Question

Discuss the evidence of kin selection as the mechanism for the evolution of euosociality in Termites.

Answer 1

Eusociality evolved repeatedly in different orders of animals, particularly the Hymenoptera (the wasps, bees, and ants). This 'true sociality' in animals, in which sterile individuals work to further the reproductive success of others, is found in termites, ambrosia beetles, gall-dwelling aphids, thrips, marine sponge-dwelling shrimp (Synalpheus regalis), naked mole-rats (Heterocephalus glaber), and the insect order Hymenoptera (which includes bees, wasps, and ants).The fact that eusociality has evolved so often in the Hymenoptera (between 8 and 11 times), but remains rare throughout the rest of the animal kingdom, has made its evolution a topic of debate among evolutionary biologists. Eusocial organisms at first appear to behave in stark contrast with simple interpretations of Darwinian evolution: passing on one's genes to the next generation, or fitness, is a central idea in evolutionary biology.

Current theories propose that the evolution of eusociality occurred either due to kin selection, proposed by W. D. Hamilton, or by the competing theory of multilevel selection as proposed by E.O. Wilson and colleagues.No single trait or model is sufficient to explain the evolution of eusociality, and most likely the pathway to eusociality involved a combination of pre-conditions, ecological factors, and genetic influences.

Mechanisms

Manipulation

Eusociality appears to be maintained through manipulation of the sterile workers by the queen.The mechanisms for this include hormonal control through pheromones, restricting food to young in order to control their size, consumption of any eggs laid by females other than the queen, and behavioral dominance. In naked mole rats, this behavioral dominance occurs in the form of the queen facing the worker head-to-head, and shoving it throughout the tunnels of the naked mole rats' burrow for quite a distance.

Group selection

1. Formation of groups: Groups could consist of parent-offspring groups or unrelated groups (in situations where cooperation is beneficial) living in a structured nest.
2. Pre-adaptations: Pre-adaptations for social living, such as progressive provisioning, will push the group further toward eusociality.
3. Mutations: Mutations will arise and be selected. Some genes are known to have been silenced in social insect history, leading to the reduction of dispersal behavior and the origin of the wingless caste.
4. Natural Selection Acts on Emergent Traits: The interactions of the individuals can be considered as part of the extended phenotype of the queen. These interactions produce emergent properties upon which natural selection can act.
5. Multi-level selection: More cooperative groups out-compete less cooperative groups.