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Gene flow      

 

Dynamics Of Diversity

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© Photos courtesy of R. Gribel.

The structure of genetic diversity at the population level is determined by factors such as the reproductive biology of the particular tree species, and seed and pollen dispersal within and among populations. Therefore, the effect of human disturbance on levels of intraspecific genetic diversity depends to some extent on the disruption it causes to the mating system and gene flow of that species. Selective logging, for example, may lead to an increase in inbreeding, which results in a reduction of genetic diversity, while forest fragmentation may disrupt pollinator behaviour, and thereby alter patterns of genetic diversity.

The outcrossing rates and pollen and seed mediated gene flow will be estimated for selected species, in order to obtain a greater understanding of the mechanisms underlying the levels and distribution of the genetic diversity identified.

Species to be analysed for the dynamics of diversity:

Partner Species for analysis of mating system Species for analysis of gene flow
CEH/CATIE Vochysia ferruginea    Vochysia ferruginea   
INRA Qualea rosea, Symphonia globulifera, Eperua falcata Qualea rosea, Symphonia globulifera
UFRJ Eugenia uniflora Eugenia uniflora
INPA Swietenia macrophylla, Pseudobombax munguba, Ceiba pentandra    Swietenia macrophylla, Pseudobombax munguba, Ceiba pentandra   

 

Mating system analysis

Outcrossing rates will be estimated for the species indicated above. The calculation will be done for the whole population (30 trees per stand) and also on an individual tree basis (15 trees per stand). The individual tree calculation will be performed on trees located in different "neighbouring" conditions, e.g. isolated or surrounded by several other trees of the same species.


Gene flow analysis

The extent of gene flow (i.e. seed and pollen flow) will be inferred from the spatial distribution of diversity on a local scale and by comparing allelic arrays of adult trees and offspring. The comparison will be done using two complementary ways depending on the molecular assay that is used. Seed dispersal will be described by analysing chloroplast DNA polymorphism, since chloroplasts are predominantly maternally inherited in angiosperms. Similarly, pollen movements can be traced by relating the distribution of rare alleles in seedlings to their occurrence in mature trees, using the SAMPL data. Paternity analysis will be conducted using the fractional paternity assignment

 

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Last modified: November 13, 2002