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GENDER DETERMINATION - Extinct Hawaiian Giant Goose
Collaborators:
Helen James, Storrs Olson and Rob Fleischer, Smithsonian Institution
Funding Partners:
Smithsonian Institution, National Geographic Society
Summary:
With the exploration of lava tubes on the "Big Island" of Hawaii, the articulated skeletons of many extinct species of birds have been discovered. Among these is the "Giant Goose", the largest endemic terrestrial vertebrate known to Hawaii. These birds were larger than Canada Geese, and were flightless, with reduced wing bones. The goose skeletons are presumed to be from those unfortunate individuals that fell through the roof of ancient lava tubes, landing within a long, dark and barren tunnel with no food sources available. Radiocarbon dating on one bone estimated its age at roughly 500 years.
Dr. Helen James and Dr. Storrs Olsen have examined many of these skeletons, now stored at the Smithsonian and at the Bishop Museum in Hawaii, and found that many adults had abnormal bony outgrowths (balloon-shaped bony exostoses) on the distal wing elements, and lamellar thickenings elsewhere. They hypothesize that those adults are males, and that the loss of flight allowed the wings to be used for aggressive male-male interactions.
While they were engaged in this and other studies among
the Hawaiian Islands, my lab was developing a way to use PCR to sex birds.
This method amplifies an intron within a gene that has "gametologues"
on both sex chromosomes (W and Z). The intron found on the W chromosome
is generally larger than that on the Z. As a result, when using the primers
reported in Kahn et al. (1998) during PCR, two products of differing sizes
are generated in females whereas there is only one sized product generated
in males. This is shown in the accompanying photo.
Our goals are to extract DNA from skeletal material, amplify it using
PCR, and determine the gender of each Giant Goose skeleton available.
Gender identification is being done without information on whether the
source skeleton had bony outgrowths. This "blind" will be removed
from the study only after Quinn has determined and recorded sex for each
sample and after James and Olson have independently determined and recorded
which skeletons have significant outgrowths/thickenings on the wings.The
lab methods used essentially follow those of Paxinos (1998). The initial
bone material was cut from either the femur or the tarsometatarsus of
approximately 20 birds within the ancient DNA facility of Dr. Robert Fleischer.
This material provides "target" material for the PCR gender
test already described above. Thus far, amplification of some of the target
samples has been successful, but further refinement of PCR is needed.