Evolution of Photoperiodic Time Measurement in the Pitcher- Plant Mosquito, Wyeomyia smithii

猪笼草蚊子 Wyeomyia smithii 光周期时间测量的演变

• 批准号: 9814438
• 负责人: William Bradshaw
• 金额: $ 36万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-15 至 2004-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814438&HistoricalAwards=false
• 关键词: Evolution; Photoperiodic; Time; Measurement; Pitcher

A wide variety of plants and animals use the length of day to synchronize theirdevelopment and reproduction with the warm days of summer and to synchronize their entry intohibernation in advance of the cold days of winter. At more northern latitudes, winter arrivesearlier when days are longer than at more southern latitudes. Consequently, northern organismsrespond to longer daylengths to switch from active development to hibernation in anticipation ofthe forthcoming winter. Many temperate plants and animals, including some of the mostproblematic agricultural pests in the United States, originated from more tropical latitudes ormigrated north after the last ice age. This migration required evolving the appropriate responsesto daylength before the immigrants could thrive in their new northern habitats. Thus, evolvedresponses to daylength to cue the seasonal programming of development, reproduction, andhibernation represent one of the most pervasive and important adaptations of temperateorganisms. The question then remains as to how they do it. What is the physiological basis for themeasuring of daylength within and between geographically distant populations? Are thephysiological processes that underlie genetic variation for day-length measuring withinpopulations the same processes that change over geographic distances; i.e., does understandinggenetic variation in the physiological clock within populations permit us to predict how thesepopulations might evolve in the future? The PIs have pursued these questions in temperatepopulations of a formerly tropical mosquito. The PIs have found that the internal biological clock(circadian rhythm) plays a role in the day-length measuring process in southern populations; but,the expression of the circadian clock declines with increasing latitudes so that northernpopulations measure day length with essentially a physiological hourglass. Yet, when unrelatedpopulations are crossed, their offspring show a reversion to the southern or ancestral switchingdaylength. This grant will help the PIs to determine whether reversion to the ancestral daylength also brings out the ancestral expression of the circadian clock. In addition to contributing to our understanding of the genetic and physiological basis foradaptive evolution of biological time measurement, results of this study have implications forphysiological adaptation to changing environments in general. If vestigial physiologicalcapabilities reside covertly within populations, physiological adaptation to environmental changemay proceed far more rapidly than would be predicted from present-day, overt genetic variationfor that trait in a population. If these covert capabilities are relics from ancestral genes lyinglatent in extant populations, then response to selection may proceed faster towards ancestral thantowards new capabilities. Hence, predicting the rate of evolution in response to environmentalchange such as global warming may depend critically upon understanding the historical role ofmasked or covert genes in physiological adaptation.

各种各样的植物和动物都会花一天的时间与夏季温暖的日子同步和繁殖，并在冬季寒冷的日子之前同步他们进入临床。 在更北部的纬度地区，几天比在南部纬度更长的时间更长的时候到达。 因此，北部有机体将较长的日间长度转变为在即将到来的冬季中从积极发展转变为冬眠。 许多温带动植物，包括美国一些最有问题的农业害虫，起源于上一个冰河时代后北部移民的更多热带纬度。 这种迁移需要在移民在其新的北部栖息地蓬勃发展之前就适当的响应日长度发展。 因此，演变为日延长，以提示发育，繁殖，andhibrnation的季节性编程是温带生物的最普遍，最重要的适应性之一。 然后，问题仍然是他们如何做到的。 它们在地理距离内部和地理距离之间的日程长度的生理基础是什么？ 是遗传变异的植物生物学过程是人群内测量与地理距离相同的过程的遗传变异；即，种群中生理时钟的理解力变化是否使我们能够预测该研究将来会如何发展？ PI在以前是热带蚊子的温带人群中提出了这些问题。 PI发现内部生物钟（昼夜节律）在南部人群的日长度测量过程中起作用。但是，昼夜节律的表达随着纬度的增加而下降，因此北部人群用生理沙漏测量日长度。 然而，当跨越无关的人群时，他们的后代向南部或祖先切换日期的归还。 该赠款将帮助PIS确定对祖先日距的归还是否还带出了昼夜节律的祖先表达。 除了有助于我们对生物学时间测量的遗传和生理基础的延伸性演变的理解之外，这项研究的结果还具有对整个不断变化环境的生理学适应性的影响。 如果遗传生理能力秘密地存在于人群中，那么对环境变化的适应性要比当今人群中该性状的明显遗传变异所预测的要快得多。 如果这些秘密的能力是现存人群中存在祖先基因的遗物，那么对选择的反应可能会更快地朝着祖先的thantowards进行新的能力。 因此，预测响应环境变化（例如全球变暖）的进化速率可能取决于了解卸载或掩盖基因在生理适应中的历史作用。