My Research Interests
- Worldview constraints on environmental literacy
Student learning is often constrained by worldview commitments (often entirely implicit) that predispose students to resist consideration and integration certain
kinds of culturally important environmental knowledge (e.g., evolutionary theory).. This is problematic because these commitments are often closely associated with deep seated religious convictions
that are difficult to address in the context of a secular university. My research focuses on identifing the nature and origins of worldview commitments
and on developing pedagogical strategies for surmounting these obstacles.
- Effects of thermal cycles on fish life history patterns
"You can keep some of the fish comfortable all of the time or all of the fish comfortable some of the time, but you can't keep all the fish comfortable all of the time" (with all due apologies to Abe Lincoln). If fish of a given species show heritable genetic variation for temperature preference, and if preference is related to growth performance, then a group of fish reared at a stable temperature should show greater variation in growth rates than fish raised in thermally variable environments. I have completed several relevant experiments and my findings are consistent with this hypothesis.
- Causes of "stunting" fish populations
"Stunting" is typically assumed to a result of overcrowding and intensified competition for limited food resources. However, available evidence does not support this supposition. I am exploring the possibility that stunting is instead an adaptive life history response to environmental conditions favoring high survival and growth rates of early history stages.
- Early life history and tactical allocation of resources
See Siems, D.P. & Sikes, R.S. 1998. Tactical tradeoffs between growth and reproduction in reponse to temporal variation in food supply. Environmental Biology of Fishes 53: 319-329.
- Natural history, evolution, and systematics of fishes
Evolutionary models of diversification generally assume an ever-branching phylogenetic tree and the resulting "tree of life" has been called the dominant visual metaphor in evolutionary biology. In contrast to this view, there is mounting evidence that lineages separate and re-unite in response to climatic and astronomical cycles. When global productivity is low, population sizes (on average) shrink and temporarily retreat to isolated metapopulations patches of suitable habitat. These smaller isolated populations then undergo independent changes in allele frequency as a result of genetic drift and, perhaps, natural and/or sexual selection. As global productivity increases, temporarily isolated populations again come into contact and these anastomizing lineages produce a expanded range of phenotypes. Natural selection sorting among these variant phenotypes produces rapid, and relatively synchronous, flurries of diversification across taxa. See also Hatch, J.T., Schmidt, K.T., Siems, D.P., Underhill, J.C., Bellig, R.A., & Baker, R.A. 2003. A New Distributional Checklist of Minnesota Fishes, With Comments on Historical Occurrence. Journal of the Minnesota Academy of Sciences.
- Roles of experience and learning in evolutionary and ecological processes
- Intraspecific variation and phenotypic plasticity
- Effects of indeterminate causality in ontogenetic and phylogenetic history
- History and philosophy of biology -- evolutionary epistemology
- Biology and society, especially the mythogenic role of evolutionary ecology
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