions with strains of the sialylated pathogen, group B Streptococcus, and with sialoglycans presented as gangliosides or in the form of sialoglycan microarrays, including variations such as N-glycolyl and O-acetyl groups. Primate Siglecs also show quantitative and qualitative intra- and interspecies variations in expression patterns on leukocytes...

‣ De Novo Transcriptome Assembly and Identification of Gene Candidates for Rapid Evolution of Soil Al Tolerance in Anthoxanthum odoratum at the Long-Term Park Grass Experiment

Gould, Billie; McCouch, Susan; Geber, Monica
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/07/2015 Português
Relevância na Pesquisa
46.99574%
Studies of adaptation in the wild grass Anthoxanthum odoratum at the Park Grass Experiment (PGE) provided one of the earliest examples of rapid evolution in plants. Anthoxanthum has become locally adapted to differences in soil Al toxicity, which have developed there due to soil acidification from long-term experimental fertilizer treatments. In this study, we used transcriptome sequencing to identify Al stress responsive genes in Anthoxanhum and identify candidates among them for further molecular study of rapid Al tolerance evolution at the PGE. We examined the Al content of Anthoxanthum tissues and conducted RNA-sequencing of root tips, the primary site of Al induced damage. We found that despite its high tolerance Anthoxanthum is not an Al accumulating species. Genes similar to those involved in organic acid exudation (TaALMT1, ZmMATE), cell wall modification (OsSTAR1), and internal Al detoxification (OsNRAT1) in cultivated grasses were responsive to Al exposure. Expression of a large suite of novel loci was also triggered by early exposure to Al stress in roots. Three-hundred forty five transcripts were significantly more up- or down-regulated in tolerant vs. sensitive Anthoxanthum genotypes, providing important targets for future study of rapid evolution at the PGE.

‣ Evolutionary Genomics Reveals Lineage-Specific Gene Loss and Rapid Evolution of a Sperm-Specific Ion Channel Complex: CatSpers and CatSperβ

Cai, Xinjiang; Clapham, David Eldon; Schwartz, Arnold
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.84562%
The mammalian CatSper ion channel family consists of four sperm-specific voltage-gated Ca2+ channels that are crucial for sperm hyperactivation and male fertility. All four CatSper subunits are believed to assemble into a heteromultimeric channel complex, together with an auxiliary subunit, CatSperβ. Here, we report a comprehensive comparative genomics study and evolutionary analysis of CatSpers and CatSperβ, with important correlation to physiological significance of molecular evolution of the CatSper channel complex. The development of the CatSper channel complex with four CatSpers and CatSperβ originated as early as primitive metazoans such as the Cnidarian Nematostella vectensis. Comparative genomics revealed extensive lineage-specific gene loss of all four CatSpers and CatSperβ through metazoan evolution, especially in vertebrates. The CatSper channel complex underwent rapid evolution and functional divergence, while distinct evolutionary constraints appear to have acted on different domains and specific sites of the four CatSper genes. These results reveal unique evolutionary characteristics of sperm-specific Ca2+ channels and their adaptation to sperm biology through metazoan evolution.; Molecular and Cellular Biology

‣ The rapid evolution of the born-again giant Sakurai’s object

Asplund, Martin; Lambert, David L; Kipper, T; Pollacco, D; Shetrone, M.D
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Artigo de Revista Científica Formato: 314439 bytes; application/pdf
Português
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The extraordinarily rapid evolution of the born-again giant Sakurai’s object following discovery in 1996 has been investigated. The evolution can be traced both in a continued cooling of the stellar surface and dramatic changes in chemical composition on a timescale of a mere few months. The abundance alterations are the results of the mixing and nuclear reactions which have ensued due to the final He-shell flash which occurred during the descent along the white dwarf cooling track. The observed changes in the H and Li abundances can be explained by ingestion and burning of the H-rich envelope and Li-production through the Cameron-Fowler mechanism. The rapidly increasing abundances of the light s-elements (including Sc) are consistent with current s-processing by neutrons released from the concomitantly produced 13C. However, the possibility that the s-elements have previously been synthesized during the AGB-phase and only mixed to the surface in connection with the final He-shell flash in the pre-white dwarf cannot be convincingly ruled out either. Since Sakurai’s object shows substantial abundance similarities with the R CrB stars and has recently undergone R CrB-like visual fading events, the “birth” of an R CrB star may have been witnessed for the first time ever. Sakurai’s object thus lends strong support for the suggestion that at least some of the R CrB stars have been formed through a final He-shell flash in a post-AGB star.; yes

‣ Rapid Evolution of Social Learning

Nunn, Charles Lindsay; Franz, M
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
Português
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Culture is widely thought to be beneficial when social learning is less costly than individual learning and thus may explain the enormous ecological success of humans. Rogers (1988. Does biology constrain culture. Am. Anthropol. 90: 819–831) contradicted this common view by showing that the evolution of social learning does not necessarily increase the net benefits of learned behaviours in a variable environment. Using simulation experiments, we re-analysed extensions of Rogers' model after relaxing the assumption that genetic evolution is much slower than cultural evolution. Our results show that this assumption is crucial for Rogers' finding. For many parameter settings, genetic and cultural evolution occur on the same time scale, and feedback effects between genetic and cultural dynamics increase the net benefits. Thus, by avoiding the costs of individual learning, social learning can increase ecological success. Furthermore, we found that rapid evolution can limit the evolution of complex social learning strategies, which have been proposed to be widespread in animals.; Human Evolutionary Biology

‣ Multiple sexual selection pressures drive the rapid evolution of complex morphology in a male secondary genital structure

Frazee, Stephen R.; Masly, John P.
Fonte: John Wiley and Sons Inc. Publicador: John Wiley and Sons Inc.
Tipo: Artigo de Revista Científica
Publicado em 23/09/2015 Português
Relevância na Pesquisa
46.85319%
The genitalia of internally fertilizing taxa represent a striking example of rapid morphological evolution. Although sexual selection can shape variation in genital morphology, it has been difficult to test whether multiple sexual selection pressures combine to drive the rapid evolution of individual genital structures. Here, we test the hypothesis that both pre‐ and postcopulatory sexual selection can act in concert to shape complex structural variation in secondary genital morphology. We genetically modified the size and shape of the posterior lobes of Drosophila melanogaster males and tested the consequences of morphological variation on several reproductive measures. We found that the posterior lobes are necessary for genital coupling and that they are also the targets of multiple postcopulatory processes that shape quantitative variation in morphology, even though these structures make no direct contact with the external female genitalia or internal reproductive organs during mating. We also found that males with smaller and less structurally complex posterior lobes suffer substantial fitness costs in competitive fertilization experiments. Our results show that sexual selection mechanisms can combine to shape the morphology of a single genital structure and that the posterior lobes of D. melanogaster are the targets of multiple postcopulatory selection pressures.

‣ Effects of rapid prey evolution on predator-prey cycles

Jones, Laura E.; Ellner, Stephen P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/09/2006 Português
Relevância na Pesquisa
47.0749%
We study the qualitative properties of population cycles in a predator-prey system where genetic variability allows contemporary rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk can have major quantitative and qualitative effects on predator-prey cycles, including: (i) large increases in cycle period, (ii) changes in phase relations (so that predator and prey are cycling exactly out of phase, rather than the classical quarter-period phase lag), and (iii) "cryptic" cycles in which total prey density remains nearly constant while predator density and prey traits cycle. Here we focus on a chemostat model motivated by our experimental system [Fussmann et al. 2000,Yoshida et al. 2003] with algae (prey) and rotifers (predators), in which the prey exhibit rapid evolution in their level of defense against predation. We show that the effects of rapid prey evolution are robust and general, and furthermore that they occur in a specific but biologically relevant region of parameter space: when traits that greatly reduce predation risk are relatively cheap (in terms of reductions in other fitness components), when there is coexistence between the two prey types and the predator...

‣ Modelling effects of rapid evolution on persistence and stability in structured predator-prey systems

Farkas, József Z.; Morozov, A. Yu.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/02/2014 Português
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In this paper we explore the eco-evolutionary dynamics of a predator-prey model, where the prey population is structured according to a certain life history trait. The trait distribution within the prey population is the result of interplay between genetic inheritance and mutation, as well as selectivity in the consumption of prey by the predator. The evolutionary processes are considered to take place on the same time scale as ecological dynamics, i.e. we consider the evolution to be rapid. Previously published results show that population structuring and rapid evolution in such predator-prey system can stabilise an otherwise globally unstable dynamics even with an unlimited carrying capacity of prey. However, those findings were only based on direct numerical simulation of equations and obtained for particular parametrisations of model functions, which obviously calls into question the correctness and generality of the previous results. The main objective of the current study is to treat the model analytically and consider various parametrisations of predator selectivity and inheritance kernel. We investigate the existence of a coexistence stationary state in the model and carry out stability analysis of this state. We derive expressions for the Hopf bifurcation curve which can be used for constructing bifurcation diagrams in the parameter space without the need for a direct numerical simulation of the underlying integro-differential equations. We analytically show the possibility of stabilisation of a globally unstable predator-prey system with prey structuring. We prove that the coexistence stationary state is stable when the saturation in the predation term is low. Finally...

‣ Are invasive plants more toxic than native plants? An example of rapid evolution after invasion

Castells Caballé, Eva
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Conferência ou Objeto de Conferência Formato: application/pdf
Publicado em //2015 Português
Relevância na Pesquisa
46.85319%
Biological invasions are excellent systems to study rapid evolution of plant chemical defenses. Current hypotheses predict a divergence of plant chemical defenses in response to a decrease in herbivory after invasion (e.g. EICA hypothesis) or in response to novel climatic conditions. Post-invasive changes in plant chemistry can modify the interactions with herbivores and facilitate invasion success. However, whether plant toxicity is changed after invasion remains to be evaluated. Senecio pterophorus is a shrub native from Eastern South Africa and a recent invader in Western South Africa (~100 years ago), Australia (>70-100 years ago) and Europe (>30 years ago). These distributional regions of S. pterophorus differ in their summer drought stress and in their interactions with herbivores. As other Asteraceae, S. pterophorus contains pyrrolizidine alkaloids (PAs) toxic to vertebrate and invertebrate herbivores. Plants from 54 populations sampled throughout the entire known worldwide distributional area, including the native and three non-native ranges, were grown under controlled conditions. First, we analyzed the levels of chemical defenses and leaf morphological traits to determine whether plant genetically-based traits diverged between native and non-native populations. Second...

‣ Evolutionary Genomics Reveals Lineage-Specific Gene Loss and Rapid Evolution of a Sperm-Specific Ion Channel Complex: CatSpers and CatSper beta;

Cai, Xinjiang
Fonte: PUBLIC LIBRARY SCIENCE Publicador: PUBLIC LIBRARY SCIENCE
Publicado em //2008 Português
Relevância na Pesquisa
46.84562%
The mammalian CatSper ion channel family consists of four sperm-specific voltage-gated Ca2+ channels that are crucial for sperm hyperactivation and male fertility. All four CatSper subunits are believed to assemble into a heteromultimeric channel complex, together with an auxiliary subunit, CatSperb. Here, we report a comprehensive comparative genomics study and evolutionary analysis of CatSpers and CatSperb, with important correlation to physiological significance of molecular evolution of the CatSper channel complex. The development of the CatSper channel complex with four CatSpers and CatSperb originated as early as primitive metazoans such as the Cnidarian Nematostella vectensis. Comparative genomics revealed extensive lineage-specific gene loss of all four CatSpers and CatSperb through metazoan evolution, especially in vertebrates. The CatSper channel complex underwent rapid evolution and functional divergence, while distinct evolutionary constraints appear to have acted on different domains and specific sites of the four CatSper genes. These results reveal unique evolutionary characteristics of sperm-specific Ca2+ channels and their adaptation to sperm biology through metazoan evolution.