Hulme, P. E. | bioRxiv Science

bioRxiv2025

Jack of all trades and master of most: Carpobrotus taxa show no trade-off in reproductive strategies

O_LIThe ability to reproduce via multiple strategies is crucial for the invasion success of alien plant species. Here, we use Carpobrotus taxa (species and hybrids) to explore how trade-offs between and within these strategies may influence plant invasion dynamics. Native to South Africa, Carpobrotus plants are globally prominent in coastal ecosystems, reproducing by seed and clonally, and frequently hybridizing in both native and introduced regions. Three genetically distinct clusters were previously identified, with evidence of hybridization within and between these clusters in native and non-native ranges. C_LIO_LIWe collected fruit samples from populations representing the genetic clusters and their hybrids across native and non-native ranges (i.e., Europe, California, and New Zealand). These genetic clusters reflect the complex taxonomy of Carpobrotus, where species boundaries are unclear due to hybridization and morphological similarity. We then assessed seed set, seed mass, germination rates, and early growth under varying abiotic conditions alongside genetic estimates of clonality. C_LIO_LIGermination rates were influenced by temperature, moisture, and nutrient levels. Non-native populations demonstrated higher seed set, seed mass, and germination success compared to native populations, indicating a stronger investment in sexual reproduction. These populations also showed higher levels of clonality, shown by lower genotypic richness, suggesting that both reproductive strategies enhance invasive potential. C_LIO_LIHigh-clonality populations produced more seeds, demonstrating that the two reproductive strategies are not mutually exclusive. These results highlight the importance of multiple reproductive strategies for the establishment and spread of Carpobrotus taxa and provide insights into the mechanisms driving their global success. C_LI

plant biology↗

bioRxiv2021

Alternative futures for global biological invasions

Scenario analysis has emerged as a key tool to analyze complex and uncertain future socio-ecological developments. However, current global scenarios (narratives of how the world may develop) have neglected biological invasions, a major threat to biodiversity and the economy. We used a novel participatory process to develop a diverse set of global biological invasion scenarios spanning a wide breadth of plausible global futures through 2050. We adapted the widely used "two axes" scenario analysis approach to develop four families of four scenarios each, resulting in 16 scenarios that were later clustered into four contrasting sets of futures. Our analysis highlighted that socio-economic developments and changes in sustainability policies and lifestyle have the potential to shape biological invasions, in addition to well-known ecological drivers, such as climate and human land use change. Our scenarios align fairly well with the recently developed shared socio-economic pathways, but the factors that drive differences in biological invasions are underrepresented there. Including these factors in global scenarios and models is essential to adequately consider biological invasions in global environmental assessments, and obtain a more integrative picture of future socio-ecological developments.

ecology↗