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1.
Seth W. Coleman Zachary W. Culumber Ashley Meaders Jennifer Henson Gil G. Rosenthal 《Environmental Biology of Fishes》2009,86(2):279-284
Ultraviolet radiation—the primary natural pollutant affecting melanomagenesis—may represent a widespread ecological stressor
for many fishes, and yet the relationship between UV-exposure and stress has not been investigated in natural fish populations.
Recent lab-based studies have sought to characterize the relationship between tumorigenesis and the induction of molecular
defenses, such as heat shock proteins. Here we show that ultraviolet radiation and heat shock protein gene expression explain
a significant amount of the variation in hyper-melanization—the phenotypic precursor to melanoma—in wild hybrids of Xiphophorus, laboratory models in cancer research. Our results suggest exposure to UV radiation causes stress which induces molecular
defense mechanisms, which in turn may facilitate tumorigenesis in natural fish populations. Studies of laboratory-based model
organisms in natural settings, like this one, may provide important insights into ecological and evolutionary relationships
obscured in controlled laboratory environments. We hope that ours is only the first of many studies to investigate the such
relationships between environmental stress, stress-induced molecular defenses, and cancer in fishes. 相似文献
2.
Physaria bellii (Brassicaceae) is a rare, outcrossing perennial endemic to shale and sandstone outcrops along the Front Range of northern
Colorado, USA. This species is locally abundant, but ranked G2/S2—imperiled because of threats to its habitat and a small
number of populations—according to NatureServe’s standardized ranking system. Leaf tissue from ten populations was analyzed
with ISSR (Inter-Simple Sequence Repeat) markers to discern the amount of genetic diversity and degree of population subdivision
in P. bellii. Genetic diversity was moderate (0.22) and a moderately high degree of population structure was found (F
ST calculated using two algorithms ranged from 0.17 to 0.24). An AMOVA partitioned most of the variation among individuals within
populations (76%), and the remainder among populations (24%). Results from a Principal Coordinates analysis were consistent
with the geographic distribution of populations. A Mantel test of the correlation between genetic and geographic distances
was highly significant (P < 0.001). The pattern of variation thus appears to be distributed along a gradient, and efforts to conserve this species
should involve preserving enough populations so that gene flow between populations is not interrupted. 相似文献
3.
Ryan A. Thum Matthew P. Zuellig Robert L. Johnson Michael L. Moody Charles Vossbrinck 《Biological invasions》2011,13(7):1687-1709
Genetic variation is increasingly recognized as an important factor influencing the establishment and spread of introduced
species, and depends on both the introduction history and partitioning of genetic variation within and among potential source
populations. We examine patterns of genetic variation in native and introduced populations of variable leaf watermilfoil,
Myriophyllum heterophyllum, using chloroplast (trnL-F) and ribosomal (ITS) DNA sequences, as well as amplified fragment length polymorphisms (AFLPs). We identify a strong phylogeographic
break distinguishing populations located on the Atlantic Coastal Plain (ACP) versus other (“Continental”) portions of the
native range. Within these distinct biogeographic regions, we also find genetic variation to be strongly partitioned among
populations as analysis of molecular variance (AMOVA) partitioned 91 and 75% of cpDNA and ITS diversity among populations,
respectively. We demonstrate that the introduced ranges of variable leaf watermilfoil (northeastern and western US) result
from multiple independent introductions from a variety of source populations, including lineages from both the ACP and Continental
portions of the native range. In addition, we used our molecular markers to demonstrate that variable leaf watermilfoil is
genetically distinct from three closely-related species that it is morphologically similar to. In particular, we demonstrate
that M. heterophyllum is clearly distinct from a morphologically similar native species in the western US, M. hippuroides—whose distinctiveness from M. heterophyllum has been questioned—and therefore confirm the introduction of M. heterophyllum in the western US. Furthermore, we provide the first evidence for hybridization between these two species. Finally, our molecular
markers identify previously unrecognized genetic variation in these four species, and therefore demonstrate the need for further
taxonomic investigation. 相似文献
4.
Cedrus libani of Lebanon is a valuable natural resource and the dominant species in its natural ecosystem. Intense and diverse anthropogenic
pressures over historical times raised concerns about its genetic vigor and continued survival. Our investigation of the genetic
diversity included samples from all remnant natural populations. Assessment of the genetic diversity using random amplified
polymorphic DNA markers revealed the persistence of considerable variation distributed within populations with low population
differentiation corroborated by Bayesian and analysis of molecular variance estimates (G
ST = 0.07, Φ
ST = 0.09). Individual assignment tests were carried out to investigate measures of gene flow. Inferences concluded that this
natural heritage is not currently threatened by inbreeding or by random genetic drift. Correlation studies investigated possible
effects of spatial distribution and environmental conditions on genetic structure. A climatic trend corresponding to a temperature–humidity
gradient correlated significantly with the level of genetic diversity, while the edaphic variation did not. 相似文献
5.
Genetic diversity and population structure of Lamiophlomis rotata (Lamiaceae), an endemic species of Qinghai–Tibet Plateau 总被引:1,自引:0,他引:1
Lamiophlomis rotata (Lamiaceae), a perennial medicinal herb, is endemic to the Qinghai–Tibet Plateau. A total of 188 individuals from eight natural
populations of L. rotata in Qinghai–Tibet Plateau (four from Tibet, two from Yunnan, and two from Qinghai) were analyzed using intersimple sequence
repeats (ISSR) and randomly amplified polymorphic DNA (RAPD) techniques. Our results revealed that the level of genetic variation
in L. rotata was relatively high (P = 94.85%, I = 0.440 ± 0.220, H
T
= 0.289 ± 0.028). Three genetic groups corresponding to the three geographic regions were detected, suggesting significant
geographic structure. Our results suggest that the highly structured geographic pattern found in L. rotata might represent diverging evolutionary processes associated with the uplifting of the Qinghai–Tibet Plateau and Quaternary
climatic oscillations. These findings imply that as many populations as possible should be preserved in situ for the conservation
of this species. Given their genetic variability and peripheral distribution, Qinghai and Yunnan populations should be assigned
priority for conservation. Optimal harvesting strategies, domestication and tissue culture of L. rotata should be developed as soon as possible to guarantee its sustainable use. 相似文献
6.
7.
Anastasia Imsiridou Alexandros Triantafyllidis Athanasios D. Baxevanis Costas Triantaphyllidis 《Biologia》2009,64(4):781-785
Wild common carp from two lakes and two rivers in Greece were genetically characterized with sequencing analysis of two mitochondrial
DNA segments: cytochrome b (1119 bp) and D-loop (646 bp). A total of 9 variable singleton sites and 7 unique haplotypes were detected. A common haplotype was found in three
out of the four populations examined, which seems to be the ancestral one and represents the European origin of common carp
from Greece. This haplotype could be also justified by the introductions reported with individuals belonging to the Central
European race, into many natural habitats in Greece. Limited genetic variation — in Evros and Aliakmonas populations — could
be due to bottleneck effects and small effective population sizes, whereas the different haplotypes found in Lake Volvi could
represent different common carp stocks. Values of sequence divergence among Greek haplotypes ranged from 0.0006 to 0.0023.
The Neighbour-Joining (NJ) phylogenetic tree constructed based on the combined sequences, reveals that the populations of
common carp from Greece belong to the European group of populations — which is highly divergent from the South East-Asia cluster
— and to the subspecies Cyprinus carpio carpio. 相似文献
8.
L. V. Frisman K. V. Korobitsyna L. V. Yakimenko A. I. Munteanu K. Moriwaki 《Russian Journal of Genetics》2011,47(5):590-602
Genetic differentiation and gene geographic variation of house mouse from the territory of Russia and neighboring countries
was examined based on the allozyme analysis of samples from natural, semisynanthropic, and obligate synanthropic populations.
The results of analysis of genetic differentiation, performed using 22 interpreted loci, as well as the data on gene geographic
variation of four allozyme markers (Idh-1, Sod-1, Aat-1, and hemoglobin) validated the hypothesis on rapid mice expansion from the south of Eastern Europe to the Pacific coast of Asia. It was demonstrated
that moving eastwards led to the formation currently expanding zones of hybridization between the “northern” M. musculus group and the “Central Asian” M. wagneri group in Siberia, and with the M. m. castaneus group in the south of the Russian Far East. The allozyme data were compared with the data of molecular genetic and karyological
analyses performed using the same experimental material. The phenomenon of hybrid zones of the house mouse from Eurasia is
discussed. 相似文献
9.
Baoying Guo Congxin Xie Shunping He Khalid Abbas Huanling Wang Dongmei Xiong Huijuan Zhang Xin Tong 《Environmental Biology of Fishes》2009,85(3):201-206
We determined the genetic diversity of geographic populations from three spawning grounds (Nyang River, Lhasa River, Shetongmon
Reach of Yarlung Zangbo River) of Glyptosternum maculatum with amplified fragment length polymorphism (AFLP) markers. Five primer combinations detected 332 products, 51 of them (15.4%)
were polymorphic in at least one population. The Shetongmon population was found to be the richest in genetic diversity as
was indicated by the percentage of polymorphic loci and heterozygosity, followed by the Nyang population and the Lhasa population.
The pair-wise genetic distance between populations were all very close, ranging from 0.0015 to 0.0042 with an average of 0.0024.
The genetic distance was not proportional to the geographic distance. The analysis of molecular variance demonstrated that
all variation occurred within populations. The average estimated fixation index (F
st) of three populations across all polymorphic loci was −0.0184, indicating the absence of genetic differences among the three
sampled populations. The differentiation among populations was not significant, and population structure was weak. Our observations
will help identify the genetic relationship among populations as the first approach to understand the genetic diversity of
Glyptosternum maculatum. 相似文献
10.
Anastrepha fraterculus is an important pest of commercial fruits in South America. The variability observed for morphological and behavioural traits
as well as genetic markers suggests that A. fraterculus represents a complex of synmorphic species rather than a single biological species. We studied the correlation between geographical
distribution and genetic variation in natural populations from Argentina and south Brazil. Fragments of the mitochondrial
gene COII were sequenced in 28 individuals. The matrix of aligned sequences was phylogenetically analysed by parsimony, yielding
a cladogram of haplotypes. Based on Templeton’s nested method, no clade showed any geographic pattern for the gene COII, indicating
lack of significant association between haplotypic variability and geographic distribution. The analysis of nucleotide substitution
distances by Neighbour-Joining algorithm showed that geographically distant populations exhibit low genetic distances. The
corresponding trees clustered the populations without showing any geographic pattern. This result suggests that the populations
studied are not reproductively isolated. 相似文献
11.
Eucalyptus camaldulensis is one of the most widely utilised eucalypts. It is also the only eucalypt that occurs across the Australian continent, playing
a key ecological role as fauna habitat and in riverbank stabilisation. Despite its ecological and economic importance, uncertainty
remains regarding the delineation of genetic and morphological variants. Nine hundred and ninety trees from 97 populations,
representing the species’ geographic range were genotyped using 15 microsatellite loci and patterns of diversity compared
with restriction fragment length polymorphisms in 29 of these populations. Both markers showed that despite having a riverine
distribution, downstream seed dispersal has had less influence than geographic distance on dispersal patterns. Spatial patterns
in the distribution of microsatellite genotypes were compared with environmental parameters and boundaries defined by river
systems, drainage basins and proposed subspecies. Significant genetic differences among populations within river systems indicated
that rivers should not be treated as a single genetic entity in conservation or breeding programmes. Strong geographic trends
were evident with 40% of variation in genetic diversity explained by latitude and moisture index. Isolation by distance and
significant correlations between genetic distance and environmental parameters for most loci suggest historical factors have
had more influence than selection on current patterns of distribution of genetic diversity. Geographic structuring of molecular
variation, together with congruence between genetic and morphological variation indicate that E. camaldulensis should be treated as a number of subspecies rather than a single variable taxon. High levels of genetic diversity and geographic
trends in the distribution of variation provide a firm basis for further exploration of the species’ genetic resources. 相似文献
12.
In ectotherms, variation in life history traits among populations is common and suggests local adaptation. However, geographic variation itself is not a proof for local adaptation, as genetic drift and gene flow may also shape patterns of quantitative variation. We studied local and regional variation in means and phenotypic plasticity of larval life history traits in the common frog Rana temporaria using six populations from central Sweden, breeding in either open‐canopy or partially closed‐canopy ponds. To separate local adaptation from genetic drift, we compared differentiation in quantitative genetic traits (QST) obtained from a common garden experiment with differentiation in presumably neutral microsatellite markers (FST). We found that R. temporaria populations differ in means and plasticities of life history traits in different temperatures at local, and in FST at regional scale. Comparisons of differentiation in quantitative traits and in molecular markers suggested that natural selection was responsible for the divergence in growth and development rates as well as in temperature‐induced plasticity, indicating local adaptation. However, at low temperature, the role of genetic drift could not be separated from selection. Phenotypes were correlated with forest canopy closure, but not with geographical or genetic distance. These results indicate that local adaptation can evolve in the presence of ongoing gene flow among the populations, and that natural selection is strong in this system. 相似文献
13.
Measurement of metabolic rates (made at 10°C) of individuals of the springtail Cryptopygus antarcticus travei from six geographically distinct populations on sub-Antarctic Marion Island were combined with mitochondrial DNA (COI) haplotype
analysis to examine in parallel both physiological and genetic variation of distinct populations. We found evidence of genetic
differentiation among populations and a general indication of long-term isolation with limited gene flow. While we found support
for an overall pattern of metabolic rate structure among populations from different geographic locations on the island (mean
rate = 0.0009–0.0029 μl O2 μg−1 h−1 for populations of a mean individual mass of 8–26 μg), we were unable to demonstrate a coherent common pattern between this
and genetic variation. However, spatial structure in metabolic rate variation was strongly related to the extent of variability
in microclimate among sites, and also showed some indication of a phylogeographic signal. Thus, over the relatively short
timescale of Marion Island’s history (<1 million years), the periodic geographic barriers that have driven population differentiation
from a molecular perspective may also have resulted in some physiological differentiation of populations. 相似文献
14.
The intraspecific phylogeography of Grant’s gazelles Nanger granti was assessed with mitochondrial DNA control region sequences. Samples of 177 individuals from 17 Kenyan and Tanzanian populations
were analysed. Three highly divergent, reciprocally monophyletic lineages were found, with among group net nucleotide distances
of 8–12%. The three lineages—notata, granti and petersii—grouped populations according to their geographic origin, encompassing populations in the north, southwest, and east, respectively.
The mtDNA lineages reflected distinct evolutionary trajectories, and the data are discussed in reference to the four currently
recognised subspecies. We suggest Grant’s gazelles be raised to the superspecies Nanger (granti) comprising three taxonomic units corresponding to the three mtDNA lineages. There was no evidence of gene flow between the
notata and granti lineages, despite their geographic proximity, suggesting reproductive isolation. These constitute evolutionary significant
units within the adaptive evolutionary framework. Due to its restricted geographic distribution and genetic and morphological
distinctiveness, we suggest the petersii lineage be raised to the species Nanger (granti) petersii within the Grant’s gazelles superspecies. 相似文献
15.
Daniel B. Thompson 《Evolution; international journal of organic evolution》1990,44(4):952-965
Patterns of geographic variation in tree-climbing ability of Peromyscus maniculatus were used to examine the influence of spatial variation in natural selection and gene flow on the genetic divergence of climbing behavior among populations. Offspring of adults of two subspecies sampled from 10 localities in montane conifer forest, conifer woodland, and desert scrub/grassland habitats were raised in the laboratory and tested to determine their tree-climbing ability (the maximum diameter artificial rod that a mouse could climb). Comparisons of mean rod-climbing scores revealed that individuals of P. m. rufinus sampled from montane conifer forest and conifer woodland in Arizona were better climbers than P. m. sonoriensis sampled from conifer woodland and desert habitats in Nevada. This result was consistent with the hypothesis that natural selection has produced large-scale adaptation in climbing behavior. However, the climbing ability of P. m. sonoriensis sampled from conifer woodland habitats on isolated mountaintops in Nevada has not evolved in response to natural selection to the degree expected. In addition, populations sampled from desert grassland habitat, adjacent to woodland P. m. rufinus in Arizona, have climbing abilities that are not significantly different from conifer woodland populations. These observations indicate that local adaptation was constrained. An estimate of the heritability of climbing ability (h2 = 0.352 ± 0.077) indicates that lack of a response to selection was not due to the absence of additive genetic variation. In addition, regressions of interpopulation differences on the degree of geographic isolation between pairs of populations do not support the hypothesis that gene flow between habitats has constrained evolution. Instead, a combination of historical events and insufficient time to respond to selection appears to have influenced geographic variation and the spatial scale of adaptation in climbing ability. 相似文献
16.
Carlo Rodolfo Largiadr Christian Peter Klingenberg Manfred Zimmermann 《Journal of evolutionary biology》1994,7(6):697-712
Two morphologically distinct subspecies of Gerris costae form a contact zone extending from the Maritime to the Western Alps. Within this area canonical trend surface analysis revealed a geographic pattern of morphometric variation consistent with topography. From North to South, and from high to low elevation there was a transition from G. c. costae-like phenotypes to phenotypes resembling pure G. c. fieberi. The same pattern was confirmed with canonical variate analysis not taking geographic location into account; it is therefore not an artifact of trend surface analysis. Comparisons of the pattern of morphometric variation of laboratory-reared offspring with the pattern of their parents sampled from natural populations show that geographic variation is mostly determined genetically. Intermediate individuals from field populations probably are natural hybrids between the two subspecies, because laboratory-reared hybrids were intermediate between the offspring of pure strains. We did not find increased morphometric variation within the contact zone. This suggests unimpeded introgression and is in contrast with an increase in size variability that is predicted to be associated with a transition between uni- and bivoltine forms. 相似文献
17.
Genetic differentiation,gene flow and the origin of infestations of the medfly,Ceratitis capitata 总被引:2,自引:0,他引:2
Gasperi G Bonizzoni M Gomulski LM Murelli V Torti C Malacrida AR Guglielmino CR 《Genetica》2002,116(1):125-135
The genetic structure of natural populations of the economically important dipteran species Ceratitis capitatawas analysed using both biochemical and molecular markers. This revealed considerable genetic variation in populations from different geographic regions. The nature of this variation suggests that the evolutionary history of the species involved the spread of individuals from the ancestral African populations through Europe and, more recently, to Latin America, Hawaii and Australia. The observed variation can be explained by various evolutionary forces acting differentially in the different geographic areas, including genetic drift, bottleneck effects, selection and gene flow. The analysis of the intrinsic variability of the medfly's genome and the genetic relationships among populations of this pest is a prerequisite for any control programme. 相似文献
18.
Christoph Reisch 《Conservation Genetics》2007,8(4):893-902
In contrast to many declining plant species Saxifraga tridactylites extended its distribution range in the man-made landscape of central Europe. The species naturally colonizes rocks and calcareous
grasslands, but has also spread enormously in anthropogenic habitats such as railway constructions during the last decades.
To analyze the genetic structure of the species 216 individuals from 8 populations in natural and 5 populations in man-made
habitats were studied using AFLPs. The molecular analysis resulted in 250 scorable fragments. Population variability, measured
as Nei’s gene diversity, Shannon’s Information Index and percentage of polymorphic bands, was slightly but not significantly
higher in populations from natural habitats and was not correlated with population size. Mantel test indicated no significant
correlation between pairwise genetic (ΦPT) and geographic distances. An analysis of molecular variance revealed significant differentiation between the two habitat
types. About 9% variability were observed between natural and man-made habitats, 21% among populations within these two habitats
and 70% within populations. In a neighbour joining cluster analysis populations from natural and man-made habitats were clearly
separated from each other. Populations of S. tridactylites from man-made habitats do, therefore, not suffer from reduced genetic diversity. The observed genetic differentiation between
populations from man-made and natural habitats could be due to reduced gene flow and/or habitat specific selection. However,
the results of the study clearly demonstrate human impact on the genetic structure of plant populations in man-made landscapes. 相似文献
19.
Takeshi Kikko Yoshiaki Kai Masayuki Kuwahara Kouji Nakayama 《Ichthyological Research》2008,55(2):141-147
The genetic variations—and the time dependence of such variations—of natural populations of the white-spotted charr ,Salvelinus leucomaenis, in the Lake Biwa water system as well as those of a hatchery-reared population were inferred from AFLP. Upon the application
of principal coordinate analysis using 118 polymorphic AFLP fragments based on the Jaccard similarity index, specimens of
each of six natural local populations from the inlet rivers of Lake Biwa grouped roughly together, suggesting that each local
population was genetically differentiated. The hatchery-reared population was shown to be closely related to the local population
in the Seri River, suggesting that the Seri River population originated from hatchery-reared charr due to extensive stocking.
Furthermore, specimens of the Yasu River grouped in a somewhat different position from the other natural populations, agreeing
well with its geographic distance from the other populations. The nucleotide diversities of six natural populations (Harihata
River, Ishida River, two reaches of the Takatoki River, Ane River, and Yasu River) in 2002 or 2003 were relatively low (π = 0.067–0.146%)
compared with that of the Seri River (0.278%) and the hatchery-reared charr (0.316%). The nucleotide diversity in the five
local populations (Ishida River, two reaches of the Takatoki River, Ane River, and Yasu River) remained at a low level from
1994 to 2002/2003, but only the nucleotide diversity in the Harihata River actually decreased. From 1994 to 2002/2003, the
nucleotide diversity in the Seri River remained at a higher level among the natural populations from 1994 to 2002/2003; it
was enhanced by the artificial release of hatchery-reared charr before 1994. In order to conserve the genetic diversity of
the white-spotted charr in the Lake Biwa water system, it is necessary to prevent the stocking of hatchery-reared charr in
reaches where hatchery-reared charr have not previously been stocked. 相似文献
20.
Rodrigo Scheihing Pedro Labarca Leyla Cardenas Roberto F. Nespolo 《Hydrobiologia》2011,671(1):193-203
One of the most important research topics in evolutionary ecology is body size evolution. Actually, several hypotheses have
been proposed to explain the many observed patterns—also known as “rules”—of body size variation in across latitude, temperature,
and time. The temperature–size rule (TSR), describes an inverse relationship between body size and temperature. We took advantage
of the “natural laboratory” that the crustacean populations at the Chilean altiplano offers, to study the TSR in ostracods.
We studied three populations of Limnocythere atacamae that are physically separated by several kilometers, and differ mainly by their permanent thermal regime. We found larger
individuals in the hotspring compared to the cold ponds. Also, in the hotspring we found a significant quadratic selection
coefficient, suggesting stabilizing selection in this population. The fitness profiles showed stabilizing selection in the
hotspring, and positive directional selection in the ponds. Our results suggest the existence of an optimal body size above
the population means. This optimal size is apparently attained in the hotspring population. Then, natural selection appears
to be promoting a shift in the mean phenotype that, for some reason, is not attained in the cold environments. Genetic slippage
and population bottleneck would explain this absence of response to selection. 相似文献