Yang Fan, Kawabata Eriko, Tufail Muhammad, Brown John J, Takeda Makio
Graduate School of Agricultural Science Kobe University Nada-ku Kobe Japan.
Institute of Tropical Agriculture and Forestry Hainan University Haikou Hainan China.
Ecol Evol. 2017 Nov 4;7(24):10592-10603. doi: 10.1002/ece3.3334. eCollection 2017 Dec.
North America has distinct types of moths (Arctiidae) characterized by red (RD)- and black (BL)-headed larvae, of which the taxonomic status is unresolved. Genetic divergence of 26 populations, based on 710 bp of the mtCOI sequence, showed two phylogenetic lineages, which could not be connected in the haplotype network with 95% confidence. The two lineages are separated by 3.1% sequence divergence and should be considered for full species status. The estimated split occurred 1.2-1.6 million years ago. The range of the RD type covered most of the continent, whereas that of the BL type was limited to eastern deciduous forests. Several biological characteristics were differentiated in the zone of cohabitation where BL had more annual generations than RD. Spring emergence of BL precedes that of RD in the field by at least 1 month, because the diapause in BL was shallow, whereas it was deep in RD. Voltinism requires discreteness of numbers, which functions as a sink of hybrids between the two parental lines that have distinct but equally adaptive reproductive strategies; BL may be more r-strategist-like and RD more K-strategist-like, because fast-developing BL has multivoltine life cycle, investing less silk proteins as the round-the-clock feeder, and slow-developing RD univoltine one investing more silk as the nocturnal feeder. Also, intensity of diapause, deep in RD and weak in BL, was grossly different, which may enforce segregation of spring adults. Allochronic speciation avoiding coincidental occurrence of adult stages is therefore the most likely scenario. Because the adults never meet in nature, large morphological differentiation is not required.
北美洲有独特类型的蛾（灯蛾科），其特征是幼虫头部为红色（RD）和黑色（BL），但其分类地位尚未确定。基于线粒体细胞色素氧化酶亚基I（mtCOI）序列710 bp对26个种群进行的遗传分化显示出两个系统发育谱系，在单倍型网络中无法以95%的置信度连接。这两个谱系的序列差异为3.1%，应考虑给予其完整物种地位。估计分化发生在120万至160万年前。RD型的分布范围覆盖了该大陆的大部分地区，而BL型的分布范围仅限于东部落叶林。在共存区域，几种生物学特征存在差异，其中BL的年世代数比RD多。在野外，BL的春季羽化比RD至少早1个月，因为BL的滞育较浅，而RD的滞育较深。化性需要数量的离散性，这起到了两个亲本系之间杂种库的作用，这两个亲本系具有不同但同样适应性的繁殖策略；BL可能更像r策略者，而RD更像K策略者，因为发育快的BL具有多化性生命周期，作为全天候取食者投入较少的丝蛋白，而发育慢的RD单化性则作为夜间取食者投入更多的丝。此外，滞育强度在RD中深而在BL中弱，差异很大，这可能促使春季成虫的隔离。因此，避免成虫阶段同时出现的异时物种形成是最有可能的情况。由于成虫在自然界中从不相遇，因此不需要大的形态分化。
