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51.
Strong selection on male plumage in a hybrid zone between a hybrid bird species and one of its parents 下载免费PDF全文
Homoploid hybrid speciation (HHS) requires reproductive barriers between hybrid and parent species, despite incomplete reproductive isolation (RI) between the parents. Novel secondary sexual trait values in hybrids may cause prezygotic isolation from both parents, whereas signals inherited by the hybrid from one parent species may cause prezygotic isolation with the other. Here we investigate whether differences in male plumage function as a premating barrier between the hybrid Italian sparrow and one of its parent species, the house sparrow, in a narrow Alpine hybrid zone. Italian sparrow male plumage is a composite mosaic of the parental traits, with its head plumage most similar to its other parent, the Spanish sparrow. We use geographical cline analysis to examine selection on three plumage traits, 75 nuclear single nucleotide polymorphisms (SNPs) and hybrid indices based on these SNPs. Several SNPs showed evidence of restricted introgression in the Alps, supporting earlier findings. Crown colour exhibited the narrowest plumage cline, representing a 37% (range 4–65%) drop in fitness. The cline was too narrow to be due to neutral introgression. Only crown colour was significantly bimodal in the hybrid zone. Bimodality may be due to RI or a major QTL, although fitness estimates suggest that selection contributes to the pattern. We discuss the implications with respect to HHS and the species status of the Italian sparrow. 相似文献
52.
Distinct sources of gene flow produce contrasting population genetic dynamics at different range boundaries of a Choristoneura budworm 下载免费PDF全文
Gwylim S. Blackburn Bryan M. T. Brunet Kevin Muirhead Michel Cusson Catherine Béliveau Roger C. Levesque Lisa M. Lumley Felix A. H. Sperling 《Molecular ecology》2017,26(23):6666-6684
Populations are often exposed to multiple sources of gene flow, but accounts are lacking of the population genetic dynamics that result from these interactions or their effects on local evolution. Using a genomic clines framework applied to 1,195 single nucleotide polymorphisms, we documented genomewide, locus‐specific patterns of introgression between Choristoneura occidentalis biennis spruce budworms and two ecologically divergent relatives, C. o. occidentalis and Choristoneura fumiferana, that it interacts with at alternate boundaries of its range. We observe contrasting hybrid indexes between the two hybrid zones, no overlap in “gene‐flow outliers” (clines showing relatively extreme extents or rates of locus‐specific introgression) and variable linkage disequilibrium among those outliers. At the same time, correlated genomewide rates of introgression between zones suggest the presence of processes common to both boundaries. These findings highlight the contrasting population genetic dynamics that can occur at separate frontiers of a single population, while also suggesting that shared patterns may frequently accompany cases of divergence‐with‐gene‐flow that involve a lineage in common. Our results point to potentially complex evolutionary outcomes for populations experiencing multiple sources of gene flow. 相似文献
53.
Data on dental sex differences in seven of the eight currently recognized subspecies of Colobus guerezareveals a range of expression of sexual dimorphism. Males of most subspecies are larger than females throughout the dentition
and this is especially pronounced for the canines and P
3
For C. g. guerezaand C. g. gallarum,however, sex differences in the canines and P
3
are less pronounced and females are often slightly larger than males in noncanine dental measurements. C. guerezasspp. occupying comparable habitats express similarities in the degree of maxillary canine dimorphism. In addition, for those
subspecies distributed above the equator, there is also a cline of decreasing maxillary canine dimorphism from west to east
in a progressively more northern direction. This cline corresponds to the occupation of increasingly more arid habitats, and
reduced dimorphism is the result of larger maxillary canine size in females. We propose that this pattern of sexual dimorphism
is related to differences in the relative intensity of predation pressure, guereza social organization, and energetic considerations.
That the mandibular canine does not exhibit a similar trend of sexual dimorphism suggests that larger maxillary canines in
females may function as weapons. 相似文献
54.
黑果蝇(D.virilis)自然群体遗传多态研究 总被引:4,自引:0,他引:4
利用9种限制性内切酶对D.virilis兰州群体作了mtDNA的RFLP分析,结合其他地区D.virilis群体的mtDNA的RFLP数据,用UPGMA法构建了聚类图。发现大陆D.virilis聚成明显的3支:兰州和青岛群体、华东群体、福建群体,呈一纬度梯度分布。单纯以地理隔离不能解释D.virilis自然群体间的遗传差异。温度依赖性的选择可能是纬度梯度分布的维持机制。 相似文献
55.
Grow with the flow: a latitudinal cline in physiology is associated with more variable precipitation in Erythranthe cardinalis 下载免费PDF全文
Local adaptation is commonly observed in nature: organisms perform well in their natal environment, but poorly outside it. Correlations between traits and latitude, or latitudinal clines, are among the most common pieces of evidence for local adaptation, but identifying the traits under selection and the selective agents is challenging. Here, we investigated a latitudinal cline in growth and photosynthesis across 16 populations of the perennial herb Erythranthe cardinalis (Phrymaceae). Using machine learning methods, we identify interannual variation in precipitation as a likely selective agent: southern populations from more variable environments had higher photosynthetic rates and grew faster. We hypothesize that selection may favour a more annualized life history – grow now rather than save for next year – in environments where severe droughts occur more often. Thus, our study provides insight into how species may adapt if Mediterranean climates become more variable due to climate change. 相似文献
56.
57.
Ecological biogeography of southern polar encrusting faunas 总被引:2,自引:0,他引:2
58.
59.
JACQUES DUPOUY DIDIER ROUSSEAU GEORGES DUSSART F.L.S. MARC VIANEY LIAUD HENRI NASSI 《Biological journal of the Linnean Society. Linnean Society of London》1993,50(4):329-338
A correspondence analysis of shell measurements taken from 521 widely dispersed specimens of the African aquatic pulmonate snail Biomphalaria pfeifferi suggests the existence of eight morphological groups. These groups appear to relate to either ecophysiological factors or to factors associated with the stability of the freshwater system rather than to aspects of geographic distribution and genetic isolation. 相似文献
60.
Many models for inference of population genetic parameters are based on the assumption that the data set at hand consists of groups displaying within-group Hardy-Weinberg equilibrium at individual loci and linkage equilibrium between loci. This assumption is commonly violated by the presence of within-group spatial structure arising from nonrandom mating of individuals due to isolation by distance (IBD). This paper proposes a model and simulation method implemented in a computer program to flexibly simulate data displaying such patterns. The program permits displaying of smooth spatial variations of allele frequencies due to IBD and more abrupt variations due to presence of strong barriers to gene flow. It is useful in assessing performance of various statistical inference methods and in designing spatial sampling schemes. This is shown by a simulation study aimed at assessing the extent to which IBD patterns affect accuracy of cluster inferences performed in models assuming panmixia. The program is also used to study the effects of spatial sampling scheme (e.g. sampling individuals in clumps or uniformly across the spatial domain). The accuracy of such inferences is assessed in terms of number of inferred populations, assignment of individuals to populations and location of borders between populations. The effect of spatial sampling was weak while the effect of IBD may be substantial, leading to the inference of spurious populations, especially when IBD was strong with respect to the size of the sampling domain. The model and program are new and have been embedded in the R package Geneland, for user convenience and compliance with existing data formats. 相似文献