INTRODUCTION    
Many have wondered how the different genera of cockatoos have evolved and how closely
cockatoos are related to one another. A unique study was undertaken to address these questions
that revealed some fascinating results.


                                      RESEARCH STUDY  
Researchers David M. Brown, a Ph.D. student at UCLA and Dr. Catherine A. Toft, professor at the
Center for Population Biology at UC Davis, conducted the study, “A Cockatoo’s Who’s Who:
Determining Evolutionary Relationships Among the Cockatoos.”  The study was published in
volume 11, No. 2., of the Exotic Bird Report in the Psittacine Research Project, Department of
Avian Sciences at the University of California at Davis.

Brown and Toft acknowledge the long history of laboring work by others studying 350 species of
parrots, beginning with Linnaeus in 1758. The two researchers learned the following facts before
they began their own investigation:


  •        Cockatoos form a unique group among parrots. Some of their more prominent
    morphological characteristics include an erectile crest, as well as a lack of dyck texture in
    their feathers that other parrots use in order to produce the colors blue and green in their
    plumage.

  •        Cockatoos have traditionally been divided into two major groups, the predominantly
    black Calyptorhynchi, Calyptorhynchus, and the predominantly white Cacatuini, including
    Cacatua.



                            EVOLUTIONARY RELATIONSHIPS
The goal of the researchers was to find evolutionary relationships among cockatoos
and the hierarchal order in which they descended from a common cockatoo ancestor. A key
element in researching cockatoo evolution was to learn whether a cockatiel is actually a cockatoo
and to which group is the cockatiel most closely related. Also, at what point in the historical
evolution of cockatoos did the Gang-gang, Galah and Major Mitchell cockatoos depart from their
common cockatoo ancestor.

To accomplish this work, Brown and Toft built an evolutionary tree by sequencing a segment of
mitochondrial DNA (a region of the ribosomal 125 gene) from 15 of 19 cockatoo species. The
researchers found that the genetic evolutionary tree confirmed that:


  •    The Palm Cockatoo was the first to diverge from a common cockatoo ancestor, next
    followed by a group that includes the Gang-gang, Red-tailed and the Cockatiel. Later
    descendents include the Galah, Major Mitchell’s and the two groups of white cockatoos.

  •       Sexually dimorphic species such as the Gang-gang, Red-tailed Black and the Cockatiel,
    are more closely related to each other than to any other cockatoo species. The researchers
    suggest that this shared trait of sexual dimorphism is most likely inherited from a common
    ancestor, rather than evolving independently.

  •     The cockatiel is indeed a cockatoo; it is most closely related to the black cockatoos in
    the genus Calyptorhynchus (the Red-tailed, Yellow-tailed, White-tailed and Glossy
    Cockatoo), and the Gang-gang Cockatoo of the genus, Callocephalon.

  •      The group of white cockatoos that include the Moluccan, Blue-eyed, Greater Sulphur-
    crested and Lesser Sulphur-crested have prominently colored crests, rounded wings and
    heavy beaks.

  •    The other group of white cockatoos containing the Red-vented, Little Corella, Ducorp’s
    and Goffins have shorter crests, slender wings and smaller beaks.

  •        The Galah and Major Mitchell’s cockatoos, based on the researcher’s DNA data, most
    likely evolved after the Palm Cockatoo and black cockatoo groups [including the cockatiel],
    but before the existence of the two white cockatoo groups.

  •      Cockatoos that evolved at the base of the evolutionary tree are distributed across  
    Australia; cockatoo species that split from their common ancestor in more recent times
    spread northward to New Guinea, Indonesia and the South Pacific Islands.



                           























                              
The GENETIC EVOLUTION of COCKATOOS
Copyright © 2002 Linda S. Rubin
                       All Rights Reserved  
Copyright 2006 Linda S. Rubin and Aves Communications & Promotions
LIMITED FIRST EDITION. Click for description, chapter excerpts & book reviews!
ORIGINAL
BOOK REVIEW
by
Dr. Rainer R.
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"Well, there is help on
the horizon and
anyone seriously
interested in color
genetics should take
a look at Linda
Rubin's book:
COCKATIEL GENETICS
MADE EASY!
Though this book is
primarily directed to
breeders of cockatiel
mutations, there is
enough information in
this volume to teach
anyone the secrets of
dealing with
recessive, sex-linked,
and dominant
mutations..."
ACBM, Vol. 65, No.12
CLICK TO READ THE
REST OF THE
REVIEW!
112 pages, 15 chapters,
glossary & more!
THE GENETIC EVOLUTION OF COCKATOOS
Which Genera Arrived First? Is a Cockatiel a Cockatoo?
  by LINDA S. RUBIN, SPBE Panel Judge
    ©2002 All Photos and Articles “All Rights Reserved” by Author.
       Written permission from author required for reprints.

First published in the June 2002 issue of BIRD TALK magazine.
Published in August 3, 2006 issue of CAGE & AVIARY BIRDS (United Kingdom)
 Published in October, 2006 issue of TALKING BIRDS (Australia)                  
ANOTHER COCKATOO
Male Gang-gang
Cockatoo
Photo
© 2005 Linda S. Rubin
Galah or
Rose-breasted
Cockatoo Photo
© 2005 Linda S. Rubin

















                                                     INTRODUCTION    
Many have wondered how the different genera of cockatoos have evolved and how closely
cockatoos are related to one another. A unique study was undertaken to address these questions
that revealed some fascinating results.


                                                    RESEARCH STUDY  
Researchers David M. Brown, a Ph.D. student at UCLA and Dr. Catherine A. Toft, professor at the
Center for Population Biology at UC Davis, conducted the study, “A Cockatoo’s Who’s Who:
Determining Evolutionary Relationships Among the Cockatoos.”  The study was published in
volume 11, No. 2., of the Exotic Bird Report in the Psittacine Research Project, Department of
Avian Sciences at the University of California at Davis.

Brown and Toft acknowledge the long history of laboring work by others studying 350 species of
parrots, beginning with Linnaeus in 1758. The two researchers learned the following facts before
they began their own investigation:


  •        Cockatoos form a unique group among parrots. Some of their more prominent
    morphological characteristics include an erectile crest, as well as a lack of dyck texture in
    their feathers that other parrots use in order to produce the colors blue and green in their
    plumage.

  •        Cockatoos have traditionally been divided into two major groups, the predominantly
    black Calyptorhynchi, Calyptorhynchus, and the predominantly white Cacatuini, including
    Cacatua.



                                           EVOLUTIONARY RELATIONSHIPS
The goal of the researchers was to find evolutionary relationships among cockatoos
and the hierarchal order in which they descended from a common cockatoo ancestor. A key
element in researching cockatoo evolution was to learn whether a cockatiel is actually a cockatoo
and to which group is the cockatiel most closely related. Also, at what point in the historical
evolution of cockatoos did the Gang-gang, Galah and Major Mitchell cockatoos depart from their
common cockatoo ancestor.

To accomplish this work, Brown and Toft built an evolutionary tree by sequencing a segment of
mitochondrial DNA (a region of the ribosomal 125 gene) from 15 of 19 cockatoo species. The
researchers found that the genetic evolutionary tree confirmed that:


  •    The Palm Cockatoo was the first to diverge from a common cockatoo ancestor, next
    followed by a group that includes the Gang-gang, Red-tailed and the Cockatiel. Later
    descendents include the Galah, Major Mitchell’s and the two groups of white cockatoos.

  •       Sexually dimorphic species such as the Gang-gang, Red-tailed Black and the Cockatiel,
    are more closely related to each other than to any other cockatoo species. The researchers
    suggest that this shared trait of sexual dimorphism is most likely inherited from a common
    ancestor, rather than evolving independently.

  •     The cockatiel is indeed a cockatoo; it is most closely related to the black cockatoos in
    the genus Calyptorhynchus (the Red-tailed, Yellow-tailed, White-tailed and Glossy
    Cockatoo), and the Gang-gang Cockatoo of the genus, Callocephalon.

  •      The group of white cockatoos that include the Moluccan, Blue-eyed, Greater Sulphur-
    crested and Lesser Sulphur-crested have prominently colored crests, rounded wings and
    heavy beaks.

  •    The other group of white cockatoos containing the Red-vented, Little Corella, Ducorp’s
    and Goffins have shorter crests, slender wings and smaller beaks.

  •        The Galah and Major Mitchell’s cockatoos, based on the researcher’s DNA data, most
    likely evolved after the Palm Cockatoo and black cockatoo groups [including the cockatiel],
    but before the existence of the two white cockatoo groups.

  •      Cockatoos that evolved at the base of the evolutionary tree are distributed across  
    Australia; cockatoo species that split from their common ancestor in more recent times
    spread northward to New Guinea, Indonesia and the South Pacific Islands.


                            
Photo © 2006 Suzanne Ravaillion
Normal Grey Cockatiel
Photo © 2005 Linda S. Rubin
Linda S. Rubin has raised and kept cockatiels and parrots for 30 years and is the
author of several books at www.CockatielsPlusParrrots.com.  She is the Founding
President of the Cockatiel Foundation, Inc., long time Board Member of the
American Federation of Aviculture, Inc., and a Certified Panel Judge for the
Cockatiel Foundation and the Society of Parrot Breeders & Exhibitors.
Many cockatiel enthusiasts have long
regarded the cockatiel as a miniature
cockatoo. The nominate grey cockatiel in
its wild form is more closely aligned to the
black cockatoos, sharing their darker
color, distinctive cheek patches and under
tail-barrings. Cockatiels similarly share the
same unique powder-down feathers, the
erectile crest characteristic of all
cockatoos, and an obvious enthrallment for
endless head scratching sessions, but with
a bonus of vocalizing with a much quieter
voice. The cockatiel – or smallest of
cockatoos – with the characteristics of a
large cockatoo built into a much smaller
“package” makes an excellent alternative
for anyone who cannot keep a larger
cockatoo.

FUTURE STUDIES
To learn more about avian research at UC Davis, or to make a donation to upcoming
projects, please contact: The Psittacine Research Project, Department of Animal
Science, University of California, One Shields Avenue, Davis, CA 95616-8521 or
email: parrots@ucdavis.edu.
THE GENETIC EVOLUTION OF COCKATOOS
Which Genera Arrived First? Is a Cockatiel a Cockatoo?
by LINDA S. RUBIN, SPBE Panel Judge
©2002 All Photos and Articles “All Rights Reserved” by Author.
Written permission from author required for reprints.

First published in the June 2002 issue of BIRD TALK magazine.
Published in August 3, 2006 issue of CAGE & AVIARY BIRDS (United Kingdom)
Published in October, 2006 issue of TALKING BIRDS (Australia)