Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina, United States of America.
C.P. Gillette Museum of Arthropod Diversity, Colorado State University, Fort Collins, Colorado, United States of America.
PLoS One. 2024 Oct 24;19(10):e0311808. doi: 10.1371/journal.pone.0311808. eCollection 2024.
Invasive species are a threat to ecosystems worldwide, but determining if a species is adventive or native is not always straightforward. The black flies that inhabit the Galapagos Islands, long known as Simulium ochraceum, are blood-feeding pests of humans and livestock. They first came to the attention of residents in 1989, suggesting a recent arrival. Earlier colonization, however, has been suggested, based largely on polymorphic genetic loci. To address questions of origin, provenance, and length of residency, we conducted a macrogenomic analysis of the polytene chromosomes of the S. ochraceum complex from seven sites in the Galapagos Islands and 30 sites in mainland Ecuador, Central America, and the Caribbean. Among 500 analyzed larvae, we discovered 88 chromosomal rearrangements representing 13 cytoforms, at least seven of which are probably full species. All evidence points to a single, cohesive cytoform with full species status in the Galapagos, conspecific with mainland populations, and widely distributed in the Neotropical Region. It has an identical, nearly monomorphic banding sequence with 10 novel fixed inversions and a subtle but unique Y-linked chromosomal rearrangement across all populations sampled in the Galapagos, the mainland, and the Caribbean. We recalled the name Simulium antillarum from synonymy with S. ochraceum and applied it to the Galapagos black flies, and we established that wolcotti is a junior synonym of antillarum. The time(s) and mode(s) of arrival of S. antillarum in the Galapagos remain uncertain, although the wide geographic distribution, including islands in the Caribbean, suggests that the species is an adept colonizer. Regardless of how long it has been in the archipelago, S. antillarum might have assumed a functional role in the streams of San Cristobal, but otherwise has had a detrimental effect on humans and livestock and potentially on the unique birds and mammals of the Galapagos Islands.
入侵物种是全球生态系统的威胁，但确定一个物种是外来的还是本地的并不总是那么简单。长期以来，栖息在加拉帕戈斯群岛的黑蝇被称为 Simulium ochraceum，是人类和牲畜的吸血害虫。它们于 1989 年首次引起居民的注意，表明它们是最近才到达的。然而，根据多态遗传基因座，人们认为它们更早就在此定居了。为了解决起源、起源地和居住时间的问题，我们对来自加拉帕戈斯群岛 7 个地点和厄瓜多尔大陆、中美洲和加勒比地区 30 个地点的 S. ochraceum 复合体的多线染色体进行了宏基因组分析。在分析的 500 只幼虫中，我们发现了 88 个染色体重排，代表 13 个细胞型，其中至少 7 个可能是完整的物种。所有证据都指向加拉帕戈斯群岛的一个单一、凝聚的细胞型，与大陆种群同属一种，在新热带地区广泛分布。它在加拉帕戈斯群岛、大陆和加勒比地区所有采样种群中都具有相同的、几乎是单态的带型序列，具有 10 个新的固定倒位和一个微妙但独特的 Y 连锁染色体重排。我们从 Simulium ochraceum 的同义词中召回了 Simulium antillarum 的名称，并将其应用于加拉帕戈斯群岛的黑蝇，我们还确定了 wolcotti 是 antillarum 的次同义词。S. antillarum 到达加拉帕戈斯群岛的时间（多个）和模式仍然不确定，尽管其广泛的地理分布，包括加勒比地区的岛屿，表明该物种是一个擅长殖民的物种。无论它在群岛上存在了多长时间，S. antillarum 可能已经在圣克里斯托瓦尔的溪流中发挥了功能作用，但它对人类和牲畜以及加拉帕戈斯群岛的独特鸟类和哺乳动物可能产生了有害影响。
