Alarm Signal - Selective Advantage

Selective Advantage

This cost/benefit tradeoff of alarm calling behaviour has sparked many interest debates among evolutionary biologists seeking to explain the occurrence of such apparently "self-sacrificing" behaviour. The central question is this: "If the ultimate purpose of any animal behaviour is to maximize the chances that an organism's own genes are passed on, with maximum fruitfulness, to future generations, why would an individual deliberately risk destroying themselves (their entire genome) for the sake of saving others (other genomes)?".

Some scientists have used the evidence of alarm-calling behaviour to challenge the theory that "evolution works only/primarily at the level of the gene and of the gene's "interest" in passing itself along to future generations." If alarm-calling is truly an example of altruism, then our understanding of natural selection becomes more complicated than simply "survival of the fittest gene".

Other researchers, generally those who support the selfish gene theory, question the authenticity of this "altruistic" behaviour. For instance, it has been observed that Vervets sometimes emit calls in the presence of a predator, and sometimes do not. Studies show that these Vervets may call more often when they are surrounded by their own offspring and by other relatives who share many of their genes. Other researchers have shown that some forms of alarm calling, for example, "aerial predator whistles" produced by Belding's Ground Squirrels, do not increase the chances that a caller will get eaten by a predator; the alarm call is advantageous to both caller and recipient by frightening and warding off the predator.

Another theory suggests that alarm signals function to attract further predators, which fight over the prey organism, giving it a better chance of escape. Others still suggest they are a deterrent to predators, communicating the animals alertness to the predator. One such case is the Eastern Swamphen (Porphyrio porphyrio), which gives conspicuous visual tail flicks (see also aposematism, handicap principle and stotting).

Considerable research effort continues to be directed toward the purpose and ramifications of alarm-calling behaviour, because, to the extent that this research has the ability to comment on the occurrence or non-occurrence of altruistic behaviour, we can apply these findings to our understanding of altruism in human behaviour.