an ant rant

Ants have a three-tiered social system. You have the queen, the male concubines, and the all-female working class. The queen has one duty and one duty only: lay eggs. The “male concubines,” or drones, are responsible for knocking up the queen. And the workers must take care of all the rest. They feed the babies, build and repair the nest, defend the colony, and wait on her majesty.

There can be multiple queens per colony, but usually just one. She is fed by the workers and lays eggs. These suckers can live for up to 20 years- longer than either the drones or workers. A queen can lay eggs from a single mating for several years. In a single lifetime, a queen can give rise to millions of ants.

The drones are the only males of a colony, and pretty much just eat and have sex. They really have the life. That’s pretty much it for them.

The worker ants are sisters- all sterile daughters of the queen. They take care of their little sisters from the time they are eggs to emerging pupae. They carefully move them from nursing chamber to nursing chamber as they go through the stages of being an egg, larvae, and pupae. They also maintain the mound by expanding, building, and maintaining the hallways by spitting on the walls for structural support. Furthermore, they do all the foraging. The sisters find food, bring it back, and organize it into a stash for the entire colony. A subset of super beefy workers- called soldiers- are in charge of defending the nest from invaders or adverse weather.

When an ant dies, her sisters will drag her little body out of the nest, as far away as possible. They do that as though they are following hospital protocol, aware of the biohazard of a degrading body or the increased possibility of disease present in that deceased ant. One experiment from a while back sought to isolate the hormone that is secreted at death, so the scientists took dead ants and rubbed them all over live ones. I bet it was pretty funny/horrible watching the unwilling test subjects being dragged out of their nest by their instinct-driven sisters.

All hymenopterans (bees, ants, and wasps) operate using a haplodiploid reproductive system. To be haploid means to have only one set of chromosomes. Diploid means to have two sets of chromosomes. You, human, are diploid, since you have two sets- one from your mama and one from your daddy. Depending on whether you’re a boy or girl, your sperm or eggs are reduced by one half so that they are haploid. That way, one haploid sperm + one haploid egg = one diploid baby.

But with ants, it’s a little different. A queen lays both fertilized and non-fertilized eggs. Unfertilized eggs develop into haploid male drones, and fertilized eggs develop into diploid female workers.

These workers share 75% of their DNA, which is clearly more than the typical 50% that human siblings share. They have their haploid drone daddy to thank for this. Since he only has one set of chromosomes to offer them, they all get the exact same set of genetic material from him. They have a 50% chance of getting either of mom’s sets of chromosomes. Add this all together, and the sister workers are on average 75% genetically similar. (Sister power! See below figure.)

The distribution of genetic material in a haplodiploid system. Each "x" represents a chromosome.

Now, you may be wondering how inbreeding is avoided, since the only males around seem to be the disturbingly genetically similar queen’s sons. But an adaptation has evolved to keep this from happening: wings. Both queens and drones are born with wings. Upon reaching maturity, drones will fly away from the nest and find a new queen to breed. Meanwhile, worker ants selectively beef up a few female larvae here and there by feeding them more nutrients… and spitting on them… to produce new queens. When a little queen is ready, she’ll fly away and shed her wings after she breed. She establishes a little nesting site and boom- a few generations later, you have a new colony. Genetic dispersal is at it again…

How would you characterize a female ant from a male ant? Their sexy bits don’t matter, since the workers are sterile and essentially androgenous. Whoever guesses the gender-determining factor in a haplodiploid system gets to choose A.) to pick the topic for the next post B.) a personalized poem written by yours truly to be featured on the blog.

Hint: I already gave you a hint in the previous sentence. Don’t be greedy.