Srygley Robert B
Smithsonian Tropical Research Institute, Apdo. 2072, Balboa, Republic of Panama.
USDA-Agricultural Research Service, Northern Plains Agricultural Research Lab, 1500 N. Central Ave., Sidney Montana, MT 59270, USA.
Insects. 2018 Aug 22;9(3):107. doi: 10.3390/insects9030107.
Research on endangered British butterflies has found that butterfly populations in small refuges evolve to allocate more mass to the thorax (flight muscle) and less to the abdomen than populations in large refuges. The observed change in mass allocation affects two morphological features relevant to flight: the flight muscle ratio (FMR) and the position of center of body mass (cm). The author tested whether a decrease in FMR or a change in cm reduced the ability to disperse by experimentally weight-loading Neotropical butterflies. In one treatment group, FMR was decreased but cm was not altered, whereas in the second group FMR was decreased and cm was repositioned further posterior. In one mark⁻release⁻recapture (MRR) experiment, butterflies dispersed relatively slowly, and treatment groups did not differ significantly. In a replicate experiment, butterflies dispersed more quickly, and control butterflies dispersed more rapidly than either treatment group. Differences in dispersal were consistent with a causal relationship between FMR and movement. A more posterior cm had little effect on dispersal beyond that due to the change in FMR. These results support the hypothesis that an increase in mass allocation to the thorax in small, dispersed refugia is due to selection on the ability to disperse.
对濒危英国蝴蝶的研究发现，与大型保护区中的蝴蝶种群相比，小型保护区中的蝴蝶种群进化出将更多质量分配到胸部（飞行肌肉）而将更少质量分配到腹部的特征。观察到的质量分配变化影响与飞行相关的两个形态特征：飞行肌肉比率（FMR）和身体质量中心（cm）的位置。作者通过对新热带蝴蝶进行实验性负重，测试了FMR的降低或cm的变化是否会降低其扩散能力。在一个治疗组中，FMR降低但cm未改变，而在第二组中FMR降低且cm进一步向后重新定位。在一项标记-释放-再捕获（MRR）实验中，蝴蝶扩散相对较慢，且各治疗组之间没有显著差异。在重复实验中，蝴蝶扩散得更快，且对照蝴蝶比任何一个治疗组扩散得都更快。扩散差异与FMR和移动之间的因果关系一致。cm位置更靠后对扩散的影响除了FMR变化所导致的之外几乎没有。这些结果支持了这样的假设，即在小型分散保护区中，向胸部分配的质量增加是由于对扩散能力的选择。
