Biology subjects

Dant, A.

Publications and source records attributed to Dant, A..

3 recordsLinked to original sources

bioRxiv2026

Near chromosome-level genome assembly for the invasive annual forb Centaurea melitensis

PremiseCentaurea melitensis (Asteraceae) is a problematic invader of grasslands globally, but little is known about its genetic makeup. Here we develop a reference genome to facilitate studies of its invasion history, genetic variation, and evolution. MethodsInbred offspring of a single individual of C. melitensis from its invasion of California, USA were used for flow cytometry to estimate genome size, and for genomic DNA extraction. DNA was sequenced with PacBio HiFi technology (yield = 85.7Gb). The genome was assembled with Hifiasm and annotated with BRAKER3. GENESPACE was used to compare gene order (synteny) with three other species within the subfamily Cichorioideae. ResultsWe estimated a mean genome size of 795.0 Mbp for C. melitensis, and our assembly totaled 696.6 Mbp in 48 contigs (N50 = 55.6 Mbp; BUSCO = 98%), with annotation of 25,157 protein-encoding genes. This included four telomere-to-telomere putative chromosomes, nine additional chromosome arms terminated by telomeric repeats, and a complete chloroplast genome. Synteny varied markedly across the genus and subfamily, suggesting a dynamic history of structural variation in the lineage of C. melitensis. DiscussionWe provide a highly complete and contiguous genome assembly to facilitate the further study of genomic variation in C. melitensis.

genomics↗

bioRxiv2026

Testing fundamental hypotheses of colonization success in the ferns

Background and AimsNon-native species are now ubiquitous members of regional floras. The factors that lead to establishment and dominance of non-native species are continuously debated. Fundamental hypotheses about drivers of invasion success include the role of phylogeny, polyploidy, genome size, and rapid niche evolution. These hypotheses have been tested in the seed plants, but ferns, the second largest group of vascular plants, have rarely been considered in these analyses, despite making up a non-trivial portion of non-native floras. MethodsWe compiled a dataset of global non-native ferns and categorized them along the invasion spectrum using descriptions from the literature and natural history collections. Using this dataset, we assessed I) the taxonomic diversity and phylogenetic clustering of non-native ferns, II) the geographic distribution of fern introductions, testing for shifts in climatic niches, and III) test for the association of invader traits across the invasion continuum, including smaller genome sizes and higher ploidal levels. Key ResultsWe generated a dataset that includes 83 taxa; of these, we classified 18 as casual, 35 as naturalized (but not invasive), and 30 as invasive. Using this dataset, we found I) weak or no phylogenetic clustering of non-native ferns, II) some regions are overrepresented as sources and recipients of introductions, III) climatic niches are often conserved between native and introduced ranges, but can differ between introductions, IV) naturalized ferns have smaller genomes, and V) invaders have higher ploidal levels. ConclusionsWe integrated regional floras, occurrence and climate data, phylogeny, and cytology to test fundamental hypotheses regarding the colonization success of ferns. This study provides insights into the ecological, genomic, and phylogenetic features associated with the colonization of new habitats by non-native ferns, a largely overlooked portion of non-native plant taxa.

evolutionary biology↗

bioRxiv2025

Applying a classification approach to categorizing urbanized landscapes in California and their invasion by the Maltese starthistle Centaurea melitensis

There is increasing evidence that the traits of organisms can differ in urban environments, but defining what makes an environment urban is difficult. There are many variables associated with increasing human impacts that might be associated with urbanization, and this makes it challenging to identify both how traits vary across diverse urbanized landscapes and the variables that might drive that variation. To better define the mosaic of urban environmental heterogeneity and identify similar types of environments that are comparable across its complexity, here we develop a multivariate landscape classification framework and apply it to classification of land area in the state of California, USA. We used a hierarchical cluster analysis to group 7,829 government census tracts into Environmental Zones based on a set of 19 independent environmental characteristics, including climate, land cover, pollution, and socio-economic variables. This analysis identified nine major Environmental Zones, which were differentiated based upon complex combinations of variables that did not align with conventional urban vs. natural dichotomies or gradients. Environmental Zones also occurred as mosaics of many zones within cities and differed in their relative abundance between cities, reflecting complex urban landscapes unique to each area. We then asked if these Environmental Zones were better able to explain trait variation than conventional urban vs. non-urban classification using a case study of the invasive, annual plant Centaurea melitensis, commonly found throughout much of California. Seeds from seventeen populations of C. melitensis were collected from six Environmental Zones, including two heavily urbanized, and four more natural/agricultural. Seeds were grown in greenhouse conditions, and eight vegetative traits were measured. No trait differed significantly between urban and non-urban sites, but four traits differed according to Environmental Types (length of longest leaf, SLA, root diameter, and the number of flowerheads). Traits differed between the heavily urbanized zones, as well as among the relatively more natural zones. Our results reveal that more complex multivariate classifications of the urban mosaic can identify similar, comparable environments across complex landscapes and better explain trait variation in organisms navigating urbanized environments.

ecology↗