Therefore, it is important to understand the genetic structures of animal populations to be able to protect the genotypic structure
of the races that face the danger of becoming extinct.
gerardii within population, and then assessed the fine-scale (i.e., within 1 x 1 m plots) genotypic structure of A.
After assigning each sampled individual to a genotype, we calculated measures of genotypic structure for each plot separately, including richness, evenness and Shannon's Diversity (Arnaud-Haond et al., 2007) and proportion of distinct genotypes (PD) (Ellstrand and Roose, 1987).
Thus, our rarefaction analysis revealed that relatively few samples could be taken from a 1 x 1 m plot to accurately reflect fine-scale genotypic structure. We recognize that other important factors that have been known to greatly impact grassland dynamics such as fire, grazing, or climate (Knapp et al., 1998) could potentially impact the underlying genetic structure of a given population of A.
The effect of asexual reproduction and intergenotypic aggression on the genotypic structure
of the sea anemone Actinia tenebrosa.
Temporal genetic changes are further evidenced in the multilocus genotypic structure
, as summarized by frequencies of parental, F.sub.1, and backcross nuclear genotypes (fig.
For example, year-to-year changes in genotypic structure within--and variance among--populations may result from differences in relative recruitment from immigrant versus resident individuals (Charlesworth and Geisei 1972; Long 1986).
One interpretation of large [F.sub.nm] would be that microgeographic genotypic structure is evident within marshes, on a finer scale than anticipated given the degree of movements by adult males and females among marshes.
The general objectives of this study were to combine laboratory breeding studies of genotype-specific life-history traits with demographic characterizations of experimental parental (i.e., allopatric) and mixed (i.e., simulated sympatric) populations to better understand the mechanisms behind changes in genotypic structure within the hybrid zone formed by G.
Six replicates of the "mixed" treatment that were not used in demographic analyses were followed concurrently to document differences in genotypic structure over time (Scribner, 1992; Scribner and Avise, submitted).
Theoretical treatments of relationships between mechanisms of population regulation and changes in population genotypic structure have shown that fitness may be defined both by innate capacity of a genotype to contribute to population growth and by the manner in which this innate capacity is regulated by population density (King and Anderson, 1971).
Both of the alleles (C and G) of the UoG-CAST polymorphism and three genotypic structures
(CC, CG, GG) were found in the CAST locus in TGC (Fig.