Biology subjects

Le Roux, J. J.

Publications and source records attributed to Le Roux, J. J..

3 recordsLinked to original sources

bioRxiv2026

Revegetation following grazing cessation drives sequential shifts in soil microbial functions and life-history strategies over decadal time scales

Revegetation is a key strategy for restoring degraded lands globally. While this process can reshape belowground microbial communities, the extent to which such changes restore soil ecosystem functions, and whether different microbial traits recover synchronously or on distinct timescales remains less clear. Understanding this is essential for evaluating restoration success, as different microbial traits underpin distinct ecosystem services, from carbon storage to plant growth promotion, and the sequence in which these are restored can inform restoration targets and provide meaningful indicators of long-term ecological recovery. To address this, we applied deep metagenomic sequencing to characterise soil microbial responses following revegetation (spanning 1-31 years prior to sampling) on grazing agricultural lands. We find that revegetation following grazing cessation drove significant and sequential shifts in dominant microbial functions and life-history strategies. Functional changes occurred in distinct phases: an early, rapid restructuring of core soil health processes, detectable as early as three years, including enrichment of nutrient retention and carbon fixation pathways, followed by a more gradual development of plant growth-promoting traits as the plant community matures. Genome-resolved analyses of nearly 500 metagenome-assembled genomes revealed a fundamental shift in dominant microbial life history strategies: from a resource-scavenging and stress tolerance profile in grazing soils to strategies that prioritise biosynthesis and growth yields in revegetated soils. These lifestyle shifts have important implications for enhancing the microbial biomass and carbon sink potential of soils. Together, these findings show that microbial functional shifts following revegetation are temporally structured - informing expectations for when key restoration targets may be achieved, and providing a practical framework for monitoring ecosystem recovery.

microbiology↗

bioRxiv2025

Tangled evolutionary history: genetically divergent taxa and hybrids characterise lantana invasions in Australia

Aimto investigate population genomics and phylogeography in invasive lantana, including its taxonomy, spatial distribution, and patterns of morphological and genetic variation across the Australian continent. Locationthe main area invaded by lantana on the Australian continent, i.e., coastal and subcoastal eastern Australia from northern Queensland to southern New South Wales up to approximately 100 km inland, across 22 degrees latitude. The native range of lantana in the Americas was also represented. Methodswe used DArTseq to generate genome-wide single nucleotide polymorphism (SNP) data for >600 individuals representing the native and Australian invaded ranges of lantana. We analysed data from >20,000 SNPs to identify distinct genetic clusters, and test the extent to which they corresponded with taxonomic descriptions and morphotype concepts used in lantana biological control. Genome sizes were estimated for a small representative subset of individuals using flow cytometry. We used MaxEnt to estimate habitat suitability for different lantana genetic clusters, and compared these predictions with observed patterns in biological control agent host-specificity. Resultsinvasive lantana in Australia consisted of several divergent genetic clusters of most likely tetraploid individuals. Gene flow between genetic clusters was limited, consistent with the notion that multiple species introductions and/or hybridisation events were part of the invasion history. Two widespread, homogeneous genetic clusters were found to be dominant in Australia; two other genetic clusters with more limited distributions were identified with potential for future spread. Biological control agent host preferences were consistent with identified genetic clusters. Main conclusionstreating invasive lantana as a single taxon may be counterproductive for effective management. Comprehensive taxonomic revision is needed to enable more precise identification of invasive taxa. Improved identification will support improved management, particularly if using biological control.

evolutionary biology↗

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↗