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Relationships between diploids, tetraploids and their triploid hybrids: Implications for evolution of polyploidy in plants.

机译：二倍体，四倍体及其三倍体杂种之间的关系：对植物中多倍体进化的影响。

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摘要

Using Galax urceolata and Chamerion angustifolium , I studied the evolutionary processes governing the origin and maintenance of autopolyploidy by examining the genetic relationships between diploid and tetraploids and the relative fitness differences and mating relationships among diploids, triploids and tetraploids.; In Galax urceolata, cytotype frequencies differed significantly, with diploids most frequent in the north-east and least frequent in the south-west part of the range. Uniform populations were either diploid (81%) or tetraploid (19%), but never triploid. Overall, populations are predominantly diploid or tetraploid but rarely evenly mixed.; RAPDs were used to investigate the genetic diversity and geographical relationships among four diploid and three tetraploid populations of G. urceolata. Populations in close geographical proximity were genetically less similar than more distant populations. Patterns of genetic variation and geographical distribution support the role of environmental heterogeneity in cytotype structure.; Diploids, tetraploids and hybrid triploids of Chamerion angustifolium were created and evaluated at six life stages to study relative fitness differences. Diploid offspring (from 2x × 2 x crosses) had significantly higher seed production and lower biomass than tetraploid offspring (from 4x × 4x crosses). Relative to diploids, the cumulative fitness of tetraploids was 0.67. Generally, triploids (from 2x × 4x, 4x × 2x crosses) had significantly lower seed production, lower pollen viability, and higher biomass than diploid individuals. Collectively, tetraploids exhibit an inherent fitness disadvantage, although partial triploid viability and fertility may help to reduce the barrier to tetraploid establishment.; To quantify the possible mating relationships between cytotypes and the ploidy of their offspring, I cross-pollinated diploid, triploid and tetraploid individuals. Seed set differed significantly among cross types, with 2 x × 2x crosses having the greatest seed set (0.71 ± 0.04). Several crosses that involved triploid parents resulted in little or no seed set. The mean seed set in diploid-tetraploid crosses was 2.06 (SE ± 0.16) with no differences between reciprocal crosses. Mean DNA content of the progeny differed significantly among cross types. The results indicated that tetraploids were produced through several pathways of mating including triploids; however, the recurrent production of tetraploids was insufficient to overcome the frequency-dependent mating disadvantage in diploid populations.
机译：我使用 Galax urceolata 和 Chamerion angustifolium ，研究了二倍体和四倍体之间的遗传关系以及相对适应性差异和交配关系，从而研究了控制多倍体起源和维持的进化过程。二倍体，三倍体和四倍体。在 Galax urceolata 中，细胞型频率差异显着，二倍体在该区域的东北部最频繁，而在西南部则最不频繁。一致的种群是二倍体（81％）或四倍体（19％），但从来没有三倍体。总的来说，种群主要是二倍体或四倍体，但很少均匀混合。用RAPDs研究了 G。urceolata 的四个二倍体和三个四倍体种群之间的遗传多样性和地理关系。从地理上讲，相距较近的种群比远处的种群遗传相似性低。遗传变异和地理分布的模式支持环境异质性在细胞型结构中的作用。创建了 Chantion angustifolium 的二倍体，四倍体和杂种三倍体，并在六个生命阶段进行了评估，以研究相对适应性差异。二倍体后代（来自2 x ×2 x 杂交）的种子产量显着高于四倍体后代（来自4 x ×4 < italic> x 叉）。相对于二倍体，四倍体的累积适应度为0.67。通常，三倍体种子（来自2 x ×4 x ，4 x ×2 x 杂交）的种子数明显较低。与二倍体个体相比，产量更高，花粉生存力更低，生物量更高。总的来说，四倍体显示出固有的适应性劣势，尽管三倍体的部分生存能力和繁殖力可能有助于减少四倍体建立的障碍。为了量化细胞类型与其后代的倍性之间可能的交配关系，我交叉授粉了二倍体，三倍体和四倍体个体。杂交类型之间的结实差异显着，其中2 x ×2 x 杂交的结实最大（0.71±0.04）。涉及三倍体亲本的几个杂交导致很少或没有结实。二倍体-四倍体杂交的平均种子集为2.06（SE±0.16），相互杂交之间没有差异。后代的平均DNA含量在杂交类型之间显着不同。结果表明四倍体是通过几种交配途径产生的，包括三倍体。然而，四倍体的再生产不足以克服二倍体种群中频率依赖的交配缺陷。

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  • 作者

    Burton, Tracy Lynn.;

  • 作者单位

    University of Guelph (Canada).;

  • 授予单位 University of Guelph (Canada).;
  • 学科 Biology Botany.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 p.6226
  • 总页数 226
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 植物学;
  • 关键词

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