Climate, geography, and the mating phenology of ants

Authors: Helms Iv, Jackson

Submitted to: Insectes Sociaux
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2022
Publication Date: 11/8/2022
Citation: Helms Iv, J.A. 2022. Climate, geography, and the mating phenology of ants. Insectes Sociaux. 70:119–125. https://doi.org/10.1007/s00040-022-00888-y.
DOI: https://doi.org/10.1007/s00040-022-00888-y

Interpretive Summary: I studied ant mating seasons by examining specimens stored in museums that were collected across the contiguous United States over the past century. I found that ant mating seasons occurred later in the year at higher elevations and latitudes. Consistent with predicted impacts of climate change, I found that ant mating seasons have been occurring about 1 day earlier each decade. About 25% of native species in the USA have shown even more rapid recent shifts by mating nearly 1 day earlier each year. This is the first study to relate ant mating seasons to geography and climate across any large region.

Technical Abstract: Understanding an organism’s phenology is crucial for predicting the effects of anthropogenic impacts like climate change. Yet we lack a basic understanding of reproductive timing in one of Earth’s most prominent animal groups—the ants. I perform the first large-scale study of the geography of ant mating phenology by synthesizing collection data from museum databases. By compiling records of specimens in reproductive condition from across the contiguous U.S. and dating back over a century, I explore how ant mating seasons vary with latitude and elevation and test whether they have shifted in response to climate change. Ant mating seasons occurred about 1 day later in the year for each 100-meter gain in elevation or degree increase in latitude and were also shorter and less variable at higher latitudes. Consistent with predicted impacts of climate change, 25% of native species have shifted their mating seasons earlier by an average of 0.9 days per year. Across all ants, mating dates have been advancing about 1 day earlier per decade. The results represent the first attempt at a regional geography of ant mating phenology, and highlight shifts in mating season as a mechanism mediating the responses of ants to climate change.