Write an essay comparing and contrasting the advantages and disadvantages for an animal able to distinguish self from non-self, using named examples

The ability to distinguish self from non-self or non-self from self is contentiously two mutually contradictory strategies and incompatible outcomes. To emphasize one is to demean the other. Yet paradoxically, the social evolution of eusocial insects to divide their societies into specialized reproductive and non-reproductive castes based on recognition system form the basis of their ecological success.1 This essay examines the adaptability of the ant species to discern self from non-self, taking the stand that while fraught with disadvantages, does confer an overall selective advantage. A four-pronged approach of reinforcement, enhancement, enrichment and re-creation will be used to complement the ant species to survive, grow and expand.

The ant species comprises of individuals living in a tightly integrated hierarchical colony, in which inter-individual conflict for reproductive privilege is diminished and the worker caste is maximized for colony efficiency in an inter-colony competition.2 The integrity of the colony is maintained by the ability to distinguish colony-mates (self) from foreign colony-mates (non-self) as well as to distinguish the function of one caste from another.3-4 Therefore, the inclusiveness of selfhood may vary within the context: it may refer to the individual, the caste or the species4.

The reinforcement of the integrity of the ant’s colony involves the use of a range of recognition systems such as chemical cues, specific learned odour and sensory modalities within the colony which control the activities of each ant to expedite.4 They play a crucial role in the social recognition evolution of ants known as kin recognition. This ensures that the benefits of altruism flow to those who share the altruist’s genes, thus preventing random fusion, parasitism, or dissolution of the colony.4 Nonetheless, these recognition systems could undergo a recognition error as it varies substantially across taxa, and occasionally within species.4 For example, the Australian meat ant (Iridomyrmex Purpureus) species constituting of vast colonies, with multiple queens or with heterogeneous microhabitat may have a mixed colony odour, therefore potentially creating confusion.5 This confusion could incur fitness cost in terms of energy expenditure and permitting competitive cost of helping a non-kin.5 Distinctively, humans are the only known species in which cooperation of genetically unrelated individuals exists5. This uniqueness of human altruism confirms our evolutionary success as a species. Similarly, the ant’s capability to display nepotism towards kin provides an immediate potential advantage. Nevertheless, research has shown that agonistic behaviour could be a double-edged sword that might turn into a self-inflicting trajectory decimation if the recognition system of the ants is compromise.5-6

The ant species often fight against other species, both intra and interspecifically.6 Although aggressive behaviour towards competitor is necessary, aggression can be costly in terms of energy spent, time lost and possible injury and death. Consequently, the ant species display two sides: one, the underground ants (Lasius Austriacus) show less hostility towards the neighbor colony than a distant colony and in contrast the weaver ants (Genus Oecophylla) responds more aggressively to neighboring colonies than the distant colonies.7 This reveals that different species of ants’ aptitude to perceive self from non-self is often ambiguous where optimal levels of aggression towards a competitor varies with the context of the interaction.7-8 This may be a disadvantage as the colony’s integrity may be compromised due to an ineffective individuals’ liability. Despite that, the colony is often well guarded because the transmission of self genes is maximized when the dilution of self is prevented hence, aggression normally occurs. 7 Yet, the shift in response of some ant species to be less aggressive prove to be the first stage of establishing peace but does not necessarily imply a lack of recognition. There may be circumstances where attacking an intruder is not worth the cost, particularly if it involves death. The lack of antagonism may also save resources, which can be invested in colony growth and reproduction, thus increasing colony fitness.7,9 The enhancement of self from non-self provides the ant species to adapt advantageous recognition flows depending on the context of interaction.

The ant’s caste system enriches individuals because it enables them to know their respective functions of one caste (self) to another (non-self). The sterile female workers exclusively lay down their lives in subservience to the queen.9-10 Yet, this occurrence represents an evolutionary enigma. The production of sterile offspring would seem to be a disadvantage. This paradox of having sterile forms prove to be a natural selective advantage at a colony level whereby workers could lead to the rapid growth and reproduction by helping their parental nest.9
Usually in a colony, the numbers of worker caste outweigh the rest; thus it could be a disadvantage especially for small colony species as it would tie down a substantial amount of resources.9 As such, worker caste altruistically restrict their reproduction to avoid overpopulation and starvation of the colony. The traits evolved due to the beneficial survival of their species to reproduce even at the cost of their reproductive success. Therefore, the shared genes can spread and increase one’s ‘Inclusive Fitness’.10-11 Correspondingly, the drones ants (males) and soldiers ants (females) too know their functions which is to mate with the queen12 and protect the colony13 respectively. These three castes are merely a tag team where multiple individuals, each performing different tasks, concurrently act to achieve the desired outcome that allows maximum advantage. With that, all three castes display altruistic behaviour whereby their collective purpose is underscored by their selfless sacrifice for the greater good of the colony via a “veil of ignorance” cloaking colony identity, to behave inclusively to the colony’s advantage.14

In the re-creation of a new ant’s generation, copulation is pivotal for sexual selection.15 The ant polyandrous species like the leafcutter ants (Atta Colombica) have shown sexually antagonistic coevolution of distinguishing self from non-self by means of their seminal fluids.15 This act displays selfish behaviour where the exposed seminal fluid of one individual (self) to the other (non-self) has proven to be detrimental, thus shows that individual is protecting their own self genes for propagation. 15 This act is similar to semen displacement as a sperm competition strategy in humans.16 The pheidole kingi ants show extreme phenotypic plasticity.17 Their female ant larvae are initially pluripotent such that they are able to develop into any forms and castes.17 The “decisions” that determine the individual's developmental pathway are influenced by quantity of the larval food, chemical cues and pheromones that reflect the social conditions of the nest. For instance, if there are many soldiers, chemicals produced by the soldiers will suppress the development of more soldiers.17 This negative developmental feedback loop ensures that appropriate numbers of different caste members are produced.17 As such, the chemical cues within the colony promotes the instinct of distinguish self from non-self within the species and affects the developmental decision of their larvae, depending on the need of the colony. Parasitic ants (Solenopsis daguerrei) habitually live in the nests of fire ants (Solenopsis Invicta).18 After usurping the host’s queen, the parasitic queen attaches herself to the fire ant queen and diverts resources from her.18 Consequently, the fire ant workers care for the imposter queen and her brood.18 This parasitic behaviour avoids all significant effort in the upbringing of her brood, predation and in turn personal growth yet, with no benefit to the host.18 The above examples illustrate that the re-creation of a new generation are self-strengthening strategies which has evolved to bring out immediate advantages.

Conclusively, the ants’ ability to discern self from non-self provides the first step towards the evolution of a remarkable functioning social system. Although this ability presents both strengths and weaknesses of the strategies and foreshadows its inherent outcomes, it can be succinctly summed up as a calculated evolutionary gamble. It provides an edge for the ant species that far outweighs the risks arising from a propensity of its species. As such, in this game of evolutionary roulette, the odds are stacked neatly complementing the ant species as a superorganism to survive, grow and expand.

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