Population genetic differentiation in taxa of Lotus (Fabaceae: Loteae) endemic to the Gran Canarian pine forest

Abstract

A survey of allozyme variation at 17 loci in 14 populations representing four taxonomically problematic Gran Canarian pine forest endemic taxa of Lotus (L. genistoides, L. holosericeus, L. spartioides and some taxonomically uncertain populations collected under the designation Lotus sp.) was conducted to examine their diversification and systematic relationships. All groups exhibited high values of genetic variation, although inbreeding was common within populations. Considerable among-population genetic homogeneity was detected, as inferred from low values of Gst within each of the groups. The high population sizes of these taxa and a lack of evidence for isolation by distance or genetic bottlenecks indicate that diversity has accumulated over a long period of environmental stability. The association of high genetic distances with low linear distances, and the substantial increase in the values of Gst when the taxa considered were merged in different combinations hint at an incipient (yet probably taxonomically insufficient) reproductive isolation. The genetic similarity between L. genistoides, L. holosericeus and L. spartioides, together with the different behaviour of the populations collected under the designation Lotus sp., may have important implications for the restructuring of the taxonomy of this group when the ongoing morphological studies are completed.

General G ST and θ inflation due to biased intra-population sampling, and its consequences for the conservation of the Canarian Flora

“…This expectation is consistent with the result ( Table 1) that the sub-samplings in Lotus (where seeds disperse by gravity, thereby fostering reproduction in small genetic neighborhoods Oliva-Tejera et al 2005), give higher G ST over-estimates than in the two species of Crambe, putative predominant outcrossers with a homomorphic sporophytic self-incompatibility system (Kroh 1964, Zuberi andDickinson 1985) and a high seed dispersal capacity; accordingly, they exhibit low F IS values (as opposed to the much higher F IS values estimated in Lotus by Oliva-Tejera et al 2005), and only moderate genetic structure (Soto et al unpublished data).…”

“…Comparisons between G ST and h estimates were obtained through the computer software FSTAT version 2.9.3.2 (Goudet 1995(Goudet , 2002 after generating all the needed files from the corresponding genotype matrices using Transformer-3 (Caujapé-Castells and Baccarani-Rosas 2005). Because G ST was estimated using GeneStat-PC 3.31 (Lewis and Whitkus 1993) in the papers where the data used are discussed (Oliva-Tejera et al 2005, 2006and Soto et al 2007a, a comparison between values of this parameter estimated by that software and FSTAT version 2.9.3.2 was also undertaken. Non-parametric Mann-Whitney U tests were used to assess the significance of the differences in the values of G ST and h.…”

“…The two Lotus databases used consist of (1) 17 loci for nine populations (359 individuals) that represent the Gran Canarian pine forest endemics L. holosericeus (six populations), L. genistoides (one population) and L. spartioides (two populations) discussed in Oliva-Tejera et al (2005), and (2) 11 loci for the easternmost islands endemic L. lancerottensis, examined in 219 individuals that represent ten populations (five from Fuerteventura and five from Lanzarote) and were discussed in Oliva-Tejera et al (2006). The Crambe database consists of 12 loci for 12 populations (726 individuals) that represent the narrowly distributed C. tamadabensis (four populations, 191 individuals) and the more widespread C. pritzellii (eight populations, 535 individuals).…”

Conservation implications of high genetic variation in two closely related and highly threatened species ofCrambe(Brassicaceae) endemic to the island of Gran Canaria:C. tamadabensisandC. pritzelii

“…In these two Crambe spp., the average genetic identities between and within taxa are significantly different ( I NEI = 0.877 and I NEI = 0.929–0.923, respectively) and the average genetic identity between them is closely similar to the interspecific values found in other Canarian endemics, such as Parolinia (Brassicaceae) ( I NEI = 0.754–0.914; Fernández‐Palacios et al ., ), in Lotus L. (Fabaceae) from the Gran Canarian pine forest ( I NEI = 0.822–0.939; Oliva‐Tejera et al ., ) or in coastal Lotus spp. ( I NEI = 0.823–0.894; Oliva‐Tejera et al ., ).…”

DNA barcodes successfully identified Macaronesian Lotus (Leguminosae) species within early diverged lineages of Cape Verde and mainland Africa

“…For 10 species we were unable to add more than one sample to represent the species and we included more than one accession for 27 species. Our analysis also included accessions from some populations that (based on previous molecular and morphological analyses) may represent four new undescribed species within the section Pedrosia (Oliva-Tejera et al 2005, 2006; Sandral et al 2006; A. Santos-Guerra, Unidad de Botanica-ICIA, pers. comm.).…”