Analysis of within‐population spatial genetic structure inAntirrhinum microphyllum(Scrophulariaceae)

Abstract

Random amplified polymorphic DNA (RAPD) markers were used to study the spatial genetic structure in two populations (Bolarque and Entrepeñas) of endangered cliff specialist Antirrhinum microphyllum Rothm. (Scrophulariaceae). Mantel tests found no significant linear correlations between geographic and genetic data. However, redundancy analysis (RDA) models developed using the spatial data as the constraining matrix were highly significant, and spatial data explained 13.6% and 11.1% of total genetic variation in Bolarque and Entrepeñas, respectively. Moran's I correlograms and Mantel correlograms revealed a positive autocorrelation in the first distance class (15 m), which suggests a patchy distribution of genetic diversity. This distribution is consistent with the genetic vicinities that are expected from the territorial behavior of main pollinator Rhodanthidium sticticum (Megachilidae), the predominant short-distance seed dispersal, and the patchy spatial distribution of available safe sites. The gradient pattern obtained in Entrepeñas was consistent with standard isolation-by-distance models. However, a differential sinusoidal pattern was obtained in Bolarque, which would indicate a more frequent gene flow between patches and might be due to lower plant density there. The spatial genetic structure coexists with a strict self-incompatibility system in the species. Simplified RDA models obtained using a stepwise forward selection comprised the easting component in Entrepeñas and the easting and northing components in Bolarque. Similar results were obtained with directional correlograms. These differential patterns can be explained by the distinct spatial arrangement of the populations (linear and bidimensional in Entrepeñas and Bolarque, respectively).

Spatial distribution pattern of a clonal species: effects of differential production of clonal and sexual offspring

“…In general, studies that have analyzed spatial autocorrelation in other species report the same pattern found for O. microdasys (Table 3), where positive autocorrelation generally occurs at distances less than 20 m when there is a deficient movement of seeds or pollen or high clonality (Garnier et al 2002;Hämmerli and Reusch 2003;Clark-Tapia et al 2005;Wilson et al 2005). However, positive autocorrelation occurs at larger distances because plantlets and agamospermic seeds are more mobile and can disperse further away or to frequent pollen flow between the same distant patches (Torres et al 2003). Although positive spatial autocorrelation in O microdasys ramets is found at similar distances in BH and IDH there are differences in the pattern, which can be explained by differences in dispersal capacity of plantlets and cladodes and the distribution of large individuals.…”

High Levels of Genetic Diversity within One Population of Rheum tanguticum on the Qinghai-Tibet Plateau have Implications for Germplasm Conservation

“…Analysis of genetic variations in the endangered species at the population level is critically important for conservation strategies because sufficient genetic variation can increase the species chance of survival [10]. Therefore, the analysis of genetic variation within and between populations becomes important not only for the conservation of the endangered species [11][12][13][14][15] but also for pharmaceutical crop development.…”

Fine-scale spatial genetic structure of an endangered marsh herb, Caldesia grandis (Alismataceae)

“…Genetic diversity may appear spatially structured on different scales, such as medium and large scales (population or region; Hedrick, 1986;Heywood, 1991;Born et al, 2008) or among neighboring individuals (Sokal et al, 1989;Epperson, 1993;Li et al, 2002;Reisch et al, 2007). Even at extremely fine scales, spatial genetic structures have been detected in some plant populations (Epperson and Clegg, 1986;Tani et al, 1998;He et al, 1999He et al, , 2000Torres et al, 2003;Vornam et al, 2004). Spatial genetic structure within plant populations is primarily determined by the effects of factors such as limited seed and pollen dispersal, vegetative reproduction, isolation in small patches, differential mortality, and microhabitat selection (Murawski and Hamrick, 1990;Epperson, 1993;Berg and Hamrick, 1994;Chung and Epperson, 1999).…”

“…These advantages include speed, low cost, and the use of small amounts of plant material (Huff et al, 1993;Heun et al, 1994;Fritsch and Rieseberg, 1992). In other studies, the spatial genetic structure of several plant species have been successfully investigated using RAPD markers (Bucci and Menozzi, 1995;Degen et al, 2001;Bouza et al, 2002;Torres et al, 2003). In a study of the population genetics of C. grandis, two molecular marker systems, RAPD and inter-simple sequence repeat, were used (Chen et al, 2006).…”