Biology subjects

Gillis, A. J.

Publications and source records attributed to Gillis, A. J..

3 recordsLinked to original sources

bioRxiv2026

Freshwater input and tidal position regulate species turnover and interaction rewiring in intertidal ecological networks

The effect that environmental conditions have on community and network assembly processes remains unclear, in part because these processes operate at multiple scales. Because marine primary producers and microinvertebrates have limited mobility, are susceptible to multiple stressors, and can be observed interacting in situ, their habitat-based interactions provide an informative system for disentangling network organising processes. We sampled 646 habitat-use networks, quantifying interactions involving habitat-users and biogenic habitat-formers over 12 months at 9 sites within Te Ihutai/Avon-Heathcote estuary in Christchurch, Aotearoa New Zealand. Using generalised dissimilarity mixed-effect models, we examined whether changes to species interactions - deconstructed into species turnover and interaction rewiring - were modulated by environmental covariates, including freshwater discharge, elevation, temperature, spatial location and season. We found that with increasing dissimilarity in sites proximity to freshwater, interaction change was more driven by rewiring, whereas differences in elevation (i.e., between channels and non-channel habitats) were driven by species turnover, with more sessile species inhabiting tidal channels. The proximity of habitats also played a strong role, with nearby networks comprising more similar interactions, and species turnover becoming more prevalent with increasing distance. Our results highlight that the relative influence and magnitude of rewiring and species turnover in controlling estuarine interaction networks was affected by the individual species distributions across the estuary and their responses to separate, but co-occurring, environmental factors. Quantification of habitat-former/user interaction networks offers robust, albeit understudied, measures of processes that can underpin community assembly, highlighting their potential importance in research, management and conservation. Open research statementData are provided for peer review. The code for produced from the project analysis and used to draft this manuscript is shared via a public GitHub repository hosted by the Tonkin Research group (repo name: EstInteractTurn). The data used in the formal analysis is hosted on Zenodo, under the corresponding authors profile (doi: 10.5281/zenodo.20619091). The data and code was prepared following strict adherence to the FAIR principles, meaning all data was saved as comma-separated values (.csv) or native R data structures (.rds).

ecology↗

bioRxiv2026

Population and community responses to the fast, slow, and seasonal components of environmental variation

Theory suggests that different components of environmental fluctuations, from daily and seasonal cycles to multidecadal trends, can have distinct and even opposing effects on species abundances and community dynamics, depending on their specific adaptations. But empirical research that deconstructs the influence of these different cycles on communities is lacking. Here, we used long-term biological monitoring data together with flow records of rivers across New Zealand to (i) investigate the role of fast, slow, and seasonal river-flow fluctuations in structuring macroinvertebrate communities; and (ii) to assess whether life-history and mobility traits mediate the response. Using joint species distribution models, we found striking differences in taxon and community responses to the different components of river flow variation. Responses to slow fluctuations were generally stronger and better predicted by traits, while responses to seasonal fluctuations were highly heterogeneous. Fast increases in flow, typical of flooding events, had pervasive negative effects on species abundances, but the severity of impact partly depended on mobility traits. Our results suggest that different ecological mechanisms underpin the response to distinct environmental fluctuations, highlighting the value of jointly considering multiple temporal scales of variation and species functional traits to understand and predict how communities reorganise under fluctuating environmental regimes.

ecology↗

bioRxiv2018

Molecular Heterogeneity and Early Metastatic Clone Selection in Testicular Germ Cell Cancer Development

BackgroundTesticular germ cell cancer (TGCC), being the most frequent malignancy in young Caucasian males, is initiated from an embryonic germ cell. This study determines intratumor heterogeneity to unravel tumor progression from initiation till metastasis.\n\nMethodsIn total 42 purified samples of four treatment-resistant nonseminomatous TGCC (NS) were investigated, including the precursor germ cell neoplasia in situ (GCNIS) and metastatic specimens, using whole genome- and targeted sequencing. Their evolution was reconstructed.\n\nResultsIntratumor molecular heterogeneity did not correspond to the supposed primary tumor histological evolution. Metastases after systemic treatment could be derived from cancer stem cells not identified in the primary cancer. GCNIS mostly lacked the molecular marks of the primary NS and comprised dominant clones that failed to progress. A BRCA-like mutational signature was observed without evidence for direct involvement of BRCA1 and BRCA2 genes.\n\nConclusionsOur data strongly support the hypothesis that NS is initiated by whole genome duplication, followed by chromosome copy number alterations in the cancer stem cell population, and accumulation of low numbers of somatic mutations. These observations of heterogeneity at all stages of tumorigenesis should be considered when treating patients with GCNIS-only disease, or with clinically overt NS.

cancer biology↗