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ADOLFO AMZQUITA ALBERTINA P. LIMA ROBERT JEHLE LINA CASTELLANOS
SCAR RAMOS ANDREW J. CRAWFORD HERBERT GASSER WALTER H
DL 《Biological journal of the Linnean Society. Linnean Society of London》2009,98(4):826-838
Evolutionary divergence in behavioural traits related to mating may represent the initial stage of speciation. Direct selective forces are usually invoked to explain divergence in mate‐recognition traits, often neglecting a role for neutral processes or concomitant differentiation in ecological traits. We adopted a multi‐trait approach to obtain a deeper understanding of the mechanisms behind allopatric divergence in the Amazonian frog, Allobates femoralis. We tested the null hypothesis that geographic distance between populations correlates with genetic and phenotypic divergence, and compared divergence between mate‐recognition (acoustic) and ecological (coloration, body‐shape) traits. We quantified geographic variation in 39 phenotypic traits and a mitochondrial DNA marker among 125 individuals representing eight populations. Geographic variation in acoustic traits was pronounced and tracked the spatial genetic variation, which appeared to be neutral. Thus, the evolution of acoustic traits tracked the shared history of the populations, which is unexpected for pan‐Amazonian taxa or for mate‐recognition traits. Divergence in coloration appeared uncorrelated with genetic distance, and might be partly attributed to local selective pressures, and perhaps to Batesian mimicry. Divergence in body‐shape traits was low. The results obtained depict a complex evolutionary scenario and emphasize the importance of considering multiple traits when disentangling the forces behind allopatric divergence. ©2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 826–838. 相似文献
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The genomes of homeothermic (warm-blooded) vertebrates are mosaic
interspersions of homogeneously GC-rich and GC-poor regions (isochores).
Evolution of genome compartmentalization and GC-rich isochores is
hypothesized to reflect either selective advantages of an elevated GC
content or chromosome location and mutational pressure associated with the
timing of DNA replication in germ cells. To address the present controversy
regarding the origins and maintenance of isochores in homeothermic
vertebrates, newly obtained as well as published nucleotide sequences of
the insulin and insulin-like growth factor (IGF) genes, members of a
well-characterized gene family believed to have evolved by repeated
duplication and divergence, were utilized to examine the evolution of base
composition in nonconstrained (flanking) and weakly constrained (introns
and fourfold degenerate sites) regions. A phylogeny derived from amino acid
sequences supports a common evolutionary history for the insulin/IGF family
genes. In cold- blooded vertebrates, insulin and the IGFs were similar in
base composition. In contrast, insulin and IGF-II demonstrate dramatic
increases in GC richness in mammals, but no such trend occurred in IGF- I.
Base composition of the coding portions of the insulin and IGF genes across
vertebrates correlated (r = 0.90) with that of the introns and flanking
regions. The GC content of homologous introns differed dramatically between
insulin/IGF-II and IGF-I genes in mammals but was similar to the GC level
of noncoding regions in neighboring genes. Our findings suggest that the
base composition of introns and flanking regions is determined by
chromosomal location and the mutational pressure of the isochore in which
the sequences are embedded. An elevated GC content at codon third positions
in the insulin and the IGF genes may reflect selective constraints on the
usage of synonymous codons.
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ABSTRACT The acoustic characteristics of an Amazonian lowland rain forest study site in southern Venezuela was analysed to determine environmental constraints upon acoustic communication. Signal degradation was measured by conducting transmission experiments at different heights above ground level. Measurements of ambient noise served to determine possible communication distances for various times of day, heights above ground level and frequencies. “Sound windows” for acoustic long-range communication were found for low frequencies, calling heights in the midstorey and calling in the morning or during the night. Sound attenuation was affected by height and frequency but not by time of day. Background noise varied remarkably with time of day and frequency and had a greater impact on communication distance than signal attenuation. 相似文献
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Roche JA Ford-Speelman DL Ru LW Densmore AL Roche R Reed PW Bloch RJ 《American journal of physiology. Cell physiology》2011,301(5):C1239-C1250
Electroporation (EP) is used to transfect skeletal muscle fibers in vivo, but its effects on the structure and function of skeletal muscle tissue have not yet been documented in detail. We studied the changes in contractile function and histology after EP and the influence of the individual steps involved to determine the mechanism of recovery, the extent of myofiber damage, and the efficiency of expression of a green fluorescent protein (GFP) transgene in the tibialis anterior (TA) muscle of adult male C57Bl/6J mice. Immediately after EP, contractile torque decreased by ~80% from pre-EP levels. Within 3 h, torque recovered to ~50% but stayed low until day 3. Functional recovery progressed slowly and was complete at day 28. In muscles that were depleted of satellite cells by X-irradiation, torque remained low after day 3, suggesting that myogenesis is necessary for complete recovery. In unirradiated muscle, myogenic activity after EP was confirmed by an increase in fibers with central nuclei or developmental myosin. Damage after EP was confirmed by the presence of necrotic myofibers infiltrated by CD68+ macrophages, which persisted in electroporated muscle for 42 days. Expression of GFP was detected at day 3 after EP and peaked on day 7, with ~25% of fibers transfected. The number of fibers expressing green fluorescent protein (GFP), the distribution of GFP+ fibers, and the intensity of fluorescence in GFP+ fibers were highly variable. After intramuscular injection alone, or application of the electroporating current without injection, torque decreased by ~20% and ~70%, respectively, but secondary damage at D3 and later was minimal. We conclude that EP of murine TA muscles produces variable and modest levels of transgene expression, causes myofiber damage due to the interaction of intramuscular injection with the permeabilizing current, and that full recovery requires myogenesis. 相似文献
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Organismic diversity, as well as distributional and ecological patterns, can be fully understood in an evolutionary framework only. Reliable phylogenetic trees are required to ‘read history’, but are not yet available for most marine invertebrate groups. Molecular systematics offers an enormous potential, but still fails for ‘all‐species approaches’ on groups with species that are rare or occur in remote areas only, simply because there is no easily collectable material available for sequence analyses. Exploring morphologically aberrant corambid nudibranch gastropods as a case study, we assess whether or not morphology‐based phylogenetic analyses can fill this gap and produce a tree that allows a detailed view on evolutionary history. Morphology‐based parsimony analysis of corambids and potential relatives resulted in a well‐resolved and remarkably robust topology. As an offshoot of kelp‐associated onchidoridid ancestors, and obviously driven by the heterochronic shortening of life cycles and morphological juvenilization in an ephemeral habitat, the ancestor of corambids originated in cool northern Pacific coastal waters. A basal clade (the genus Loy) diverged there, adapting to live on soft bottoms under successive reversals of paedomorphic traits. The more speciose Corambe lineage radiated preying upon short‐lived encrusting bryozoa in a high‐energy kelp environment. Selection favoured transformation of the mantle into a cuticle‐covered shield, and successive paedomorphic translocations of dorid anal gills to the protected ventral side of the body, where compensatory, multiple gills evolved. Corambe species probably first colonized tropical American seas, and then radiated in worldwide temperate waters: this is explained by the excellent long‐distance dispersal abilities afforded by rafting on kelp, with the subsequent divergence of colonizers in allopatry. The competitive coexistence of Corambe pacifica MacFarland & O'Donoghue, 1929 and Corambe steinbergae (Lance, 1962) off California is the result of independent colonization events. The closing of the Isthmus of Panama separated the latter species from a flock that have radiated within warm Atlantic waters since then. Our case study shows that morphological structures, if investigated in depth, bear the potential for an efficient phylogenetic analysis of groups that are still elusive to molecular analyses. Tracing character evolution and integrating a wide range of geographic, biological, and ecological background information allowed us to reconstruct an evolutionary scenario for corambids that is detailed and plausible, and can be tested by future molecular approaches. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 585–604. 相似文献
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Y Deng J Zhao D Sakurai KM Kaufman JC Edberg RP Kimberly DL Kamen GS Gilkeson CO Jacob RH Scofield CD Langefeld JA Kelly ME Alarcón-Riquelme BIOLUPUS GENLES Networks JB Harley TJ Vyse BI Freedman PM Gaffney KM Sivils JA James TB Niewold RM Cantor W Chen BH Hahn EE Brown PROFILE BP Tsao 《Arthritis research & therapy》2012,14(Z3):A5
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Horizontal transmission, vertical inactivation, and stochastic loss of mariner-like transposable elements 总被引:13,自引:5,他引:8
Horizontal transmission has been well documented as a major mechanism for
the dissemination of mariner-like elements (MLEs) among species. Less well
understood are mechanisms that limit vertical transmission of MLEs
resulting in the "spotty" or discontinuous distribution observed in closely
related species. In this article we present evidence that the genome of the
common ancestor of the melanogaster species subgroup of Drosophila
contained an MLE related to the mellifera (honey bee) subfamily. Horizontal
transmission, approximately 3-10 MYA, is strongly suggested by the
observation that the sequence of the MLE in Drosophila erecta is 97%
identical in nucleotide sequence with that of an MLE in the cat flea,
Ctenocephalides felis. The D. erecta MLE has a spotty distribution among
species in the melanogaster subgroup. The element has a high copy number in
D. erecta and D. orena, a moderate copy number in D. teissieri and D.
yakuba, and was apparently lost ("stochastic loss") in the lineage leading
to D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. In D.
erecta, most copies are concentrated in the heterochromatin. Two copies
from D. erecta, denoted De12 and De19, were cloned and sequenced, and they
appear to be nonfunctional ("vertical inactivation"). It therefore appears
that the predominant mode of MLE evolution is vertical inactivation and
stochastic loss balanced against occasional reinvasion of lineages by
horizontal transmission.
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