Investigating the role of a kinesin gene in butterfly mimicry

蝴蝶物种之间的模仿是进化和适应的经典例子。色彩鲜艳的新热带赫利柯乌斯蝴蝶是最好的研究例子之一，但模仿的分子遗传学基础仍然知之甚少。特别是，模仿为研究进化的重复性提供了机会，因为相同的模式在不同的谱系中一次又一次地出现。该项目分为两个大的领域，首先，我们使用尖端测序技术来绘制H.Melpomene基因组的遗传图谱。这将被用来帮助组装目前正在生成的基因组序列。这将形成一项全基因组范围的关于黑斑潜蝇小种间适应性差异的调查的基础。该物种不同的地理种群形成了狭窄的杂交区，在那里它们进行杂交和交换基因。因此，控制翅膀模式的基因组的狭窄区域在广泛重组的背景下进行了遗传分化。这为确定导致机翼图案分化的变化提供了一个强大的机会。我们将首先通过低覆盖率的基因组重测序来表征种族内部和种族之间的变异。然后，我们将使用新的‘序列捕获’技术来丰富感兴趣区域的基因组DNA，这些感兴趣的区域来自96个个体，这些个体取自黑麦草的6个表型小种。这项实验旨在对包含翅膀图案基因的两个染色体区域和位于整个基因组的另外12,000个可变点进行采样。这将为抽样的六个种群之间的平行差异提供独特的全基因组分析。特别是，我们的目标是确定a)有多少基因组涉及颜色模式分歧，b)相同的区域是否涉及独立的杂交区，c)估计与翅膀模式分歧有关的等位基因的年龄，d)确定假定的功能位点，以便进一步分析。该项目的第二个主要目标是研究驱动蛋白基因，该基因代表了控制黑斑潜蝇红色前翼带的一个强有力的候选基因。我们将研究不同表型之间Kinesin基因表达模式的空间分布，以检验空间调控是否是模式调控的基础。许多基因通过选择性剪接产生了不同的变异，产生了含有不同形式外显子的蛋白质的变异形式。选择性剪接是一种潜在的强大但未被探索的机制，可能会产生进化相关的变异。我们有证据证明动蛋白基因的选择性剪接，这里将描述该基因的异构体，并测试异构体表达与翅膀表型之间的相关性。我们将研究该基因的分子功能，包括寻找与动蛋白相互作用的其他分子，并进行测试以确认其运动功能。最后，我们将开发转基因方法来明确测试在黑斑潜蝇不同小种的翼型规格中动蛋白基因的功能。红带的主效基因显性控制意味着我们期望能够通过在黄带表型中表达‘红色’Kinesin等位基因来产生红带表型。这将为导致蝴蝶图案变化的基因提供第一次明确的功能测试。

Mimicry among butterfly species is a classic example of evolution and adaptation. The brightly coloured neotropical Heliconius butterflies are one of the best studied examples, but the molecular genetic basis of mimicry remains poorly understood. In particular mimicry offers an opportunity to study the repeatability of evolution, as the same patterns emerge again and again in divergent lineages. The project falls into two broad areas, first we use cutting edge sequencing technology to make a genetic map of the H. melpomene genome. This will be used to help assemble the genome sequence currently being generated. This will form the basis for a genome-wide survey of adaptive divergence between H. melpomene races. Divergent geographic populations of this species form narrow hybrid zones where they hybridise and exchange genes. Thus, narrow regions of the genome controlling wing patterns are genetically differentiated against a background of extensive recombination. This offers a powerful opportunity to identify changes responsible for wing pattern differentiation. We will first characterise variation within and between races by genome resequencing at low coverage. Then we will use novel 'sequence capture' technology to enrich genomic DNA for regions of interest from 96 individuals, taken from six phenotypic races of H. melpomene. The experiment will be designed to sample two chromosomal regions containing wing patterning genes, and a further 12,000 variable sites located across the genome. This will offer a unique genome-wide analysis of parallel divergence between the six populations sampled. In particular we aim to determine a) how much of the genome is involved in colour pattern divergence b) whether the same regions are implicated across independent hybrid zones c) estimate the age of the alleles involved in wing pattern divergence and d) identify putative functional sites for further analysis. The second major aim of the project is to investigate the kinesin gene that represents a strong candidate locus for controlling the red forewing band of H. melpomene. We will study the spatial distribution of kinesin gene expression patterns between divergent phenotypes, in order to test whether spatial regulation underlies pattern regulation. Many genes show different variants generated by alternative splicing, generating variant forms of the protein containing alternative forms of the exons. Alternative splicing is a potentially powerful but under-explored mechanism that could generate evolutionarily relevant variation. We have evidence for alternative splicing the Kinesin gene, and here will characterise the isoforms of this gene and test for correlations between isoform expression and wing phenotype. We will investigate the molecular function of the gene, including a search for other molecules that interact with the kinesin protein, and test to confirm its motor function. Finally, we will develop trangenics methods for explicitly testing the function of the kinesin gene in wing pattern specification in divergent races of H. melpomene. The major gene dominant control of the red band means that we expect to be able to generate a red-banded phenotype by expressing the 'red' kinesin allele in a yellow banded phenotype. This will provide the first explicit test of function for a gene causing pattern variation in any butterfly.