Reproductive biology, genetic variation and conservation of the rare endemic dysploid Delphinium bolosii (Ranunculaceae)

Relationships between heterozygosity and fitness in the Iberian threatened larkspur Delphinium bolosii (Ranunculaceae)

“…Furthermore, outcrossing rates calculated from mean fixation indices indicate random mating within populations. These data are somewhat surprising, despite the fact that this species is primarily outcrossing, because spontaneous selfing can reach 20% (Bosch et al, 1998) and limited rhizomatous growth was also observed. Given that, in the field, D. bolosii exhibits a limited establishment of seedlings and a scarce seed bank reserve, in addition to low germination rates obtained in the greenhouse, it is likely that the real contribution of new seeds to the population's survival is low in this species.…”

“…Pollination of this species is entomophilous, mainly by Hymenoptera, but also by Lepidoptera and Diptera (Bosch et al, 1998). Breeding is mainly outcrossing, although this species is selfcompatible and autogamy may achieve 20% of total seed set in bagged flowers (Bosch et al, 1998). Limited vegetative reproduction by rhizome multiplication is also possible, as in other perennial Delphinium species (Richter et al, 1994).…”

“…Some data on differential traits are available, including chromosome number (2n ¼ 18 for D. bolosii and 2n ¼ 16 for D. fissum) and some morphological (increased flower size, particularly spur length, and stamen number for D. bolosii) and reproductive characters (increased selfing rates in D. bolosii) (Bosch et al, 1998). D. bolosii is a narrow endemic species which currently has only two populations: one is located in Ulldemolins, Priorat (PRI), containing 2,600 rosettes; the other is located in Rubio´de Baix, La Noguera (LNO), which harbours about 2,300 rosettes.…”

“…After dispersal, the seeds are dormant until germination in early spring, although establishment of new seedlings has been observed to be quite limited. Also, the seed bank reserve has been estimated to be very poor (Bosch et al, 1998). In early spring, new rosettes from settled rhizomes of previous years are formed, some of which (at a rate of about 15-20%) may produce an erect stem with an inflorescence.…”

“…D. bolosii appears to exhibit a significant mechanism of rootstock bank, as observed in Delphinium gypsophilum (Lewis and Epling, 1959), in which plants remain dormant as rhizomes until conditions become favourable. Pollination of this species is entomophilous, mainly by Hymenoptera, but also by Lepidoptera and Diptera (Bosch et al, 1998). Breeding is mainly outcrossing, although this species is selfcompatible and autogamy may achieve 20% of total seed set in bagged flowers (Bosch et al, 1998).…”