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By Valerie Shore If you're a male resident killer whale, it's unlikely you'll father any calves until you're well into your 20s. In fact, you might not get to be a dad at all. This is one of several surprises emerging out of a study of killer whale genetics by Lance Barrett-Lennard, a PhD student at the University of British Columbia. The study is mainly funded by the adoption program.  Barrett-Lennard is analysing DNA from tiny skin and blubber samples taken from 170 killer whales in B.C. and Alaska. The study has already told us a great deal about how killer whale populations off the northeast
Pacific coast are related to one another (see Blackfish Sounder, 1997). Further analysis - of paternity trends and genetic variations among clans - has now revealed some fascinating information about how and whom resident killer whales are choosing as their mates.
Although Barrett-Lennard can't get into specifics until he defends his thesis later this year, he's willing to tantalize us with a few general observations. First of all, almost all of the fathers identified in his paternity analysis are older animals. Since the average life expectancy of a male killer whale is about 29, "old" means mid-20s and up, although a few bulls live into their 30s and 40s. Another fairly clear pattern is that some males have sired multiple calves, while the majority seem to have fathered none. "This is a 'some guys have all the luck' sort of deal," he says, "and is common in animals where males are bigger than females." In such species, though, males usually fight over females. Since there's no evidence of this happening among killer whales, the logical conclusion is that female killer whales are doing the choosing. "Male killer whales are doing something else to impress females, and perhaps one of those things is living a long time," suggests Barrett-Lennard. As for who the dads are, we'll have to wait a little while longer to find out all the details. Barrett-Lennard says the fathers of about one-third of the resident calves sampled have been identified "with a high degree of confidence." Other calves have several father candidates. For example, Misty's (A62) dad is probably W2, while her older brother Echo's (A55) dad is either Calvert (D5) or H2. On a much broader scale, the genetics work is confirming early dialect studies by researcher Dr. John Ford (Vancouver Aquarium), who speculated that discrete calls - unique to certain pods and family groups - are being used by the whales to avoid inbreeding. In other words, whales are choosing partners that don't sound like themselves. We'll tell you more in the next newsletter. Stay tuned.  All pictures and audio © Vancouver Aquarium Marine Science Centre 1999 |