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Functional selection and population divergence
In many species of gobiid fishes native to island streams, juveniles are flushed to the ocean after hatching and must climb massive waterfalls (up to 10,000x body length) to return to adult habitats. Before reaching waterfalls these fish must swim through gauntlets of predators. My lab is collaborating with Heiko Schoenfuss and Matt Julius (St. Cloud State) and Margaret Ptacek (Clemson) on studies of biomechanics, ecology, and population genetics that examine how these remarkable fishes survive such extreme demands, focusing on species from the Hawaiian Islands.
Functional studies have examined waterfall-climbing mechanics in goby juveniles and adults (Schoenfuss and Blob 2003, 2007; Blob et al. 2006, 2007); recolonization of volcanically disturbed streams (Schoenfuss et al. 2004); goby feeding mechanics and performance (Maie et al. 2009a, 2009b, 2014; Cullen et al. 2013); and differences in the performance of goby suckers (Maie et al. 2007; Maie et al. 2012, 2013) and muscle fiber types (Cediel et al. 2008; Maie et al. 2011) across species. We have extended this work to evaluate morphological and genetic divergence between populations across the archipelago (Hawai’i vs. Kaua’i) subject to different levels of selection for climbing performance versus evasion of predators (Schoenfuss et al. 2013; Moody et al. 2015). We found significant morphological divergence between juveniles from these islands that met our predictions based on the primary pressure each presents: streamlined bodies to improve climbing on younger Hawai’i, where waterfalls are close to shore, versus taller bodies to aid thrust production for predator escape on older Kaua’i, where most falls have eroded further inland (Blob et al. 2008, 2009, 2010). We have also conducted laboratory selection experiments for both climbing performance and predator evasion, providing evidence that these pressures generated observed patterns of morphological divergence through the tradeoff between their competing demands (Blob et al. 2008, 2009, 2010).
This material is based upon work supported by the National Science Foundation under Grant No. 0817794. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.
Current directions
• We are currently comparing locomotor performance data from these populations to test if morphological differences do, in fact, relate to performance differences that provide a basis for evolutionary divergence by selection.
• We are also expanding this project to comparisons with related species in other ocean basins, including the Caribbean (Schoenfuss et al. 2011; Kawano et al. 2013) and Indian Ocean, testing the generality of patterns identified in the Hawaiian Islands.
Related publications
Blob, R. W., S. M. Kawano, K. N. Moody, W. C. Bridges, T. Maie, M. B. Ptacek, M. L. Julius, H. L. Schoenfuss. 2010. Morphological selection and the evaluation of potential tradeoffs between escape from predators and the climbing of waterfalls in the Hawaiian stream goby Sicyopterus stimpsoni. Integrative and Comparative Biology 50: 1185-1199. Available HERE
Blob, R. W., W. C. Bridges, T. Maie, R. A. Cediel, M. M. Bertolas, M. B. Ptacek, M. L. Julius, H. L. Schoenfuss. 2008. Morphological selection in an extreme flow environment: body shape and waterfall-climbing success in the Hawaiian stream fish Sicyopterus stimpsoni. Integrative and Comparative Biology 48: 734-749. Available HERE (corregendium)
Blob, R. W., Wright, K. M, Becker, M, Maie, T., Iverson, T. J., Julius, M. L., Schoenfuss, H. L. 2007. Ontogenetic change in novel functions: waterfall climbing in adult Hawaiian gobiid fishes. Journal of Zoology 273: 200-209. Available HERE
Blob, R. W., Rai, R., Julius, M. L., Schoenfuss, H. L. 2006. Functional diversity in extreme environments: effects of locomotor style and substrate texture on the waterfall-climbing performance of Hawaiian gobiid fishes. Journal of Zoology 268: 315-324. Available HERE
Cediel, R. A., R. W. Blob, G. D. Schrank, R. Plourde, and H. L. Schoenfuss. 2008. Muscle fiber type distribution in climbing Hawaiian gobioid fishes: ontogeny and correlations with locomotor performance. Zoology (Jena) 111: 114-122. Available HERE
Cullen, J. A., T. Maie, H. L. Schoenfuss, R. W. Blob. 2013. Evolutionary novelty versus exaptation: Oral kinematics in feeding versus climbing in the waterfall-climbing Hawaiian goby Sicyopterus stimpsoni. PLoS One 8: e53274. doi:10.1371/journal.pone.0053274. Available HERE
Julius, M. L., Blob, R. W., Schoenfuss, H. L. 2005. The survival of Sicyopterus stimpsoni, an endemic Hawaiian gobiid fish, relies on the hydrological cycles of streams: evidence from changes in algal composition of diet through growth stages. Aquatic Ecology 39: 473-484. Available HERE
Kawano, S. M., W. C. Bridges, H. L. Schoenfuss, T. Maie, R. W. Blob. 2013. Differences in locomotor behavior correspond to different patterns of linear and nonlinear morphological selection in two species of waterfall-climbing gobiid fishes. Evolutionary Ecology 27:949-969. Available HERE
Leonard, G., T. Maie, K. Moody, G. Schrank, R.W. Blob, H. L. Schoenfuss. 2012. Finding paradise: cues directing the migration of the waterfall climbing Hawaiian gobioid fish Sicyopterus stimpsoni. Journal of Fish Biology 81:903-920. Available HERE
Maie, T., S. Furtek, H. L. Schoenfuss, R. W. Blob. 2014. Feeding performance and functional modulation of the Hawaiian sleeper, Eleotris sandwicensis (Gobiodei: Eleotridae): implications for selection pressures on prey. Biological Journal of the Linnean Society 111:359-374. Available HERE
Maie, T., H. L. Schoenfuss, R. W. Blob. 2013. Musculoskeletal determinants of pelvic sucker function in Hawaiian stream gobiid fishes: interspecific comparisons and allometric scaling. Journal of Morphology 733-742. Available HERE
Maie, T., H. L. Schoenfuss, R. W. Blob. 2012. Performance and scaling of a novel locomotor structure: adhesive capacity of climbing gobiid fishes. Journal of Experimental Biology 215:3925-3936. Available HERE (Featured Inside JEB)
Maie, T., A. B. Meister, G. L. Leonard, G. D. Schrank, R. W. Blob, H. L. Schoenfuss. 2011. Jaw muscle fiber type distribution in Hawaiian gobioid stream fishes: histochemical correlations with feeding ecology and behavior. Zoology (Jena) 114:340-347. Available HERE
Maie, T., M. P. Wilson, H. L. Schoenfuss, R. W. Blob. 2009. Feeding kinematics and performance of Hawaiian stream gobies, Awaous guamensis and Lentipes concolor: linkage of functional morphology and ecology. Journal of Morphology 270: 344-356. Available HERE
Maie, T., H. L. Schoenfuss, R. W. Blob. 2009. Jaw lever analysis of Hawaiian gobioid stream fishes: a simulation study of morphological diversity and functional performance. Journal of Morphology 270: 976-983. Available HERE
Maie, T., H. L. Schoenfuss, and R. W. Blob. 2007. Ontogenetic scaling of body proportions in waterfall-climbing gobiid fishes from Hawai’i and Dominica: implications for locomotor function. Copeia 2007: 756-765. Available HERE
Moody, K. N., S. N. Hunter, M. J. Childress, R. W. Blob, H. L. Schoenfuss, M. J. Blum, M. B. Ptacek. 2015. Local adaptation despite high gene flow in the waterfall-climbing Hawaiian goby, Sicyopterus stimpsoni. Molecular Ecology 24:545-563. Available HERE (Featured in Molecular Ecology News and Views)
Schoenfuss, H. L., T. Maie, K. N. Moody, K. E. Lesteberg, R. W. Blob, T. C. Schoenfuss. 2013. Stairway to heaven: evaluating levels of biological organization correlated with the successful ascent of natural waterfalls in the Hawaiian stream goby, Sicyopterus stimpsoni. PLoS One 8: e84851. doi:10.1371/journal.pone.0084851. Available HERE
Schoenfuss, H. L., T. Maie, S. M. Kawano, R. W. Blob. 2011. Performance across extreme environments: comparing waterfall climbing among amphidromous gobioid fishes from Caribbean and Pacific islands. Cybium 35:361-369. Available HERE
Schoenfuss, H. L., and R. W. Blob. 2007. The importance of functional morphology for fishery conservation and management: applications to Hawaiian amphidromous fishes. Bishop Museum Bulletin in Cultural and Environmental Studies 3: 125-141. Available HERE
Schoenfuss, H. L., M. L. Julius, and R. W. Blob. 2004. Colonization of a recent, volcanically formed freshwater habitat: an example of primary succession. Ichthyological Explorations of Freshwaters 15: 83-90. Available HERE
Schoenfuss, H. L. and R. W. Blob. 2003. Kinematics of waterfall climbing in Hawaiian freshwater fishes (Gobiidae): vertical propulsion at the aquatic-terrestrial interface. Journal of Zoology 261: 191-205. Available HERE
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