Ecological speciation by temporal isolation in a population of the stonefly Leuctra hippopus (Plecoptera, Leuctridae). Issue 5 (10th February 2017)

• Record Type: Journal Article
• Authors: Boumans, Louis; Hogner, Silje; Brittain, John; Johnsen, Arild
• Is Part Of: Ecology and evolution. Volume 7:Issue 5(2017:Mar.)
• Page Start: 1635
• Page End: 1649
• Publication Date: 2017-02-10
• Subjects: AFLP -- cytochrome c oxidase subunit I -- freshwater insects -- genetic differentiation -- incipient speciation -- RAD‐based SNPs; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.2638
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Stream dwelling invertebrates are ideal candidates for the study of ecological speciation as they are often adapted to particular environmental conditions within a stream and inhabit only certain reaches of a drainage basin, separated by unsuitable habitat. We studied an atypical population of the stonefly Leuctra hippopus at a site in central Norway, the Isterfoss rapids, in relation to three nearby and two remote conspecific populations. Adults of this population emerge about a month earlier than those of nearby populations, live on large boulders emerging from the rapids, and are short‐lived. This population also has distinct morphological features and was studied earlier during the period 1975–1990. We reassessed morphological distinctness with new measurements and added several analyses of genetic distinctness based on mitochondrial and nuclear sequence markers, as well as AFLP fingerprinting and SNPs mined from RAD sequences. The Isterfoss population is shown to be most closely related to its geographical neighbors, yet clearly morphologically and genetically distinct and homogeneous. We conclude that this population is in the process of sympatric speciation, with temporal isolation being the most important direct barrier to gene flow. The shift in reproductive season results from the particular temperature and water level regime in the Isterfoss rapids. The distinct adult body shape and loss of flight are hypothesized to be an adaptation to the unusual habitat. Ecological diversification on small spatial and temporal scales is one of the likely causes of the high diversity of aquatic insects. Abstract : Speciation by temporal isolation is theoretically expected to play a role in aquatic insects with a short, synchronized adult life stage, but has been very little documented so far. Our study uses convergent results of AFLP and RAD‐based SNP analyses to show that a stonefly population that emerges 1 month earlier than nearby conspecific populations is indeed genetically homogeneous and divergent. The temporal isolation is linked to the flooding of this population's habitat in spring, which necessitates an early completion of the adult stage.