Although predictable in its areas of occurrence, the humpback whale migration remains for many aspects still poorly understood. Nuclear DNA analysis has revealed a low level of relatedness among whales using the same migratory corridor, and that closely related individuals do not tend to travel in spatial association. Yet it still remains uncertain whether whales from different matrilineally discrete feeding stocks travel along the same migratory corridor for then mixing in common breeding waters. The western and central South Pacific Ocean is the only ocean basin where thousands of islands and reefs occur as suitable wintering habitat for humpback whales, so their migratory behaviour may not be constrained by habitat. Here we analysed the sex-specific and temporal distributions of 42 mitochondrial haplotypes detected in 135 humpback whales sampled off Eastern Australia throughout one annual migration. A noticeable difference was found in haplotypic composition between northbound males and females, suggesting that the two sexes of any single matrilineal stock might select differential, only partially overlapping, migratory routes. We hypothesize that males most closely related to the females that migrate north-south off eastern Australia appear to migrate north elsewhere, perhaps past New Zealand. The scant behavioural data available from New Zealand support this hypothesis.
Genetic evidence for sex-specific migratory behaviour in the western south Pacific humpback whales
BERTORELLE, Giorgio
2010
Abstract
Although predictable in its areas of occurrence, the humpback whale migration remains for many aspects still poorly understood. Nuclear DNA analysis has revealed a low level of relatedness among whales using the same migratory corridor, and that closely related individuals do not tend to travel in spatial association. Yet it still remains uncertain whether whales from different matrilineally discrete feeding stocks travel along the same migratory corridor for then mixing in common breeding waters. The western and central South Pacific Ocean is the only ocean basin where thousands of islands and reefs occur as suitable wintering habitat for humpback whales, so their migratory behaviour may not be constrained by habitat. Here we analysed the sex-specific and temporal distributions of 42 mitochondrial haplotypes detected in 135 humpback whales sampled off Eastern Australia throughout one annual migration. A noticeable difference was found in haplotypic composition between northbound males and females, suggesting that the two sexes of any single matrilineal stock might select differential, only partially overlapping, migratory routes. We hypothesize that males most closely related to the females that migrate north-south off eastern Australia appear to migrate north elsewhere, perhaps past New Zealand. The scant behavioural data available from New Zealand support this hypothesis.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
