DISSERTATION RESEARCH: The adaptive significance of shell color variation in the flat periwinkle Littorina obtusata

海洋蜗牛Littorina obtusata以贝壳颜色的显著多样性而闻名。贝壳的颜色预计会影响可见光的吸收，而可见光又可能会影响体温和健康。先前的结果表明，缅因湾贝壳颜色多样性的模式是由热状况的变化驱动的。在更热、更暴露的缅因湾栖息地，较浅的贝壳颜色出现的频率更高，而较冷地区的种群则以深色为主。此外，操纵性实验表明，浅壳颜色的蜗牛在炎热、干燥的条件下具有健康优势。这项拟议的研究将进一步测试贝壳颜色和适合度之间的关系，检查冷应激下的生长和死亡率，以及田间对热应激的行为反应。这项拟议的研究将提供一个令人信服的例子，说明热状况的变化作为自然种群中的一种选择性力量的重要性。这样的例子很少见，特别是在具有重大生态相关性的自然系统中。此外，了解生物体如何应对和适应多变的温度制度，可能会产生关于哪些种群和物种最容易受到环境变化影响的具体预测，并更好地为保护重要生态系统所使用的方法提供信息。监测钝顶螺壳颜色频率的分布可能被证明是追踪气候变化对生态群落影响的一种经济、易用的方法。

The marine snail Littorina obtusata is noted for remarkable diversity in shell color. Shell color is expected to affect absorption of visible light that may in turn impact body temperature and fitness. Previous results suggest that patterns of shell color diversity in the Gulf of Maine are driven by variation in thermal regime. Lighter shell colors increase in frequency in hotter, more exposed habitats in the Gulf of Maine whereas dark colors dominate populations in cooler areas. In addition, manipulative experiments demonstrated that light shell colored snails are at a fitness advantage under hot, dry conditions. The proposed study will further test the relationship between shell color and fitness, examining growth and mortality rates under cold stress and behavioral responses to thermal stress in the field. The proposed study will provide a compelling example of the importance of variation in thermal regime as a selective force in natural populations. Such examples are rare, particularly in natural systems with significant ecological relevance. Further, understanding how organisms respond and adapt to variable thermal regimes may generate concrete predictions as to which populations and species are most vulnerable to environmental change and better inform the methods used to protect important ecosystems. Monitoring the distribution of shell color frequencies in L. obtusata may prove to be a cost-effective, tractable method for tracking the effects of climate change in ecological communities.