speciation continuum: ecological and chromosomal divergence in the Simulium arcticum complex (Diptera: Simuliidae)

• Published in: Biological journal of the Linnean Society Vol. 115; no. 1; pp. 13 - 27
• Main Authors: Conflitti, Ida M, Shields, Gerald F, Murphy, Robert W, Currie, Douglas C
• Format: Journal Article
• Language: English
• Published: Oxford Published for the Linnean Society of London by Blackwell [etc.] 01.05.2015; Blackwell Publishing Ltd; Oxford University Press
• Subjects: canonical correspondence analysis; chromosome inversions; chromosome rearrangements; chromosomes; correspondence analysis; cryptic species; cytotypes; Diptera; habitats; local adaptation; MAXENT; niche models; North America; northern Rocky Mountains; sibling species; Simuliidae; Simulium arcticum; North America; Rocky Mountain region
• ISSN: 0024-4066; 1095-8312
• DOI: 10.1111/bij.12480

Chromosome inversions may be involved in adaptation and speciation. We investigate ecological diversification among members of the Simulium arcticum species complex at different stages of chromosome divergence. Our analyses focus on two geographical scales. First, we assess ecological divergence of sibling species throughout North America using niche modelling methods. Then, using canonical correspondence analysis, we investigate habitat associations of sibling species and cytotypes in the northern Rocky Mountains ecoregion, where cytotypes tend to occur. Despite significant overlap in predicted distributions, all sibling species are ecologically unique. On the other hand, we discover various degrees of ecological divergence for cytotypes. Some cytotypes are ecologically distinct and perhaps are in their initial stages of incipient speciation. Other cytotypes are ecologically associated with one another or with particular sibling species. Thus, for members of the S. arcticum complex, ecological and chromosomal differences tend to develop early in lineage formation. Ecological distinctiveness of sibling species and cytotypes suggests that local adaptation may be involved in diversification of these chromosomal forms. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 13–27.