Central and peripheral Hornungia petraea populations: patterns and dynamics

摘要: Summary 1 More or less continuous distributions tend to become fragmented towards species’ distribution limits. Peripheral isolated populations of a species are predicted have lower population sizes and densities than central populations, as result environmental and/or genetic stress. Population at the periphery may be reduced by decreased reproduction higher interannual variation in reproduction. In particular, fecundity survival likely favourable growing conditions. 2 We compared annual Hornungia petraea (Brassicaceae) two contrasting regions range scale within regions. Ten Italy (central range) 10 German (peripheral) were monitored for three periods from spring 1999 2001. 3 All life-cycle stages, adult plant density, seed production pre- post-dispersal bank density studied nested sampling design various demographic factors was attributed effects countries, country temporal effects. 4 Peripheral had centre distribution, both plants bank. 5 Fecundity strongly influenced effects, but only affected minor degree study region. High not reflected high either bank. Significant regional differences were, however, found seasonal dynamics, which more pronounced peripheral Italian populations. 6 We conclude that dynamics key factor explaining H. patterns, particularly where fewer seeds incorporated into