Collaborative Research: RUI: Measuring reciprocal natural selection in a contact zone in an obligate pollination mutualism

这个项目解决了进化生态学中的一个基本问题；植物和昆虫传粉者之间的共同进化如何创造生物多样性。约书亚树（Yucca brevifolia）是一种多刺的树状沙漠植物，是美国西部的标志性物种。这些树之所以引人注目，不仅是因为它们奇异的外表，还因为它们高度专业化和不同寻常的授粉方式。它们仅由两种丝兰蛾在Tegeticula属授粉；反过来，飞蛾只通过在花中产卵来繁殖。约书亚树和它的传粉者之间的这种关系是一种极端的相互依存关系；飞蛾和植物的繁殖完全依赖彼此。为约书亚树授粉的两种丝兰蛾在解剖结构的关键特征上有所不同，尤其是雌蛾产卵器的大小和形状，雌蛾产卵器是用来将卵注入约书亚树花朵的器官。最近的研究表明，这两种飞蛾产卵的特定树木在花解剖结构的特征上有所不同；在由产卵器较大的飞蛾授粉的树木中，飞蛾插入产卵器的路径较长，而在由产卵器较短的飞蛾授粉的花朵中，飞蛾插入产卵器的路径较短。飞蛾和它们授粉的植物之间的解剖匹配可能反映了共同进化的历史，但这一假设从未得到验证。该项目将提供概念证明，该假设可以通过互惠移植实验进行测试，以量化作用于昆虫和植物的自然选择。此外，该项目将评估利用分子遗传技术重建传粉媒介家庭关系的可行性。约书亚树是美国西南部莫哈韦沙漠生态系统的重要物种，受到气候变化的威胁，其大部分地区都濒临灭绝。这个项目的结果将为当地和联邦的保护工作提供信息，通过扩大约书亚树的范围来拯救它们。该项目将招收一些本科生，他们来自一个以本科生为主的机构，接受分子遗传学和进化生态学的研究训练。

This project addresses a fundamental question in evolutionary ecology; how does coevolution between plants and their insect pollinators create biodiversity. Joshua trees (Yucca brevifolia) are spiny, tree-like desert plants that are an iconic species of the American West. The trees are remarkable not only for their bizarre appearance, but also for their highly specialized and unusual means of pollination. They are pollinated exclusively by two species of Yucca moth in the genus Tegeticula; the moths, in turn, reproduce solely by laying their eggs in the flowers. This relationship between the Joshua tree and its pollinators is one of extreme interdependence; both the moth and the plant are entirely reliant upon one another for reproduction. The two species of Yucca moth that pollinate the Joshua tree differ in key features of their anatomy, particularly the size and shape of the female moth ovipositor, the organ used to inject their eggs into the Joshua tree flower. Recent work has shown that the particular trees on which these two moth species lay their eggs differ in features of their floral anatomy; the path through which the moth must insert her ovipositor is longer in trees that are pollinated by moths with a larger ovipositor, and shorter in flowers pollinated by moths with a shorter ovipositor. This anatomical match between the moths and the plants they pollinate likely reflects a history of coevolution, but this hypothesis has never been tested. This project will provide proof of concept that the hypothesis can be tested using reciprocal transplant experiments to quantify natural selection acting on the insects and the plants. In addition, the project will assess the feasibility of using molecular genetic techniques to reconstruct family relationships in the pollinators. The Joshua tree is a keystone species of the Mojave Desert ecosystem of the southwest USA, and is threatened by climate change with extinction over much of its range. Results from this project will inform local and federal conservation efforts to save Joshua trees through expansion of their range. This project will engage a number of undergraduates from a predominately undergraduate institution with research training in molecular genetics and evolutionary ecology.