Sex-specific sterility caused by extreme temperatures is likely to create cryptic changes to the operational sex ratio in Drosophila virilis.
Sex-specific sterility caused by extreme temperatures is likely to create cryptic changes to the operational sex ratio in Drosophila virilis.
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极端温度引起的性别特异性不育可能会对果蝇的操作性性别比产生神秘的变化。
DOI：
10.1093/cz/zoaa067
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发表时间：
2021-06
期刊：
影响因子：
2.2
通讯作者：
Parratt SR
中科院分区：
文献类型：
--
作者：
Walsh BS;Mannion NLM;Price TAR;Parratt SR
气候变化正在增加短期热冲击的频率和严重程度，威胁到自然种群的持久性。然而，大多数研究人为环境变化的进化后果的工作都集中在自然选择上，而对性选择的影响关注较少。性选择运作的条件是一个有争议的话题，但一个普遍观察到的模式是，种群的有效性比例（OSR）是决定受精竞争程度和配偶选择范围的关键（Weir et al. 2011）。因此，如果高温影响种群中生殖雄性与雌性的比例，这可能会影响性选择。亚致死温度可以使一系列生物系统中的个体绝育，包括植物、昆虫、珊瑚、鸟类和哺乳动物（见Walsh et al. 2019a）。如果高温对一种性别的生殖影响大于另一种性别，这可能会导致种群OSR的隐性变化（Petry et al. 2016）。然而，尽管人们普遍认为高温下的生育能力丧失在男性中比在女性中更常见（Iossa 2019），但很少有研究在相同条件下测量两性的生育能力（Walsh et al. 2019b）。在观察到对温度的敏感性在性别之间存在差异的情况下（Janowitz and Fischer 2011; Zwoinska et al. 2020），尚未考虑对人口性比例的影响。此外，如果长期不育，自然选择、性选择和种群动态更有可能受到性别比例偏差的影响。然而，迄今为止，两性二态热致不育的模式尚未在生物体的生殖寿命中显示出来。在这里，我们的目的是测试热应激是否会对世界果蝇果蝇雄性和雌性的生育能力产生不同的影响，以及这是否会随着时间的推移在种群性别比例中产生隐性偏差。具体来说，我们假设蛹热应激会显著延迟成年性成熟，并且在相同条件下，雄性比雌性更严重。为了做到这一点，我们将蛹暴露在38摄氏度的亚致死热休克中4小时，以模拟正午热浪的峰值。我们选择加热蛹，因为它们是不动的，不能在行为上逃避自然界的热应激。我们随后检查了完全不育和蛹后代生产在一个生态现实的寿命在雄性和雌性。我们结合雄性和雌性的时间序列数据预测了热致不育对OSR的影响，并讨论了其对性选择的潜在影响。具体方法见补充资料。我们发现，新闭合的雄毛蝇的可育率受到性别和温度的交互作用的显著影响。虽然雌性的生育能力不受热应激的显著影响，但雄性的性成熟如果暴露在38℃的蛹（Cox比例风险试验相互作用项：风险比（HR）¼À1）显著延长。4866, v2 1¼16:275，P< 0.001；图1A和B)。此外，我们发现从未产生后代的个体比例可以通过性别和处理之间的显著相互作用来预测，其中暴露于热应激的雄性比对照组或任何热处理的雌性更有可能永久不育（v2 1¼5.657,P¼0.017；补充图S1）。这是一个相对较小的影响，表明大多数男性在实验期间的某个时候恢复了生育能力。我们发现对照雄性在羽化后7天达到性成熟，在…
Climate change is increasing the frequency and severity of short-term heat shocks that threaten the persistence of natural populations. However, most work addressing the evolutionary consequences of anthropogenic environmental change has focused on natural selection, with less attention paid to the impacts on sexual selection. The conditions under which sexual selection operates is a topic of debate, but a generally observed pattern is that the operational sex ratio (OSR) of a population is key to determining both the extent of competition for fertilizations and the scope for mate choice (Weir et al. 2011). Therefore, if high temperatures affect the ratio of reproductive males to females in a population, this could influence sexual selection. Sub-lethal temperatures can sterilize individuals from a range of biological systems, including plants, insects, corals, birds, and mammals (reviewed in Walsh et al. 2019a). If high temperatures affect reproduction in one sex more than the other, this may create cryptic shifts in the OSR of a population (Petry et al. 2016). However, although fertility loss at high temperatures is generally thought to be more common in males than in females (Iossa 2019), very few studies measure fertility in both sexes under identical conditions (Walsh et al. 2019b). Where sensitivity to temperature has been observed to vary between the sexes (Janowitz and Fischer 2011; Zwoinska et al. 2020), the effect on population sex ratios has not been considered. Furthermore, natural selection, sexual selection, and population dynamics are more likely to be affected by biased sex ratios if sterility is long-lasting. However, to date, patterns of sexually dimorphic heat-induced sterility have not been shown over organisms’ reproductive life spans. Here, we aim to test whether heat stress differentially affects male and female fertility in the cosmopolitan fruit fly Drosophila virilis and if this creates cryptic bias in population sex ratios over time. Specifically, we hypothesize that pupal heat stress will significantly delay adult sexual maturation and that this will be more severe in males compared to females under identical conditions. To do this, we exposed pupal D. virilis to a sub-lethal heat shock of 38 C for 4 h to simulate the peak of a mid-day heat wave. We chose to heat pupae because they are immobile and cannot behaviorally escape heat stress in nature. We subsequently examined both complete sterility and pupal offspring production over an ecologically realistic lifespan in both males and females. We combine male and female time-series data to predict the effect of heat-induced sterility on the OSR, and discuss its potential consequences on sexual selection. Detailed methods are described in the Supplementary Materials. We found that the rate at which newly eclosed D. virilis become fertile is significantly influenced by the interaction between sex and temperature. While female fertility is not significantly affected by heat stress, male sexual maturation is significantly extended if they are exposed to 38 C as pupae (Cox proportional hazard test interaction term: hazard ratio (HR) ¼ À1. 4866, v2 1 ¼ 16: 275, P< 0.001; Figure 1A and B). Furthermore, we found that the proportion of individuals that never produced offspring was predicted by a significant interaction between sex and treatment, wherein males exposed to heat stress were more likely than controls or females in any heat treatment to be rendered permanently sterile (v2 1 ¼ 5.657, P ¼ 0.017; Supplementary Figure S1). This is a relatively small effect, showing that most males recovered fertility at some point during the experiment. We found that control males reached sexual maturity 7days post eclosion, in …
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影响因子：
2.7
作者：
Janowitz, Susann A.;Fischer, Klaus
通讯作者：
Fischer, Klaus
影响因子：
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