Biology subjects

Sommer, B.

Publications and source records attributed to Sommer, B..

5 recordsLinked to original sources

bioRxiv2026

Larval thermal tolerances and future dispersal potential of the subtropical-to-temperate sea urchin Tripneustes australiae

The distribution and dispersal of marine ectotherms is mediated by their thermal tolerances, and as the oceans warm species distributions are shifting. Developmental thermal tolerances of marine invertebrates with a pelagic life-history phase can be used to predict the potential for local extinctions and range extensions. In southeast Australia, Tripneustes australiae is an ecologically important sea urchin species as it undergoes periodic outbreaks and can transform ecosystems through intense herbivory. We investigated the embryonic and early larval developmental tolerances of T. australiae with respect to its current distribution, to predict current and future dispersal capacity. The optimal thermal window for survival, normal development and developmental progression of T. australiae ranged between 17 and 23{degrees}C, with probability of survival at these temperatures remaining above 85% throughout the experiment. This developmental thermal window overlaps with the current thermal regime experienced across the adult distribution. This suggests that T. australiae may have a similar thermal window in its adult and early larval life history stages. Further, T. australiae may have the potential to persist at its warm-range edge into the future and to disperse and range shift poleward in coming decades. Indeed, we show that the temperature at which larvae have a 50% probability of survival may extend poleward across the Bass Strait by 2100. The persistence of T. australiae in its mid-range, its potential to disperse poleward, and increased grazing pressure from periodic outbreaks, may impact temperate macroalgal habitats already at risk from warming and concentrated grazing by other sea urchin taxa.

zoology↗

bioRxiv2025

Interactive delineation and quantification of anatomical structure with virtual reality

A virtual environment, equipped with suitable data representations, interaction techniques, and method interfaces, can facilitate effective human-in-the-loop analytics of 3D data. Motivated by this observation, we propose Brainacle, a native editor for the interactive delineation and quantification of anatomical structures in virtual reality. We validate this in a case study, where we process the gross brain regions of 20 individual animals from six different species of African cichlid fish from the tribe Lamprologinii, endemic to Lake Tanganyika in Africa. The software presented in this article can be used to quickly visualise and obtain an overview of imaged animal tissues, visually communicate features of interest, interactively add delineations, and perform different measurements in the same 3D environment. Brainacle is made available free of charge at https://brainacle.org and on the research data repository DaRUS.

bioinformatics↗

bioRxiv2025

Putting causality into context: Causal capture escapes the visual adaptation of causality

Results from psychophysical studies using visual adaptation suggest that launch detectors in the visual system underlie the perception of causality in simple visual events. These detectors respond to events in which one stimulus collides with another stimulus (i.e., a launch), and do not respond to events where one stimulus passes over another (i.e., a pass). Prolonged visual adaptation to launches significantly reduces observers propensity to see causal launches at the same retinotopic location. This finding could be taken to indicate that launch detectors are necessary for the local detection of causal launches. However, contextual events--that are spatially separated from the test event location--shift observers perception of a causal relation in the direction of the type of contextual event (Scholl & Nakayama, 2002), providing evidence for spatial integration beyond a specific retinotopic location. Here, we used visual adaptation as a tool to investigate whether the contextual influence on causal perception relies on local launch detectors. Before and after adaptation, we determined the proportion of reported launches in ambiguous test events in the presence of no context, launch context, and pass context events. We hypothesized that if the contextual influence relies on (unadapted) local launch detectors, then visual adaptation should affect the contextual influence on causal perception. Before adaptation, a launch-context event increased the proportion of reported launches (while a pass context event decreased it). Visual adaptation to launches significantly decreased the proportion of reported launches in no-context trials, but did not affect perceptual reports in no-context trials. In fact, contextual influences, expressed relative to no-context trials, emerged strongly after adaptation. This result suggests that context effects override strong negative aftereffects from adaptation, indicating that contextual influences operate at a level that bypasses the local launch detector at the adapted location.

neuroscience↗

bioRxiv2022

High-latitude marginal reefs support fewer but bigger corals than their tropical counterparts

AimDespite the awareness that climate change impacts are typically detrimental to tropical coral reefs, the effect of increasing environmental stress and variability on the population size structure of coral species remains poorly understood. This gap in knowledge limits our ability to effectively conserve coral reef ecosystems because size specific dynamics are rarely incorporated. Our aim is to quantify variation in the size structure of coral populations along a tropical-to-subtropical environmental gradient. Location20 coral populations along a latitudinal gradient on the east coast of Australia ([~]23{degrees}S to 30{degrees}S). Time PeriodBetween 2010 and 2018. Major taxa studiedScleractinian corals. MethodsWe apply two methods to quantify the relationship between environmental covariates and coral population size structure along a latitudinal environmental gradient. First, we use linear regression with summary statistics, such as median size as response variables; a method frequently favoured by ecologists. The second method is compositional functional regression, a novel method using entire size-frequency distributions as response variables. We then predict coral population size structure with increasing environmental stress and variability. ResultsCompared to tropical reefs, we find fewer but larger coral colonies in marginal reefs, where environmental conditions are more variable and stressful for corals in the former. Our model predicts that coral populations may become gradually dominated by larger colonies (> 148 cm2) with increasing environmental stress. Main conclusionsWith increasing environmental stress and variability, we can expect shifts in coral population size structure towards more larger colonies. Fewer but bigger corals suggest low survival, slow growth, and poor recruitment. This finding is concerning for the future of coral reefs as it implies populations may have low recovery potential from disturbances. We highlight the importance and usefulness of continuously monitoring changes to population structure over large spatial scales. Data availabilityData is supplied in the supplementary information, or upon request. Once accepted for publication it will be made openly available on Dryad.

ecology↗

bioRxiv2021

Coral assemblages at higher latitudes favour short-term potential over long-term performance

The persistent exposure of coral communities to more variable abiotic regimes is assumed to augment their resilience to future climatic variability. Yet, while the determinants of coral population resilience across species remain unknown, we are unable to predict the winners and losers across reef ecosystems exposed to increasingly variable conditions. Using annual surveys of 3171 coral individuals across Australia and Japan (2017-2019), we explore spatial variation across the short- and long-term dynamics of competitive, stress-tolerant, and weedy assemblages to evaluate how thermal variability mediates the structural composition of coral communities. We illustrate how, by promoting short-term potential over long-term performance, coral assemblages can reduce their vulnerability to stochastic environments. However, compared to stress-tolerant, and weedy assemblages, competitive coral taxa display a reduced capacity for elevating their short-term potential. Accordingly, future climatic shifts threaten the structural complexity of coral assemblages in variable environments, emulating the degradation expected across global tropical reefs.

ecology↗