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Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter Dec 2004

Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter

Biology Faculty Research

The generality and causes of Bergmann's rule have been debated vigorously in the last few years, but Bergmann's clines are rarely explained in the context of life-history theory. We used both traditional and phylogenetic comparative analyses to explore the causes of latitudinal and thermal clines in the body size of the eastern fence lizard (Sceloporus undulatus). The proximate mechanism for larger body sizes in colder environments is delayed maturation, which results in a greater fecundity but a lower survival to maturity. Life-history theory predicts that a higher survivorship of juveniles in colder environments can favor the evolution of a Bergmann's …


A Modeling Study Of Benthic Detritus Flux's Impacts On Heterotrophic Processes In Lake Michigan, Changsheng Chen, Lixia Wang, Jianhua Qi, Hedong Liu, Judith Wells Budd, David J. Schwab, Dmitry Beletsky, Henry Vanderploeg, Brian Eadie, Thomas Johengen, James Cotner, Peter J. Lavrentyev Jul 2004

A Modeling Study Of Benthic Detritus Flux's Impacts On Heterotrophic Processes In Lake Michigan, Changsheng Chen, Lixia Wang, Jianhua Qi, Hedong Liu, Judith Wells Budd, David J. Schwab, Dmitry Beletsky, Henry Vanderploeg, Brian Eadie, Thomas Johengen, James Cotner, Peter J. Lavrentyev

Biology Faculty Research

Effects of sediment resuspension-induced benthic detrital flux on the heterotrophic part of the microbial food web in Lake Michigan were examined using a three-dimensional (3-D) coupled biological and physical model. The model was driven by the realistic meteorological forcing observed in March 1999. Wind-induced surface wave dynamics were incorporated into the physical model to generate the bottom flux. The model-generated benthic detrital flux was assumed to be proportional to the difference between model-calculated and critical stresses at the bottom. The model results indicate that detrital flux at the bottom was a key factor causing a significant increase of phosphorus and …


Heritability Of Nectar Traits: Why Do We Know So Little?, Randall J. Mitchell Jun 2004

Heritability Of Nectar Traits: Why Do We Know So Little?, Randall J. Mitchell

Biology Faculty Research

Although floral and extrafloral nectar traits are important for plant reproduction and defense, we know little about their genetic basis. Only a handful of studies have quantified heritable variation for nectar traits, primarily in controlled environments that minimize environmental variation. Most such studies have reported strong genetic influences, with heritabilities often >0.35. However, because nectar traits are often very responsive to environmental variation, even substantial amounts of genetic variation may be swamped out in the,field. Environmental variation deserves to be studied in its own right, including exploration of genotype X environment interaction for nectar traits . Most genetic studies of …


Distribution And Dynamics Of Nitrogen And Microbial Plankton In Southern Lake Michigan During Spring Transition 1999-2000, Wayne S. Gardner, Peter J. Lavrentyev, Joann F. Cavaletto, Mark J. Mccarthy, B. J. Eadie, Thomas Johengen, James Cotner Mar 2004

Distribution And Dynamics Of Nitrogen And Microbial Plankton In Southern Lake Michigan During Spring Transition 1999-2000, Wayne S. Gardner, Peter J. Lavrentyev, Joann F. Cavaletto, Mark J. Mccarthy, B. J. Eadie, Thomas Johengen, James Cotner

Biology Faculty Research

[ 1] Ammonium and amino acid fluxes were examined as indicators of N and microbial food web dynamics in southern Lake Michigan during spring. Either (NH4+)-N-15 or a mixture of N-15-labelled amino acids (both at 4 muM N final concentration) was added to Lake Michigan water. Net fluxes were measured over 24 h under natural light and dark conditions using deck-top incubators and compared to microbial food web characteristics. Isotope dilution experiments showed similar light and dark NH4+ regeneration rates at lake ( 6 versus 5 nM N h(-1)) and river-influenced ( 20 versus 24 nM N h(-1)) sites. Ammonium …


Maintenance Of Androdioecy In The Freshwater Shrimp, Eulimnadia Texana: Field Estimates Of Inbreeding Depression And Relative Male Survival, Stephen C. Weeks, Richard L. Bernhardt Feb 2004

Maintenance Of Androdioecy In The Freshwater Shrimp, Eulimnadia Texana: Field Estimates Of Inbreeding Depression And Relative Male Survival, Stephen C. Weeks, Richard L. Bernhardt

Biology Faculty Research

Androdioecy is a rare form of reproduction, only found in a few plant and animal species, wherein males co-exist with hermaphrodites. This particular form of mixed mating (mixtures of outcrossing and self-fertilization) is predicted to be evolutionarily unstable, with most androdioecious populations thought to be in a transition from hermaphroditism to dioecy, or vice versa. One well-studied androdioecious species is the freshwater clam shrimp Eulimnadia texana. A model by Otto et al. (1993), exploring the stability of this androdioecious system, predicts that males can co-exist with hermaphrodites when males fertilize an average of over twice the number of offspring that …