Habitat loss and pollution are two of the greatest global threats to biodiversity. Due to their widespread prevalence, these threats often co-occur, yet their interactive effects on organisms remain poorly understood. Some reptiles are vulnerable to these threats because they have specific microclimate requirements for embryonic development and because pollutants are maternally transferred to their eggs; both incubation temperature and pollutants affect reptile sex determination. In aquatic turtles, females often select nest sites in recently planted agricultural fields but the impact of nesting in polluted agricultural habitats is not understood. We examined the influences of crop agriculture and mercury pollution on nest microclimate and offspring sex ratios of Chelydra serpentina. We hypothesized that crop growth in agricultural fields would shade and cool turtle nests, decrease moisture levels, increase male offspring production, and interact with maternally-derived mercury to impact sex determination. As predicted, nests shaded by crops had lower average temperatures (−2.5 °C) and moisture levels (−107 kPa) than control nests. In field and laboratory experiments, agricultural thermal regimens increased the proportion of male offspring in clutches and this effect was intensified in the presence of mercury. Global temperatures are expected to rise within the 21st century and to have a feminizing effect on reptiles with temperature-dependent sex determination. That prediction should be refined to incorporate how the cooling effect of some local habitat conditions (e.g., agricultural fields), and interactions between anthropogenic land-use and common pollutants, will interact with climate change to influence sex ratios of reptiles with temperature-dependent sex determination.

生境的丧失和污染是对生物多样性的全球最大的两个威胁。由于它们的普遍流行，这些威胁经常同时发生，但它们对生物的相互作用影响仍然知之甚少。一些爬行动物很容易受到这些威胁的影响，因为它们对胚胎发育有特定的微气候要求，而且污染物是由母体转移到它们的卵中的；孵化温度和污染物都会影响爬行动物的性别决定。在水龟中，雌性经常在最近种植的农田中选择巢穴，但人们并未了解筑巢在受污染的农业栖息地中的影响。我们研究了农作物农业和汞污染对蛇纹夜蛾巢小气候和后代性别比的影响。。我们假设农田中的农作物生长会遮蔽并冷却龟窝，降低水分含量，增加雄性后代的产量，并与母体来源的汞相互作用，从而影响性别确定。如预测的那样，被农作物遮蔽的巢穴的平均温度（-2.5°C）和水分含量（-107 kPa）低于对照巢穴。在野外和实验室实验中，农业热疗增加了离合器中雄性后代的比例，并且在存在汞的情况下，这种影响加剧了。预计全球温度将在21世纪内上升，并且通过确定温度的性别来对爬行动物产生女性化的影响。应当对该预测进行完善，以纳入某些当地栖息地条件（例如农田）的降温效果，