Zakas Christina, Rockman Matthew V
Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY, USA.
Int J Dev Biol. 2014;58(6-8):593-9. doi: 10.1387/ijdb.140088mr.
The marine polychaete Streblospio benedicti exhibits two distinct larval types, making it a model for the study of developmental evolution. Females produce either large eggs or small ones, which develop into distinct lecithotrophic or planktotrophic larvae with concomitant morphological and life-history differences. Here, we investigate the inheritance of key morphological traits that distinguish the larval types. We used genetic crosses to establish the influence of maternal and zygotic differences on larval phenotypes. We found a large maternal effect on larval size and the number of larval chaetae, while the number and length of these chaetae were also strongly influenced by zygotic genotype. Interestingly, the distribution of larval phenotypes produced by these crosses suggests traits intermediate to the two parental types should not be uncommon. Yet, despite gene flow between the types in natural populations, such intermediates are rarely found in nature, suggesting that selection may be maintaining distinct larval modes.
海洋多毛纲动物本氏链虫（Streblospio benedicti）表现出两种不同的幼虫类型，使其成为研究发育进化的一个模型。雌性会产出大卵或小卵，这些卵会发育成不同的卵黄营养型或浮游营养型幼虫，同时伴有形态和生活史方面的差异。在这里，我们研究区分幼虫类型的关键形态特征的遗传情况。我们通过遗传杂交来确定母体和合子差异对幼虫表型的影响。我们发现母体对幼虫大小和幼虫刚毛数量有很大影响，而这些刚毛的数量和长度也受到合子基因型的强烈影响。有趣的是，这些杂交产生的幼虫表型分布表明，介于两种亲本类型之间的性状应该并不罕见。然而，尽管自然种群中不同类型之间存在基因流动，但在自然界中很少发现这种中间类型，这表明选择可能在维持不同的幼虫模式。
