Velez Sebastian, Feder Jeffrey L
Department of Biological Sciences, 290c Galvin Life Science Bldg., University of Notre Dame, Notre Dame, Indiana 46556, USA.
Mol Ecol. 2006 Apr;15(5):1393-404. doi: 10.1111/j.1365-294X.2005.02793.x.
Bioluminescent colour in the Jamaican click beetle, Pyrophorus plagiophthalamus, is an ideal system for studies moving from gene to landscape to gain a holistic understanding of the molecular, ecological, and historical bases for adaptation. Previous studies have established the genetics of bioluminescent colour variation in the beetle to the level of the nucleotide base pair in the target gene luciferase. Three different luciferase colour alleles affecting ventral light organ colour [yellow-green (vYG), yellow (vYE), and orange (vOR)] were found segregating in P. plagiophthalamus populations. These alleles differ from each other in a number of replacement mutations (14 total), the majority of which (11) have a measurable effect on colour. Phylogenetic analysis revealed a long-term adaptive trend on Jamaica towards longer wavelength bioluminescence, culminating in the most recently derived vOR allele. Here, we further investigate the historical and geographic context of adaptive colour evolution by testing a vicariance model for the origins of the extant ventral light organ polymorphism: that the vOR allele arose and differentiated in an isolated deme on the east side of Jamaica before spreading westward. Comparisons of colour phenotypes, luciferase coding sequences, the third intron of the gene, mtDNA, and microsatellite data provided evidence for past population subdivision on Jamaica and ongoing gene flow, as has been found for other island endemics. However, the pattern of differentiation supported the allopatric divergence of vYG and vYE alleles. The vOR gene appears to have arisen relatively recently from a vYE precursor and postdates the period of major biogeographic isolation. We discuss the implications of the results for discerning ecological causation in the adaptive sequence from nucleotide to landscape to population change for bioluminescent colour.
牙买加叩甲（Pyrophorus plagiophthalamus）的生物发光颜色是一个理想的研究系统，可用于从基因到景观的研究，以全面了解适应的分子、生态和历史基础。先前的研究已经确定了该甲虫生物发光颜色变异的遗传学，达到了目标基因荧光素酶中核苷酸碱基对的水平。在牙买加叩甲种群中发现了三种不同的荧光素酶颜色等位基因，它们影响腹侧发光器官的颜色[黄绿色（vYG）、黄色（vYE）和橙色（vOR）]。这些等位基因在多个替换突变（共14个）上彼此不同，其中大多数（11个）对颜色有可测量的影响。系统发育分析揭示了牙买加长期以来朝着更长波长生物发光的适应性趋势，最终形成了最近衍生的vOR等位基因。在这里，我们通过测试现存腹侧发光器官多态性起源的隔离分化模型，进一步研究适应性颜色进化的历史和地理背景：即vOR等位基因在牙买加东侧的一个孤立种群中出现并分化，然后向西扩散。颜色表型、荧光素酶编码序列、该基因的第三个内含子、线粒体DNA和微卫星数据的比较，为牙买加过去的种群细分和持续的基因流动提供了证据，这与其他岛屿特有物种的情况相同。然而，分化模式支持vYG和vYE等位基因的异域分歧。vOR基因似乎相对较新地从vYE前体中产生，并且晚于主要生物地理隔离时期。我们讨论了这些结果对于识别从核苷酸到景观再到种群变化的适应性序列中生物发光颜色的生态因果关系的意义。
