The effect of segregation of flowering time on fine-scale spatial genetic structure in an alpine-snowbed herb Primula cuneifolia

Abstract

The flowering phenology of alpine-snowbed plants varies widely depending on the time of snowmelt. This variation may cause spatial and temporal heterogeneity in pollen dispersal, which in turn may influence genetic structure. We used spatial autocorrelation analyses to evaluate relative effect of segregation in flowering time and physical distance on fine-scale spatial genetic structure (SGS) of a snowbed herb Primula cuneifolia sampled in 10-m grids within a continuous snow patch (110 Â 250 m) using nine allozyme loci. Although the individual flower lasts for p10 days, flowering season varied over 50 days from late June to the middle of August within the plot. The effect of flowering phenology on SGS was assessed using spatial autocorrelation analyses based on the pairwise kinship coefficients for all sampled plants (control pairs), plants with flowering overlap (co-flowering pairs) and plants with separate flowering season (non-coflowering pairs). The degree of SGS increased as the extent of flowering segregation increased: co-flowering pairs o control pairs o non-co-flowering pairs, indicating substantial effect of restriction in gene flow due to phenological heterogeneity. Flowering segregation caused by snowmelt timing is a critical factor for reinforcing the fine-scale SGS in this species.

Small-scale patterns in snowmelt timing affect gene flow and the distribution of genetic diversity in the alpine dwarf shrub Salix herbacea

“…A 1-month shift in phenology imposes a strong barrier to pollen flow between microhabitats, as S. herbacea flowers are only receptive to pollen for approximately 2 weeks (Beerling, 1998). Strong flowering time differentiation within short distances is not uncommon and has been reported in snowmelt gradients in Scandinavia for S. herbacea (Wijk, 1986b) and in other alpine species (Kudo, 1992;Kudo and Ito, 1992;Jones et al, 1997;Kudo et al, 1999;Shimono and Kudo, 2005;Hirao and Kudo, 2008;Shimono et al, 2009;Wipf et al, 2009;Elmendorf et al, 2012). Some of these exhibit genetically differentiated, phenologically isolated subpopulations Yamagishi et al, 2005;Hirao and Kudo, 2008;Shimono et al, 2009).…”

“…Such small-scale genetic differentiation due to flowering-time divergence and restricted gene flow via pollen has been reported in the majority of studies on snowmelt-driven genetic differentiation Yamagishi et al, 2005;Hirao and Kudo, 2008;Shimono et al, 2009). Seed dispersal, however, can counteract isolation driven by barriers to pollen flow, because seed dispersal occurs later in the season when all winter snow has melted (Kudo and Hirao, 2006).…”

“…In order to predict a species' potential to persist in changing conditions, investigations of the small-scale genetic structure present within species today are needed. Until now, only a few studies have studied genetic diversity and migration at this spatial scale (Hirao and Kudo, 2008;Shimono et al, 2009).…”

Local Scale Genetic Diversity and its Role in Coping with Changing Climate

“…Small-scale genetic diferentiation (measured by the F ST , which is the ixation index, a measure of population diferentiation due to genetic structure) has been reported in the majority of studies on snowmelt-driven genetic diferentiation [11,[19][20][21].…”

Local differentiation of flowering phenology in an alpine-snowbed herb Gentiana nipponica

“…Therefore, the optimal flowering schedule may be different between populations that inhabit different snowmelt conditions. Second, the flowering period of individual populations strongly depends on the time of snowmelt, and this may cause a temporal separation of flowering season between adjacent populations (Kudo 1991), resulting in genetic isolation via pollen dynamics (Hirao and Kudo 2008).…”