Consequences of low mate availability in the rare self-incompatible species Brassica insularis.
Self-incompatibility systems prevent self-fertilization in angiosperms. Although numerous S alleles are usually maintained by negative frequency-dependent selection, the number of S alleles can be low in small populations, which limits mate availability and reduces fecundity in endangered populations of self-incompatible plants. Despite the increasing evidence of the negative effect of self-incompatibility in small populations, the direct link between the number and the distribution of S alleles and their reproductive consequences has been rarely reported. Brassica insularis is a rare self-incompatible species with medium to very small populations. Results of a previous study showed that the smallest population has very few S alleles. We investigated whether reduced mate availability affects reproduction in this species. We compared the pollination success and the fruit set in 4 populations differing in population size and number of S alleles. Our results suggest that reproduction may be negatively affected by the low S-allele diversity in the smallest population. Nevertheless, other populations also had reduced fruit set that could not be attributed to self-incompatibility alone.
Glémin
Sylvain
S
Institut des Sciences de l'Evolution (UM2-CNRS), Université Montpellier 2, France. glemin@univ-montp2.fr
Petit
Christophe
C
Maurice
Sandrine
S
Mignot
Agnès
A
D001937:Brassica / Q000502:physiology*; D003247:Conservation of Natural Resources; D005638:Fruit; D011058:Pollen; D011156:Population Density; D012098:Reproduction