Short Note: A Record of Twin Fetuses in a Harbor Porpoise (Phocoena phocoena) Stranded on the Dutch Coast

IJsseldijk, Lonneke L.; Gröne, Andrea; Hiemstra, Sjoukje; Hoekendijk, Jeroen; Begeman, Lineke

doi:10.1578/am.40.4.2014.394

Cited by 3 publications

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“…Furthermore Jonsgård (1953) reported a fin whale with six foetuses of varying sizes. Multiple foetuses are less frequent in Odontocetes than in Mysticetes (Lockyer, 1984), although they have been reported in sperm whales ( Physeter macrocephalus ) (Matsuura, 1940; Ohsumi, 1965; Gambell, 1972; Best et al ., 1984; Clarke et al ., 2011), short finned pilot whale ( Globicephala macrorhynchus ) (Escorza et al ., 1994), striped dolphin ( Stenella coeruleoalba ) (Tobayama et al ., 1970), bottlenose dolphin ( Tursiops truncatus ) (conjoined twins; Dabin et al ., 2004; Kompanje, 2005; Aytemiz et al ., 2014, and non-conjoined twins; Gray & Conklin, 1974; Lacave, 1991), Risso's dolphin ( Grampus griseus ) (Gassner & Rogan, 1997), beluga whale ( Delphinapterus leucas ) (Osborn et al ., 2012), short-beaked common dolphin ( Delphinus delphis ) (González et al ., 1999), Dall's porpoise ( Phocoenoides dalli ) (Nakamatsu, 2001) and harbour porpoise (IJsseldijk et al ., 2014). Of these cases, the striped dolphin, sperm whale, common dolphin, Risso's dolphin, Dall's porpoise, harbour porpoise and conjoined twins of the bottlenose dolphins were free-living individuals that stranded dead, the others were all captive animals.…”

Section: Discussionmentioning

confidence: 99%

“…In delphinid species an offspring's weight is approximately 10–15% that of the dam (Slijper, 1966). This high birth weight would not favour the survival of multiple foetuses and is likely to result in spontaneous abortion or death of the female (Perrin & Donovan, 1984; IJsseldijk et al ., 2014). Infection with Brucella is a well known cause of abortion and reproductive failure in terrestrial animals (Radostits et al ., 2007) and Brucella sp.…”

Section: Discussionmentioning

confidence: 99%

“…Twinning in odontocetes appears to be a rare occurrence but has been reported in several species upon examination of dead animals (González et al ., 1999; Nakamatsu, 2001; IJsseldijk et al ., 2014). No reports exist of the survival of multiparous births in this sub-order, where uniparous births are the norm (Perrin & Donovan, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Twin foetuses in an Atlantic white-sided dolphin (Lagenorhynchus acutus) stranded on the coast of Scotland, UK

Davison¹,

Dagleish

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et al. 2016

J. Mar. Biol. Ass.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Twin foetuses in an Atlantic white-sided dolphin (Lagenorhynchus acutus) stranded on the coast of Scotland, UK

Davison¹,

Dagleish

Read

et al. 2016

J. Mar. Biol. Ass.

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Exploring the effects of methodological choices on the estimation and biological interpretation of life history parameters for harbour porpoises in Norway and beyond

Frie,

Lindström

2024

PLoS ONE

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This study investigates effects of subtle methodological choices on the estimation and biological interpretation of age, growth and reproductive parameters for harbour porpoises. The core analyses are based on a focal Norwegian data set built on samples from 134 harbour porpoises caught incidentally in gillnet fisheries along the Norwegian coast during autumn 2016 and spring 2017. Two contrasting practices for interpretation of seasonal and ontogenetic characteristics of tooth growth layer formation resulted in significant age differences among spring samples of young porpoises and for older animals across seasons. In turn, these differences affected estimates of age at maturity and asymptotic lengths, respectively. We also found significant differences in male age at maturity between two well-documented maturity criteria and between mathematical estimators of age at maturity for both sexes. Two different criteria for corpus albicans classification furthermore resulted in different patterns of ovarian corpora accumulation, which may affect some estimates of fecundity rates and contaminant loads. Both corpora accumulation patterns were also found in reanalysed data from German and Greenlandic porpoises. Based on tabulated overviews of methodological choices made in previous harbour porpoise studies, we argue that several of the issues mentioned above have wider relevance and may affect the validity of meta-analyses as a tool for estimating harbour porpoise sensitivity to extrinsic pressures. Differences in cause of death (COD) composition between data sets can have a similar effect. We demonstrate this in a meta-analysis of published harbour porpoise pregnancy rates, showing significantly higher values for trauma-killed samples compared to samples comprising mixed COD categories. COD also affected the estimated impacts of three previously analysed extrinsic predictors as well as an added predictor for vessel noise levels. We discuss the potential contributions of methodological, biological and anthropogenic factors in shaping observed regional differences in estimates of harbour porpoise life history parameters.

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Molecular confirmation of twinning in the West Indian Manatee (Trichechus manatus)

et al. 2022

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Few twinning events have been recorded in the West Indian manatee (Trichechus manatus, Sirenia: Trichechidae) and no previous published study has provided confirmation of this phenomenon based in molecular tools. Here we investigate a possible case of twinning in an endangered Brazilian population of T. manatus using molecular tools. We analyzed two male neonates found stranded in Ceará State, on the northeastern coast of Brazil. The DNA of both individuals was isolated, and 10 microsatellite loci were amplified and genotyped. Following the identification of the alleles, the probabilities of identity by descent (∆7 and ∆8) and relatedness (rxy) were calculated using estimators that evaluate inbreeding. The two individuals shared most of the alleles, with differences in the genotypes being identified in only two loci. All the estimators identified a level of relatedness compatible with that found between siblings (selfed or outbred), indicating they were dizygotic twins. This is the first confirmed case of fraternal twins in free-ranging West Indian manatees in South America. The recognition of this type of twinning provides elements to improve actions for the rehabilitation of stranded animals and their subsequent release to the environment.

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Short Note: A Record of Twin Fetuses in a Harbor Porpoise (Phocoena phocoena) Stranded on the Dutch Coast

Cited by 3 publications

References 0 publications

Twin foetuses in an Atlantic white-sided dolphin (Lagenorhynchus acutus) stranded on the coast of Scotland, UK

Twin foetuses in an Atlantic white-sided dolphin (Lagenorhynchus acutus) stranded on the coast of Scotland, UK

Exploring the effects of methodological choices on the estimation and biological interpretation of life history parameters for harbour porpoises in Norway and beyond

Molecular confirmation of twinning in the West Indian Manatee (Trichechus manatus)

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