Patterns of genetic and phenotypic variation inIris hayneiandI. atrofusca(Irissect.Oncocyclus = the royal irises) along an ecogeographical gradient in Israel and the West Bank

Abstract

Iris haynei and I. atrofusca are two closely related narrow endemics distributed vicariously along an ecogeographical north-south gradient in Israel and the West Bank. To obtain baseline information of the taxonomic status, conservation and population history of these taxa, we investigated patterns of phenotypic variation and the partitioning of genetic variation within and among populations using dominant random amplified polymorphic DNA (RAPD) markers. Multivariate (principal components analysis) and taxonomic distance analyses based on morphometric traits from eight populations revealed no unambiguous separation into two distinct groups. Results of genetic analyses for nine populations differed only slightly when either allele- or marker-based approaches were employed. Mean within-population diversity was high (0.258 for Nei's expected heterozygosity), but there was no significant relationship between genetic diversity and either population size or latitude. Although the range-wide estimate of GST ( approximately 0.20) revealed relatively high differentiation among populations this value was inflated because of a small, but significant, component of molecular variance among regions viz. taxa ( approximately 5%). Limited long-distance dispersal capabilities in conjunction with a linearized habitat distribution are proposed to contribute to the approximate isolation by distance pattern observed. It also appears that extant populations are currently deviating from equilibrium conditions because of primary divergence of a formerly more widespread ancestral population. Given the absence of deep genetic and phenotypic subdivision among northern (I. haynei) vs. central/southern (I. atrofusca) populations, we argue for a revision of their species status. Nonetheless, we recommend conservation attention to these geographically differentiated segments as separate management units, which can be seen as an instructive example of incipient species formation.

Differentiation between two self-compatible cytotypes of Herbertia lahue (Iridaceae): evidence from genotypic and phenotypic variation

“…This approach was effective for detecting some variations between cytotypes of Sisyrinchium micranthum Cav. (Tacuatiá et al 2012b) and among closely related taxa of Iris L. (section Oncocyclus), supporting some taxonomic decisions in this species complex (Arafeh et al 2002;Saad and Mahy 2009).…”

Morning floral heat as a reward to the pollinators of the Oncocyclus irises

“…The flowers of I. atrofusca and I. atropurpurea are uniformly dark-purple to brown, while the flowers of I. hermona are bicolor, with heavy dark-spotted outer horizontal petals (falls), and bluishwhite inner vertical ones (standards) (Avishai and Zohary 1980;. According to the current taxonomy (Fragman et al 1999) these populations are considered as separate species, but recent studies suggest that the whole group may be treated as one taxon (Arafeh et al 2002;Avishai and Zohary 1980;.…”

Genetic diversity and fitness in Scabiosa columbaria in the Swiss Jura in relation to population size

“…Statistical analysis of RAPD banding patterns were based on four assumptions: (i) RAPD fragments behave as diploid, dominant markers with alleles being either present (amplified) or absent (nonamplified); (ii) comigrating fragments represent homologous loci; (iii) polymorphic loci are inherited in a nuclear (Mendelian) fashion (Arafeh et al 2002); and (iv) populations are in Hardy-Weinberg equilibrium (HWE; F is = 0). This last assumption is supported by results from Van Treuren et al (1993.…”