毛乌素沙地锦鸡儿（Caragana）种群形态变异

以柠条锦鸡儿（Ｃａｒａｇａｎａｋｏｒｓｈｉｎｓｋｉｉ）人工种群为对照，研究了自然分布在内蒙古毛乌素沙地各类生境（硬梁、覆沙硬梁、覆沙软梁、覆沙滩地和沙丘）的９个锦鸡儿种群的具分种意义的形态特征的变异。荚果长度在一个植株内是比较稳定的性状；但在各个种群内、种群间变异很大，覆盖了小叶锦鸡儿（Ｃ．ｍｉｃｒｏｐｈｙｌｌａ）、中间锦鸡儿（Ｃ．ｉｎｔｅｒｍｅｄｉａ）和柠条锦鸡儿３个种的范围。同一生境不同种群以及不同生境种群的比较，说明，．决定荚果长度的主要是遗传因素，环境因子如水分条件可能只起次要作用。每个自然种群荚果长度的分布出现几个峰值，说明种群遗传组成的异质性。小叶形状和被毛的资料也说明各个种群内和种群间的异质性。看来，该地区锦鸡儿是上述３种锦鸡儿的杂种带（Ｈｙｂｒｉｄｚｏｎｅ）．形态变异资料也说明毛乌素沙地在遗体多样性方面也是生态过渡带。

MORPHOLOGICAL VARIATIONS OF CARAGANA POPULATIONS IN THE MAOWUSUS SANDY GRASSLAND

ompared with artificial forest of Caragana korshinskii,morphological variation withinand among nine natural populations of Caragana at different ecological niches including hardridge,hard ridge with sand cover,smooth ridge with sand cover,lowland with sand cover andsand dune was investigated.The results showed that pod length was a stable character withina single individual,but varied widely within a population and among populations to such anextent that variation covered a range of three species(C. korshinskii,C. intermedia,and C.mi-crophylla).A comparison between populations in same and different niches indicates that themajor factor which influenced pod length was genetic one rather than environmental.Morethan one peak appreared in a pod length distribution curve implied genetic heterogeneitywithin and among populations. The data on leaflet shape and pubescence supported geneticdiversity existed among individuals. It seems that peashrub plants in Maowusu region is a hy-brid zone among three species of Caragana.Morphological variation of Caragana agreed thatMaowusu Sandy Grassland belongs to an ecotone in a sense of genetic diversity.