Body size evolution under character release in the ground beetle Carabus japonicus
Body size evolution under character release in the ground beetle Carabus japonicus
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DOI：
10.1111/jbi.12575
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发表时间：
2015-11-01
影响因子：
3.9
通讯作者：
Sota, Teiji
中科院分区：
文献类型：
--
作者：
Okuzaki, Yutaka;Sugawara, Hisashi;Sota, Teiji
目的通过分析日本步甲异地种群体型地理变异与栖息地温度的关系以及与更大的同属物种日本步甲的共生/异位关系，验证异地种群体型特征释放假说。方法研究日本步甲种群在不同地点的体长和生殖器大小的地理差异，以考察栖息地温度和与日本步甲共生/异位的影响。为了确定是否满足释放性状的条件，我们估计了普通庭园饲养的个体大小的遗传差异，并通过分子系统发育分析估计了种群之间的系统发育关系。结果虽然个体大小与年平均气温呈正相关，但在温暖地区的一些异地种群中，个体大小始终较小，但在一些异地种群中，个体大小较大。不同种群间的体尺差异是可遗传的。卫星岛异地日本血吸虫种群来源于同域大陆种群。在少数共面区域，线粒体单倍型在物种间共享，这表明物种之间发生了生殖干扰。我们还发现生殖器大小不受共生/异位繁殖的影响，但与体型呈正相关。主要结论我们证明了异地日本血吸虫体型的增加是通过特征释放过程来进化的。然而，并不是所有异位人群的身体都变大了，因此表明一些额外的环境因素也参与其中。身体大小和相关生殖器尺寸的地理差异可能导致种群间的合子前生殖隔离，并促进异地分化导致物种形成。
AimWe tested the hypothesis of character release in body size among allopatric populations of the carabid beetle Carabus japonicus by analysing geographical variation in body size in relation to habitat temperature and sympatry/allopatry with the larger congeneric species Carabus dehaanii.LocationThe main and satellite islands of Kyushu in the south-western part of the Japanese archipelago.MethodsWe studied geographical variation in the body length and genital size of C. japonicus populations at different sites to examine the effects of both habitat temperature and sympatry/allopatry with C. dehaanii. To determine whether the conditions for character release were fulfilled, we then estimated the heritable differences in body size by common garden rearing, and estimated the phylogenetic relationships among populations by molecular phylogenetic analysis.ResultsWhile body size was positively correlated with annual mean temperature, it was consistently small in sympatry but larger in some allopatric populations in warmer regions. The body size differences among populations were heritable. Allopatric C. japonicus populations on satellite islands were derived from the sympatric mainland populations. In a few sympatric areas, mitochondrial haplotypes were shared between the species because of introgressive hybridization, suggesting the occurrence of reproductive interference between the species. We also found that genital size was not affected by sympatry/allopatry, but was positively correlated with body size.Main conclusionsWe demonstrated that the increased body size of allopatric C. japonicus has evolved through a character release process. However, not all allopatric populations had enlarged body size, thus suggesting that some additional environmental factors are also involved. Geographical differentiation in body size and associated genital dimensions may result in prezygotic reproductive isolation among populations and promote allopatric differentiation leading to speciation.