Biology subjects

Ruxton, G. D.

Publications and source records attributed to Ruxton, G. D..

4 recordsLinked to original sources

bioRxiv2026

The evolution of socially modulated dispersal

Dispersal plays a key role in ecology and evolutionary biology, including as a mechanism that reduces local competition. However, dispersers often suffer a fitness disadvantage relative to nondispersers, which may lead individuals to prefer that others disperse rather than dispersing themselves. Hence, if individuals can force their neighbours to disperse, they may be favoured to do so rather than voluntarily dispersing for the good of others. Besides forcing dispersal, individuals might also improve their neighbours ability to disperse. Here, we investigate the evolutionary drivers and consequences of socially modulated dispersal. We find that: (1) there are three possible stable evolutionary outcomes, involving only voluntary dispersal, only socially modulated dispersal, or coexistence of the two; (2) although social modulation that does not improve dispersal success can only be favoured if it is less costly than dispersal itself, social modulation that facilitates dispersal can be favoured even if it is highly expensive for the facilitator; (3) facilitated dispersal may, counterintuitively, lead to a reduced overall level of dispersal; and (4) social modulation can be either welcome or unwelcome from the perspective of the disperser. These predictions emphasise that the evolution of dispersal depends on individuals abilities to both disperse and modulate.

evolutionary biology↗

bioRxiv2025

Extraordinary adaptations: Functional and evolutionary synergy of trait components can explain the existence of leaf masquerade

One of the most enduring mysteries in biology concerns the evolution of complex adaptations made up of interacting component traits. When these component traits lack an obvious adaptive function in isolation from one another, their origin requires either non-adaptive, intermediate evolutionary steps or their simultaneous, synergistic evolution. We tested these alternatives using the powerful but accessible example of leaf masquerade in katydids, where in some species, highly modified wings strikingly mimic vegetation to avoid predator recognition. Combining a field predation experiment with a phylogenetic comparative analysis of wing morphology in 51 Neotropical katydid species, we show that colour and shape synergistically interact to enhance survival in the wild, and modifications in both traits evolved concurrently during diversification of this clade. Our findings identify the functionality of masquerade camouflage in the wild and highlight how synergy between individual traits fosters evolution of extraordinarily specialised adaptations.

evolutionary biology↗

bioRxiv2021

The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly

In a variety of aposematic species, the conspicuousness of an individuals warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments and in protecting against oxidative damage. We raised monarch butterflies (Danaus plexippus) on their milkweed host-plants (Apocynaceae) with increasing quantities of cardenolides to test whether (1) the sequestration of secondary defences is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (2) that reduced oxidative state can decrease the capacity of individuals to produce aposematic displays. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: males with high levels of oxidative damage become less conspicuous with increased sequestration of cardenolides, whereas those with low oxidative damage become more conspicuous with increased levels of cardenolides. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate a physiological linkage between the production of coloration and protection from autotoxicity, and differential costs of signalling in monarch butterflies.

evolutionary biology↗

bioRxiv2021

Comparing two circular distributions: advice for effective implementation of statistical procedures in biology

Many biological variables, often involving timings of events or directions, are recorded on a circular rather than linear scale, and need different statistical treatment for that reason. A common question that is asked of such circular data involves comparison between two groups or treatments: Are the populations from which the two samples drawn differently distributed around the circle? For example, we might ask whether the distribution of directions from which a stalking predator approaches its prey differs between sunny and cloudy conditions; or whether the time of day of mating attempts differs between lab mice subject to one of two hormone treatments. An array of statistical approaches to these questions have been developed. We compared 18 of these (by simulation) in terms of both abilities to control type I error rate near the nominal value, and statistical power. We found that only eight tests offered good control of type I error in all our test situations. Of these eight, we are able to identify Watsons U2 test and MANOVA based on trigonometric functions of the data as offering the best power in the overwhelming majority of our test circumstances. There was often little to choose between these tests in terms of power, and no situation where either of the remaining six tests offered substantially better power than either of these. Hence, we recommend the routine use of either Watsons U2 test or MANOVA when comparing two samples of circular data.

animal behavior and cognition↗