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Evidence for natural selection in a fern hybrid zone
Author(s) -
Kentner Edward K.,
Mesler Michael R.
Publication year - 2000
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2656653
Subject(s) - fern , biology , biological dispersal , context (archaeology) , natural selection , population , ecology , range (aeronautics) , habitat , natural population growth , selection (genetic algorithm) , botany , paleontology , materials science , demography , artificial intelligence , sociology , computer science , composite material
Morphological characters, chloroplast DNA, and allozymes were used to analyze the distribution of individuals within a hybrid population of the ferns Polystichum munitum and P. imbricans in northwestern California. Microsites within the population were characterized according to soil moisture and light levels reaching the plants. In sites with low soil moisture and high light levels, all of the ferns were genetically and morphologically like P. imbricans. In contrast, ferns with the genetic and morphological identity of P. munitum predominated in moist shady sites. Intermediate sites supported very few P.munitum , a wide variety of hybrid recombinants, and a majority of ferns with P. imbricans characteristics. The pattern of variation within the population is noteworthy because of the close proximity of the habitat extremes and the long‐range dispersal of fern spores. We conclude that natural selection along environmental gradients must be a major factor in determining the ecological and genetic associations within the hybrid zone. The results of this study are evaluated in the context of the fern life cycle and compared to the assumptions of models explaining the establishment and maintenance of hybrid zones, which vary in the role attributed to environmentally mediated natural selection.