Isolation and characterization of eight microsatellite loci in the icefish <i>Chaenocephalus aceratus</i> (Perciformes, Notothenioidei, Channichthyidae)

Determining the timing, extent and underlying causes of interspecific gene exchange during or following speciation is central to understanding species' evolution. Antarctic notothenioid fish, thanks to the acquisition of antifreeze glycoproteins during Oligocene transition to polar conditions, experienced a spectacular radiation to >100 species during Late Miocene cooling events. The impact of recent glacial cycles on this group is poorly known, but alternating warming and cooling periods may have affected species' distributions, promoted ecological divergence into recurrently opening niches and/or possibly brought allopatric species into contact. Using microsatellite markers and statistical methods including Approximate Bayesian Computation, we investigated genetic differentiation, hybridization and the possible influence of the last glaciation/deglaciation events in three icefish species of the genus Chionodraco. Our results provide strong evidence of contemporary and past introgression by showing that: (i) a substantial fraction of contemporary individuals in each species has mixed ancestry, (ii) evolutionary scenarios excluding hybridization or including it only in ancient times have small or zero posterior probabilities, (iii) the data support a scenario of interspecific gene flow associated with the two most recent interglacial periods. Glacial cycles might therefore have had a profound impact on the genetic composition of Antarctic fauna, as newly available shelf areas during the warmer intervals might have favoured secondary contacts and hybridization between diversified groups. If our findings are confirmed in other notothenioids, they offer new perspectives for understanding evolutionary dynamics of Antarctic fish and suggest a need for new predictions on the effects of global warming in this group.

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“…(), Susana et al . () and Papetti et al . () and were cross‐amplified in C. hamatus , C. myersi and C. rastrospinosus .…”

Section: Methodsmentioning

confidence: 82%

Evidence for past and present hybridization in threeAntarctic icefish species provides new perspectives on an evolutionary radiation

et al. 2013

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“…Nine microsatellite markers were genotyped in both species using previously published primers: Ca26 was originally isolated from C. aceratus (Susana et al . ), Cr15, Cr38, Cr127, Cr236, Cr259 from Chionodraco rastrospinosus (Papetti et al . ) and Trne20, Trne53, Trne66 from Trematomus newnesi (Van Houdt et al .…”

Section: Methodsmentioning

confidence: 99%

Population divergences despite long pelagic larval stages: lessons from crocodile icefishes (Channichthyidae)

Damerau¹,

Matschiner

Salzburger

et al. 2013

Molecular Ecology

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Dispersal via pelagic larval stages plays a key role in population connectivity of many marine species. The degree of connectivity is often correlated with the time that larvae spend in the water column. The Antarctic notothenioid fishes develop through an unusually long pelagic larval phase often exceeding 1 year. Notothenioids thus represent a prime model system for studying the influence of prolonged larval phases on population structure in otherwise demersal species. Here, we compare the population genetic structure and demographic history of two sub-Antarctic crocodile icefish species (Chaenocephalus aceratus and Champsocephalus gunnari) from the Scotia Arc and Bouvet Island in the Atlantic sector of the Southern Ocean to delineate the relative importance of species-specific, oceanographic and paleoclimatic factors to gene flow. Based on 7 (C. aceratus) and 8 (C. gunnari) microsatellites, as well as two mitochondrial DNA markers (cytochrome b, D-loop), we detect pronounced population genetic structure in both species (amova FSTs range from 0.04 to 0.53). High genetic similarities were found concordantly in the populations sampled at the Southern Scotia Arc between Elephant Island and South Orkney Islands, whereas the populations from Bouvet Island, which is located far to the east of the Scotia Arc, are substantially differentiated from those of the Scotia Arc region. Nonetheless, haplotype genealogies and Bayesian cluster analyses suggest occasional gene flow over thousands of kilometres. Higher divergences between populations of C. gunnari as compared to C. aceratus are probably caused by lower dispersal capabilities and demographic effects. Bayesian skyline plots reveal population size reductions during past glacial events in both species with an estimated onset of population expansions about 25 000 years ago.

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“…Microsatellites Cr15, Cr38, Cr127, Cr236, Cr259 were originally isolated from Chionodraco rastrospinosus (Papetti et al 2006), Trne20, Trne35, Trne37, Trne53, Trne55, Trne66 from Trematomus newnesi (Van Houdt et al 2006), and Ca26 from Chaenocephalus aceratus (Susana et al 2007). Marker sets for each species were composed of 8-10 microsatellites, depending on the ampliWcation success (Online Resource 1).…”

Section: Microsatellite Genotyping and Data Analysismentioning

confidence: 99%

Comparative population genetics of seven notothenioid fish species reveals high levels of gene flow along ocean currents in the southern Scotia Arc, Antarctica

et al. 2012

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The Antarctic Wsh fauna is characterized by high endemism and low species diversity with one perciform suborder, the Notothenioidei, dominating the whole species assemblage on the shelves and slopes. Notothenioids diversiWed in situ through adaptive radiation and show a variety of life history strategies as adults ranging from benthic to pelagic modes. Their larval development is unusually long, lasting from a few months to more than a year, and generally includes a pelagic larval stage. Therefore, the advection of eggs and larvae with ocean currents is a key factor modulating population connectivity. Here, we compare the genetic population structures and gene Xow of seven ecologically distinct notothenioid species of the southern Scotia Arc based on nuclear microsatellites and mitochondrial DNA sequences (D-loop/cytochrome b). The seven species belong to the families Nototheniidae (Gobionotothen gibberifrons, Lepidonotothen squamifrons, Trematomus eulepidotus, T. newnesi) and Channichthyidae (Chaenocephalus aceratus, Champsocephalus gunnari, Chionodraco rastrospinosus). Our results show low-population diVerentiation and high gene Xow for all investigated species independent of their adult life history strategies. In addition, gene Xow is primarily in congruence with the prevailing ocean current system, highlighting the role of larval dispersal in population structuring of notothenioids.

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Isolation and characterization of eight microsatellite loci in the icefish Chaenocephalus aceratus (Perciformes, Notothenioidei, Channichthyidae)

Cited by 10 publications

References 7 publications

Evidence for past and present hybridization in threeAntarctic icefish species provides new perspectives on an evolutionary radiation

Evidence for past and present hybridization in threeAntarctic icefish species provides new perspectives on an evolutionary radiation

Population divergences despite long pelagic larval stages: lessons from crocodile icefishes (Channichthyidae)

Comparative population genetics of seven notothenioid fish species reveals high levels of gene flow along ocean currents in the southern Scotia Arc, Antarctica

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