Compensatory Responses to Copulatory Organ Damage in the Western Black Widow

Experimental alterations of morphological traits during development can reveal life history tactics and resource allocation patterns. I examined effects of amputation of a structure directly involved with mating compared to one that is less associated with fitness. I amputated one of the paired external copulatory organs (palps) of juvenile male black widow spiders Latrodectus hesperus), and compared changes in life history traits and fitness to males with amputated legs and controls. I show that palps are more likely to be regenerated than legs, smaller juveniles are more likely to regenerate, and mating success is adversely affected in all adults that suffered early amputation. The pre-existing relationship between juvenile size and development was a critical determinant of regeneration, however no life history costs of regeneration were evident. I conclude that plasticity in life history facilitates regeneration, and that this may mask trade-offs involved in compensatory effects at the population level.MAS