Genetic diversity and differentiation in a southern beech subjected to introgressive hybridization

Marchelli, Paula; Gallo, LA

doi:10.1046/j.1365-2540.2001.00882.x

Cited by 35 publications

(26 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In Matane, only 34% of the observed hybrid offspring had fathers with exotic compo- sity may therefore lead to a lack of suitable partners, which may in turn decrease the competition that nonconspecifi c pollen experiences from P. balsamifera pollen. Such a relationship between population size and hybridization rate has been observed repeatedly, for example in the tree genera Eucalyptus ( Field et al, 2008 ) and Nothofagus ( Marchelli and Gallo, 2001 ). An extreme form was studied by Vanden Broeck et al (2004) , who analyzed the offspring from a single isolated female of P. nigra and found that it consisted completely of hybrids.…”

Section: Resultsmentioning

confidence: 55%

Complex patterns of hybridization between exotic and native North American poplar species

Meirmans

Lamothe

Gros‐Louis

et al. 2010

American J of Botany

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 55%

Complex patterns of hybridization between exotic and native North American poplar species

Meirmans

Lamothe

Gros‐Louis

et al. 2010

American J of Botany

View full text Add to dashboard Cite

show abstract

“…Gallo et al . ; Kennington & James ; Marchelli & Gallo ). Several nonexclusive factors could account for this result.…”

Section: Discussionmentioning

confidence: 99%

Fine‐scale environmental control of hybridization in oaks

et al. 2012

View full text Add to dashboard Cite

Natural hybridization is attracting much interest in modern speciation and conservation biology studies, but the underlying mechanisms remain poorly understood. In particular, it is unclear why environmental changes often increase hybridization rates. To study this question, we surveyed mating events in a mixed oak stand and developed a spatially explicit individual-based hybridization model. This model, where hybridization is frequency-dependent, pollen is nonlimiting and which allows immigrant pollen to compete with local pollen, takes into account species-specific pollen dispersal and sexual barriers to hybridization. The consequences of pollen limitation on hybridization were studied using another simple model. The results indicate that environmental changes could increase hybridization rates through two distinct mechanisms. First, by disrupting the spatial organization of communities, they should decrease the proportion of conspecific pollen available for mating, thus increasing hybridization rates. Second, by decreasing the density of conspecifics, they should increase pollen limitation and thus hybridization rates, as a consequence of chance pollination predominating over deterministic pollen competition. Altogether, our results point to a need for considering hybridization events at the appropriate level of organization and provide new insights into why hybridization rates generally increase in disturbed environments.

show abstract

“…While few natural population studies have explicitly measured relative population size, similar patterns have been observed in Nothofagus , with higher hybridization rates for isolated trees surrounded by compatible species (hybrid rate; 80%) compared to trees within dense conspecific stands (0%; Gallo et al . 1997; Marchelli & Gallo 2001). In an allozyme study of E. argutifolia , the small populations exhibited the highest hybridization rates in progeny arrays (47%; Kennington & James 1997).…”

Section: Discussionmentioning

confidence: 99%

Relative frequency of sympatric species influences rates of interspecific hybridization, seed production and seedling performance in the uncommon Eucalyptus aggregata

et al. 2008

View full text Add to dashboard Cite

Summary 1.Habitat fragmentation can alter the relative frequency of cross-compatible species within an area, which can affect the levels of interspecific hybrid production and reduce the viability of small populations through genetic and demographic swamping. For 18 populations of Eucalyptus aggregata , we examined the effects of absolute and relative population size (compared with its congeners E. rubida , E. viminalis and E. dalrympleana ) on hybrid production, genetic diversity and subsequent seed production and seedling performance. 2. Relative population size was strongly negatively correlated with rates of hybrid seed production, suggesting increased hybridization when the potential sources of interspecific pollen outnumber the sources of intraspecific pollen for E. aggregata trees. 3. Genetic diversity was negatively correlated with relative population size which suggests that hybridization may maintain diversity lost through bottlenecks and drift following reductions in population size. However, the presence of fertile hybrid adults, and introgressed leaf traits within populations exhibiting high hybridization rates, suggests that small E. aggregata populations may be vulnerable to genetic swamping by common congeners. 4. Amongst an array of population parameters (population sizes, genetic diversity and inbreeding), seed production was only positively correlated with relative population size, whereby sites with low relative population sizes tended to produce fewer seed. This could be due to the action of pre-zygotic barriers which removes inviable hybrid genotypes as levels of interspecific pollen flow increase. 5. Germination and survivorship displayed a similar positive correlation with relative population size, suggesting post-zygotic hybrid breakdown may also contribute towards to demographic swamping of remnant populations. 6. Synthesis . Our results suggest that relative population size is an important parameter determining rates of hybrid production, seed production and seedling performance. Furthermore, relative population size has stronger effects on population fecundity than absolute population size, genetic diversity and levels of inbreeding. Relative population sizes > 0.5 (i.e. at least equal frequencies of parentals) may be required to avoid the deleterious effects of genetic and demographic swamping on the viability of rare species.

show abstract

Genetic diversity and differentiation in a southern beech subjected to introgressive hybridization

Cited by 35 publications

References 15 publications

Complex patterns of hybridization between exotic and native North American poplar species

Complex patterns of hybridization between exotic and native North American poplar species

Fine‐scale environmental control of hybridization in oaks

Relative frequency of sympatric species influences rates of interspecific hybridization, seed production and seedling performance in the uncommon Eucalyptus aggregata

Contact Info

Product

Resources

About