New paper out! Plants regulate grassland arthropod communities through biomass, quality, and habitat heterogeneity

My second dissertation chapter is now out in Ecosphere! This paper used a factorial experiment of NPK fertilization and clipping (to mimic grazing) to manipulate plant biomass, habitat heterogeneity, and plant quality and quantify their effects arthropod abundance and diversity. Thus, I demonstrate the direct and indirect effects of plants on grassland arthropod communities. I ran this experiment at the University of Oklahoma Biological Station in the summer of 2017. I used both pitfall traps and bugvacs to show that grassland insect community abundance, activity, and diversity respond to fertilization and simulated grazing via effects on microclimate, habitat space, and nutrient quality. I also show how nutrients buffer microclimate via increased plant volume.

This was a fun project to work on and resulted in a lot of lab time – I had to count and identify >150,000 arthropods. You can read the full paper here.

 

 

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New paper out! Using metabolic and thermal ecology to predict temperature dependent ecosystem activity: a test with prairie ants

My second paper of 2018 (and first of my dissertation) is out in Ecology! This paper used weekly baiting over a seven-month period to demonstrate how seasonal and daily temperature differences affect foraging for resources by ants. I did this project back in 2016 and it started as a way for me to learn some common Oklahoma ant species. However, once I began consistently baiting, I noticed recruitment patterns to different nutrients (and discovery rate of baits) was changing with temperature.

We first show that the discovery rate of both food resources (salt and sugar) accelerated with soil temperature, but this increase was typically capped at midday due to extreme surface temperatures. We then tested the prediction that sodium demand accelerates with temperature, premised on a key thermal difference between sugar and sodium: sugar is stored in cells, while salt is pumped out of cells proportional to metabolic rate, and hence temperature. We found strong support for the resulting prediction that recruitment to NaCl baits accelerates with temperature more steeply than recruitment to 1% sucrose baits.

We then performed a follow-up experiment in 2017 with a range of sugar concentrations. This experiment verified that temperature-dependent recruitment to sucrose concentrations of 20% (mimicking rich extrafloral nectaries), while noisy, was still only half as temperature dependent as recruitment recorded for 0.5% NaCl.

This was a fun paper to work on. You can click here to read the whole paper.

New paper out! Combat, co-existence, and resource partitioning in acorn-dwelling Temnothorax ants

My first paper of 2018 (and the first paper I’ve published) is out in Insectes Sociaux! This paper used a combination of field surveys and lab experiments to examine the structuring of acorn-nesting Temnothorax assemblages. This project was done over a 2 year period while I was an undergraduate at George Washington University.

We first show that T. longispinosus and T. curvispinosus nest in a specialized subset of available acorns and that nests had a uniform pattern of spacing consistent with spatial displacement from competition. Next, we performed preference experiments which demonstrated some level of differentiation in resource use among species within the specialized range of nest properties used by the ants in nature, potentially reducing competition during nest selection.

Finally, we performed competition experiments, separately testing both intraspecific pairs before testing interspecific competition.

In both intraspecific competition experiments, we found high mortality that increased when ants were initially in nests closer together. T. curvispinosus mortality also increased with the number of combatants, consistent with a battle of attrition between opposing sides. In contrast, T. longispinosus mortality decreased during battles as the number of combatants increased. In the interspecific battles, both T. curvispinosus and T. longispinosus sustained some mortality, but escalated battles did not occur.

This was a fun project that demonstrates direct competition over nesting sites is an important mechanism underlying the dispersion of Temnothorax nests and therefore the structuring of acorn-nesting Temnothorax assemblages.

If you would like to read the entire paper, you can click here.