The characterisation and identification of a naturally occurring hybrid in the genusLeucaena (Leguminosae: Mimosoideae)

Hughes, Colin E.

doi:10.1007/bf00986251

Cited by 15 publications

(12 citation statements)

References 46 publications

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“…Many L. ϫ mixtec trees are reported to have grown from seed purchased as ''guaje verde'' (L. leucocephala), which were either sown deliberately or discarded in backyards. This finding is in line with evidence that most L. ϫ mixtec individuals had L. leucocephala as the female parent (28). Although it is of no use for food, this hybrid provides tangible evidence of spontaneous backyard hybridization and the complex and serendipitous pathways by which such spontaneous hybrids may be disseminated, often unwittingly, via backyards and kitchen middens.…”

Section: Resultssupporting

confidence: 70%

“…2). This finding is as expected for triploids between tetraploid L. leucocephala, itself with two divergent sequence types, and one of two diploid species from the L. esculenta clade (26,28). Spontaneous backyard hybridization in Leucaena was first suggested by the sporadic, but widespread, occurrence of this hybrid in six states in S-C Mexico (28) (Figs.…”

Section: Resultsmentioning

confidence: 61%

“…Artificial crossing experiments have shown that crossability among species is high (27). In addition, two named hybrids, L. ϫ mixtec, a putative sterile triploid between tetraploid L. leucocephala and diploid L. esculenta, and L. ϫ spontanea, a putative fertile hybrid between tetraploid L. leucocephala and L. diversifolia, have been proposed (26,28,29). Furthermore, several other putative hybrids found growing in backyards in south-central (S-C) Mexico (Fig.…”

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confidence: 99%

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Serendipitous backyard hybridization and the origin of crops

Hughes

Govindarajulu

Robertson

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Backyard gardens, dump heaps, and kitchen middens are thought to have provided important venues for early crop domestication via generation of hybrids between otherwise isolated plant species. However, this process has rarely been demonstrated empirically. For the majority of polyploid crops, it remains uncertain to what extent hybridization and polyploidization preceded domestication or were precipitated by human activities. Using archaeological, ethnobotanical, geographical, and genetic data, we investigate the extent and significance of predomestication cultivation, backyard sympatry, and spontaneous hybridization for the Mimosoid legume tree Leucaena, which is used as a food crop throughout south-central Mexico. We show that predomestication cultivation was widespread, involved numerous independent transitions from the wild to cultivation, and resulted in extensive artificial sympatry of 2-6 species locally and 13 species in total. Using chloroplast and rapidly evolving nuclear-encoded DNA sequences, we demonstrate that hybridization in Leucaena has been extensive and complex, spawning a diverse set of novel hybrids as a result of juxtaposition of species in cultivation. The scale and complexity of hybridization in Leucaena is significantly greater than that documented for any other Mexican plant domesticates so far. However, there are striking parallels between Leucaena and the other major Mexican perennial domesticates Agave and Opuntia, which show very similar domestication via backyard hybridization pathways. Our results suggest that backyard hybridization has played a central role in Mesoamerican crop domestication and demonstrate that the simple step of bringing species together in cultivation can provide a potent trigger for domestication.domestication ͉ Leguminosae ͉ Leucaena ͉ Mesoamerica

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 61%

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confidence: 99%

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Serendipitous backyard hybridization and the origin of crops

Hughes

Govindarajulu

Robertson

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…However, parallel to diffusion, independent cultivation of stands along the distribution range of wild populations, and even along the range of cultivation (planting) increases genetic variation (Blumler 1992), differentiation, and adequacy of cultigens to a range of environments. This complements with gene flow across land races and even subspecies or species (Hughes and Harris 1994).…”

Section: The Role Of Dispersalmentioning

confidence: 90%

Genetics of Wild and Managed Populations of Leucaena esculenta Subsp. esculenta (Fabaceae; Mimosoideae) in La Montaña of Guerrero, Mexico

Zárate

Pérez-Nasser

Casas

2005

Genet Resour Crop Evol

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Genetic consequences of silvicultural management of Leucaena esculenta subsp. esculenta were analyzed from eight allozyme loci in half-sib families of one wild and one managed in situ (selectively cleared) population from La Montaña de Guerrero region, Central Mexico. A reference sample (including wild, feral and cultivated individual plants) from the states of Morelos, Puebla and Guerrero, Mexico was also analyzed. Genetic variation, population structure and mating system were analyzed. All loci showed high variation (75-87.5% polymorphic loci at 95% level; 2.4-2.8 mean number of alleles per locus). All progenies showed heterozygous deficiency, but both wild and managed parental inbreeding coefficients were negative, suggesting heterosis. Progenies of managed populations differed from those of the wild and reference samples (Nei's unbiased identities 0.874-0.934). Biparental inbreeding is suggested by Wright's-statistics ( f ¼ 0.313), and by outcrossing rate estimates: t m ¼ 0.644 (SE 0.094), and 0.645 (SE 0.193); t s ¼ 0.576 (SE 0.189), and 0.523 (SE 0.182), for managed and wild samples respectively. Population differentiation is significant (Â ¼ 0.210). The species is self-incompatible and deviations from the mixed mating model were found. Indirect estimates of products of effective population size (N e ) by the proportion of migrants (N m ) were moderate, as were the N e values. Variation due to ecotypic differentiation (related to altitude), prolonged artificial selection, and introduction from other areas is supported. A model of domestication of seed-propagated trees is suggested, based on extensive and in situ selection of locally adapted populations, and their diffusion to other areas.

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“…Nuclear rDNA shows Mendelian inheritance; it is present in multiple copy number, so that detection via hybridization is easier; each unit is composed by highly conserved regions flanked by more variable sequences, so that both PCR-mediated synthesis of homologous probes and detection of unique restriction fragments are straightforward. 1992, HUGHES & HARRIS 1994. 1990, RIESEBERG & al.…”

Section: Discussionmentioning

confidence: 99%