Molecular differentiation and diversity of Forcipomyia taiwana (Diptera: Ceratopogonidae) based on the mitochondrial cytochrome oxidase II sequence

Genetic Differentiation of the Bloodsucking Midge Forcipomyia taiwana (Diptera: Ceratopogonidae): Implication of the Geographic Isolation by the Central Mountain Ranges in Taiwan

Forcipomyia (Lasiohelea) taiwana, a small bloodsucking midge, thrives in moderately moist habitats and is commonly found in grassy and bushy areas at an elevation below 250 m. This species exhibits a diurnal biting pattern and shows a marked preference for human blood. Although not known to transmit arthropod-borne diseases, the bites of F. taiwana can induce severe allergic reactions in some individuals. As a significant nuisance in Taiwan, affecting both daily life and the tourism industry, comprehensive studies on its population genetics across different geographical regions remain scarce. The central mountain ranges in Taiwan, comprising more than two hundred peaks above 3000 m in elevation, extend from the north to the south of the island, creating distinct eastern and western geographical divisions. This study utilizes microsatellite markers to explore the genetic differentiation of F. taiwana populations located in the eastern and western regions of the mountain ranges. Our findings reveal substantial genetic differentiation among populations inhabiting Taiwan's western region compared to those in the eastern region. This indicates that the topographical barriers presented by the mountain ranges significantly restrict gene flow, particularly given the species' limited active flight ability and habitat preferences. Although passive dispersal mechanisms, like wind or human activity, could contribute, this study concludes that the gene flow of F. taiwana between the western and eastern regions is primarily influenced by topographical constraints.

Differentiation in stag beetles, Neolucanus swinhoei complex (Coleoptera: Lucanidae): four major lineages caused by periodical Pleistocene glaciations and separation by a mountain range

Taxonomic debates on Neolucanus swinhoei complex consisting of N. swinhoei, N. doro doro, N. doro horaguchii, and N. euganiae, distributed exclusively in Taiwan, have been ongoing for several decades because of their overlapping morphological characters. To clarify their taxonomic status and phylogeographical history, we analyzed nine morphological characteristics and four molecular amplicons. Phylogenetic inferences based on COI+16S rDNA+wingless showed one eastern and three western lineages, with the latter consisting of one low-hill and two montane lineages. Intermingled DNA sequences from different populations within each lineage, many low FST values, and a high variance component between lineages indicate the possibility of gene flow among populations. However, positive relationships were observed between the genetic divergences of 16S rDNA and its FST values with geographic distance. A divergence estimation based on COI+16S revealed that these beetles might have originated from Asian mainland and differentiated into western and eastern lineages ca. 1Mya, with the differentiation of the western lineages occurring approximately 0.50-0.75Mya. Isolation by mountain ranges and limited flying capability of these beetles as well as populations retreat to and expansion from refugia in response to glaciation cycles have resulted in the current distribution of N. swinhoei complex. Although most morphological characters are variable and undistinguishable, multi-dimensional scaling analysis based on measurable characteristics could recognize hill N. swinhoei as a cluster distinct from the others. However, based on the realities of genetic admixture, shared phylogeographical history and overlapping characteristics, all of these stag beetles should be regarded as Neolucanus swinhoei Bates, 1866.