Niche expansion of the invasive plant species Ageratina adenophora despite evolutionary constraints

Abstract

Aim Ecological inferences drawn from studies on niche dynamics of invasive species are often limited due to difficulties in disentangling evolutionary adaptations of the fundamental niche from demographic and interspecific processes shaping the realized niche. We used Ageratina adenophora, an invasive plant with restricted evolutionary potential to investigate shifts in the realized climatic niche independent of potential evolutionary adaptations. Location Native Mexican range; exotic ranges in Asia, the USA, the Canary Islands and Australia. Taxon Invasive Asteraceae A. adenophora (Spreng.) R.M.King & H.Rob. Commonly known as Crofton weed. Methods We compiled a robust occurrence dataset of A. adenophora for its native Mexican range and four exotic ranges (Asia, USA, Canary Islands, and Australia) and quantified pairwise niche overlap (Schoener's D) and niche dynamic (stable, unfilling and expansion) indices between the native and exotic ranges in reduced climatic space using smoothed occurrence densities. Niche shift was statistically tested using niche equivalency tests. Results The value of niche overlap (Schoener's D) differed considerably, ranging from relatively high between Mexico and Asia to low between Mexico and Australia. The niche dynamic indices indicated highest level of niche stability in Asia while highest degree of unstable niche was detected in Australia due to both niche expansion and unfilling. The niche similarity tests indicated that the native niche is more similar to the exotic niche than any randomly sampled niche from the exotic range. However, the niche equivalency tests showed evidence of niche differentiation as the observed niche overlap was lower than expected by chance for all pairwise comparisons. Jointly these tests indicate that despite the similarity, the native niche is not perfectly identical to any of the exotic niches. Main conclusions The current study has direct implications for understanding range expansion of invasive species even in the absence of evolutionary adaptation. Our study indicates that invasive species can occupy different, non‐consistent realized climatic niches in different parts of the world, thus limiting the transferability of species distribution models and corresponding risk assessments or future projections.

Predicting the Current and Future Distribution of the Invasive Weed Ageratina adenophora in the Chitwan–Annapurna Landscape, Nepal

“…Our predictions suggest that the minimum temperature in the coldest month is the most influential factor for the distribution of A. adenophora. This is in line with the findings of other researchers (Wang and Wang 2006;Zhu et al 2007;Wang et al 2017;Lamsal et al 2018;Thapa et al 2018;Datta et al 2019). According to our model, the minimum temperature in winter (Bio 6) alone contributes MountainResearch about 49% to the habitat suitability model (Table 2), and the probability of occurrence of the weed decreased to almost 0 below the minimum winter temperature of 18C (Appendix S3, Supplemental material, https://doi.org/10.1659/MRD-JOURNAL-D-19-00069.1.S1).…”

Evaluation of foliar fungus‐mediated interactions with below and aboveground enemies of the invasive plant Ageratina adenophora

“…The invasive plant Ageratina adenophora (Sprengel) R. M. King and H. Robinson is a perennial herb of the Compositae family that is native to Central America. The spread of A. adenophora is considered to be a severe problem in more than 30 countries in Asia, Africa, Oceania, Europe and North America (Datta et al., 2019). In China, this weed has been reported to reduce the diversity of native plant species, crop production in agricultural land and forage production in pastures; moreover, this weed is poisonous to domestic animals (Poudel et al., 2019).…”

Geographical distribution of the dispersal ability of alien plant species in China and its socio-climatic control factors

“…Possible reasons for this include the fact that high-risk alien plant species rely more on natural dispersal strategies, and rely less on anthropogenic strategies apart from accidental introduction (e.g., speirochory or introduced involuntarily via mixing with grain or fodder) 14 , 35 , 48 , 49 . For example, Ageratina adenophora (common name: crofton weed; rank I), which was accidentally introduced to China from Mexico, is a notorious weed that exerts considerable ecological impacts and causes substantial economic losses 50 , 51 . The species exhibits three natural dispersal modes–trichometeorochory, hydrochory, and zoochory–and two anthropogenic dispersal modes, agochory and speirochory (Supplementary Material 1 and 2 ) 14 , 35 .…”