The coexistence of hybrid and parental Daphnia: the role of parasites
The coexistence of hybrid and parental Daphnia: the role of parasites
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DOI：
10.1098/rspb.2006.3523
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
J. Wolinska;Kerstin Bittner;D. Ebert;P. Spaak
中科院分区：
文献类型：
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作者：
J. Wolinska;Kerstin Bittner;D. Ebert;P. Spaak
通过跟踪宿主基因型频率随时间的变化，在自然种群中研究了寄生虫驱动的时滞负频率依赖性宿主选择。然而，这种动态还没有在更高的分类水平上被考虑，例如亲本物种和它们的杂交物种之间。在对一个水蚤杂交系统的实地研究中，我们发现一个水蚤分类群最初感染相对较少，但在感染频率大幅增加后，就变成了过度感染。这一发现与寄生虫向最常见的宿主分类群进化的观点是一致的。在两个实验中，我们研究了负频率依赖选择模型的假设是否适用于我们的宿主分类群系统。首先，我们证明了寄生虫可以改变分类群竞争的结果；其次，我们证实了在野外观察到的一个宿主分类群的过度感染具有遗传基础。我们的研究结果表明，在物种水平上结合寄主-寄生虫相互作用可以让我们更全面地了解驱动水蚤杂交系统中动态分类群共存的力量。更一般地说，我们认为如果杂交种与亲本类群共生，在自然条件下观察到的感染模式可能是相当短暂和不稳定的。
Parasite driven time-lagged negative frequency-dependent selection of hosts has been studied in natural populations by following changes in host genotype frequencies over time. However, such dynamics have not been considered at higher taxonomic levels, for example, between parental species and their hybrids. In a field study on a Daphnia hybrid system, we observed that one Daphnia taxon first was relatively under-infected, but became over-infected after a strong increase in frequency. This finding is consistent with the idea of parasite evolution towards the most frequent host taxon. In two experiments, we investigated whether the assumptions made by a model of negative frequency-dependent selection apply to our host taxa system. First, we showed that the parasite can change the outcome of taxa competition and secondly, we confirmed that the over-infection of one host taxon observed in the field has a genetic basis. Our results indicate that the incorporation of host–parasite interactions at the species level may allow us to gain a more complete picture of forces driving dynamic taxa coexistence in Daphnia hybrid systems. More generally, we suggest that if hybrids coexist in sympatry with parental taxa, the infection patterns as observed under natural conditions may be rather temporal and unstable.