Conservation of gene diversities in plant populations with a mixed sexual and asexual reproduction system

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The variance effective size was defined in terms of stage-specific parameters of populations which are composed of multiple demographic stages, reproducing either sexually or asexually. Applying the equations to two populations of a perennial herb species F.camtschatcensis which has a complex life cycle and reproduces asexually by dispersion of bulbs in ordinary habitat conditions, the effective to census size ratio (Ne/N) and the population size required for long-term conservation were estimated to be less than about 0.3, and larger than a few thousands, respectively. Numerical computations of the equations for some fictious combinations of the demographic and reproductive parameters revealed that species or populations with a higher recruitment rate with shorter persistence of mature individuals tend to have a large Ne/N,and consequently, maintain a higher genetic diversity with a given census size N.This trend was observed between the two populations of F.camtschatcensis surveyed. Conservation genetic effects of controlling the demographic and reproductive variables were also discussed by the numerical computations to be summarized into four points ; first, increased survival rate of juveniles causes increase in Ne/N,second, accelerated transition to higher (more developed) stages tends to enlarge Ne/N and relative fractions of individuals of higher stages, third, longer persistence of adult (mature) individuals lessens Ne/N and the fraction of juveniles, and tourth, regression of adults to juvenile stage as observed in many perennial herb species acts to decrease Ne/N without causing any change in the fractions of the stages.