The Social World of Slime

Social behaviour in animals is not uncommon, and we are rarely surprised to observe cooperation in nature. However, most explanations for cooperative behaviour rely upon a certain level of cognitive ability. Cooperating willy-nilly leaves individuals open to cheaters, so successful and long-term cooperation between individuals often relies upon individual recognition. Many social groups are composed of relatives. This makes a lot of sense, as helping relatives yields benefits without the need for reciprocation in the future, because relatives share genes. But still, you might expect that even this requires basic intelligence – you need to be able to recognise who are your relatives.

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Reasons Why Evolution Is True Part VII:

Few species go through life without interacting with an other, but some interactions are more intimate than others. Pollination is an example of an interaction that, in some species, has become very intimate indeed! Most dedicated pollinators show adaptations to this, such as pollen baskets in bees, but these are often generic adaptations that enable the individual to visit many different species of plant. Equally, plants have adaptations to attract a variety of different insects. Different pollinators (bees, birds, moths) have different visual systems, and thus different flower colouration can be used to attract pollinators of different species. The timing of flower and pollinator emergence is also carefully timed in order to ensure maximum cross-over between the two. Pollinators generally gain food from the relationship, whilst plants achieve dispersal of their genes without having to physically move themselves.

Some plant-pollinator interactions are more intimate, more specific. This can lead to more extreme adaptations, as the two species become increasingly specialised for interacting with one another. Possibly the most extreme plant-pollinator relationship exists between the fig and the fig wasp. Young fig wasps emerge as larvae inside a tiny fig. The larvae feed on the fruit of the fig until they are ready to mature into adults, which again occurs within their fig prison. As adults, the wasps mate, collecting pollen from their birth fig before they leave. The male fig wasps then dig their way out of the fruit, creating a path for the females to emerge from. The male fig wasps are not well suited to life outside the fig, however, and often die shortly after making their escape. The females fly off and find a new fig plant where they can lay their eggs. Squeezing through the tiny entrance hole, known as the ostiole, the female enters a new fig and deposits her eggs inside the fruit, simultaneously depositing pollen on the fig’s reproductive parts.

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Ants: Civilisation in Minature III

Crime and Punishment

Ant societies are remarkably complex and ants exhibit extremely high levels of cooperation. Workers will often sacrifice their own lives to defend the safety of the nest. However, just like human societies, ant nests are also rife with conflict. Where there is cooperation there will always be individuals who try to take advantage and cheat the system.

The defining characteristic of ant colonies (and social insects in general) is reproductive division of labour, where reproduction is dominated by one or a few individuals, known as queens. In this matriarchal system, reproduction is forbidden for most colony members, and in many ant species worker ants are physically incapable of mating. Despite being unable to mate, due to their unusual genetic system, ant workers can still lay male eggs. This gives them the opportunity to try and cheat the system, and in many ant species workers have been found to illicitly try and lay eggs, when the queen isn’t looking. Such crimes do not go unpunished, however, and in many species the honest workers will punish cheaters, either through physical aggression, or by destroying the illegally laid eggs.

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