Paternal effects on seed germination: a barrier to the genetic assimilation of an endemic plant taxon?

• We used a crossing experiment to investigate post-zygotic barriers that might limit introgression between a pair of closely-related, gynodioecious plant species - the widespread weed Silene vulgaris and the local Swedish endemic S. uniflora ssp. petraea. The study not only considered the effects of hybridization on conventionally-used (primary) fitness components such as seed set and progeny survival, but also provided a test for the effects of interspecific hybridization on characters with more subtle or habitat-specific effects on fitness. We detected highly significant paternal effects on seed germination properties, with the germination characteristics of hybrid seed resembling those of the species that served as the pollen donor. These paternal effects on germination represent a potentially strong barrier to interspecific introgression in the two species' natural habitats, where an inappropriate germination response in the habitat of the maternal parent may lead to the failure of seedling establishment. Interspecific crosses had weak or variable effects on progeny survival, flowering and sex ratio, but these effects could not be interpreted in terms of barriers to introgression. Our results indicate that nuclear restorers in S. vulgaris have the capacity to suppress cytoplasmic male-sterility genes in its endemic congener.

Subject headings

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Keyword

cytonuclear interaction

germination

gynodioecy

hybridization

introgression

local adaptation

paternal effect

post-zygotic barrier

sex ratio bias

Silene

Publication and Content Type

art (subject category)

ref (subject category)