Morphological differentiation across the invasive range in Senecio madagascariensis populations

Abstract

Invasive species are characterized by their ability to colonize new habitats and establish populations away from their native range. In this sense, these plants are expected to have plastic responses to adapt to the environmental pressures during the invasion process. Hence, the role of natural selection is essential because it might favor the occurrence of advantageous traits. However, gene flow can counteract natural selection because immigrants introduce genes adapted to different conditions, with these introductions tending to homogenize allelic frequencies. In this work, we explore the effect of natural selection in invasive populations of S. madagascariensis in Argentina. We quantified leaf area, head number, and length of internodes and inflorescence from material spanning 54 years (1962–2016) and then compared between the edge versus established ranges. Our results show differences in all the measured plant traits among the sampled areas. However, only leaf area was statistically significant, which evidences different responses under the same environmental pressures in the areas located in the edge and established ranges. On the other hand, unlike homogeneous areas, the areas characterized by phenotypically diverse individuals were related to higher dispersal ability. In this sense, long-distance dispersal between neighboring areas may have had an important role in the recorded values. Furthermore, the implications of natural selection and founder effect in the invasion of S. madagascariensis are discussed.

Vegetation of a hill grassland of the Paititi Natural Reserve (Pampa biome) and early detection of non-native species acting as invasive

“…It belongs to the Asteraceae family and is native to South Africa and Madagascar. It is a toxic species, recognized as invasive in different parts of the world (Dematteis et al, 2020). S. madagascariensis has been reported in the Argentinean Pampas as a weed in extensive farmlands in the past (Verona et al, 1982), while it is currently a problem in cattle fields and a growing concern in farms under no-tillage systems and in ruderal areas (Ahumada et al, 2016;Dematteis et al, 2020;Diez de Ulzurrun personal communication, 2022).…”

“…It is a toxic species, recognized as invasive in different parts of the world (Dematteis et al, 2020). S. madagascariensis has been reported in the Argentinean Pampas as a weed in extensive farmlands in the past (Verona et al, 1982), while it is currently a problem in cattle fields and a growing concern in farms under no-tillage systems and in ruderal areas (Ahumada et al, 2016;Dematteis et al, 2020;Diez de Ulzurrun personal communication, 2022). It is a species with a high production of seeds per plant and easy to disperse thanks to a hairy pappus, characteristics that determine their invasive nature.…”

Elevated nitrogen deposition and co-evolutionary history shape competition between an invasive plant and its competitors during range expansion

“…During their range expansion, invasive plants encounter environmental heterogeneity that might lead to differentiation across populations (Dematteis et al 2020;Helsen et al 2020;Zhang et al 2022). This differentiation may re ect upon species performance and to diverse responses to the increase of nitrogen deposition.…”

“…Drastic differences across populations usually encountered between a central population where the species initially established in the introduced range and an edge population where the invasive plant has established recently. While the central population shares a longer co-evolutionary history with co-occurring competitors (old competitors), the edge population recently co-occurs with its competitors at the expansion front (new competitors) (Dematteis et al 2020;Halbritter et al 2015;Tabassum, Leishman 2020). The differentiation on growth and competitiveness among invasive populations since time of establishment can signi cantly affect the competition dynamic with their competitors and determine invaders further expansion (Farooq et al 2017; Kilkenny, Galloway 2016).…”