Hybridization phenomenon in cetacean and pinniped species

• Published in: Neotropical Biology and Conservation
• Main Authors: Schaurich, Miriane do Nascimento, Lopes, Fernando Ricardo Vieira, Oliveira, Larissa Rosa de
• Format: Article in Journal/Newspaper
• Language: Portuguese
• Published: Neotropical Biology and Conservation 2012
• Subjects: Balaenoptera musculus
• Online Access: https://revistas.unisinos.br/index.php/neotropical/article/view/nbc.2012.73.06; https://doi.org/10.4013/nbc.2012.73.06

The hybridism is the result of mating between two individuals from different and reproductively isolated gene pools accepted as species that usually generate infertile offspring. The evolutionary consequences of this phenomenon vary depending on the mating system, hybrid’s frequency, the degree of reproductive isolation and the genetic differences between the parental species as well as their speciation process. Hybrids have been recorded frequently in aquatic and terrestrial mammals, both in nature and captivity. We review studies published in peer-reviewed journals between 1940 and 2010, in which hybrid cases were reported for cetaceans and pinnipeds. We found 37 scientific papers recording 1,201 hybrids: 57 in cetaceans (nature = 27; captivity = 30) and 1,144 in pinnipeds (nature = 1,137; captivity = 7). A possible explanation for this phenomenon in the wild could be the close phylogenetic relatedness between parental species and also the potential absence of conspecific breeding partners. This last factor could be a result of population decline due to commercial exploitation occurred in the past. This fact is valid for pinnipeds, but especially true for blue whales, Balaenoptera musculus. It is important to note that about 99% of pinniped hybrids were reported in sympatric breeding colonies along the subantarctic islands, which facilitate the hybridization. Outbreeding depression followed by loss of genetic variability and reduction of evolutionary potential and consequently increasing the risk of extinction are the most important results of the hybridism.Key words: aquatic mammals, Cetartiodactyla, Carnivora, hybrids, outbreeding depression, conservation threats. O hibridismo é resultado do cruzamento entre indivíduos com conjuntos gênicos diferentes e isolados considerados como espécies que geram prole, frequentemente, infértil. As consequências evolutivas desse fenômeno dependem da aptidão, frequência de ocorrência do híbrido, mecanismos de isolamento reprodutivo e processos de especiação que envolvem ...