Aim The evolutionary history of narrow endemic species has received little attention compared with that of more widely distributed species. Small effective population sizes and long-term isolation of many narrow endemic species make research on their genetic make-up important for their future conservation. In this study we investigated the genetic variation and historical distribution of an isolated plant, the monospecific genus Pseudomisopates, as an example of the phylogeographical history of narrow endemics.Location Central Range, Iberian Peninsula, Mediterranean Europe.Methods We used amplified fragment length polymorphisms (AFLPs), nuclear and plastid DNA sequences and species distribution modelling. Sequence data were analysed using statistical parsimony, molecular dating, and a coalescent-based Bayesian model of isolation with migration. Genetic diversity and differentiation analyses based on AFLP data were performed. We compared the detection of clones using AFLPs with the results of a previous study that used simple sequence repeats (SSRs).Results AFLP analysis revealed that SSRs underestimate clone number. The coalescent-based Bayesian model of isolation with migration suggested a late Pleistocene divergence between the populations of Pseudomisopates on two mountain massifs (Gredos and La Serrota), despite the presence of a large area suitable for population admixture. Moderate to high levels of genetic diversity and high effective population sizes were inferred.Main conclusions Our results imply that the levels of genetic diversity within narrow endemic species from Mediterranean mountains could primarily be driven by extrinsic historical factors, rather than by intrinsic species-specific factors depending on their own biological characteristics. Narrow endemics are widely believed to harbour low genetic diversity because of small effective population sizes. However, this study and others on narrow endemic angiosperms demonstrate that narrow endemism does not necessarily result in low genetic diversity.

Clonal growth can be a double-edged sword for endangered species, because the short-term insurance against extinction may incur a longer-term hazard of creating small inbred populations with low fecundity. In the present study, we quantify the advantages and disadvantages of clonal growth regarding the fitness of the central Iberian monotypic endangered genus Pseudomisopates. Preliminary studies showed that the species is self-incompatible and exhibits extensive clonal growth with plants flowering profusely. However, seeds at many sites seemed to be unviable, and no seedlings have been observed in the field. A fully replicated nested sampling design (n = 100) was conducted to explore genetic (using seven SSR loci) and environmental factors potentially affecting seed viability, such as: 1) clonal and genetic diversity, 2) spatial genetic structure, and 3) environmental factors (shrub cover and grazing). Generalized Linear Mixed Models were fitted relating genetic and environmental variables to reproductive variables (seed viability and flower display). Our results indicate that the relatively low genotypic diversity of the population (PD = 0.23), as quantified by SSRs, and the strong spatial genetic structure observed are congruent with intense clonal growth. This clonal growth is enhanced by unfavorable environmental conditions, such as canopy closure and grazing. Under these circumstances, both flower display and mate availability decrease, thus hindering sexual reproduction. Indeed, a mixed reproductive system (clonal and sexual) to escape environmental stochasticity is crucial for the survival of Pseudomisopates, a species inhabiting a disturbance-prone ecosystem.

Pollen limitation occurs when sexual reproduction is decreased due to inadequate pollen receipt. Limitation is usually associated with the quality and the quantity of pollen; still, most studies do not discriminate between the two. We used handpollination experiments and observations of floral visitors to determine the mating system and limitations to seed production of the Spanish endangered species Pseudomisopates rivas-martinezii. We tested for agamospermy, autogamy, obligated autogamy, cross-pollination and supplementation. The response variables considered were fruit set, seed set and viable seed set. Previous studies indicated that (i) the species exhibits extensive clonal growth, (ii) plants flower profusely in summer, (iii) seeds showed to be highly unviable, and (iv) no seedlings were observed in the field. We found that P. rivas-martinezii is predominantly self-incompatible, has an unexpected generalized pollination system considering its occluded corolla, and is limited by qualitative rather than quantitative pollen limitation. These results indicate that, in addition to other presumed environmental factors, the low seed viability of this self-incompatible species is due to pollen quality limitation as a result of reduced mate availability.

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