Biology subjects

Farrior, C. E.

Publications and source records attributed to Farrior, C. E..

6 recordsLinked to original sources

bioRxiv2026

Undying leafcutter-ant colonies: The oldest Atta texana leafcutter-ant colonies are estimated to grow older than 100 years

Tropical Atta leafcutter-ant colonies reach a maximum lifespan of 15-20 years because each colony has only a single queen, queens live for maximally 15-20 years, and colonies do not requeen after queen death. At the northern range limit of leafcutter ants in Louisiana, however, we found that the mortality rate of Atta texana colonies is consistent with a life expectancy of 65-75 years and a maximum colony lifespan exceeding 100 years. Annual mortality of established A. texana colonies in Louisiana is only 1-2% compared to 10-25% in tropical Atta species. Exceptional longevity of A. texana colonies is due to (i) absence of Nomamyrmex army-ant predators specialized to raid Atta colonies; (ii) polygyny of A. texana colonies, creating a unique social organization in A. texana colonies that differs from the monogynous colonies typical for all other Atta species; and (iii) adoption of young queens by old colonies, possibly facilitated by low genetic diversity in range-limit populations of A. texana. Centenarian longevity of A. texana colonies was so far unknown because, from the 1930s to the turn of the century, research prioritized eradication of A. texana as a forestry pest, and landscape-wide pesticide application by aircraft eliminated old A. texana colonies. After the most harmful pesticides were banned 30-50 years ago, A. texana populations recovered, yet A. texana required decades to regain its earlier niche in the forest ecology. In undisturbed habitat, well-established old A. texana colonies with large territories appear to recruit young queens especially well. Old age of a colony therefore does not necessarily increase mortality as in typical lifespan-limiting processes where age drives senescence and mortality (old age [->] mortality); instead, well-rooted residency that is correlated to age of an A. texana colony increases the chance of rejuvenation via queen adoption, reduces or eliminates reproductive senescence of a colony, and consequently prolongs colony lifespan (well-established residency [->] rejuvenation [->] long life). Large size attained in old age imparts potentially unending life.

ecology↗

bioRxiv2025

Plant diversity and water regime have distinct effects on soil fungal communities that are linked to plant productivity

The soil microbiome both shapes and is shaped by the ecological consequences of drought and plant diversity loss. Sequencing soil fungal communities in a biodiversity experiment, we found that water addition, plant species richness, and plant phylogenetic diversity all impacted soil fungal composition, and increased the arbuscular mycorrhizal fungi (AMF) richness in particular. The richness of different fungal functional guilds all increased with plant functional trait diversity but were related to different above- and below-ground plant functional traits -- AMF richness was negatively associated with root traits that indicate mycorrhizal dependence, whereas diverse soil pathogens generally co-occurred with plant traits linked to faster life histories. Unexpectedly, the effect of plant diversity loss on fungal diversity did not interact with the effects of either the watering treatment or the community weighted mean of plant traits. Shifts in AMF richness and soil fungal taxa due to plant diversity loss were further associated with reduced plant productivity and diversity effects. Overall, our results indicate that changes in water input and loss in plant taxonomic, phylogenetic, and functional diversity can negatively impact soil fungal communities, and through changes in soil microbiome, may also reduce plant productivity. This negative effect of plant diversity loss is consistent across water regimes and plant community-level traits, suggesting a general vulnerability of soil microbiome and ecosystem productivity towards the biodiversity crisis.

ecology↗

bioRxiv2025

Strengthening intraguild predation increases the temporal variability of biomass across all trophic levels in model food webs

Multiple global-change forces, from habitat alterations to warming, are altering food webs and trophic interaction strengths. Such changes in trophic interactions have important implications, as it is a tenet of ecology that trophic interactions are linked to the functioning and stability of ecosystems. For example, changes in the presence or strength of intraguild predation (IGP), the consumption of a predator by another predator that competes for shared prey, can have cascading effects on the biomasses of species and trophic levels. For this reason, IGP can affect key ecosystem functions at the base of the food web and is of special interest to practitioners of biological pest control. However, the relationship between IGP and ecosystem stability is not yet well understood, especially whether and how IGP might affect the stability of non-adjacent lower trophic levels including primary producers. In this study we simulate the dynamics of a six-species, four-trophic-level food web plus a limiting nutrient to explore the relationship between IGP strength and the temporal variability of species- and trophic group-biomass. By varying the IGP rate given the abundance of the eaten predator, we find that the model food web abruptly shifts between equilibria in which all species maintain either constant biomass or stable limit cycles where all trophic levels exhibit sustained and significant oscillations. While complex feedback in the model creates a divergence between the IGP functional response and the resulting realized IGP strength, both stronger IGP functional responses and stronger realized IGP are associated with a higher likelihood of oscillations. Furthermore, analyses indicate that the strongest consumptive interaction induces the oscillating behavior in an indirect effect initiated by the change in IGP. Overall, these results suggest that as food web structure changes in ecosystems worldwide, strengthening IGP runs the risk of inducing destabilizing effects that extend to the base of food webs, while weakening IGP could confer stability to ecosystem functions such as primary production. Finally, we discuss relevance to management, including the implication that IGP among biological control agents should be minimized to maintain stable crop production.

ecology↗

bioRxiv2023

Tree demographic strategies largely overlap across succession in Neotropical wet and dry forest communities

Secondary tropical forests play an increasingly important role for carbon budgets and biodiversity conservation. Understanding successional trajectories is therefore imperative for guiding forest restoration and climate change mitigation efforts. Forest succession is driven by the demographic strategies - combinations of growth, mortality and recruitment rates - of the tree species in the community. However, our understanding of demographic diversity in tropical tree species stems almost exclusively from old-growth forests. Here, we assembled demographic information from repeated forest inventories along chronosequences in two wet (Costa Rica, Panama) and two dry (Mexico) Neotropical forests to assess whether the range of demographic strategies present in a community shifts across succession. We calculated demographic rates for >500 tree species while controlling for canopy status to compare demographic diversity in early successional (0-30 years), late successional (30-120 years) and old-growth forests. We quantified demographic diversity using two-dimensional hypervolumes of pairs of demographic rates and assessed whether shifts in demographic strategies were caused by intra-specific changes in demographic rates across succession or by species turnover. We expected that demographic strategies would shift from faster life-histories (fast growth, high mortality, high recruitment) in early successional forests to slower life histories (slow growth, low mortality, low recruitment) in old-growth forests and that shifts would be stronger in wet than in dry forests due to more pronounced differences in environmental conditions between early successional and old-growth forests. We also expected that demographic diversity would increase with succession. We found that demographic strategies largely overlapped across successional stages and that early successional stages already covered the full spectrum of demographic strategies found in old-growth forests. An exception was a group of species characterized by exceptionally high mortality rates that was confined to early successional stages in the two wet forests. Demographic diversity did not increase with succession. Our results suggest that current understanding of demographic strategies of tropical tree species, which has been generated mostly from long-term forest monitoring plots in old-growth forests, is largely representative of demographic diversity in general, and that demographic diversity recovers quickly during succession.

ecology↗

bioRxiv2019

Demographic tradeoffs predict tropical forest dynamics

Assessing vegetation feedbacks with the climate system and planning sustainable management in tropical forests requires efficient, yet accurate, predictions of the joint dynamics of hundreds of tree species. With increasing information on tropical tree life-histories, our predictive understanding is no longer limited by species data, but by the ability of existing models to make use of it. Using a demographic forest model, we show that the basal area and compositional changes during forest succession in a Neotropical forest can be accurately predicted by representing tropical tree diversity (hundreds of species) with only five functional groups spanning two essential tradeoffs - the growth-survival and stature-recruitment tradeoffs. This data-driven modeling framework substantially improves our ability to predict consequences of anthropogenic impacts on tropical forests.

ecology↗

bioRxiv2018

Plants maximize competition while minimizing competitors belowground: a theoretical analysis of incentives for root competition in space

Recent research shows that shared access to belowground resources drives plants to overproliferate fine roots competitively, limiting community-level aboveground biomass. Models of this phenomenon are commonly based on an assumption that belowground resources and fine roots are thoroughly well mixed. In reality, of course, fine roots are spatially structured by individual. Here we investigate how costs of sending roots through horizontal space influence incentives for fine-root overproliferation. We find that these costs restrain overproliferation to the net benefit of community aboveground biomass. And further, the costs eliminate incentives for individuals to grow fine roots beyond their closest neighbors. Plants that interact with the fewest competitors benefit the most in relative fitness from overproliferation of fine roots. Effectively, individual-based optimization of root allocation in space increases the effects of competition while decreasing the number of individual competitors for each individual.\n\nBecause an individuals optimal competitive network consists of only the closest neighbors, we predict the full effects of competition are achieved just shortly after disturbance, making competition belowground an almost inescapable pressure on plants. Together these results have important implications for predicting plant interaction networks, patterns of carbon allocation, and ecosystem carbon storage.

ecology↗