Formulation and estimation of the effective size of stage-structured populations in Fritillaria camtschatcensis, a perennial herb with a complex lifehistory
K. Yonezawa et al., Formulation and estimation of the effective size of stage-structured populations in Fritillaria camtschatcensis, a perennial herb with a complex lifehistory, EVOLUTION, 54(6), 2000, pp. 2007-2013
The effective population size (N-e) is formulated based on a stage-structur
ed population model and is estimated for two populations of Fritillaria cam
tschatcensis (L.) Ker-Gawl. (Liliaceae), a perennial, mainly clonally repro
ducing herb. Plants in these populations change life-history stages year by
year, either upward or downward across three unambiguously identifiable st
ages: one-leaf, nonflowering; multileaf nonflowering; and multileaf, flower
ing stages. Plants of all stages produce clonal progeny (bulblets) each yea
r, and death of plants occurs only in the first stage. The populations are
nearly at equilibrium in both population size and stage structure. N-e is e
stimated to be 20-30% of the census population size (N), leading to the pre
diction that a population size of about 20,000 or more will be needed to co
nserve the normal level of the gene diversity (N-e greater than or equal to
5000). With the current demographic pattern of this species, accelerated g
rowth of the first-stage plants with reduced survival of the second- and th
ird-stage plants will increase both the annual (N-y/N) and generation time
(N-e/N) effective sizes of population.