オーストラリア半砂漠地域へのキク科植物の適応進化の解析

在野外考察期间(9月21日至10月30日，在维多利亚、新南威尔士州、钱斯兰、北领地和南澳大利亚州)，我们采集了约120个Asutrariae和Gnaphalieae的种群样本，并调查了它们的栖息地状况。除了捐赠给澳大利亚州立大学和国家港湾的标本外，所有的收藏品都被带回了日本，并为以下研究服务。对23属68种103个居群和3属6个种的8个居群的染色体数目进行了测定。虽然Pncheeae的基本染色体数x=10是保守的，但在Gnaphalieae中发现了频繁的异倍体。Podolepis(n=12-3)、Pogonolepis(n=6-4)、Rhodanthe(n=11-5)、Tricanthodium(n=4-3)等。干旱地区的物种经常表现出一年生习性。为了弄清物种间的亲缘关系和适应澳大利亚干旱地区的染色体数目、习性和形态特征的进化趋势，我们比较了短毛豆属植物叶绿体matK基因的核苷酸序列，并构建了分子系统发育树。两种树都一致支持这些属的单系性。根据花药附属物和花柱的形态、地理分布和染色体数目的变异模式，将短梗划分为4个类群。异倍体从n=9减少，习性从多年生转变为一年生，果实形态从简单转变为复杂，这些都是在几个独立的突变体中产生的，被认为是适应干旱或季节性干旱条件的。对短梗菊属68个分类群和澳大利亚菊科7个近缘属8个种进行了核型分析。

We have collected about 120 population samples of Asutralian Astereae and Gnaphalieae and investigated their habitat condition during the field expeditions (from Sept.21 to Oct.30 for Victoria, New South Wales, Qeensland, Northern Territory and South Australia). All of collections, except the donating speciments to Australian State and National Harbaria, have been brought back to Japan and served to the following researches. Chromosome numbers from 103 populations attributed 68 species of 23 genera of Gnepharieae and from 8 populations attributed 6 species of 3 genera of Pulcheeae were determined. The frequent dysploidy has been found in Gnaphalieae although the basic chromosome number x=10 is conservative in Pulcheeae. They are in Podolepis (n=12-3) , Pogonolepis (n=6-4) , Rhodanthe (n=11-5) , Tricanthodium (n=4-3) and so on. Species of arid regions frequently display an annual habit. To clarify the species relationship between species and the evolutionary trends in Chromosome number, habit and morphological characters adapting to the Australian arid regions, we have compared the nucleotide sequence of matK gene of chloroplast and constructed the molecular phylogenetic trees in Brachyscome. Both trees are consistent the support the monophyly of these genera. Brachyscome is divided into 4 clusters corresponding to the morphology of anther appendage and style, geographical distribution and the variation pattern of chromosome number. The dysploid reductions from n=9, the change of habit from perennial to annual and the change of fruit morphology from simple to complex have been derived in several independent leneages and are regarded to be adaptive in arid or seasonally dry conditions. Karyotype analyzes were made on 68 taxa of Brachyscome and 8 species of 7related Australian Astereae genera.