Natural Hybridization as an Evolutionary Process

Arnold, Michael L.

doi:10.1146/annurev.ecolsys.23.1.237

Cited by 272 publications

(356 citation statements)

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“…In order to reduce the risk of outbreeding depression, conservationists commonly agree to prevent mating between distantly related individuals from geographically distinct conspecific populations or subspecies (Arnold 1992;Roques et al 2001). In contrast to this, our data (this study) and that of Pitra et al (2002) suggest that intraspecific outbreeding actually happens in nature when individuals from distinct populations/lineages meet.…”

Section: Conservation Implicationscontrasting

confidence: 83%

Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

et al. 2006

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Phylogeographic and population genetic studies using sequence information are frequently used to infer species boundaries and history; and to assess hybridization and population level processes. In this study, partial mitochondrial DNA (mtDNA) control region (423 bp) and cytochrome b sequences (666 bp) of Oryx beisa sampled from five isolated localities in its entire current range in Africa were analyzed to investigate the extent of genetic variation and differentiation between populations. We observed high nucleotide diversity at the control region in the total sample (6.3%) but within populations, it varied considerably ranging from 1.6% to 8.1%. Population pairwise genetic differentiation was generally significantly high (ranging from F ST = 0.15, P<0.01 to F ST = 0.54, P<0.001). In the total sample, 29 and 12 haplotypes were observed in the control region and the cytochrome b data sets respectively. For both data sets, the haplotypes cluster into three distinct clades (sequence divergence ranged from 6.0%-12.9% to 0.8%-1.0% for the control region and cytochrome b sequences, respectively) that do not correspond to sampling locations. Two of these clades are found in the same localities (Samburu and Marsabit), which represent the O.beisa beisa subspecies, whereas the last clade represents the fringe-eared oryx (O. beisa callotis). We interpret these findings in terms of an ancient hybridization and introgression between two formerly isolated taxa of Oryx beisa.

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Section: Conservation Implicationscontrasting

confidence: 83%

Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

et al. 2006

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“…Given that it has been over 20 years since hybrids were first described in these populations, it is just as likely that these individuals are the result of selfing or backcrossing. In many systems with documented high degrees of hybridization, the majority of individuals were backcrossed or selfed hybrids rather than original F 1 hybrids (Arnold 1992(Arnold , 1997Cruzan and Arnold 1994;Nason et al 1992;Rieseberg 1995).…”

Section: Discussionmentioning

confidence: 99%

Using genetic and morphological analysis to distinguish endangered taxa from their hybrids with the cultivated exotic pest plant Lantana strigocamara (syn: Lantana camara)

2010

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Because highly invasive species can rapidly assimilate rare taxa, we questioned whether two Florida endangered Lantana depressa varieties existed 21 years after Sanders documented their widespread hybridization with exotic Lantana strigocamara, and whether morphological traits could accurately discriminate genetic individuals. Stepwise discriminant analysis of morphological characters discriminated the three taxa, correctly classifying 98, 91, 89% of L. strigocamara, L. depressa var. depressa, and var. floridana. Hybrids blurred taxonomic distinctions of varieties and reduced classification accuracy by 7-17%. Species-specific Random Fragment Length Polymorphism (RFLP-PCR) confirmed hybridization has occurred. Intersimple Sequence Repeat (ISSR) fingerprints analyzed with STRUCTURE identified three groups indicating introgression. Morphological traits significantly, but weakly correlated with q ratios (P = 0.0001; r 2 = 0.45). Although L. strigocamara introgression is widespread and ongoing, wild populations contain individuals that are predominantly L. depressa genome, supporting actions to remove adventive L. strigocamara, prevent its sale, and promote sales of genetically confirmed natives.

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“…If these plants can self, which seems likely as both parental species can and do, then it is possible that a proportion of those individuals with an F 1 hybrid RFLP-PCR pattern are also second generation of hybrid origin. Previous studies have found that even in systems in which there is a high level of hybridization, the majority of individuals present in the population have arisen due to backcrossing or selfing rather than from F 1 hybrids crosses (Arnold 1992(Arnold , 1997Cruzan and Arnold 1994;Nason et al 1992;Reiseberg 1995). The presence of backcrossed and/or selfed individuals increases the likelihood of genetic assimilation, making the identification of hybrids even more difficult in future generations (Rhymer and Simberloff 1996).…”

Section: Discussionmentioning

confidence: 99%

Hybridization between the threatened plant, Lespedeza leptostachya Englem. and its co-occurring congener Lespedeza capitata Michx.: morphological and molecular evidence

et al. 2010

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Natural hybridization is common in the genus Lespedeza. No hybrids between Lespedeza leptostachya Englem. and Lespedeza capitata Michx. are formally recognized in any of the current floras, however observations in the field suggest that hybridization might occur in many of their shared habitats. Putative hybrids were compared to L. leptostachya and L. capitata using morphological measurements and screened for the presence of species-specific trnL-F gene region (cpDNA) and the ITS gene region (nrDNA). A discriminate analysis of 10 morphological measurements identified the hybrids as intermediate to both parents with two PCA axes explaining 99% of the variation between taxa. The presence of hybrids was confirmed by genetic markers with individuals morphologically identified as hybrids having cpDNA trnL-F genotypes identical to L. leptostachya and the ITS (nrDNA) phenotypes in most cases contain the ITS genotype of both parents, however, some putative hybrid individuals contained the ITS genotype of only one parents. Those individuals with L. leptostachya ITS and trnL-F could be a case of misclassification, but the presence of both L. capitata ITS genotypes and L. leptostachya trnL-F genotypes suggest segregation has occurred, which may result from either selfing or backcrossing.

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Natural Hybridization as an Evolutionary Process

Cited by 272 publications

References 0 publications

Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

Using genetic and morphological analysis to distinguish endangered taxa from their hybrids with the cultivated exotic pest plant Lantana strigocamara (syn: Lantana camara)

Hybridization between the threatened plant, Lespedeza leptostachya Englem. and its co-occurring congener Lespedeza capitata Michx.: morphological and molecular evidence

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