Social insect 


Over the past 100 million years, social insects have reshaped our planet. It is difficult to overstate the impact these animals have had on terrestrial environments as keystone members of ecosystems, processors of organic material, and drivers of natural selection. There are over 13,000 and 4,000 described species of ants and termites, respectively, each a unique assemblage of morphology and behavior. It is widely believed that eusociality is a primary component of social insect success measured as species richness and ecological impact. One goal in this area is to document patterns of diversification and extinction among social insects and better understand the factors that lead to differential success among eusocial lineages. Pictured above is a ~20 million year old piece of amber from the Dominican Republic with several ant workers trapped inside.

A simplified visualization of ant abundance increasing in the fossil record. The X-axis corresponds to the percentage of ants in amber fossil deposits relative to all other insects (that is, on average, ants made up about 6% of all insects in amber 50 million years ago); y-axis is millions of years before present. Data modified from Grimaldi & Agosti 2000, Dlussky & Rasnitsyn 2002, LaPolla & al. 2013.

increasing in abundance

Today, ants and termites are highly abundant – in some environments comprising a larger percentage of biomass than all vertebrates combined – and therefore have a significant impact on terrestrial ecology worldwide. However, this was not always the case. Because ants in particular have a rich fossil record, it is possible to trace their increase in abundance by comparing their prevalence in fossil deposits over time. While ants and termites diverged from their solitary relatives in the Cretaceous and Jurassic periods (approximately 120 and 150 million years ago respectively), each did not become significantly abundant until the Paleocene or Eocene, approximately 50 million years ago. Why did it take as much as 100 million years before these insects became dominant members of terrestrial ecosystems? What factors led to this relatively abrupt shift? Why did some lineages persist and become ecologically impactful while others underwent extinction? How has social behavior impacted ant and termite evolution over time?  By studying living and extinct species, we work to address these questions.