Genetic divergence and units for conservation in the Komodo dragon Varanus komodoensis

Ciofi, Claudio; Beaumont, Mark A.; Swingland, Ian R.; Bruford, Michael William

doi:10.1098/rspb.1999.0918

Cited by 195 publications

(254 citation statements)

References 32 publications

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“…We selected the most likely number of clusters given the data by choosing the number of clusters where we observed the largest difference in log likelihoods (DK) (Evanno et al, 2005). Finally, the overall pattern of population genetic structure among regions was assessed with a Bayesian approach developed by Ciofi et al (1999) and implemented in the program 2MOD by MA Beaumont (http://www.rubic.rdg.ac.uk/~mab/software.html). Two models are evaluated: (1) the gene flow model, which assumes that gene frequencies within populations are caused by a balance between genetic drift and gene flow, and (2) the drift model, in which allele frequencies within populations are evolving purely through drift.…”

Section: Patterns Of Population Subdivisionmentioning

confidence: 99%

Mito-nuclear discordance in the degree of population differentiation in a marine goby

et al. 2010

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An increasing number of phylogeographic studies on marine species shows discordant patterns in the degree of population differentiation between nuclear and mitochondrial markers. To understand better which factors have the potential to cause these patterns of discordance in marine organisms, a population genetic study was realized on the sand goby Pomatoschistus minutus (Pallas 1770; Gobiidae, Teleostei). Sand gobies from eight European locations were genotyped at eight microsatellite markers. Microsatellites confirmed the global phylogeographical pattern of P. minutus observed with mitochondrial DNA (mtDNA) markers and nuclear allozyme markers. Three groups consistent with the mitochondrial lineages were defined (the Mediterranean, Iberian and North Atlantic groups) and indications of a recent founder event in the northern Baltic Sea were found. Nevertheless, differences in the degree of population differentiation between the nuclear and mitochondrial markers were large (global F ST -values for microsatellites ¼ 0.0121; for allozymes ¼ 0.00831; for mtDNA ¼ 0.4293). Selection, sex-biased dispersal, homoplasy and a high effective population size are generally accepted as explanations for this mitonuclear discrepancy in the degree of population differentiation. In this study, selection on mtDNA and microsatellites, male-biased dispersal and homoplasy on microsatellite markers are unlikely to be a main cause for this discrepancy. The most likely reason for the discordant pattern is a recent demographical expansion of the sand goby, resulting in high effective population sizes slowing down the differentiation of nuclear DNA.

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Section: Patterns Of Population Subdivisionmentioning

confidence: 99%

Mito-nuclear discordance in the degree of population differentiation in a marine goby

et al. 2010

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“…In the drift model (corresponding to our model 2) it is assumed that an ancestral panmictic population is separated into several independent units which start diverging purely by genetic drift, whereas the gene-flow model assumes that the gene frequencies within subpopulations are determined by a balance between genetic drift and immigration (corresponding to models 3-5). The program uses a coalescent theory and a Markov's chain Monte Carlo simulation approach with Metropolis-Hastings sampling to explore the alternative models, as described in Ciofi et al (1999). Two independent simulations with 100 000 iterations were carried out to check the convergence of the posterior probabilities of the models.…”

Section: Population Structurementioning

confidence: 99%

“…In order to analyse whether or not there has been any gene flow between the subpopulations, we used the program 2MOD (Ciofi et al 1999) to estimate the relative likelihoods of drift vs. immigration models since a certain time. In the drift model (corresponding to our model 2) it is assumed that an ancestral panmictic population is separated into several independent units which start diverging purely by genetic drift, whereas the gene-flow model assumes that the gene frequencies within subpopulations are determined by a balance between genetic drift and immigration (corresponding to models 3-5).…”

Section: Population Structurementioning

confidence: 99%

Genetic structure and gene flow in an endangered perennial grass, Arctophila fulva var. pendulina

et al. 2005

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Arctophila fulva var. pendulina is a rare endemic perennial grass confined to seashore and riverbank meadows around the Bothnian Bay, the northernmost part of the Baltic Sea. The number of A. fulva populations has decreased during the last few decades in Finland and Sweden, and nowadays there are only eight populations left in the drainage area of the Bothnian Bay. We investigated the distribution of genetic variation within and between six subpopulations in the largest remaining population at Liminka Bay, Finland, using amplified fragment length polymorphism (AFLP) markers. Relatively high amounts of variation were found in the subpopulations, the mean Nei's expected heterozygosity being typical (0.267) for an outcrossing species. Despite the fact that no seedlings or viable seeds of A. fulva have been found in the previous field studies, the observed high genotypic diversity suggested that sexual reproduction has played an important role at some time during the history of the studied A. fulva population. Analysis of population structure revealed a low level of genotypic differentiation (U ST =0.046) between subpopulations, and also significant sub-structuring within subpopulations. Isolation-by-distance between subpopulations was present on scales larger than 1 km. The overall pattern of genetic variation within and between subpopulations suggest that the population has characters of both stepping-stone and metapopulation models. Because our results suggested that subpopulations are more or less ephemeral, the conservation and management effort in this species should be targeted to conservation of the required habitat of the species instead of extant subpopulations.

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“…Demographic history was assessed using BOTTLENECK [31] and MSVAR v. 1.3 [32] with various priors (electronic supplementary material, tables S5 and S6). Evolution under gene flow versus drift was tested with 2MOD [33].…”

Section: (V) Microsatellite Loci Genotyping Of San Cristóbal Marine Imentioning

confidence: 99%

Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana

et al. 2015

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The effects of the direct interaction between hybridization and speciation-two major contrasting evolutionary processes-are poorly understood. We present here the evolutionary history of the Galápagos marine iguana (Amblyrhynchus cristatus) and reveal a case of incipient within-island speciation, which is paralleled by between-island hybridization. In-depth genome-wide analyses suggest that Amblyrhynchus diverged from its sister group, the Galápagos land iguanas, around 4.5 million years ago (Ma), but divergence among extant populations is exceedingly young (less than 50 000 years). Despite Amblyrhynchus appearing as a single long-branch species phylogenetically, we find strong population structure between islands, and one case of incipient speciation of sister lineages within the same island-ostensibly initiated by volcanic events. Hybridization between both lineages is exceedingly rare, yet frequent hybridization with migrants from nearby islands is evident. The contemporary snapshot provided by highly variable markers indicates that speciation events may have occurred throughout the evolutionary history of marine iguanas, though these events are not visible in the deeper phylogenetic trees. We hypothesize that the observed interplay of speciation and hybridization might be a mechanism by which local adaptations, generated by incipient speciation, can be absorbed into a common gene pool, thereby enhancing the evolutionary potential of the species as a whole.

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Genetic divergence and units for conservation in the Komodo dragon Varanus komodoensis

Cited by 195 publications

References 32 publications

Mito-nuclear discordance in the degree of population differentiation in a marine goby

Mito-nuclear discordance in the degree of population differentiation in a marine goby

Genetic structure and gene flow in an endangered perennial grass, Arctophila fulva var. pendulina

Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana

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