RADseq and mate choice assays reveal unidirectional gene flow among three lamprey ecotypes despite weak assortative mating: Insights into the formation and stability of multiple ecotypes in sympatry

Hume, J. B., Recknagel, H. , Bean, C. W., , Adams, C. E. and Mable, B. K. (2018) RADseq and mate choice assays reveal unidirectional gene flow among three lamprey ecotypes despite weak assortative mating: Insights into the formation and stability of multiple ecotypes in sympatry. Molecular Ecology, 27(22), pp. 4572-4590. (doi:10.1111/mec.14881) (PMID:30252984)

Hume, J. B., Recknagel, H. , Bean, C. W., , Adams, C. E. and Mable, B. K. (2018) RADseq and mate choice assays reveal unidirectional gene flow among three lamprey ecotypes despite weak assortative mating: Insights into the formation and stability of multiple ecotypes in sympatry. Molecular Ecology, 27(22), pp. 4572-4590. (doi:10.1111/mec.14881) (PMID:30252984)

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Abstract

Adaptive divergence with gene flow often results in complex patterns of variation within taxa exhibiting substantial ecological differences among populations. One example where this may have occurred is the parallel evolution of freshwater‐resident nonparasitic lampreys from anadromous‐parasitic ancestors. Previous studies have focused on transitions between these two phenotypic extremes, but here, we considered more complex evolutionary scenarios where an intermediate freshwater form that remains parasitic is found sympatrically with the other two ecotypes. Using population genomic analysis (restriction‐associated DNA sequencing), we found that a freshwater‐parasitic ecotype was highly distinct from an anadromous‐parasitic form (Qlake‐P = 96.8%, Fst = 0.154), but that a freshwater‐nonparasitic form was almost completely admixed in Loch Lomond, Scotland. Demographic reconstructions indicated that both freshwater populations likely derived from a common freshwater ancestor. However, while the nonparasitic ecotype has experienced high levels of introgression from the anadromous‐parasitic ecotype (Qanad‐P = 37.7%), there is no evidence of introgression into the freshwater‐parasitic ecotype. Paradoxically, mate choice experiments predicted high potential for gene flow: Males from all ecotypes were stimulated to spawn with freshwater‐parasitic females, which released gametes in response to all ecotypes. Differentially fixed single nucleotide polymorphisms identified genes associated with growth and development, which could possibly influence the timing of metamorphosis, resulting in significant ecological differences between forms. This suggests that multiple lamprey ecotypes can persist in sympatry following shifts in adaptive peaks, due to environmental change during their repeated colonization of post‐glacial regions, followed by periods of extensive gene flow among such diverging populations.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Recknagel, Mr Hans and Mable, Professor Barbara and Adams, Professor Colin and Bean, Professor Colin
Authors: Hume, J. B., Recknagel, H., Bean, C. W.,, Adams, C. E., and Mable, B. K.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Molecular Ecology
Publisher:Wiley
ISSN:0962-1083
ISSN (Online):1365-294X
Published Online:25 September 2018
Copyright Holders:Copyright © 2018 John Wiley and Sons Ltd
First Published:First published in Molecular Ecology 27(22): 4572-4590
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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