DISSERTATION RESEARCH: Are offspring polymorphic species hedging their bets?

论文研究：后代多态物种是否在两面下注？

• 批准号: 1702050
• 负责人: D. Lawrence Venable
• 金额: $ 1.98万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702050&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; offspring; polymorphic; species

Stock markets are dynamic. Therefore, investors hedge their bets by investing in multiple stocks simultaneously or dividing investments between stocks and bonds. This reduces the chance of complete loss due to a stock crash but also reduces potential gains when a stock dramatically rises. Similarly, organisms may have evolved bet hedging strategies that allow them to cope with dynamic environments. To date the evidence supporting the existence of biological bet-hedging strategies stems primarily from theoretical work. To robustly assess evidence for bet hedging in nature, this study takes advantage of a fascinating reproductive strategy, termed offspring polymorphism, in which organisms produce multiple different kinds of offspring simultaneously. This strategy can be observed across many life forms including animals (e.g. frogs) and bacteria but is especially common in plants. Investigators will test the hypothesis that seed-polymorphism plants produce one seed or offspring type that is good at surviving in dry years and one that is good at surviving in wet years. This research will help scientists gain a better understanding of how organisms cope with change. This will increase predictive power about organisms' responses to environmental change and increasing desertification. Outreach to the public will occur, and undergraduate students will be trained as part of this work. Through the combination of an innovative field experiment and stochastic population models parameterized with long-term field and experimental data, the researchers will rigorously evaluate seed polymorphism as a bet hedging strategy in Pectocarya heterocarpa, a winter, desert annual species. P. heterocarpa is particularly suitable as it produces three visually distinct and spatially separated seed types which are easy to distinguish and count. These morphs will be sown in a natural field setting under various rain reducing shelters to examine how seeds differ in their germination timing, growth, and fitness under different rainfall regimes. The ecologists will combine this data with multi-decadal temporal and spatial demographic data on P. heterocarpa. They will then parameterize density-dependent and independent models to rigorously evaluate offspring polymorphism as a bet hedging strategy. Specifically, the density-independent model will allow researchers to find optimal seed ratios under different environmental regimes while the density-dependent models allow for an adaptive dynamics approach to find evolutionary stable seed polymorphism strategies.

股票市场是动态的。因此，投资者通过同时投资多只股票或将投资分为股票和债券来对冲他们的赌注。这减少了由于股票崩盘而完全损失的机会，但也减少了股票大幅上涨时的潜在收益。同样，生物体可能已经进化出更好的对冲策略，使它们能够科普动态环境。迄今为止，支持生物赌注对冲策略存在的证据主要来自理论研究。为了有力地评估自然界中赌注对冲的证据，这项研究利用了一种迷人的生殖策略，称为后代多态性，即生物体同时产生多种不同类型的后代。这种策略可以在许多生命形式中观察到，包括动物（例如青蛙）和细菌，但在植物中尤其常见。研究人员将检验这样的假设，即种子多态性植物产生一种种子或后代类型，这种种子或后代类型在干旱年份和潮湿年份都能存活。这项研究将帮助科学家更好地了解生物体如何科普变化。这将提高生物体对环境变化和日益严重的荒漠化的反应的预测能力。通过一个创新的田间实验和随机种群模型的长期田间和实验数据的参数化相结合，研究人员将严格评估种子多态性作为一种赌注对冲策略，在Pectocarya heterocarpa，一个冬季，沙漠一年生物种。P.heterocarpa是特别合适的，因为它产生三种视觉上不同且空间上分离的种子类型，其易于区分和计数。这些变种将播种在不同的雨水减少庇护所下的自然领域设置，以研究种子如何在不同的降雨条件下不同的发芽时间，生长和健身。生态学家将联合收割机将这些数据与P. heterocarpa的数十年时间和空间人口统计数据相结合。然后，他们将参数化密度依赖和独立模型，以严格评估后代多态性作为赌注对冲策略。具体来说，密度无关模型将允许研究人员在不同的环境制度下找到最佳的种子比例，而密度依赖模型允许一个自适应动力学方法来找到进化稳定的种子多态性策略。