Origin and evolution of Fragaria cascadensis

多倍体杂交物种形成是植物物种形成的主要驱动力之一。所有被子植物的祖先可能是多倍体，几种重要农作物的祖先也是如此(如小麦(Triticum L.)和草莓(Fragaria L.)为了了解多倍体杂交物种的进化，有必要知道哪些亲本物种对基因组做出了贡献。这可能是困难的，特别是当发生几个杂交事件时。花序花属(Rosaceae)是一属23种植物，其中包含重要的粮食作物F×ananassa Duschesne ex Rozier。在Fragaria，23种中有11种是多倍体杂交种。有四倍体、六倍体、八倍体和十倍体物种，其中许多物种早已为人所知。2012年，描述了一个新的十倍体物种，Fragaria Cascadens Hummer。本种的祖先尚不清楚，但有人认为它是F.Vesca L.亚种的杂交。Bratteata(A.Heller)Staudt和F.virginiana Mill.亚种。Platypetala(Rydb.)史陶德。由于它目前分布在美国俄勒冈州的喀斯喀特山脉，其演化的可能时间框架是大约10,000年前俄勒冈州更新世冰川融化之后。在这个项目中，我想研究这种十倍体物种的起源和进化。我将使用靶浓缩Hyb-Seq获得超过10,000个核基因组和质体组的基因座，这些基因座可以与潜在亲本物种的数据集进行比较，并与Fragaria Vesca参考基因组进行比对。利用适当的近似贝叶斯计算方法，可以测试不同的原点模型(单一原点和多个原点)，并计算出发散时间。其目的是了解瀑布花起源的时间、地点和频率，以及从那时起它是如何进化的。

Polyploid hybrid speciation is one of the major driver of plant speciation. The ancestor of all angiosperms was probably polyploid, as were the ancestors of several important crop plants (e.g., wheat (Triticum L.) and strawberry (Fragaria L.)). To understand the evolution of polyploid hybrid species it is necessary to know which parental species contributed to the genome. This can be difficult, especially when several hybridization events occurred. Fragaria (Rosaceae) is a genus of 23 species containing the important crop species F. ×ananassa Duschesne ex Rozier. In Fragaria 11 of 23 species are polyploid hybrid species. There are tetra-, hexa-, octo- and decaploid species of which many are long known. In 2012 a new decaploid species, Fragaria cascadensis Hummer, was described. The ancestors of this species remain unclear, but it is suggested that it is a hybrid of F. vesca L. subsp. bracteata (A. Heller) Staudt and F. virginiana Mill. subsp. platypetala (Rydb.) Staudt. Due to its present distribution in the Cascade Range in Oregon (USA) a possible time frame for its evolution is after the melting of the Pleistocene glaciers in Oregon ca. 10,000 years ago. In this project I want to investigate the origin and evolution of this decaploid species. I will use target enrichment Hyb-Seq to obtain more than 10,000 loci of the nuclear genome and the plastome that can be compared with datasets of the potential parental species and aligned to the Fragaria vesca reference genome. With appropriate approximate Bayesian computation methods different models of origin (single vs. multiple origin) can be tested and divergence times will be calculated. The aim is to understand when, where and how often Fragaria cascadensis originated and how it evolved since then.