Biology subjects

Terry, J. C. D.

Publications and source records attributed to Terry, J. C. D..

4 recordsLinked to original sources

bioRxiv2026

Hierarchical permutation entropy regression identifies decadal decline in the intrinsic predictability of butterfly populations

Short-term population dynamics are shaped by both external environmental stochasticity and endogenous ecological dynamics. The extent to which population trajectories maintain predictable temporal structure reflects underlying determinism and sets limits on inherent forecastability. Permutation entropy quantifies this intrinsic predictability using the relative frequency of short fluctuation motifs. However, requirements for long timeseries have restricted ecological applications. Here, I introduce a Bayesian hierarchical regression framework, incorporating entropy-neutral priors, that estimates expected permutation entropy from shorter, spatially-distributed ecological datasets. I validate the approach's capacity to detect the impact of increasing environmental variance through simulations. Applied to four decades of UK butterfly data, the approach identified increasing permutation entropy across 35 species, consistent with an increasing role of stochastic weather events. Outlier weather events did not have a consistent relationship with permutation entropy, highlighting the potential for environmental forcing to both disrupt and constrain trajectories. With this flexible approach, permutation entropy offers complementary perspectives on longstanding questions around forecasting and population dynamics.

ecology↗

bioRxiv2022

How temporal turnover in community composition is linked to anthropogenic pressure

Understanding the mechanisms behind biodiversity is central to assessing and forecasting anthropogenic impacts on ecological communities. However, quite how intrinsic ecological processes and external environmental drivers act together in natural systems to influence local temporal turnover is currently largely unexplored. Here, we determine how human impacts affect multiple metrics of bird community turnover to establish the ecological mechanisms behind compositional change. We used US Breeding Bird Survey data to calculate transect-level rates of three measures of temporal species turnover: a) short-term (initial rate of decline of Sorensen similarity), b) long-term (asymptotic Sorensen similarity), and c) overall species accumulation rate (species-time relationship exponents) over 2692 transects across 27 habitat types. We then hierarchically fit linear models to estimate the effect on these turnover metrics of anthropogenic impact via the Human Modification Index proxy, while accounting for observed species richness, the size of the species pool and annual environmental variability. We found broadly consistent impacts of increased anthropogenic pressures across diverse habitat types. The Human Modification Index was associated with greater turnover at long-timescales, but marginally slower short-term turnover. The species accumulation rate through time was not notably influenced. Examining anthropogenic impacts on different aspects of species turnover in combination allows greater ecological insight. Observed human impacts on short-term turnover were the opposite of existing expectations and suggest humans are disrupting the background turnover of these systems, rather than simply driving rapid directed turnover. The increased long-term turnover was driven by more frequent species changes between core and occasional status rather than greater arrival of new species. These results highlight the role of intrinsic dynamics and caution against simple interpretations of increased species turnover as reflections of environmental change. Open Research StatementNo new empirical data are used in the manuscript as all primary data is publicly available, as cited in the manuscript. Our code repository (including fitted model objects and markdown documents detailing all steps) is available at https://figshare.com/s/f5b9152ff7643efb347d.

ecology↗

bioRxiv2021

Mechanisms of biodiversity between Campylobacter sequence types in a flock of broiler-breeder chickens.

A long-term study of Campylobacter sequence types was used to investigate the competitive framework of the Campylobacter metacommunity, and understand how multiple sequence types simultaneously co-occur in a flock of chickens. A combination of matrix and patch-occupancy models were used to estimate parameters describing the competition, transmission, and mortality of each sequence type. It was found that Campylobacter sequence types form a strong hierarchical framework within a flock of chickens, and occupied a broad spectrum of transmission-mortality trade-offs. Upon further investigation of how biodiversity is thus maintained within the flock, it was found that the demographic capabilities of Campylobacter, such as mortality and transmission, could not explain the broad biodiversity of sequence types seen, suggesting that external factors such as host-bird health and seasonality are important elements in maintaining biodiversity of Campylobacter sequence types.

microbiology↗

bioRxiv2020

Molecular analyses reveal consistent food web structure with elevation in rainforest Drosophila - parasitoid communities

The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila-parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5{degrees} Celsius in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5-9 host and 5-11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are diverse enough to be representative, yet still amenable to field and laboratory experiments.

ecology↗