Breeding System, Karyotype and Variation Within and Between Populations of Rutidosis leptorrhynchoides F Muell (Asteraceae, Inuleae)

Abstract

The endangered plant species, Rutidosis leptorrhynchoides (button wrinklewort), is now known from only a few populations in each of two regions separated by approximately 500 km in south-eastern Australia. Plants were examined from several populations from each region.

No differences in chromosome number or morphology were observed among plants or populations. All counts were diploid, 2n = 26.

Viable progeny were obtained following self-pollination and allozyme analysis indicated that these progeny were the result of selfing and not agamospermy. This species is not an obligate outcrosser and does not have a classical pre-zygotic self-incompatibility system. However, outcross pollen may have an advantage over self pollen and this species may thus be preferentially outcrossing. The pollen: ovule ratios (mean 3186 ± 48.5) were consistent with this hypothesis.

Allele frequencies at allozyme loci diferred little between populations, with an estimated 97% of the variation within populations. There was no correlation between genetic distance and geographic distance. In contrast, for the leaf dimensions of plants germinated and raised together in a glasshouse there were differences between plants from the two regions.

It is recommended that populations from both regions should be conserved.