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Articles 1 - 2 of 2
Full-Text Articles in Biology
Origin Of The Eumetazoa: Testing Ecological Predictions Of Molecular Clocks Against The Proterozoic Fossil Record, Kevin J. Peterson, Nicholas J. Butterfield
Origin Of The Eumetazoa: Testing Ecological Predictions Of Molecular Clocks Against The Proterozoic Fossil Record, Kevin J. Peterson, Nicholas J. Butterfield
Dartmouth Scholarship
Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge/eumetazoan and cnidarian/bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas …
Knowing When To Draw The Line: Designing More Informative Ecological Experiments, Kathryn L. Cottingham, Jay T. Lennon, Bryan L. Brown
Knowing When To Draw The Line: Designing More Informative Ecological Experiments, Kathryn L. Cottingham, Jay T. Lennon, Bryan L. Brown
Dartmouth Scholarship
Linear regression and analysis of variance (ANOVA) are two of the most widely used statistical techniques in ecology. Regression quantitatively describes the relationship between a response variable and one or more continuous independent variables, while ANOVA determines whether a response variable differs among discrete values of the independent variable(s). Designing experiments with discrete factors is straightforward because ANOVA is the only option, but what is the best way to design experiments involving continuous factors? Should ecologists prefer experiments with few treatments and many replicates analyzed with ANOVA, or experiments with many treatments and few replicates per treatment analyzed with regression? …