A recent paper of mine was published today online in the January issue of Ecology:
Oufiero, C.E., M.R. Walsh, D.N. Reznick, and T. Garland, Jr. 2011. Swimming performance trade-offs across a gradient in community composition in Trinidadian killifish (Rivulus hartii). Ecology 92:170-179.
In this paper we examined the sprint speed and critical swimming speed of R. hartii from three different communities across three river drainages in Trinidad. We set out to determine if fish from areas with large piscivorous predators (HP) had increased sprint speeds and reduced critical swimming speeds (a measure of endurance) compared to two low predation sites. We also compared the two low predation sites to determine if there is divergence in these swimming performance measures based on the presence of guppies (Poecilia reticulata). We found that HP fish had increased sprint speeds and reduced critical swimming speeds, consistent with predictions; but no difference in the two low predation sites. We also found differences in caudal fin length and fineness ratio, with HP fish having longer tails and increased fineness ratio, suggesting a more elongate and slim body. However, neither of these traits were significant predictors of locomotor performance. Our results demonstrate the effect of predators on locomotor abilities, and morphological characteristics. The replicate rivers suggests these traits have evolved in response to selection from predators. However, more experiments are needed to determine the ecological significance of the divergence in these traits and if there is genetic basis to these differences in swimming performance. For example, determining if individuals with increased sprint speeds have increased survival in natural streams.
Please feel free to email me for a reprint of the paper and some more information can be found under Swimming Performance in Research.
Here is an example of one of the low predation collection sites where R. hartii occur with guppies.