- Chromosome complements of ten species of shorebirds, order
Charadriiformes, were analyzed and compared. Mitotic chromosomes
from the pigeon guillemot (Cepphus columba), Heermann's gull (Larus
heermanni), the California gull (L. californicus), the western gull
(L. occidentalis), the American avocet (Recurvirostra americana),
the western willet (Catoptrophorus semipalmatus), Wilson's snipe
(Capella gallinago), the wandering tattler (Heteroscelus incanum), and
the black oystercatcher (Haematopus bachmani) were examined in this
Short term cultures of bone marrow cells from each of these
species provided a source of rapidly dividing cells. Mitosis was
arrested with colchicine and the cells exposed to a hypotonic environment
prior to fixation in Carnoy's acetic-alcohol without chloroform.
Fixed cells were resuspended in a 45% aqueous solution of acetic acid,
air dried onto warmed cover slips and stained with lactic-acetic-orcein.
In addition to these mitotic chromosomes, meiotic chromosomes
of the black tern (Chlidonias niger) were fixed, air dried, stained and
Study of the slides of mitotic chromosomes revealed a marked
similarity of karyotype in six of the ten species. These six were the
oystercatcher, avocet, the three species of gulls and the pigeon
guillemot. Study of the meiotic chromosomes of the black tern showed
that it also had a chromosome complement similar to these six species.
Three species, the western willet, Wilson's snipe and the
wandering tattler, all members of the family Scolopacidae, were found
to possess karyotypes quite different from the other members of the
order. These last three species had diploid numbers between 90 and
100 and karyotypes which included many acrocentric elements but few
metacentrics. This is in contrast to the other seven species which all
had diploid numbers near 70 and karyotypes containing many nonacrocentric
Finally, chromosomes of the domestic chicken (Gallus domesticus),
a member of the closely related order Galliformes, were compared
to the shorebird species. This comparison lead to the conclusion
that the seven species, with diploid numbers near 70 and many
non-acrocentric macrochromosomes, are evolutionarily descended
along a common shorebird line and have many karyotypic characteristics
in common with members of the closely related order Galliformes.
Because of the markedly different karyotypes of the three members of the family Scolopacidae (snipe, willet and tattler) the
suggestion is made that this family may have evolved from a different
phylogenetic line than the other members of the order Charadriiformes.