High resolution microsatellite based analysis of the mating system allows the detection of significant biparental inbreeding in Caryocar brasiliense, an endangered tropical tree species

Article Abstract:

The mating system of four populations of the endangered tropical tree species Caryocar brasiliense has been investigated using genetic data from 10 microsatellite loci. High levels of biparental inbreeding were seen likely because of the limited flight range of pollinators and restriction in seed dispersal. Results indicate the Cerrado fragmentation could limit gene flow by isolating seed dispersers and territorial small-sized bat pollinators inside fragments. Conservation of nonisolated populations may be needed to foster outcrossing events between unrelated individuals to maintain species viability. High polymorphism of microsatellite markers gives great ability to discriminate selfing events from outcrossing events between close relatives

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Non-transmissibility of the Y chromosome through the female line in androhermaphrodite plants of Melandrium album

Article Abstract:

Nontransmissibility of the Y chromosome via the female line in androhermaphrodite Melandrium album plants is discussed. To see whether or not the Y chromosome could be so transmitted, an androhermaphrodite was crossed with an X-ray-induced hermaphrodite with a large deletion on the Y chromosome making it not able to pass through male or female meiosis. The nontransmissibility is likely the result of the absence of an X chromosome in embryo sac formation or an imbalance of X/Y chromosomes in developing endosperm.

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Size-specific fecundity and the influence of lifetime size variation upon effective population size in Abies balsamea

Article Abstract:

Size-specific fecundity in plants has been studied in Abies balsamea, the balsam fir, with attention to the influence of lifetime size variation on effective population size. Demographically stable size distribution can be found in natural wave-generating populations of balsam fir. Fecundity variance is expected to be smaller in trees and other long-lived perennials than in annuals because density-dependent mortality operates more strongly in the prereproductive phase of long-lived plants.

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