Co-operation Continued

Eusociality

• In social insects apparent self-sacrifice reaches the point where large numbers of individuals are completely sterile; they never reproduce themselves but spend their whole adult lives devoted to rearing the young of others.
  • Why do they do this?
  • How can sterility evolve?
• Eusocial - reproduction in a colony
  
• One breeding queen, many 'sterile' female workers, plus a few male drones
• Occasional production of fertile daughters - fed on royal jelly
• Extreme altruism in colonies of hymenoptera
• Workers cannot reproduce but will sacrifice themselves for welfare of group
  • E.g. bee sting might cause a worker bee to die
    
  • Ant colony - live in structured colonies containing different types of members each with a specific role. Part of a biological programmed cycle. In many species, all the winged males and winged virgin queens from all the nearby colonies in the population each leave from their different nests and meet at a central place to mate, using pheromones to guide each other to a breeding ground. After mating, the males die off, while females try to establish a new colony. The few that are successful settle in a suitable spot, lose their wings and begin laying eggs, selectively fertilising some used stored sperm they've saved up from mating. Fertilised eggs grow into female workers who care for the queen and her eggs. They will defend the colony and forage for food whilst unfertilised eggs grow into males whose job is to wait until they are ready to leave the nest and reproduce, beginning the cycle again.
    • So how do worker ants decide what to do and when?
      • They dont really. Although they have no method of international communication, individual ants do interact with one another through touch, sound and chemical signals. These stimuli accomplish many things from serving as an alarm to other ants if one is killed, to signaling when a queen is nearing the end of her reproductvie life. One of the most impressive collective capabilities of an ant colony is to thoroughly and efficiently explore large areas without any predetermined plan. Most species of ants have little or no sense of sight and can only smell things in their vicinity. Combined with their lack…