Natalia Villavicencio1, Emily Lindsey1, Anthony D. Barnosky1, Charles Marshall1!Enrique Bostelmann2 (and much credit to Fabiana Martín3 and Luis Borrero4)!

!1UC Berkeley, USA 2Museo Nacional de Historia Natural, Uruguay!

3CEHA, IPA, Universidad de Magallanes, Chile 4CONICET, Argentina!

Ecological state change and megafaunal extinctions in southern Patagonia, South America!

 

Joaquin  Arroyo-­‐Cabrales  Jessica  Blois  Luis  Borrero  Enrique  Bostelman    Jose  Capriles  Flores  Edward  Davis    Rodolfo  Dirzo  Tom  Guilderson  Elizabeth  Hadly  Melissa  Kemp  Claudio  Latorre  Fabiana  MarGn  Jean  Noel  MarInez  Greg  McDonald    Chris  Moy  Alexis  Mychajliw  Gustavo  PoliIs    Jose  Prado  Ricardo  Souberlich  Ascanio  Rincon  Blaine  Schubert  Tom  Stafford  Anna  Thanukos  Lisa  White  

South America Holds Promising Information!•  Most taxa lost in Quaternary megafauna extinctions!•  Archaeological and paleoclimate records available !•  Temporal overlap between Climate change, human arrival and extinctions!•  Extinction chronology shows interesting pattern!

 

Barnosky  et  al.,  2004  

Southern Patagonia

Pollen  record  site  

Lago  Guanaco  Torres  del  Paine  

Río  Rubens  

Cerro  Benítez,  ÚlAma  Esperanza  sites  

Luis  Borrero  

Fabiana  MarGn  

Archeological  Paleontological  sites  

Cuevas  Lago  SoLa  1  y  4  

Cueva  Escondida  

Alero  Dos  Herraduras  

Cueva  del  Milodón  

Cueva  del  Medio  

Cueva  Chica  Alero  Pedro  Cárdenas  

Cerro  Benítez  

Holocene

Late Pleistocene

Role of biotic versus abiotic drivers in causing ecological state changes?!

•  3 megafauna species!

!•  Many humans!•  Warmer!•  Forest/shrubland dominant!

•  ~12 megafauna species!!

!

!!•  Few humans!•  Cold!•  Grassland dominant!

Today Pleistocene Lake Terrace

Cueva  del  Milodón  

Alero  Dos  Herraduras  

Last Glacial Maximum

GLACIER

LAKE

Cerro  Benítez  

Alero  Dos  Herraduras  

Cueva  del  Milodón  

Cerro  Benítez  

State Change-Climate!

Alkenone-­‐based  SST  (°C)  Pacific  Coast  

Glacier  retreat  (km)  

Temperature  (°C)  AntacAca  

Glacier  retreat  (km)  

Warming  Onset:  ~14.8  kyBP  

 

Warming  End:  ~10.1  kyBP  

From  Kilian  and  Lamy  2012  

State Change-Climate!

Alkenone-­‐based  SST  (°C)  Pacific  Coast  

Glacier  retreat  (km)  

Temperature  (°C)  AntarcAca  

Glacier  retreat  (km)  

Warming  Onset:  ~14.8  kyBP  

 

Warming  End:  ~10.1  kyBP   Cooling:  

~12.4-­‐  11  kyBP  

AntarcAc  Cold  Reversal  ACR  

Lago  Guanaco  Moreno  et  al.,  2010  

12  

11  

10  

9

8

7

6

5

4

3

2

1

0Nothofagus-­‐Poaceae  Index  

Torres  del  Paine  Heusser  1995  

State Change-Vegetation!Río  Rubens  

Markgraf  and  Huber  2010  

Nothofagus    

8

9

5

4

3

1

0Poaceae    

Pollen  %  

14  

12  

10  

11  

7

13  

Temperature  (°C)  

Lago  Guanaco  Torres  del  Paine  

Río  Rubens  

Cerro  Benítez,  ÚlAma  Esperanza  sites  

N  

11.5  ky  BP        

~11  ky  BP        

~10.5  ky  BP        

State Change-Fire Frequency!

hgp://media.nj.com/star-­‐ledger/photo/2012/02/10510812-­‐standard.jpg  

Río  Rubens  (52°04’S)  

Torres  del  Paine  (50°59’S)  

Huber  et  al.,  2004  

Torres del Paine after a forest fire!

Torres  del  Paine  

Río  Rubens  

Cerro  Benítez,  ÚlAma  Esperanza  sites  

N  

~10.6  ky  BP      ~11  ky  BP  

     

Charcoal  

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Human-­‐ExInct  Megafauna  Coexistence  

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Megafauna extinction chronology - AMS on bone, dung, skin and hair!Human occupation chronology-dates on charcoal and modified bones!

Open landscape. Grassland dominates over forests/shrubland!

Glacial lake retreating, land available to colonize. Rapid landscape change. .!

~9.5! Megafauna species are gone!

Humans arrive!~13!

Warming onset over Antartica!~14.8!

~14.6! Earliest Megafauna dates!

~10.1!Warming trend over Antartica ends!

~11! ACR ends! Vegetation change begins; Nothofagus increases!

~10.5!

~11.5! More Humans?!~12.4! ACR begins!

~14.6!

~ 9.5!

~14.8!

ABIOTIC!(Climate)!

DRIVERS OF STATE-CHANGE!

BIOTIC!(People)!

Increase vegetational diversity!

Decrease megafauna diversity!

~10.1!

~13!

InteracAon  

?  

?  Synergy    

~10.5!

~11.5!

Mosaic vegetation !!Climate change !!

But not the same over all of South America … future work!

Barnosky  and  Lindsey  2010  

Next Steps!•  More radiocarbon dates to tighten megafauna

extinction chronology!

•  Ecosystem modeling to understand how many animals per species would have to disappear per generation in order to cause extinction over hundreds or thousands of years!

•  Comparisons with other regions of South America!

IB259: Brett Archuleta!"Jeffrey Benca!"Seth Kauppinen !"Deise Cruz-Santos!"Cheryl Hojnowski!"Renske Kirchholtes!"Emily Moskal!"Guin Wogan!

!FIELD WORK: Fabiana Martín!

! ! Luis Borrero!" " Daniel Karmelic!

!R-code for CIs: Corey Bradshaw "

" " Frédérik Saltré!!

For helpful discussion: Allison Stegner!" " " Juan E. Guevara!" " " UCMP community!

!

Many thanks to: !