Data from: Genetic evidence for landscape effects on dispersal in the army ant Eciton burchellii

Inhibited dispersal, leading to reduced gene flow, threatens populations with inbreeding depression and local extinction. Fragmentation may be especially detrimental to social insects because inhibited gene flow has important consequences for cooperation and competition within and among colonies. Army ants have winged males and permanently wingless queens; these traits imply male-biased dispersal. However, army ant colonies are obligately nomadic and have the potential to traverse landscapes. Eciton burchellii, the most regularly nomadic army ant, is a forest interior species: colony raiding activities are limited in the absence of forest cover. To examine whether nomadism and landscape (forest clearing and elevation) affect population genetic structure in a montane E. burchellii population we reconstructed queen and male genotypes from 25 colonies at seven polymorphic microsatellite loci. Pairwise genetic distances among individuals were compared to pairwise geographic and resistance distances using regressions with permutations, partial Mantel tests, and random forests analyses. Though there was no significant spatial genetic structure in queens or males in montane forest, dispersal may be male-biased. We found significant isolation by landscape resistance for queens based on land cover (forest clearing), but not on elevation. Summed colony emigrations over the lifetime of the queen may contribute to gene flow in this species and forest clearing impedes these movements and subsequent gene dispersal. Further forest cover removal may increasingly inhibit Eciton burchellii colony dispersal. We recommend maintaining habitat connectivity in tropical forests to promote population persistence for this keystone species.

扩散受阻导致基因交流减少，会使种群面临近交衰退与局部灭绝的威胁。生境破碎化对社会性昆虫的危害可能尤为显著，因为基因交流受阻会对种群内部及种群间的合作与竞争产生重要影响。行军蚁具有有翅雄蚁与永久性无翅蚁后的特征，这一特性暗示其扩散存在雄性偏倚性。但行军蚁蚁群专性游牧，具备穿越复杂生境的潜力。布氏游蚁（Eciton burchellii）是游牧习性最为规律的行军蚁物种，属于林内栖息类群：在缺乏森林植被覆盖的情况下，蚁群的觅食活动会受到限制。为探究游牧习性与景观因子（森林砍伐与海拔）是否会影响山地布氏游蚁种群的遗传结构，本研究从25个蚁群中提取蚁后与雄蚁的基因组信息，通过7个多态性微卫星位点完成基因分型。本研究采用置换回归、偏曼特尔检验（partial Mantel test）与随机森林分析，将个体间的两两遗传距离与两两地理距离、阻力距离进行对比分析。尽管山地森林中的蚁后与雄蚁均未呈现显著的空间遗传结构，但其扩散模式仍可能存在雄性偏倚。研究发现，基于土地覆盖（森林砍伐）的景观阻力对蚁后存在显著的隔离效应，但基于海拔的隔离效应并不显著。蚁后一生内蚁群的总迁徙次数或可促进该物种的基因交流，而森林砍伐会阻碍这些迁徙行为与后续的基因扩散。进一步移除森林植被可能会愈发严重地抑制布氏游蚁的蚁群扩散。本研究建议在热带森林中维持生境连通性，以助力这一关键物种种群的存续。