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

The 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.

We 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.

Germination 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.

High-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.