Invasion dynamics of two alien Carpobrotus (Aizoaceae) taxa on a Mediterranean island: I. Genetic diversity and introgression.
This study, based on morphological and isozyme analysis, clearly discriminates two invasive Carpobrotus taxa, C. edulis and C. acinaciformis, in the Hyères archipelago off the southeastern coast of France. However, three different allelic combinations demonstrate the presence of intermediate individuals resulting from an introgression of part of the C. edulis genome into that of C. acinaciformis. Both taxa have higher than average genetic (C. edulis: P(0.95)=62.5%, A=2.25+/-0.70, H(o)=0.329+/-0.324; C. acinaciformis: P(0.95)=75%, A=2.38+/-0.42, H(o)=0.645+/-0.109) and clonal diversities (C. edulis: IP=0.37; C. acinaciformis: IP=0.48). Furthermore, C. acinaciformis has an excess of heterozygotes (F=-0.585+/-0.217), probably due to introgression. The relationship between the probability of clonal identity for two individuals and distance indicates that C. acinaciformis relies more on clonal reproduction than on sexual recruitment (seed recruitment/vegetative propagation=u/v=0.027), in contrast to C. edulis, whose probability of clonal identity did not vary with distance. The overwhelming clonal growth and high genetic diversities of C. acinaciformis and the previously recorded invasion potential for C. edulis raises concern for intensified invasion via hybridisation.
Suehs
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Institut Méditerranéen d'Ecologie et de Paléoécologie (UMR CNRS 6116), Université d'Aix-Marseille III, Faculté des Sciences et Techniques de Saint-Jérôme, Case 461, F-13397 Marseille Cédex 20, France. csuehs@mail.utexas.edu
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D035722:Aizoaceae / Q000033:anatomy & histology / Q000502:physiology*; D003710:Demography; D004586:Electrophoresis; D035264:Flowers / Q000033:anatomy & histology*; D005602:France; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D006824:Hybridization, Genetic; D007527:Isoenzymes; D018515:Plant Leaves / Q000033:anatomy & histology*; D011157:Population Dynamics; D012098:Reproduction / Q000502:physiology
D007527:Isoenzymes