Landscape genetics of alpine-snowbed plants: comparisons along geographic and snowmelt gradients

Abstract

The genetic structure of three snowbed-herb species (Peucedanum multivittatum, Veronica stelleri, and Gentiana nipponica) was analyzed using allozymes across nine populations arranged as a matrix of three snowmelt gradients  three geographic locations within 3 km in the Taisetsu Mountains, northern Japan. Phenologically asynchronous populations are packed within a local area in alpine snowbeds, because flowering season of alpine plants depends strongly on the timing of snowmelt. Moderate genetic differentiation was detected among local populations in every species (F ST ¼ 0.03-0.07). There was a significant correlation between the geographic distance and genetic distance in the P. multivittatum populations, but not in the V. stelleri and G. nipponica populations. On the other hand, a significant correlation between the phenological distance caused by snowmelt timing and genetic distance was detected in the V. stelleri and G. nipponica populations, but not in the P. multivittatum populations. The snowmelt gradient or geographic separation influenced hierarchical genetic structure of these species moderately (F RT o0.04).Restriction of gene flow due to phenological separation and possible differential selection along the snowmelt gradient may produce genetic clines at microgeographic scale in these species.

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

“…In an alpine region, the snowmelt gradient is a critical landscape feature affecting genetic structure of plants (Hirao and Kudo, 2004). Our study demonstrates that flowering segregation among individual plants substantially reinforces the SGS even in a continuous snow patch.…”

“…Study system and flowering phenology A survey plot was established in 2003 in a continuous snow patch on a gentle slope at Kaun-daira, the central part of the Taisetsu Mountains in Hokkaido, northern Japan (for details, see Hirao and Kudo, 2004). After snowmelt, more than 10 000 flowering individuals of P. cuneifolia occurred within the plot (110 Â 250 m), where flowering density was about 1-5 inflorescences per m 2 .…”

“…Although contemporary pollen dispersal often varies depending on ecological factors such as population density (Levin and Kerster 1969), flowering phenology (Schmitt, 1983;Kitamoto et al, 2006) and seasonal changes in pollinator activity (Hirao et al, 2006), the historical gene flow across generations appears to be consistent in shaping the finescale SGS along a snowmelt gradient. Furthermore, the larger scale analyses of genetic structure in several alpine herb species (Peucedanum multivittatum, Veronica stelleri and Gentiana nipponica (Hirao and Kudo, 2004); Erythronium grandiflorum (Yamagishi et al, 2005)) revealed that the effect of snowmelt gradient on genetic structures varied among species. Overall genetic processes including the breeding system, population dynamics, genetic drift and selective force must be considered to understand hierarchical genetic structures and their significance for evolutionary potential.…”

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

“…This species is distributed widely along the range of the snowmelt gradient, and the flowering season of individual populations depends strongly on snowmelt time (Kudo and Suzuki 1999;Hirao and Kudo 2004). Gentiana nipponica is a late-flowering species in snowbed plant communities (Kudo 1991), populations in late-snowmelt habitats suffer especially from the short period for seed maturation.…”

“…Because flowering time and period of alpine plants are strongly influenced by the time of snowmelt, gene flow via pollination process may be restricted between neighboring populations that inhabit different snowmelt sites owing to phenological isolation (Hirao and Kudo 2004). Therefore, alpine plant species with a wide distribution range along the snowmelt gradient should be a good material for the study of local adaptation of flowering phenology (Kudo and Hirao 2006).…”