Contrasting spatio‐temporal climatic niche dynamics during the eastern and western invasions of spotted knapweed in North America

Abstract

Aim The spotted knapweed (Centaurea stoebe), a plant native to south-east and central Europe, is highly invasive in North America. We investigated the spatiotemporal climatic niche dynamics of the spotted knapweed in North America along two putative eastern and western invasion routes. We then considered the patterns observed in the light of historical, ecological and evolutionary factors.Location Europe and North America.Methods The niche characteristics of the east and west invasive populations of spotted knapweed in North America were determined from documented occurrences over 120 consecutive years . For this investigation, the 2.5 and 97.5 percentiles of values along temperature and precipitation gradients, as given by the two first axes of a principal components analysis (PCA), were calculated. We additionally measured the climatic dissimilarity between invaded sites and the native niche using a multivariate environmental similarity surface (MESS) analysis.Results Along both invasion routes, the species established in regions with climatic conditions that were similar to those in the native niche. An initial spread in ruderal habitats always preceded spread in (semi-)natural habitats. In the east, the niche gradually increased over time until it reached limits similar to the native niche. Conversely, in the west the niche abruptly expanded after an extended time lag into climates not occupied in the native range; only the native cold niche limit was conserved.Main conclusions Our study reveals that different niche dynamics have taken place during the eastern and western invasions. This pattern indicates different combinations of historical, ecological and evolutionary factors in the two ranges. We hypothesize that the lack of a well-developed transportation network in the west at the time of the introduction of spotted knapweed confined the species to a geographically and climatically isolated region. The invasion of dry rangelands may have been favoured during the agricultural transition in the 1930s by release from natural enemies, local adaptation and less competitive vegetation, but further experimental and molecular studies are needed to explain these contrasting niche patterns fully. Our study illustrates the need and benefit of applying large-scale, temporally explicit approaches to understanding biological invasions.

The population genetics of the fundamental cytotype-shift in invasive Centaurea stoebe s.l.: genetic diversity, genetic differentiation and small-scale genetic structure differ between cytotypes but not between ranges

“…In the native range, diploids are more common in central Europe, while tetraploids prevail in southeastern Europe (Broennimann et al 2014). However, their native distributions overlap widely and include several mixed-ploidy populations (Mráz et al 2012b).…”

“…In the invasive range, the first recorded introductions of NA4x were in the late nineteenth century, followed by a lag-phase of 50 years. Subsequently, the species spread rapidly along ruderal transport corridors of two separate invasion routes: one expanding from the east coast and one from the west coast (Broennimann et al 2014). Nowadays, C. stoebe is a widespread, notorious weed that causes tremendous economic damage in the North American grasslands (Corn et al 2006).…”

“…), which constitutes a polyploid complex including a diploid (predominantly) monocarpic cytotype and a polycarpic tetraploid cytotype (Mráz et al 2011). The complex is native to Europe and Asia Minor with diploids representing the majority of native populations (Broennimann et al 2014). Both cytotypes occupy relatively similar habitats (i.e.…”

Aliens on the Move: Transportation Networks and Non-native Species

“…This plant, native to south east and central Europe, arrived in North America in the late 1800s and by the year 2000 it was already found in most contiguous American states (Sheley et al 1998). The mechanisms that enabled such a fast dispersal were unclear for a long time, but a recent reconstruction of the patterns of invasion of this plant showed a close agreement between the extent of colonized areas and its velocity dispersal on one side, and the spatial coverage and development of the railway network in the USA on the other (Broennimann et al 2014). For instance, the wave of invasion was much faster and wider in the eastern states, where a denser and older network exists.…”

Revisão taxonômica, filogenia e evolução do nicho ecológico de Tynanthus Miers (Bignonieae, Bignoniaceae)

“…Despite the great breath of studies on niche evolution, the exact role of niche conservatism and niche overdispersion remains to be determined. A better understanding of the level of lability of ecological features is critical for a clearer understanding of community structure (e.g., Stephens & Wiens 2009;Vamosi et al 2009), and species distribution patterns in tropical vs. temperate regions (e.g., Buckley et al 2010;Hawkins et al 2011;Jansson et al 2013), as well as allows for a better evaluation of species' persistence under climate change (e.g., Wiens et al 2009;Maiorano et al 2013), and biological invasions (e.g., Petitpierre et al 2012;Broennimann et al 2014), among others (reviewed by Wiens et al 2010;Peterson 2011 We then conducted a multivariate comparison between all species pairs. In those comparisons, niche overlap between taxa was quantified using the PCA-env technique proposed by Broennnimann et al (2012), in R. For those analyses, the first two axes of the Principal Component Analysis (PCA) calibrated on the entire climatic space of the study area, including species occurrences, were considered .…”