Limitations and Next Steps

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Pleistocene History of Amazonian Birds as
Reconstructed by Ecological Niche Modeling
Elisa Bonaccorso Natural History Museum and
Biodiversity Research Center, and Department of
Ecology and Evolutionary Biology The University
of Kansas
2
THE REFUGIA HIPOTHESIS
Haffer, J. 1969. Speciation in Amazonian forest
birds
Speciation of birds in the Amazon had been
produced by cycles of expansion and contraction
of forest environments during the Pleistocene
During glacial periods, reduced temperature and
humidity in the lowlands of South America left
relatively small islands of tropical
rainforests surrounded by xeric habitats
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THE REFUGIA
Haffer, J. 1969. Speciation in Amazonian forest
birds
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Palynological Evidence
Colinvaux et al. 1996
Western Amazon was forested in the Pleistocene
as it is now
(One site in north-western Amazon)
Hoorn C. 1997
Palynological data give no indication of major
vegetational changes in the drainage basin (of
the Amazon)
(Amazon Fan)
ALTERNATE HYPOTHESES
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OBJECTIVE
To study how changes in climatic conditions
during the Last Glacial Maximum might have
affected the patterns of distribution of
Amazonian forest and savanna species, using
ecological niche modeling
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Testing Haffers Hipothesis
Predictions
Reduction and fragmentation in the potential
distributions of forest birds
Expansion in the potential distributions of
savanna birds
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Ecological Niche Modeling GARP
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Data Set
Aspect Slope Topographic Index
Topographic Layers1
Present2
Temperature Precipitation
Climatic Layers
21,000 Years Ago3
Hadley Centre Canadian Center
1US Geological Survey (http//edcdaac.usgs.gov/gto
po30/hydro/)
2Intergovernmental Panel on Climate Change
(http//www.ipcc.ch)
3Paleoclimate Modeling Intercomparison Project
(http//www-lsce.cea.fr/pmip/)
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Data Set
Forest species
Campephilus rubricollis Formicarius
colma Phylidor pyrrhodes Automolus
infuscatus Pipra coronata Tangara mexicana
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Data Set
Savanna species
Athene cunicularia Sublegatus modestus Sporophila
plumbea Emberizoides herbicola Ammodramus
humeralis
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Forest species an example
Tangara mexicana
Occurrence points
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Forest species an example
Tangara mexicana
Present Potential Distribution
Low model agreement ( absence)
High model agreement ( presence)
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Forest species an example
Tangara mexicana
Potential Distribution
Present
Hadley Scenario (21,000 yrs ago)
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Forest species an example
Tangara mexicana
Potential Distribution
Present
Hadley Scenario (21,000 yrs ago)
Canadian Scenario (21,000 yrs ago)
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Savanna Species an example
Athene cunicularia
Occurrence points
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Savanna Species an example
Athene cunicularia
Present Potential Distribution
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Savanna Species an example
Athene cunicularia
Potential Distribution
Present
Hadley Scenario (21,000 yrs ago)
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Savanna Species an example
Athene cunicularia
Potential Distribution 21,000 Years Ago
Present
Hadley Scenario (21,000 yrs ago)
Canadian Scenario (21,000 yrs ago)
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Forest All Species
Present Potential Distribution
Campephilus rubricollis Formicarius
colma Phylidor pyrrhodes Automolus
infuscatus Pipra coronata Tangara mexicana
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Forest All Species
Potential Distribution
Present
Hadley Scenario (21,000 yrs ago)
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Forest All Species
Potential Distribution
Present
Canadian Scenario (21,000 yrs ago)
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Forest All Species
Potential Distribution 21,000 Years Ago Hadley
and Canadian averaged
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Savanna All Species
Present Potential Distribution
Athene cunicularia Sublegatus modestus Sporophila
plumbea Emberizoides herbicola Ammodramus
humeralis
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Savanna All Species
Potential Distribution
Present
Hadley Scenario (21,000 yrs ago)
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Savanna All Species
Potential Distribution
Present
Canadian Scenario (21,000 yrs ago)
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Savanna All Species
Potential Distribution 21,000 Years Ago Hadley
and Canadian averaged
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Haffers Refugia?
Potential Distribution 21,000 Years Ago Forest
All Species Hadley and Canadian
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Haffers Refugia?
IMERI
GUIANA
BELEM
NAPO
INAMBARI
RONDONIA
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Conclusions so far

• Potential distribution of forest birds contracted
  and fragmented during the last glacial maximum
• Potential distribution of savanna birds expanded
  during the same period
• Contraction of potential distributions of forest
  species may have created places that retained
  suitable habitat during the last Glaciation
• But, were these changes strong enough to produce
  speciation in the Amazon Basin?

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Limitations and Next Steps

• localities
• Broaden study in terms of taxa included,
  particularly towards groups that have speciated
  within the Basin
• Enrich the suite of climate scenarios included so
  as to reduce sensitivity to particular
  assumptions in building climatologies
• Move from Global to Regional climate
  scenarios
• Need to extend study to focus on key plant taxa
  (indicator species) in forest versus savanna
  habitats

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Acknowledgements
American Museum of Natural History, Paul Sweet
and Joel Cracraft Field Museum of Natural
History Los Angeles County Museum of Natural
History, Kimball Garrett Museum of Vertebrate
Zoology - University of California,
Berkeley Museum of Comparative Zoology - Harvard
University Smithsonian Institution, Chris
Milensky and James Dean Yale Peabody Museum of
Natural History - Yale University
Mark Robbins, KU Natural History Museum
Collection Study Grant from AMNH
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Thanks! elisab_at_ku.edu