A LIFE‐HISTORY BASED STUDY OF POPULATION GENETIC STRUCTURE: SEED BANK TO ADULTS IN PLANTAGO LANCEOLATA

Abstract

Abstract. -We explored the extent to which the soil seed bank differed genetically and spatially in comparison to two actively growingstages in a natural population of Plantago lanceolata. All seedbank seeds, seedlings,and adults of P. lanceolata within eight subunits in a larger population were mapped, subjected to starch gelelectrophoresis, and allozyme analysis in 1988. Gel electrophoresis was also used to estimate the mating system in two years, 1986 and 1988. The spatial distributions of seeds, seedlings, and adults were highly coincident. Allele frequencies of the dormant seeds differed significantly from those of the adults for four of the five polymorphic loci. In addition, a comparison ofthe genotype frequencies of the three life-history stages indicated that the seed bank had an excessofhomozygotes. Homozygosity, relative to Hardy-Weinberg expectations, decreased during the life cycle (for seed bank, seedlings, and adults respectively: F;t = 0.19, 0.09, 0.01; F;, = 0.14, 0.04, -0.12). Spatial genetic differentiation increased sixfold during the life cycle: (for seed bank, seedling and adults: F" = 0.02, 0.05, 0.12). The apparent selfingrate was 0.01 in 1986 and 0.09 in 1988. These selfingrates are not large enough to account for the elevated homozygosity of the seed bank. Inbreeding depression, overdominance for fitness, and a "temporal Wahlund's effect" are discussed as possible mechanisms that could generate high homozygosity in the seed bank, relative to later life-history stages. In Plantago lanceolata, the influence of the mating system and the "genetic memory" of the seed bank are obscured by the time plants reach the reproductive stage.

Ant-Mediated Seed Dispersal Alters Pattern of Relatedness in a Population of Trillium grandiflorum

“…sibship were individually ground and wicks stored at Ϫ80ЊC. Maternal and seedling samples were subject to starch gel electrophoresis in 1992 and 1994, respectively, using protocols described in Tonsor et al (1993). Five polymorphic loci (number of alleles) were resolved: mdh1 (2), mdh2 (3), got1 (3), got2 (3), and 6pgd (3).…”

Can Soil Seed Banks Serve as Genetic Memory? A Study of Three Species with Contrasting Life History Strategies

“…[14]. Secondly, it could be attributed to a temporal Wahlund effect [14], but see [20]. Thirdly, Vitalis et al .…”

“…Despite their effort, scientists have been unable to conclusively confirm such a role of seed banks in evolutionary dynamics of plant populations [9], [11]–[17]. While some authors have demonstrated differences between seed banks and aboveground populations such as higher genetic diversity of seed bank populations [9], [13], higher heterozygosity of aboveground populations [11]–[15] or significant differences in allele frequencies [11], [12], [14], [15], studies of others show no differences in any of the population genetic parameters investigated [16], [17]. This discrepancy stems partly from different methodological approaches to comparing genetic diversity parameters of seed banks with the parameters of different stages of aboveground populations (i.e., seedlings or adults, or combination of both).…”

“…Such large-scale, multipopulation studies are necessary to test whether there are any broad genetic differences between soil seeds and surface plants rather than mere idiosyncratic differences between these life-history stages in particular populations. These studies will also allow to test the hypothesis that seed banks reduce the rate of population differentiation by retaining alleles preserved from different generations [13], [14].…”

Analyzing the Spatial Structure of Broughtonia cubensis (Orchidaceae) Populations in the Dry Forests of Guanahacabibes, Cuba

“…WHILE ECOLOGICAL STUDIES OF EPIPHYTIC VASCULAR PLANTS have continued along the lines of classic descriptive studies (Went 1940, Johansson 1974, those focusing on ecological processes and population dynamics have become more common, including studies on factors affecting seedling recruitment and establishment (Ackerman et al 1996, Callaway et al 2002, Jacquemyn et al 2007, spatial distribution (Tremblay 1997, Zotz & Vollrath 2002, Otero et al 2007, Jacquemyn et al 2009), demography (Tonsor et al 1993, Hietz 1997, Kalisz et al 2001, Zotz et al 2005, Janeèková et al 2006, Zotz & Schmidt 2006, evolution of pollination strategies (Ackerman 1986), and genetic structure of the population (Tremblay & Ackerman 2001, Trapnell et al 2004, Trapnell & Hamrick 2006.…”