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Benthic vs. Planktivorous Threespine Stickleback Fish ( Gasterosteus aculeatus )

Benthic vs. Planktivorous Threespine Stickleback Fish ( Gasterosteus aculeatus ). Peter J. Park Dept. of Biology and Chemistry Nyack College June 22, 2012. Learning Objectives. 1. To introduce a “supermodel” 2. To turn shapes into numbers

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Benthic vs. Planktivorous Threespine Stickleback Fish ( Gasterosteus aculeatus )

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  1. Benthic vs. Planktivorous Threespine Stickleback Fish (Gasterosteus aculeatus) Peter J. Park Dept. of Biology and Chemistry Nyack College June 22, 2012

  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. 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

  5. Sea-run threespine stickleback

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

  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 largebenthic invertebratesbenthic stickleback • Deep lakes do not have benthic invertebrates, making smallerplankton the predominant food source planktivore stickleback

  8. Threespine Stickleback Adaptive Radiation

  9. Meet the ancestor

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

  11. Show videos of lakes

  12. 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

  13. PAUSE

  14. The Model Adaptation is driven by prey specialization Benthics Planktivores (Limnetics) 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 )

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

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

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

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

  19. THE BIG PICTURE?

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

  21. 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

  22. 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

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