Latitudinal trends in growth and phenology of the invasive alien plant Impatiens glandulifera (Balsaminaceae)

Abstract

Geographical differentiation of populations can be interpreted as a result of adaptive processes in response to environmental gradients and biotic interactions. Such adaptations are particularly interesting in invasive alien species which have been present in an area for a relatively short time. There are few observations of latitudinal trends in alien plants, and no account exists for Impatiens glandulifera, a problematic annual weed in most countries of central and north‐western Europe. Here we describe variation in growth and phenology in 26 populations of this species from nine European regions in a common garden in Denmark. Above‐ground biomass (an estimate of fecundity), height and basal diameter were lower in the northern populations which were first to produce flowers. Some differences were also observed in biomass allocation to leaves, flowers and fruits, albeit without a latitudinal pattern. The latitudinal trends in growth and survival disappeared in a field experiment, probably due to suboptimal site conditions. Most variation in plant traits was explained by differences among regions with some minor effects of populations within regions. Besides latitude, no other geographical, climatic or population trait correlated with the observed differences in growth and phenology. Differences in latitude may mainly represent variation in length of the growing season. The causes and potential consequences of such latitudinal trends for population dynamics and dispersal of alien plants are discussed.

Artificial selection shifts flowering phenology and other correlated traits in an autotetraploid herb

“…Plants in early flowering selection lines not only flowered earlier but were also smaller with smaller display sizes than those in late flowering lines, a group of traits often found in plants with a shorter lifespan (Olsson and Agren, 2002;Kollmann and Bañ uelos, 2004;Griffith and Watson, 2005). Some taxa that share these traits also have smaller flowers and produce fewer seeds per fruit, like the early flowering selection lines (Dole, 1992).…”

Adaptation and colonization history affect the evolution of clines in two introduced species

“…Because founding events can generate genetic structure and deviations from the equilibrium balance between gene flow, drift and selection (Whitlock & McCauley, 1990, 1999McCauley et al, 1995), multiple introductions can quickly generate patterns that resemble isolation by distance or clinal variation when sources establish at different points of introduction (for example, Roman, 2006;Keller & Taylor, 2008). Numerous studies of species invasions have reported latitudinal clines for traits such as body size and mass, height, number of stems, flowering time, fecundity and physiology (Johnston & Selander, 1964;Weber & Schmid, 1998;Huey et al, 2000;Kollmann & Banuelos, 2004;Maron et al, 2004Maron et al, , 2007Leger & Rice, 2007;Montague et al, 2008). Although colonization history is expected to have a major influence on the population and quantitative genetics of introduced species, few studies have attempted to control for colonization history when analysing clines (but see Maron et al, 2004).…”

The biology of invasive alien plants in Canada. 9. Impatiens glandulifera Royle

“…A common garden experiment conducted in Denmark revealed a latitudinal pattern whereby plants from northern populations were found to have reduced above-ground biomass, basal stem diameter, and height and were able to reproduce more quickly (Kollmann and Ban˜uelos 2004).…”

“…(c) Intra-specific Variation * Impatiens glandulifera exhibits significant phenotypic variation which may be due largely to differences in soil moisture or climate regime (Beerling and Perrins 1993;Kollmann and Ban˜uelos 2004). The usual form of the plant is tall with a small number of branched stems although shorter, many-branched specimens with shorter leaves and internodes do occur (Beerling and Perrins 1993).…”