Biology subjects

Parr, C. L.

Publications and source records attributed to Parr, C. L..

3 recordsLinked to original sources

bioRxiv2025

The economic strategies of superorganisms

The leaf economics spectrum links strategies of plant investment in resource-acquiring leaves to overall fitness. We test whether an economic spectrum can also explain variation in ecological strategies of ant species across environmental gradients, where colony investment in workers is analogous to plant investment in leaves. A fast return of resource investment was associated with large colonies of smaller, less robust, short-lived workers with low nitrogen:phosphorus ratios. Slow resource payback was associated with small colonies of densely built, energetically conservative and longer-lived workers with high nitrogen:phosphorus ratios. Species representing the entire economic continuum co-occurred in all communities. Phylogenetic analyses suggest genus level conservation of core investment templates. These results unify studies of plants and ants, suggesting common economic principles apply across the tree of life.

ecology↗

bioRxiv2025

Wood ants on the edge: how do thecharacteristics of linear edges affect thepopulation dynamics of an edgespecialist?

Landscape structure modulates species dispersal by presenting barriers or opportunities. Slow-dispersing edge specialists, e.g. the northern hairy wood ant (Formica lugubris), are likely to be most affected by topography and land management practices, because they require adjacent contrasting habitats, e.g. to access both food and sunlight. In managed forests, canopy gaps are often linear and anthropogenic, such as paths, firebreaks, and roads (collectively rides), and their orientation determines shade distribution. Using data spanning 10 years, we ask how ride orientation and width affect the distribution and dispersal of three F. lugubris populations in the North York Moors, UK. Ride orientation clearly affected nest abundance, with a higher nest density on rides oriented north-south (N-S) or east-west (E-W) (cardinal directions) than on those oriented NE-SW or NW-SE (intercardinal directions). Conforming to predictions based on sunlight availability, N-S oriented rides were occupied more symmetrically than E-W ones, where the north side was used predominantly. Nests were generally larger on narrower rides. Ride orientation also clearly affected dispersal: wood ants dispersed c15 m/year along rides oriented in cardinal directions, compared with only c5 m/year on rides oriented intercardinally. Our results show that ride characteristics (width, orientation), resulting directly from forestry practices, influence the distribution and dispersal of an ecosystem engineer woodland species; this may also apply to other forest-edge specialists. As wood ants can suppress defoliating pests, these findings could benefit forest management; forest planners could encourage wood ant colonisation of plantation forest by ensuring linear features contribute to north-south and east-west connectivity.

ecology↗

bioRxiv2021

Termites have developed wider thermal limits to cope with environmental conditions in savannas

The most diverse and abundant family of termites, the Termitidae, evolved in warm, wet African tropical forests. Since then, they have colonised grassy biomes such as savannas. These environments have more extreme temperatures than tropical forests, and greater temporal fluctuations (both annually and diurnally) that are challenging for soft-bodied ectotherms. We propose that that a likely mechanism that facilitated the expansion from forest to savanna was the widening of physiological limits of savanna termite species in order to cope with more extreme environmental conditions. We sampled termites directly from mound structures across an environmental gradient in Ghana, and recorded the thermal tolerance of individual termites, both critical thermal maximum (CTmax) and critical thermal minimum (CTmin). We estimated colony thermal tolerance by taking an average of each tested individual, and modelled these data against several environmental factors (canopy cover above the mound, rainfall and temperature). We found that savanna termite species had significantly higher CTmax values, and significantly lower CTmin values, than forest species. In addition, areas with high canopy cover were significantly associated with low CTmax values, and areas with higher average daily rainfall were significantly associated with higher CTmin values. Our results suggest that the widening of thermal tolerances has occurred in savanna termite species, probably in response to the more extreme temperatures found in those environments.

physiology↗