Post date: Apr 03, 2017 5:18:57 PM
An Advanced Access version of a new water strider paper is online at Behavioral Ecology. In the study, we document how a simple reduction in pool size and group size drives dramatic changes in water strider mating dynamics. Notably, the scramble competition and promiscuity typically seen in studies of larger pools and groups of water striders was often replaced in small groups by single-male dominated systems resembling harem polygyny. These changes emerged and became stable in small pools over the course of a few days but were quickly reversed if water striders were placed back into large social groups. This study provides insights into possible environmental mechanisms contributing to the evolution of mating systems and mating tactics.
See the article online at: https://academic.oup.com/beheco/article/3057960/Altered-physical-and-social-conditions-produce#62154235
Altered physical and social conditions produce rapidly reversible mating systems in water striders
Sih et al. 2017 Behavioral Ecology
ABSTRACT
Mating systems can vary within-species but the environmental drivers and behavioral mechanisms underlying this variation are seldom investigated experimentally. We experimentally assessed how individual behavioral plasticity in response to changes in pool and group size resulted in fundamental shifts in mating systems in water striders. We observed the same animals in larger and smaller pools, mimicking variation in pool size in natural streams, and observed a rapid, reversible change in the entire mating system. In large pools, striders exhibited scramble promiscuity with intense sexual conflict. Most males were active, harassing and driving females into hiding. Matings were frequent and typically lasted for more than 100 min. In contrast, when placed in small pools, the same animals often exhibited harem polygyny where the largest male drove other males into hiding, but allowed females to be relatively active. Matings were less frequent and of much shorter duration. Harem polygyny took several days to emerge after animals were moved to small pools, while these same animals returned to scramble promiscuity within hours after being moved to larger pools. Such variability in mating systems likely has important implications for the evolution of individual mating tactics.