In an ant colony, different workers have physical differences from each other despite them all having the same parents. What determines the difference in the workers?
In: Biology
It’s complicated – different species have different castes, and achieve these castes through a variety of mechanisms, both genetic and environmental. However, there seems to be a common thread across these factors: size. Ant castes always have quite distinct sizes, with workers being the smallest and queens being the biggest, with soldiers and sub-queens somewhere in the middle. Castes appear to gain and lose features based on their size, and the middle-sized castes have features that are somewhere between those of a worker and a queen (for example, middle-sized castes often have better eyes than workers but worse eyes than queens).
What this means is that it appears ants have evolved mechanisms that link their physiology to their size, so that by modifying the size of the larvae, the traits of a particular adult caste are automatically created. Want to make a worker? Just keep the larvae small. Want to make a soldier? Make it bigger. Want to make a queen? Fertilise the egg and make it even bigger. Size regulation itself is a matter of complicated environmental and genetic interplay, such as availability of food, temperature level and presence of growth hormones, as well as deliberate actions by other ants to modify the ratio of workers, soldiers and queens produced – for example, in some species queens will inject eggs with certain hormones that reduce size, to prevent other queens appearing, if the number of queens is already high enough.
The theory is that the ant larvae develop differently based on how they are fed during development. The amount they are fed and what they are fed are the usual trigger. A well fed larva that is being fed the ant equivalent of “royal jelly” will grow to be a new queen. Worker ants and soldier ants are each fed differently.
Male ants are usually spawned when the queen fertilizes the egg with sperm. Unfertilized eggs always develop into female ants.
For humans, baby’s always have a mix of both their parents genes, and most of their characteristics come from their DNA. Other living things don’t necessarily use the same scheme of mixing parental DNA for all offspring.
Ants, along with many insects, work differently. An ant egg that has been fertilized by sperm becomes a female ant. An egg that hasn’t been fertilized becomes a male ant. The queen mostly lays fertilized eggs, and only lays unfertilized eggs a once a year in preparation for mating season.
Once the female eggs hatch, how they are fed as larvae (babies) effects how they grow up. If they are fed special hormones, then they will grow up to be a queen. If they are not fed the hormones, they grow up to be workers. So the workers of the colony decide when to make a new queen, not the queen herself, because the workers are the ones feeding the larvae. This allows the workers to make a new queen if they need to replace her for any reason.
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