2018
Hume, J.B., Recknagel, H., Bean, C.W., Adams, C.E. & Mable, B.K.
In: Molecular Ecology, vol. 27, iss. 22, pp. 4572–4590, 2018.
Abstract | Links | BibTeX | Tags: conservation, genetics, management, speciation
@article{nokey,
title = {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},
author = {Hume, J.B., Recknagel, H., Bean, C.W., Adams, C.E. & Mable, B.K. },
url = {https://doi.org/10.1111/mec.14881},
year = {2018},
date = {2018-09-25},
urldate = {2018-09-25},
journal = {Molecular Ecology},
volume = {27},
issue = {22},
pages = {4572–4590},
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.},
keywords = {conservation, genetics, management, speciation},
pubstate = {published},
tppubtype = {article}
}
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.
2015
Bracken, F.S.A., Hoelzel, A.R., Hume, J.B. & Lucas, M.C.
In: Molecular Ecology, vol. 24, iss. 6, pp. 1188–1204, 2015.
Abstract | Links | BibTeX | Tags: barrier, evolution, genetics, speciation
@article{nokey,
title = {Contrasting population genetic structure among freshwater-resident and anadromous lampreys: the role of demographic history, differential dispersal, and anthropogenic barriers to movement},
author = {Bracken, F.S.A., Hoelzel, A.R., Hume, J.B. & Lucas, M.C.},
url = {https://doi.org/10.1111/mec.13112},
year = {2015},
date = {2015-02-16},
urldate = {2015-02-16},
journal = {Molecular Ecology},
volume = {24},
issue = {6},
pages = {1188–1204},
abstract = {The tendency of many species to abandon migration remains a poorly understood aspect of evolutionary biology that may play an important role in promoting species radiation by both allopatric and sympatric mechanisms. Anadromy inherently offers an opportunity for the colonization of freshwater environments, and the shift from an anadromous to a wholly freshwater life history has occurred in many families of fishes. Freshwater-resident forms have arisen repeatedly among lampreys (within the Petromyzontidae and Mordaciidae), and there has been much debate as to whether anadromous lampreys, and their derived freshwater-resident analogues, constitute distinct species or are divergent ecotypes of polymorphic species. Samples of 543 European river lamprey Lampetra fluviatilis (mostly from anadromous populations) and freshwater European brook lamprey Lampetra planeri from across 18 sites, primarily in the British Isles, were investigated for 13 polymorphic microsatellite DNA loci, and 108 samples from six of these sites were sequenced for 829 bp of mitochondrial DNA (mtDNA). We found contrasting patterns of population structure for mtDNA and microsatellite DNA markers, such that low diversity and little structure were seen for all populations for mtDNA (consistent with a recent founder expansion event), while fine-scale structuring was evident for nuclear markers. Strong differentiation for microsatellite DNA loci was seen among freshwater-resident L. planeri populations and between L. fluviatilis and L. planeri in most cases, but little structure was evident among anadromous L. fluviatilis populations. We conclude that postglacial colonization founded multiple freshwater-resident populations with strong habitat fidelity and limited dispersal tendencies that became highly differentiated, a pattern that was likely intensified by anthropogenic barriers.},
keywords = {barrier, evolution, genetics, speciation},
pubstate = {published},
tppubtype = {article}
}
The tendency of many species to abandon migration remains a poorly understood aspect of evolutionary biology that may play an important role in promoting species radiation by both allopatric and sympatric mechanisms. Anadromy inherently offers an opportunity for the colonization of freshwater environments, and the shift from an anadromous to a wholly freshwater life history has occurred in many families of fishes. Freshwater-resident forms have arisen repeatedly among lampreys (within the Petromyzontidae and Mordaciidae), and there has been much debate as to whether anadromous lampreys, and their derived freshwater-resident analogues, constitute distinct species or are divergent ecotypes of polymorphic species. Samples of 543 European river lamprey Lampetra fluviatilis (mostly from anadromous populations) and freshwater European brook lamprey Lampetra planeri from across 18 sites, primarily in the British Isles, were investigated for 13 polymorphic microsatellite DNA loci, and 108 samples from six of these sites were sequenced for 829 bp of mitochondrial DNA (mtDNA). We found contrasting patterns of population structure for mtDNA and microsatellite DNA markers, such that low diversity and little structure were seen for all populations for mtDNA (consistent with a recent founder expansion event), while fine-scale structuring was evident for nuclear markers. Strong differentiation for microsatellite DNA loci was seen among freshwater-resident L. planeri populations and between L. fluviatilis and L. planeri in most cases, but little structure was evident among anadromous L. fluviatilis populations. We conclude that postglacial colonization founded multiple freshwater-resident populations with strong habitat fidelity and limited dispersal tendencies that became highly differentiated, a pattern that was likely intensified by anthropogenic barriers.
2013
Hume, J.B., Adams, C.E., Mable, B.W. & Bean, C.W.
Sneak male mating tactics between lampreys exhibiting alternative life history strategies Journal Article
In: Journal of Fish Biology, vol. 82, iss. 3, pp. 1093–1100, 2013.
Abstract | Links | BibTeX | Tags: evolution, speciation
@article{nokey,
title = {Sneak male mating tactics between lampreys exhibiting alternative life history strategies},
author = {Hume, J.B., Adams, C.E., Mable, B.W. & Bean, C.W. },
url = {https://doi.org/10.1111/jfb.12047},
year = {2013},
date = {2013-02-25},
urldate = {2013-02-25},
journal = {Journal of Fish Biology},
volume = {82},
issue = {3},
pages = {1093–1100},
abstract = {Interspecific sneak male mating tactics between paired lamprey species are described for the first time. Although alternative mating tactics among petromyzontids have been described previously, including intraspecific sneak males, the presence of sneak male tactics between parasitic and non-parasitic forms suggests that high levels of gene flow between putative lamprey species could remain high, despite large body size discrepancies.},
keywords = {evolution, speciation},
pubstate = {published},
tppubtype = {article}
}
Interspecific sneak male mating tactics between paired lamprey species are described for the first time. Although alternative mating tactics among petromyzontids have been described previously, including intraspecific sneak males, the presence of sneak male tactics between parasitic and non-parasitic forms suggests that high levels of gene flow between putative lamprey species could remain high, despite large body size discrepancies.
Hume, J.B., Adams, C.E., Mable, B. & Bean, C.W.
Post-zygotic hybrid viability in sympatric species pairs – a case study from European lampreys Journal Article
In: Biological Journal of the Linnaean Society, vol. 108, iss. 2, pp. 378–383, 2013.
Abstract | Links | BibTeX | Tags: evolution, speciation
@article{nokey,
title = {Post-zygotic hybrid viability in sympatric species pairs – a case study from European lampreys},
author = {Hume, J.B., Adams, C.E., Mable, B. & Bean, C.W. },
url = {https://doi.org/10.1111/j.1095-8312.2012.02007.x},
year = {2013},
date = {2013-01-17},
urldate = {2013-01-17},
journal = {Biological Journal of the Linnaean Society},
volume = {108},
issue = {2},
pages = {378–383},
abstract = {Ecological speciation mechanisms are widely assumed to play an important role in the early stages of divergence between incipient species, and this especially true of fishes. In the present study, we tested explicitly for post-zygotic barriers to gene flow between a sympatric, recently diverged lamprey species pair that likely arose through ecological divergence. Experimental in vitro hybridization between anadromous parasitic Lampetra fluviatilis and resident nonparasitic Lampetra planeri resulted in a high proportion of embryos capable of attaining the burrowing pro-larval stage, strongly indicating no post-zygotic barriers to gene flow between these species. A sympatric, locally-adapted resident parasitic form of L. fluviatilis was also found to successfully hybridize with both members of this species pair. The consequences of these findings are discussed in the context of lamprey speciation.},
keywords = {evolution, speciation},
pubstate = {published},
tppubtype = {article}
}
Ecological speciation mechanisms are widely assumed to play an important role in the early stages of divergence between incipient species, and this especially true of fishes. In the present study, we tested explicitly for post-zygotic barriers to gene flow between a sympatric, recently diverged lamprey species pair that likely arose through ecological divergence. Experimental in vitro hybridization between anadromous parasitic Lampetra fluviatilis and resident nonparasitic Lampetra planeri resulted in a high proportion of embryos capable of attaining the burrowing pro-larval stage, strongly indicating no post-zygotic barriers to gene flow between these species. A sympatric, locally-adapted resident parasitic form of L. fluviatilis was also found to successfully hybridize with both members of this species pair. The consequences of these findings are discussed in the context of lamprey speciation.