Adaptative Value

Beacon Hypothesis

In the first half of the 20th century, the major hypothesis for the adaptive value of pteroptyx’s firefly-tree behavior was focused on group benefit. In 1938, Buck published his “beacon hypothesis” asserting that fireflies in the dense mangrove swamps of Southeast Asia couldn’t rely on individual line-of-sight navigation the way roving fireflies do. Instead, males congregated in trees where their combined flashes were brighter and visible from a greater distance to both other males and females.

Challenges to the beacon hypothesis

In the 1960s and 1970s, models based on group selection came into question throughout biology. The fitness of the individual was re-emphasized and models that assigned whole benefit to a group were doubled unless, in line with the selfish gene hypothesis, group members were related or reciprocally altruistic.

In 1973, in response to this sea change, Lloyd published a new hypothesis based on the premise that the benefits of synchronous flashing "must accrue to the male that is behaving in this manner." He suggested that the function of a male's flash was to brighten his location on the tree, attracting a female to his particular location whereupon communication must change to a different channel before mating could occur.

In 1978, the Bucks responded that evaluating synchronous rhythmic flashing, a group behavior, based on individual benefit seemed paradoxical, since male fireflies can't avoid synchronizing with one another and "one firefly cannot be a better synchronizer than another."

Small group benefit

The competing hypotheses were resolved by a model with two levels of male/male competition. The first of these hypothesized competition between small groups on a tree and the second between individuals within the small groups. Therefore, as Lloyd proposed, large-grop synchrony isn't a competition but makes competition between individuals possible. According to the current hypothesis, once a female is attracted to the group, an individual male brightens his flash or aims his lantern toward her in order to stand out from the group.

Mechanism-based hypothesis

Males synchronize as a means of jamming avoidance. If one male's flash resets the other's pacemaker back to basal levels, then given certain known timing hindrances, the later male will never be able to flash. However, if the later male synchronizes with the earlier flash, it can complete cycle despite the neural imperative to flash in response to light.

All of this: Greenfield 1994


From Kitakyushu tourism site