Heterosis and outbreeding depression in interpopulation crosses spanning a wide range of divergence
Heterosis and outbreeding depression in interpopulation crosses spanning a wide range of divergence
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DOI：
10.1111/j.1558-5646.1999.tb04560.x
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发表时间：
1999-12-01
期刊：
影响因子：
3.3
通讯作者：
Edmands, S
中科院分区：
文献类型：
--
作者：
Edmands, S
以潮间桡足类加州虎足虫为模式生物，研究了交叉距离对适合度的影响，并探讨了相关的遗传机制。跨越地理距离（5米至2007公里）和遗传距离（0.2%至22.3%的序列差异为606 bp的线粒体COI基因片段）的广泛范围的12对人群之间进行了杂交。对于每对群体，三个健身组件（孵化数，存活数，变态数）进行了测量，在多达16个队列，包括父母，相互F-1，F-2，F-3，和第一代回交杂交。每组队列的比较允许内和位点间基因相互作用的估计。相对于亲本，F-1杂种表现出适应性增加的趋势，与群体分化无关，方差减少，在某些情况下与群体分化相关。与此形成鲜明对比的是，F-2杂种的适合度下降，方差增加，这两者都对应于人口的分歧。这些模式的遗传学解释表明，优势的有益影响和破坏共同适应的有害影响都被种群间进化距离的增加所放大。由于T. californicus雌性，重组的影响可以通过比较F-1杂种雄性和与亲本回交的雌性来评估。重组和非重组回交杂种表现出下降的健身与人口的分歧，表明染色体之间的分离有助于打破共适应。虽然有两个回交类型之间的平均健身没有差异，重组回交表现出更大的方差比nonrecombinational回交健身，这表明染色体内的父母的基因组合的分裂既有利又有害的影响。
The intertidal copepod Tigriopus californicus was used as a model organism to look at effects of crossing distance on fitness and to investigate the genetic mechanisms responsible. Crosses were conducted between 12 pairs of populations spanning a broad range of both geographic distance (5 m to 2007 km) and genetic distance (0.2% to 22.3% sequence divergence for a 606-bp segment of the mitochondrial COI gene). For each pair of populations, three fitness components (hatching number, survivorship number, and metamorphosis number) were measured in up to 16 cohorts including parentals, reciprocal F-1, F-2, F-3, and first-generation backcross hybrids. Comparisons of each set of cohorts allowed estimation of within- and between-locus gene interaction. Relative to parentals, F-1 hybrids showed a trend toward increased fitness, with no correspondence with population divergence, and a decrease in variance, which in some cases correlated with population divergence. In sharp contrast, F-2 hybrids had a decrease in fitness and an increase in variance that both corresponded to population divergence. Genetic interpretation of these patterns suggests that both the beneficial effects of dominance and the detrimental effects of breaking up coadaptation are magnified by increasing evolutionary distance between populations. Because there is no recombination in T. californicus females, effects of recombination can be assessed by comparing F-1 hybrid males and females backcrossed to parentals. Both recombinant and nonrecombinant backcross hybrids showed a decline in fitness correlated with population divergence, indicating that segregation among chromosomes contributes to the breakup of coadaptation. Although there was no difference in mean fitness between the two backcross types, recombinational backcrosses showed greater variance for fitness than nonrecombinational backcrosses, suggesting that the breakup of parental gene ombinations within chromosomes has both beneficial and detrimental effects.