Calsbeek Ryan, Sinervo Barry
Department of Ecology and Evolutionary Biology, Earth and Marine Sciences Building, A316, University of California, Santa Cruz, CA, 95064, USA.
Center for Tropical Research, Institute of the Environment, University of California at Los Angeles, 1609 Hershey Hall, Box 951496, Los Angeles, CA, 90095-1496, USA.
Oecologia. 2002 Aug;132(3):468-477. doi: 10.1007/s00442-002-0975-8. Epub 2002 Aug 1.
Territoriality drives the evolution of many mating systems, yet has remained an extremely difficult trait to measure in the wild. Classic studies rely on the theoretical framework of resource holding potential (RHP) as a predictor of success in territory acquisition. However, mounting evidence suggests that an individual's RHP may change over short time scales. Previous studies suggest that RHP is best understood by considering two categories of territoriality, resource defending and resource usurping potential (RDP and RUP, respectively). In a population of the side-blotched lizard, Uta stansburiana, blue-throated males defend territories near their natal site (RDP) while mature orange-throated males use their RUP to sequester high quality territories from defending territorial males. We tested differences in territoriality by releasing pairs of maturing male lizards onto experimentally altered territories that had improved thermal qualities owing to the addition of rock piles. Dyads of males competed for these thermal resources and the females that were released on rock piles. Early in the season, when throat colors were not yet fully expressed, large male body size predicted contest victories irrespective of throat color. This pattern changed however, with the onset of the breeding season and maturation of throat color. Orange males tended to usurp territories from blue males within 2 weeks of contest initiation. Large male body size still influenced these contests, but after one more week, throat color was the sole factor explaining variance in territory ownership. We demonstrate the ontogeny of territoriality relating to body size and throat color during maturation, and suggest a novel approach to assessing territoriality and aggression in the wild.
领地性推动了许多交配系统的进化，但在野外仍然是一个极难测量的特征。经典研究依赖于资源持有潜力（RHP）的理论框架，将其作为领地获取成功的预测指标。然而，越来越多的证据表明，个体的RHP可能在短时间尺度内发生变化。先前的研究表明，通过考虑两类领地性，即资源防御和资源篡夺潜力（分别为RDP和RUP），能更好地理解RHP。在侧斑蜥蜴（Uta stansburiana）种群中，蓝喉雄性在其出生地附近保卫领地（RDP），而成熟的橙喉雄性则利用其RUP从保卫领地的雄性手中夺取高质量领地。我们通过将成对的成年雄性蜥蜴放到经过实验改造的领地上来测试领地性的差异，这些领地由于添加了石堆而具有更好的热环境。雄性二元组竞争这些热资源以及被放到石堆上的雌性。在季节早期，当喉部颜色尚未完全显现时，无论喉部颜色如何，雄性体型大预示着竞争胜利。然而，随着繁殖季节的开始和喉部颜色的成熟，这种模式发生了变化。橙色雄性在竞争开始后的2周内倾向于从蓝色雄性手中夺取领地。雄性体型大仍然影响这些竞争，但再过一周后，喉部颜色成为解释领地归属差异的唯一因素。我们展示了成熟过程中与体型和喉部颜色相关的领地性个体发育，并提出了一种在野外评估领地性和攻击性的新方法。
