CHARA-VULGARIS AND C-CONTRARIA - PATTERNS OF REPRODUCTIVE ISOLATION FOR 2 COSMOPOLITAN SPECIES COMPLEXES
CHARA-VULGARIS AND C-CONTRARIA - PATTERNS OF REPRODUCTIVE ISOLATION FOR 2 COSMOPOLITAN SPECIES COMPLEXES
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DOI：
10.1111/j.1558-5646.1972.tb00193.x
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发表时间：
1972-01-01
期刊：
影响因子：
3.3
通讯作者：
PROCTOR, VW
中科院分区：
文献类型：
--
作者：
GRANT, MC;PROCTOR, VW
本研究主要从普通轮藻和轮藻无性系杂交的Vantage出发，探讨了普通轮藻和轮藻无性系杂交的可能性。相反，（1）形态学方法的轮藻系统学的有用性，（2）适用性，轮藻，埃利希-乌鸦建议，小，当地人口可能往往是进化的单位和（3）繁殖模式，当地和世界范围内，现存的两个形态相似的物种复合体内和之间。结果表明，传统的形态学方法，充其量，在定义生殖单位的用处有限。在一致的情况下，可以检测到两个群体之间的遗传差异（例如小枝皮层化的程度，苞片细胞的长度，染色体数目）生殖隔离总是存在的。与此相反，许多情况下，完全不相容的检测没有伴随表型不连续性。在每个形态复合体中发现的生殖隔离的频繁和不可预测的发生，强烈支持轮藻的进化单位是小的本地种群的论点;尽管起源于15，000 km以上的植物之间的一些杂交产生了部分可育的后代。基因流动的隐含限制，再加上两个物种复合体的单倍性，雌雄同株，自交不亲和的性质，提供了一种情况下，遗传漂变可能变得重要，并在同一时间，升级的意义，产生遗传多样性的内在模式（如多倍体）。由于在小群体中存在这种差异，今天在“C. vulgaris和C. contraria complex”是指在生殖上分离的亚基数量远大于表型上不同的亚基数量之间的显著差异。试图在一个单一的分类学处理中同时反映两种分歧的表达，过去是，将来可能仍然是极其困难的。
This study considered, primarily from the vantage point of attempted crosses between clonal cultures of Chara vulgaris and C. contraria, (1) the usefulness of morphological approaches to charophyte systematics, (2) the applicability, to the charophytes, of the Ehrlich-Raven suggestion that the small, local population may often be the unit of evolution and (3) the breeding patterns, local and world-wide, extant within and between two morphologically similar species complexes. Results indicate that traditional morphological approaches are, at best, of limited usefulness in defining reproductive units. Where consistent, heritable differences between two populations could be detected (e.g. extent of branchlet cortication, length of bract cells, chromosome number) reproductive isolation invariably existed. In contrast, numerous instances of complete incompatibility were detected without concomitant phenetic discontinuities. The frequent and unpredictable occurrence of reproductive isolation, found within each morphological complex, strongly supports the contention that the unit of evolution in the charophytes is the small local population; notwithstanding some crosses between plants originating over 15,000 km apart which gave rise to partially fertile progeny. The implied restriction of gene flow, coupled to the haplobiontic, monoecious, self-compatible nature of the two species complexes provides a situation in which genetic drift could become important and, at the same time, upgrades the significance of intrinsic modes of generating genetic diversity (e.g. polyploidy). As a consequence of such divergence in small populations, there exists today within the "C. vulgaris and C. contraria complexes" a marked disparity between the much larger number of reproductively isolated, than phenotypically distinct, subunits. Attempts to reflect both expressions of divergence simultaneously within a single taxonomic treatment have been and probably will continue to be exceedingly difficult.