Subject: Info: Study of whale dandruff shows (fwd)

Michael Williamson (pita@whale.simmons.edu)
Thu, 8 Aug 1996 14:58:59 -0400 (EDT)

Study of whale dandruff shows kinship

By SUSAN MILIUS
 UPI Science Writer
   WASHINGTON, August 5 (UPI) -- Studying whales' equivalencientists said
Monday they have at last figured out some of the kinship
patterns in the groups of sperm whales once called harems.
   "The beautiful thing about whales is that they are constantly
sloughing skin," said Jonathan Wright from Dalhousie University in
Halifax, Nova Scotia.
   When a whale dives, it leaves behind its version of dandruff, flecks
of dark old skin, some pieces no bigger than a human fingernail, some
more the size of the palm of a hand. Collecting bits of shed skin gives
scientists tissue samples for genetic analysis without invasive sampling
like shooting darts into the animals.
   Wright, Hal Whitehead and other colleagues used sloughed skin for the
most ambitious genetic analysis yet of kinship in the clusters of older
female and young sperm whales that swim together in the warmer
latitudes.
   The study, published in the Proceedings of National Academy of
Sciences, focused on so-called pods of 10 to 30 sperm whales, which
scientists "used to think of harems," Wright said. However, he
dismissed the term as an imprecise leftover from an era when almost all
biologists were male.
   The modern view of the sperm whale lifestyle recognizes that females
spend their lives swimming in tropical or near tropical waters in pods
with young of both sexes.
   Males eventually peel away from the pod, sometimes joining bachelor
groups for while. They mature into solitary adults, cruising farther and
farther north toward the Arctic and Antarctic.
   A male journeys back to the tropics to mate every five or six years,
according to the current estimate.
   Researchers now have evidence about what happens next, thanks to the
new genetic analysis. A visiting male seems to mate with several of the
females in a particular pod before moving on to another pod.
   The new analysis also confirmed that the youngsters in a pod are
related to the adult females, as if several moms and their kids started
swimming together for a while. And for the first time, researchers have
genetic evidence about when the males leave, which seems to be at age
five or six.
   This information of kinship may help the biologists who study so-
called altruism in animals, Wright said. Whales indeed do things that
would be called altruistic in a human, including suckling the baby of
another female as well as babysitting and defending other female whales'
offspring.
   These acts of "kindness" might make sense if the helpful whale had
some genetic connection with the animals that benefit, Wright said.
   The new evidence for tight kinship in a pod of sperm whales fits well
with what scientists know about family values in other whale species,
said Cathy Schaeff, whale biologist and professor at American University
in Washington. "Whales are very social," she said.
   In orcas, for example, "the moms are responsible for the mates of
their sons," she said. Young whales trail along with their mothers,
finding mates when the mothers visit another group of orcas.
   Recognizing just how sperm whales find their mates and how families
stick together will help conservationists figure out how to preserve
genetic diversity in the population, Schaeff said.