1. Dept. of Biology and Chemistry
Benthic vs. Planktivorous Threespine Stickleback Fish (Gasterosteus aculeatus)
Peter J. Park
Dept. of Biology and Chemistry
Nyack College
June 22, 2012
My research has focused on the brain and behavior – and their relationship to ecology and evolution.

2. Learning Objectives 1. To introduce a “supermodel”
2. To turn shapes into numbers
3. To provide and instructional walk-through of shape analysis software (free software!)
4. To minimize the math (but not without providing references)
5. To teach concepts in ecology and evolution using a single species
6. To encourage fun applications

3. Proximate vs. Ultimate Causation

4. Gasterosteus aculeatus
The Model
Gasterosteus aculeatus
species complex
• 3 forms: marine, sea-run, freshwater.
• freshwater populations were founded by sea-run stickleback.
• occur along coastal waters of the northern hemisphere.
• Sea-run stickleback colonized a vast array postglacial lakes. (In southcentral Alaska, lakes are less than 20,000 years old. )
• derived lake populations: natural, replicated recently derived experiments
•contemporary sea-run populations: can be used to infer ancestral condition
Show stickleback
Show mini-plot
Show major plot: “This is Cook Inlet, AK”
Matanuska-Susitna Valley – Alaska Range (left) and Talkeetna Mountains (right)
The threespine stickleback is an excellent model to study evolution. 4

5. Sea-run threespine stickleback

6. Ecology Evolution Proximate (present) mechanisms
Independently-derived freshwater populations
Proximate (present) mechanisms
Ecology
Evolution
Ultimate (past) mechanisms
Living representatives of sea run fish are analogs of the ancestor 6 6

7. Stickleback: at the interface of ecology then and now
Migratory, breeding sea-run fish can get into lakes.
If lake then becomes land-locked, then a derived freshwater population is borne, founded by these sea-run fish.
Along opposite ends of a continuum of lake types are shallow lakes and deep lakes.
In these lakes, anatomical changes in fish from derived freshwater populations is driven by what they eat.
Shallow lakes are dominated by large benthic invertebrates  benthic stickleback
Deep lakes do not have benthic invertebrates, making smaller plankton the predominant food source  planktivore stickleback

8. Threespine Stickleback Adaptive Radiation8

9. Meet the ancestor

10. Benthic-Planktivore Ecological Dichotomy
The Model
Benthic-Planktivore Ecological Dichotomy
Sea-Run Ancestor
Shallow Lake
structurally complex
benthic invertebrates
Deep Lake
structurally simple
plankton * 10

11. Show videos of lakes

12. • subjects: field-caught 1-year-old juveniles
Protocol
• subjects: field-caught 1-year-old juveniles
• motivation: food deprivation for 24-36hrs
• 2 trials per day
• 50 trial maximum
Collection of subjects
collection method: Gee minnow traps set overnight

14. PAUSE

15. Adaptation is driven by prey specialization
The Model
Adaptation is driven by prey specialization
Benthics
Planktivores (Limnetics)
Snout shape helps fish handle their respective prey more efficiently
Specialize on:
Detecting prey:
Handling prey:
Maneuvering:
Foraging behavior:
Benthic invertebrates
Small Eyes
Short Snout
Deep-bodied
Forages on benthos
Plankton
Large Eyes
Long Snout
Streamlined
Forages in open water
(Lavin and McPhail 1985, 1986; Walker 1997; Aguirre 2007 )

16. Body Shape
(Walker 1997; Aguirre et al. 2009)

17. (Park & Aguirre unpub. data)
Body Shape
(17.02% )
(33.85%)
(Park & Aguirre unpub. data)

18. Allopatric Populations – divergent ecotypes occur in different lakes
BENTHICS
PLANKTIVORES

19. Sympatric Populations – divergent ecotypes occur in the same lake
BENTHICS
BENTHICS
PLANKTIVORES

21. THE BIG PICTURE?

22. Scales
Dorsal Fin
Tail Fin
Jaw
Anal Fin
Pectoral Fin
Pelvic Fin 22

23. suction feeding, grazing
Swordfish
Sheepshead
Rockfish
Mackerel
Barracuda
Sheephead
Pelagic Fish
elongate, slender
poor at turning
ram or filter feeding
Bottom-dwelling Fish
stout, deep-bodied
highly maneuverable
suction feeding, grazing 23

24. ACKNOWLEDGEMENTS Michael A. Bell Windsor E. Aguirre Joan M. Miyazaki
Deborah A. Spikes
Michael P. Kroessig
Marvin H. O’Neal III
Kathleen Nolan
Darrel R. Falk
ABLE
Nyack College
Stony Brook University