Data from: No evidence for maintenance of a sympatric Heliconius species barrier by chromosomal inversions

Mechanisms that suppress recombination are known to help maintain species barriers by preventing the breakup of coadapted gene combinations. The sympatric butterfly species Heliconius melpomene and Heliconius cydno are separated by many strong barriers, but the species still hybridize infrequently in the wild, and around 40% of the genome is influenced by introgression. We tested the hypothesis that genetic barriers between the species are maintained by inversions or other mechanisms that reduce between-species recombination rate. We constructed fine-scale recombination maps for Panamanian populations of both species and their hybrids to directly measure recombination rate within and between species, and generated long sequence reads to detect inversions. We find no evidence for a systematic reduction in recombination rates in F1 hybrids, and also no evidence for inversions longer than 50 kb that might be involved in generating or maintaining species barriers. This suggests that mechanisms leading to global or local reduction in recombination do not play a significant role in the maintenance of species barriers between H. melpomene and H. cydno.

已知抑制遗传重组的机制可通过阻止共适应基因组合的解体，助力维持物种生殖屏障。同域分布的蝴蝶物种红带袖蝶（Heliconius melpomene）与赛德诺袖蝶（Heliconius cydno）之间存在多重强生殖隔离屏障，但二者仍会在野外发生零星杂交，且约40%的基因组受到基因渐渗的影响。我们验证了如下假说：物种间的遗传屏障由染色体倒位或其他可降低种间重组率的机制所维持。我们为两个物种及其杂交后代的巴拿马种群构建了精细尺度重组图谱，以直接测定种内与种间的重组率，并通过长序列读段检测染色体倒位。研究发现，F1杂交子代的重组率并无系统性降低，也未发现长度超过50kb的、可能参与形成或维持物种屏障的染色体倒位。这表明，导致全局或局部重组率降低的机制，在红带袖蝶与赛德诺袖蝶的物种屏障维持中并未发挥显著作用。