So, we've had some ants in our house lately. I find ants fascinating little creatures, but I'm not so jazzed about them showing up in my kitchen. In an attempt to make lemonade out of these little lemons on my counter, I've been doing some reading about ants in the bay area.
A few years ago, the California Academy of Sciences started the Bay Area Ant Survey to try to figure out the diversity of ants in the San Francisco bay area. They enlisted the public, asking folks to collect ants and send them in to be identified. If you go to their website, you can look up your part of the bay and see what's there. So far, the project has identified more than 100 ant species. Wow!
The ants in my kitchen are most likely Argentine ants (Linepithema humile). These ants are native to northern Argentina, Uruguay, Paraguay, and southern Brazil, and have probably been introduced to the United States multiple times. These ants come inside when it's hot looking for water and when it's wet to get out of the rain. Argentine ants live in colonies, like honeybees and termites, with non-reproductive female workers serving reproductive queens. Unlike honeybees, Argentine ant colonies have multiple queens at the same time (which also makes the colonies hard to get rid of once they've moved in).
There is an ongoing debate among ant researchers about the existence on Argentine ant supercolonies. In 2000, the Tsutsui lab at University of California-San Diego published a paper suggesting that California Argentine ants are less genetically diverse than populations in their native Argentina, and used this evidence to explain the lack of aggression between California populations. The Gordon lab at Stanford has refuted the supercolony idea, suggesting that there are indeed breaks in this colony and that these breaks are evident in the genes of different populations if you look at the right genes. As an aside, I saw Deborah Gordon speak at an Ask the Scientist event a few years ago and she was fantastic. She's a super-engaging speaker who's honestly thrilled by her organism and wants to teach other people about it. If you get a chance to hear her talk I'd highly recommend going.
Gordon Lab at Stanford
Tsutsui Lab at Berkeley