Chromosomal basis of viability differences in Tigriopus californicus interpopulation hybrids
Chromosomal basis of viability differences in Tigriopus californicus interpopulation hybrids
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DOI：
10.1111/j.1420-9101.2006.01145.x
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发表时间：
2006-11-01
影响因子：
2.1
通讯作者：
Edmands, S.
中科院分区：
文献类型：
--
作者：
Harrison, J. S.;Edmands, S.
Tigriopus californicus 种群之间的杂交会导致回交和 F-2 杂种崩溃，以实现各种适应性相关的测量。这种混合崩溃的程度与进化分歧相关。我们使用映射到单个染色体的标记评估了非重组回交杂种中活力差异的染色体基础。为了评估进化分歧的影响，我们将一个种群与三个不同的种群杂交：两个远缘相关（类似于 18% 线粒体 COI 序列分歧）和一个密切相关（类似于 1% 线粒体 COI 序列分歧）。我们发现，所有三个群体间杂交都导致大多数研究基因座与预期孟德尔比率存在显着偏差。在除一例之外的所有情况下，偏差都是由于亲本纯合子的缺陷造成的。这种模式意味着加州 T. californicus 群体携带显着的遗传负荷，并且有益的显性和有害的纯合子-杂合子相互作用的组合显着影响杂交活力。连锁不平衡的配对检验检测到相对较少的显着相互作用。对于两个不同的杂交，单个染色体的影响高度一致。这两个杂交在绝大多数染色体上也显示出雌性比雄性更高的杂合子过量。
Crosses between populations of Tigriopus californicus result in backcross and F-2 hybrid breakdown for a variety of fitness related measures. The magnitude of this hybrid breakdown is correlated with evolutionary divergence. We assessed the chromosomal basis of viability differences in nonrecombinant backcross hybrids using markers mapped to individual chromosomes. To assess effects of evolutionary divergence we crossed one population to three different populations: two distantly related (similar to 18% mitochondrial COI sequence divergence) and one closely related (similar to 1% mitochondrial COI sequence divergence). We found that all three interpopulation crosses resulted in significant deviations from expected Mendelian ratios at a majority of the loci studied. In all but one case, deviations were due to a deficit of parental homozygotes. This pattern implies that populations of T. californicus carry a significant genetic load, and that a combination of beneficial dominance and deleterious homozygote-heterozygote interactions significantly affects hybrid viability. Pairwise tests of linkage disequilibrium detected relatively few significant interactions. For the two divergent crosses, effects of individual chromosomes were highly concordant. These two crosses also showed higher heterozygote excess in females than males across the vast majority of chromosomes.