Biology subjects

Guirguis, J.

Publications and source records attributed to Guirguis, J..

4 recordsLinked to original sources

bioRxiv2026

Evolutionary dynamics of temporal niche among tetrapods

The diversification of biodiversity progresses as newly evolving species adapt to occupy available niche space - including the temporal dimension. Throughout the history of life, animal species adapted to occupy specific regions, or all regions (cathemerality), of the day-night temporal spectrum. While adaptive radiation theory is predicted to drive much of the global proliferation of biodiversity, the role that the day-night temporal dimension plays in offering ecological opportunity for lineages to diversify remains fundamentally neglected. Using a dataset spanning 19,940 species from across all four main tetrapod lineages (amphibians, squamates (restricted to lizards), mammals and archosaurs), we perform the very first evolutionarily standardised temporal niche diversification analysis and the first to include substantial number of ectotherms. We examine temporal niche as a source of ecological opportunity for adaptive radiation and contrast how lineages have leveraged ecological opportunity spread across 24h time. Findings revealed that tetrapods most frequently transitioned towards diurnality, suggesting a general opening of ecological opportunity in diurnal niche space since the K-Pg mass extinction. Moreover, amphibians are faster and more flexible than amniotes in temporal niche evolution, supported by a relatively higher speed of temporal niche transition and by spending relatively more in time cathemerality, potentially compensating for limitations in geographic dispersal. This interpretation suggests the day-night temporal niche dimension interacts with the geographic dimension, as it exhibits processes which unfold in parallel to (independent of) the geographic dimension as well as processes which unfold in response to what occurs in the geographic dimension.

evolutionary biology↗

bioRxiv2026

'Occam's bias' undermines inferences from phylogenetic linear models

Phylogenetic modelling has consolidated as the analytical standard to address hypotheses about the patterns and dynamics of biodiversity in inter-specific contexts. These analyses are traditionally performed implementing phylogenetic linear models where single outcomes are regressed against multiple predictors without explicitly modelling the relationships amongst predictors. A prevailing, yet largely overlooked consequence of neglecting these relationships is what we introduce as Occams bias - a statistical distortion arising where the model has fewer cause-effect connections than predicted by theory. Here, we propose that Occams bias is likely to have impacted a wide range of inferences about ecological and evolutionary processes made from phylogenetic linear models across the literature, and thus, that the adoption of approaches to address this bias are critical. We present an empirical test of the long-standing hypothesis that interspecific variation in life-history traits influences the likelihood of extinction risk across 13,949 species of terrestrial vertebrates to show the impacts of Occams bias in phenomenological inference. Our study calls for a re-evaluation of hypotheses tested using the traditional linear modelling structure and advocate the use and continued development of multi-response model structures that account for all causal pathways in phylogenetic analyses.

evolutionary biology↗

bioRxiv2025

Temporal niche influences higher extinction risk among diurnal tetrapods from tropical regions

Anthropocene extinctions of biodiversity vary dramatically through geographic and phylogenetic space, with certain regions and lineages concentrating high defaunation rates, while others remain nearly unchanged.This heterogeneity in biodiversity erosion results from (spatial and phylogenetic) variation in the interactions between species fitness-relevant traits and environmental threats that trigger extinctions. Evidence reveals that factors including life histories, ecophysiology, and resource-use generalism influence variation in species declines under rapidly changing environments. An emerging hypothesis predicts that species spread across different locations of the 24h diel spectrum are exposed to different anthropogenic pressures on demographic stability (e.g. daytime contact with humans), which can trigger differential extinction risk among diurnal, nocturnal and cathemeral (day-night active) species. However, this hypothesis remains largely neglected. Only a single large-scale test exists, which documented higher declines among diurnal mammals. Here, we address this hypothesis across tetrapods globally, spanning >23,000 species across both endotherms and ectotherms for the first time. Our results reveal that cathemerality is significantly associated with a lower probability of undergoing population declines across tetrapods (except birds), while diurnality is associated with higher extinction risk category in amphibians. Collectively, our results suggest that the role of temporal niche in extinction is significant but variable across tetrapods.

evolutionary biology↗

bioRxiv2022

Temporal and spatial patterns of vertebrate extinctions during the Anthropocene

The human-induced annihilation of modern biodiversity is dragging the planet into a mass extinction that has already altered patterns of life globally. Among vertebrates, over 500 species have become extinct or possibly extinct in the last five centuries - an extinction rate that would have taken several millennia without human intervention. Vertebrate extinctions have often been quantified as cumulative counts that reveal sharp increases in losses over time. Here, we quantify global tetrapod extinctions since the 1400s using numbers of species losses across successive and independent time periods until present. Our results reveal that extinctions were low and fundamentally restricted to islands in pre-industrial times, experiencing a significant increase and spread over continental mainland following the onset of the industrial revolution. Recent amphibian extinctions alarmingly exceed the extinctions of all tetrapods, while extinctions of island birds account for a third of all extinctions. Finally, we quantified the relationship between human population growth (HPG, as a proxy for aggregate human effects on the environment) and extinctions between 1800-2000, to then predict that an estimated 838 tetrapod species will go extinct between 2030-2100 based on United Nations HPG projections. These findings further warn humanity about the need to sustainably control HPG and the destructive impacts of rapid environmental change on ecosystems worldwide.

ecology↗