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Morph‐ratio variation, population size and female reproductive success in distylous Pulmonaria officinalis (Boraginaceae)
Author(s) -
BRYS R.,
JACQUEMYN H.,
BEECKMAN T.
Publication year - 2008
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2008.01569.x
Subject(s) - boraginaceae , biology , officinalis , reproductive success , population , variation (astronomy) , botany , pollinator , zoology , pollination , pollen , demography , physics , astrophysics , sociology
Theory predicts that morph ratios in heterostylous populations are governed by negative frequency‐dependent selection typically resulting in equal morph ratios at equilibrium. Previous work on the distylous perennial herb Pulmonaria officinalis , however, showed asymmetric mating between floral morphs and a weak self‐incompatibility system, with the long‐styled morph (L‐morph) producing significantly higher seed set following intramorph crosses and even selfing than the short‐styled morph (S‐morph), two aspects thought to affect female fecundity and morph‐ratio variation. Here, we evaluated morph ratios and population size of all known P. officinalis populations in the northern part of Belgium. Morph ratios deviated significantly from 1 : 1 (range 0.09–1 L‐morph frequency, mean = 0.58). Relative fecundity of the S‐morph (i.e. mean seed set of the S‐morph/mean seed set of the L‐morph) was on average 0.73, was positively related to the frequency of the L‐morph, and reached 1 (similar levels of female fecundity) at an average L‐morph frequency of 0.66 in the population. As some small populations had the S‐morph in majority, our results suggest that local morph ratios are influenced both by the relative fecundity of L‐ and S‐morph individuals and by stochastic processes in small populations.