Altruistic Trait-a feature that reduces the fitness of an individual but provides a benefit to the population or species.

A classic example of an altruistic behavior is the “warning call” given by many species of animals including ground squirrels, prairie dogs, and passerine birds.
Asian Koel (Eudynamys scolopacea)- Male in Kolkata Im IMG 7575
In many species, organisms are altruistic among non-relatives. Altruistic acts among non-relatives can be the result of reciprocal altruism. Reciprocal altruism can be interpreted as 'I will be willing to be altruistic towards you now, if you are willing to be altruistic towards me later on'. Thus, an individual is willing to pay a cost now in hopes of receiving a benefit in the future.