Studying Birds in the Brazilian Amazon
John Bates & Jason Weckstein
Introduction
These birds represent three populations of toucans sampled by John, Jason, and Alex during their 2007 Amazonian Expedition, as well as other earlier collecting trips.
The dots represent locations where specimens from the three populations were found. As you can see, each population lives within specific, river-bordered Areas of Endemism—zones containing species unique to that region.
continue
The original images from Handbook of the Birds of the World, Volume 7, have been modified for use in this interactive.
Introduction
For years, scientists believed these toucans to be different populations of the same species: the Ivory-billed Araçari (Pteroglossus azara).
But the work of John, Jason, and Alex's team is revealing that perhaps the birds' relationships—and the Areas of Endemism—need to be
re-evaluated.
Replicate the team's experiments to find out why.
begin
Range Map
Mapping out the ranges for Ivory-billed Araçari populations, the team verified that A and B must be crossing the Solimões to interbreed, since they're genetically identical.
However, neither A nor B is crossing the lower reaches of the Japurá where it approaches the Solimões. Population C is evolving in isolation within its own tiny territory!
But just how big a barrier is the Japurá to gene sharing between other animals?
continue
Take the DNA samples and drop them in the test tubes.
Conclusion
It tells us two things.
First, you and the team have redefined the family trees of both Ivory-billed Araçari and their chewing lice, proving that there's more diversity in Amazonia than previously understood.
continue
Conclusion
By demonstrating that more than one species experiences a barrier to interbreeding along the lower reaches of the Japurá, you and the team have helped confirm the existence of a previously unrecognized Area of Endemism (recently named the Jaú.) Congratulations!
Through research like this, we can continue to identify and study species that are evolving in isolation and take appropriate actions to protect them and their habitats.
start over
Step 1: Physical Comparison
The first stage in determining family relationships between birds involves detailed comparisons of their physical traits: their size, coloration, and even their birdcalls.
Let's begin by taking measurements of birds from each population to see if they differ in size.
beginDo you see BIG differences in the birds' sizes?
(HINT: millimeters are tiny units of measurement.)
When the team measured the wings, bills, tails, and other features of several specimens from each Ivory-billed Araçari population, the birds appeared to be virtually the same size.
a.
- beak:126.3 mm
- wing:127.9 mm
- tail:90.7 mm
b.
- beak:127.2 mm
- wing:135.4 mm
- tail:89.6 mm
c.
- beak:127.0 mm
- wing:131.0 mm
- tail:90.1 mm
Next, listen to recordings of individuals and flocks from each population to compare
their birdcalls.
Do you see BIG differences in the birds' appearances?
(HINT: like humans, toucans can probably recognize faces from their own flock.)
You're right!
Sorry...
Remember, toucans' facial features and bills are key factors for distinguishing
different species.
When the team compared the appearance of several specimens from each Ivory-billed Araçari population, their plumage appeared to be virtually identical,
but their eye rings and bills differed.
Good job! You've confirmed the team's results by demonstrating that the three Ivory-billed Araçari populations appear to be almost identical—that's why they've long been considered members of the same species.
continueDo you hear BIG differences in the birdcalls?
(HINT: pay attention only to pitch, tone, and rhythm, not the speed or number of calls.)
Sorry...
Remember, the speed and number of the birdcalls can change based on the mood and size of the population.
When the team compared the calls and sonograms of several specimens from each Ivory-billed Araçari population, the pitch, tone, and rhythm of the calls were virtually identical
You're right!
When the team compared the calls and sonograms of several specimens from each Ivory-billed Araçari population, the pitch, tone, and rhythm of the calls were virtually identical.
Next, closely examine birds from each population to see if their plumage, eyes, and
bills differ.
Reclassifying Relationships
But by confirming the differences between their eye-ring and bill coloration, you've also helped each population earn recognition as a subspecies of Ivory-billed Araçari.
Pteroglossus azara mariae
Pteroglossus azara flavirostris
Pteroglossus azara azara
Let's see if the DNA of these birds tells the same story...
Step 2: Genetic Comparison
Today's scientists don't have to rely on appearances alone to classify species. They have another tool in their toolbox: genetic sequencing.
Take a DNA sample of birds from each Ivory-billed Araçari population to
determine their relationships.
Do you see ANY differences in the birds' genes?
(HINT: slide the bar slowly along the gene sequences, then select which bird's DNA doesn't match.)You're right!Are you sure?
Compare the DNA sequences again and select the one that is different.When the team compared samples of DNA taken from several specimens of each Ivory-billed Araçari population, the DNA of population C didn't match the other two!
Good job! You've confirmed the team's results by demonstrating that, although they appear almost identical, population C (P.a. azara) is genetically distinct from the other two Ivory-billed Araçari populations.
continue
Reclassifying Relationships
By confirming that population C is genetically distinct, you and the team have altered our understanding of the Ivory-billed Araçari family tree. Populations A and B share the same twig, while C branches off on its own.
This may mean that population C should be reclassified as a species,
not a subspecies!
Let's look at a map to see what's keeping these species on separate evolutionary tracks.
Step 3: Range Mapping
To understand why species begin evolving separately, scientists look at the landscape for
barriers that prevent interbreeding.
Let's examine the range maps to see what separates each Ivory-billed Araçari population.
beginStep 4: Parasite Comparison
To see if this same evolutionary pattern of isolation held true for other species, the team tried another experiment: comparing the genes of a common parasite.
Take DNA samples of Chewing Lice found on each Ivory-billed Aracari population to determine their relationships.
beginDo you see ANY differences in these louse genes?
(HINT: slide the bar slowly along the gene sequences, then select which louse's DNA doesn't match
the others.)You're right!Are you sure?
Compare the DNA sequences again and select the one that is different.When the team compared samples of DNA taken from several specimens of Chewing Lice found on the three Ivory-billed Aracari populations, the genes of the lice from population C were unique.
Good job! You've confirmed the team's results by demonstrating that, although the lice appear almost identical, those found on population C are genetically distinct from those found on the other two Ivory-billed Araçari populations.
continueReclassifying Relationships
By revealing the true family trees of both Ivory-billed Araçari and their parasites, you've demonstrated that there's more genetic diversity in Amazonia than previously understood.
Let's look at a map to see how this new knowledge affects Amazonia's Areas of Endemism.