Increased number of hybrids between benthic and limnetic three‐spined sticklebacks in Enos Lake, Canada; the collapse of a species pair?

Kraak, Sarah; Mundwiler, Beat; Hart, Paul J. B.

doi:10.1111/j.1095-8649.2001.tb02300.x

Cited by 39 publications

(39 citation statements)

References 18 publications

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“…It corresponds with findings by Koeslag (1995) and Doebeli (1996) and see Bolnick and Fitzpatrick (2007), while others have found that some postzygotic isolation is necessary for speciation to happen and be maintained (Liou & Price 1994;Kelly & Noor 1996;Hostert 1997;Bolnick and Fitzpatrick 2007). Recent empirical work has also shown that the collapse of the species pair in Enos Lake, British Columbia (Kraak et al, 2001;Taylor et al 2006) has been accompanied by a loss of postmating isolation (Behm et al, 2010).…”

Section: Discussionsupporting

confidence: 80%

“…In nature reproductive isolation between benthics and limnetics is not complete either. Current estimates are that about 1-2% of adult fish are hybrids (McPhail 1992;Schluter & McPhail 1992, but see Kraak et al 2001); this is partly after selection (Gow et al 2007) and might well correspond to the production of about 4% hybrid offspring per generation. Of course, a value of τ = 0.5 allows for matings between benthics and limnetics, although rarely.…”

Section: The Models and Their Resultsmentioning

confidence: 99%

“…Recent work and commentary has emphasised the fragility of the species pairs and their vulnerability to ecological change (Kraak et al, 2001;Taylor et al 2006;Gow et al, 2006;Wootton 2009;Hendry et al, 2009;Behm et al, 2010). This could mean that either the species pairs have not yet established irreversible barriers to mating, which is probably the consensus right now, or the pairs are not the result of true speciation (Wootton 2009;Hendry et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…In nature some hybrids occur (McPhail 1984(McPhail , 1992(McPhail , 1994Kraak et al 2001). Hybrids are of intermediate morphology, and tend to perform intermediately in both habitats: they do worse than limnetics in the limnetic habitat (where benthics do even worse), and they do worse than benthics in the benthic habitat (where limnetics do worst) (Schluter 1993(Schluter , 1995Gow et al 2007).…”

Section: The Benthic and Limnetic Stickleback Species Pairsmentioning

confidence: 99%

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Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

Kraak

Hart

2011

Org Divers Evol

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We investigate the plausibility of sympatric speciation through a modelling study.We built up a series of models with increasing complexity while focussing on questioning the realism of model assumptions by critically checking them against a particular biological system, namely the sympatric benthic and limnetic species of threespine stickleback in British Columbia, Canada. These are morphologically adapted to their feeding habits: each performs better in its respective habitat than do the hybrids with intermediate morphology. Firstly, preference is based on similarity where mating preference may result from "imprinting" on conspecifics encountered in their preferred foraging habitat. Here, speciation occurs easily -ecological hybrid inferiority is not necessary. Hybrid inferiority reinforces stringency of assortative mating. Secondly, individual preferences exist for different trait values. Here, speciation occurs when linkage disequilibrium between trait and preference develops and some hybrid inferiority is required. Finally, if the morphology subject to disruptive selection, frequency-dependent competition, and mate choice, is coded for by two loci, linkage disequilibrium between the two loci is required for speciation. Speciation and reinforcement of stringency of choosiness are possible in this case too, but rarely. Results demonstrate the contingency of speciation, with the same starting point not necessarily producing the same outcome. The study resulted in flagging issues where models often lack in biological realism and issues where more empirical studies could inform on whether assumptions are likely valid.3 keywords: assortative mating, benthic/limnetic species pairs, disruptive selection, frequencydependent resource competition, reinforcement, sympatric speciation.4

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Section: Discussionsupporting

confidence: 80%

Section: The Models and Their Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: The Benthic and Limnetic Stickleback Species Pairsmentioning

confidence: 99%

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Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

Kraak

Hart

2011

Org Divers Evol

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“…For instance, a critical factor in the persistence of species pairs would appear to be conserving the current species composition (i.e., keeping invasive species out and conserving coastal cutthroat trout), rather than forming specific abiotic environmental management criteria. The collapse of the Enos Lake species pair into a hybrid swarm following the appearance of the American signal crayfish, Pacifastacus leniusculus (Kraak et al 2001;Taylor et al 2006), and extinction of the Hadley Lake species pair following the introduction of the brown bullhead (Hatfield 2001) are examples of the devastating impact that invasive species can have on stickleback species pairs. That being said, habitat loss and degradation is the number one threat to freshwater fishes in Canada, and the effect of invasive species is often compounded by habitat change (Dextrase and Mandrak 2006).…”

Section: Origin and Persistence Of Species Pairsmentioning

confidence: 99%

Environmental determinants of threespine stickleback species pair evolution and persistence

OrmondChad

RosenfeldJordan

TaylorEric

2011

Can. J. Fish. Aquat. Sci.

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Threespine stickleback (Gasterosteus aculeatus) species pairs are found in four watersheds in southwestern British Columbia, Canada, and are listed as Endangered under the federal Species at Risk Act. Their origin is thought to be through a double-invasion process followed by character displacement; however, this hypothesis does not consider whether speciation is dependent on unique environmental factors necessary to support two species with separate habitat and resource requirements, which may be essential both for their evolution and persistence. To test whether species pair lakes have unique attributes, we compared abiotic and biotic factors of species pair lakes to lakes with only a single population of stickleback. There were no clear environmental differences between species pair and non-species pair lakes, but species pairs were only present in lakes with low fish species diversity, suggesting that evolution and persistence of species pairs requires a simplified fish community. Our study suggests that colonization history rather than unique lake attributes (related to either physical habitat or trophic resources) facilitated the evolution of stickleback species pairs and that the fish assemblage in lakes may affect resource availability and speciation potential as strongly as the limnological attributes of the lakes themselves.Résumé : Les paires d'espèces d'épinoches à trois épines (Gasterosteus aculeatus) se retrouvent dans quatre bassins versants du sud-ouest de la Colombie-Britannique, Canada, et figurent sur la liste des espèces menacées d'après la loi fédérale sur les espèces en péril. On pense que leur origine s'explique par un processus de double invasion suivi par une divergence phénotypique; cependant, cette hypothèse ne considère pas si la spéciation dépend de caractéristiques uniques du milieu né-cessaires pour le maintien de deux espèces avec des besoins différents d'habitat et de ressources, qui peuvent être essentielles tant pour leur évolution que pour leur persistance. Afin de tester si les lacs qui possèdent des paires d'espèces ont des caractéristiques uniques, nous avons comparé les facteurs abiotiques et biotiques des lacs à paire d'espèces avec ceux des lacs à une seule population d'épinoches. Il n'y a pas de différence environnementale claire entre les lacs avec ou sans paires d'espèces, mais les paires d'espèces ne sont présentes que dans les lacs à faible diversité de poissons, ce qui laisse croire que l'évolution et la persistance de paires d'espèces exigent une communauté simplifiée de poissons. Notre étude fait penser que c'est l'histoire de la colonisation plutôt que les caractéristiques uniques du lac (reliées à l'habitat physique ou aux ressources trophiques) qui a facilité l'évolution des paires d'espèces d'épinoches et que le peuplement des poissons dans les lacs peut affecter la disponibilité des ressources et le potentiel de spéciation aussi fortement que les caractéristiques limnologiques des lacs eux-mêmes.[Traduit par la Rédaction]

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A genetically distinct hybrid zone occurs for two globally invasive mosquito fish species with striking phenotypic resemblance

Wilk

Horth

2016

Ecology and Evolution

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Hybrid zones allow for the investigation of incipient speciation and related evolutionary processes of selection, gene flow, and migration. Interspecific dynamics, like competition, can impact the size, shape, and directional movement of species in hybrid zones. Hybrid zones contribute to a paradox for the biological species concept because interbreeding between species occurs while parental forms remain distinct. A long‐standing zone of intergradation or introgression exists for eastern and western mosquito fish (Gambusia holbrooki and G. affinis) around Mobile Bay, AL. The region has been studied episodically, over decades, making it perfect for addressing temporal dynamics and for providing a deeper understanding of the genetics of these periodically reclassified fishes (as species or subspecies). We used six microsatellite markers to assess the current population structure and gene flow patterns across 19 populations of mosquito fish and then compared our results with historical data. Genetic evidence demonstrates that the current hybrid zone is located in a similar geographic region as the historical one, even after three decades. Hybrid fish, however, demonstrate relatively low heterozygosity and are genetically distinct from western and eastern mosquito fish populations. Fin ray counts, sometimes used to distinguish the two species from one another, demonstrate more eastern (G. holbrooki) phenotype fish within the molecular genetic hybrid zone today. Mosquito fish are globally invasive, often found on the leading edge of flooded waters that they colonize, so the impact of hurricanes in the wake of climate change was also evaluated. An increase in the frequency and intensity of hurricanes in the hybrid region has occurred, and this point warrants further attention since hurricanes are known to move these aggressive, invasive species into novel territory. This work contributes to our classical understanding of hybrid zone temporal dynamics, refines our understanding of mosquito fish genetics in their native range, evaluates important genotype–phenotype relationships, and identifies a potential new impact of climate change.

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Increased number of hybrids between benthic and limnetic three‐spined sticklebacks in Enos Lake, Canada; the collapse of a species pair?

Cited by 39 publications

References 18 publications

Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

Environmental determinants of threespine stickleback species pair evolution and persistence

A genetically distinct hybrid zone occurs for two globally invasive mosquito fish species with striking phenotypic resemblance

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