The ecological principle of competitive exclusion states that species competing for identical resources cannot coexist, but this principle is paradoxical because ecologically similar competitors are regularly observed. Coexistence is possible under some conditions if a fluctuating environment changes the competitive dominance of species. This change in competitive dominance implies the existence of tradeoffs underlying species' competitive abilities in different environments. Theory shows that fluctuating distance between resource patches can facilitate coexistence in ephemeral patch competitors given a functional tradeoff between species dispersal ability and fecundity. We find evidence supporting this tradeoff in a guild of five ecologically similar nonpollinating fig wasps, and subsequently predict local among patch species densities. We also introduce a novel `colonization index' to estimate relative dispersal ability among ephemeral patch competitors. We suggest that a dispersal ability-fecundity tradeoff and spatiotemporally fluctuating resource availability commonly cooccur to drive population dynamics and facilitate coexistence in ephemeral patch communities.
Ficus petiolaris wasp count data
Includes counts of all female non-pollinating fig wasps from the syconia of the Sonoran Desert rock fig, Ficus petiolaris. The data file includes the site, tree and syconia (`Fruit') labels from each syconia sampled (rows); the data also includes columns indicating tree lat-lon coordinates, pollinating foundresses arriving to the syconia (corpses remain within syconia), fruit volume, counts of all wasp species, and the number of neighbours a tree has within a 1 km radius. The pollinator (`Poll') is an unnamed (as of 2015) species of Pegoscapus. Wasps `LO1', `SO1', and `SO2' are all unnamed species of the genus Idarnes, and wasps `Het1' and `Het2' are both unnamed species of the genus Heterandrium. The wasps `Physo' and `Aepoc' are wasps of unnamed species of the genera Physothorax and Aepocerus, respectively; `NA' denotes missing values.
wasp_data.csv
Ficus petiolaris wasp wing loadings
This file includes measurements to estimate wing loading for 83 wasps (rows) of the species of interest in Duthie et al. (2015): LO1 (unnamed Idarnes), SO1 (unnamed Idarnes), SO2 (unnamed Idarnes), Het1 (unnamed Heterandrium), and Het2 (unnamed Heterandrium). Each row is a single wasp, and columns show the site, tree, and fruit from which the wasp was sampled. Lengths and widths of wasp heads, thoraxes, and abdomens are included as measured at their widest points (e.g., for the wasp abdomen, the whole length of the segment is reported, along with an estimate of its width at the widest point). Wing areas were calculated using wing images and ImageJ software.
wing_loadings.csv
Ficus petiolaris wasp egg loads
File includes estimates of wasp egg loads from 54 wasps (rows) of the following species: LO1 (unnamed Idarnes), SO1 (unnamed Idarnes), SO2 (unnamed Idarnes), Het1 (unnamed Heterandrium), and Het2 (unnamed Heterandrium). Both mature and immature egg counts were estimated, and columns include the site, tree, and fruit from which the wasp was sampled.
egg_loads.csv
R code for Ficus petiolaris wasp data analysis
The subsequent code replicates the analyses used in Duthie et al. (2015) American Naturalist. All data were collected in 2010 in the field from populations of Sonoran Desert rock fig (Ficus petiolaris) trees. For this analysis, three files are needed: `wasp_data.csv', `wing_loadings.csv', and `egg_loads.csv'.
analysis.R
