Molecular identification of hybrids between the two largest whale species, the blue whale (Balaenoptera musculus) and the fin whale (B. physalus)

Abstract

Three anomalous balaenopterid whales, one pregnant female and two sterile males, were investigated by applying molecular approaches in order to establish their identity. The analysis showed that the whales were species hybrids between the blue and the fin whales. The female and one of the males had a blue whale mother and a fin whale father. The other male had a fin whale mother and a blue whale father. The difference between the mitochondrial cytochrome b gene of the two species suggests that they separated greater than or equal to 3.5 million years ago. The sequences of the mitochondrial control region of the blue and the fin whales differ by 7%. The difference in the mtDNA control region between three blue whale mtDNA haplotypes was less than or equal to 1%, about one tenth of the difference between the two species.

The mitochondrial DNA molecule of sumatran orangutan and a molecular proposal for two (Bornean and Sumatran) species of orangutan

“…We make the present species status proposal, however, despite the fact that the two orangutans produce fertile offspring in captivity. The reason for this is that we do not consider hybridization incompatibility as an absolute parameter in this context because it has been shown previously that distinct species, such as the fin and the blue whales, which show pronounced molecular differences (Table 3), may still produce fertile offspring in their natural environment (Spilliaert et al 1991;Arnason et al 1991b). Among plants the difficulty of using hybridization incompatibility as a parameter for species distinction has been given detailed treatment (Stebbins 1950).…”

Captive-born intergeneric hybrid of a Guiana and bottlenose dolphin: Sotalia guianensis×Tursiops truncatus

“…Hybrids have also been described in wild cetaceans, although confirming such events with DNA analysis has been more difficult. Known or suspected hybrids include: five fin whale (Balaenoptera physalus)  blue whale (B. musculus) [Arnason et al, 1991, Be´rube´and Aguilar, 1998], one bottlenose dolphin  Atlantic spotted Fig. 4.…”

Life history told by a whale-louse: a possible interaction of a southern right whale Eubalaena australis calf with humpback whales Megaptera novaeangliae

“…observ.). Reports about interactions between two mysticetes species are less common than interactions between mysticetes and odontocetes [26,27].…”