Biological Scaling Problems and Solutions in Amphibians.
Size is a primary feature of biological systems that varies at many levels, from the organism to its constituent cells and subcellular structures. Amphibians populate some of the extremes in biological size and have provided insight into scaling mechanisms, upper and lower size limits, and their physiological significance. Body size variation is a widespread evolutionary tactic among amphibians, with miniaturization frequently correlating with direct development that occurs without a tadpole stage. The large genomes of salamanders lead to large cell sizes that necessitate developmental modification and morphological simplification. Amphibian extremes at the cellular level have provided insight into mechanisms that accommodate cell-size differences. Finally, how organelles scale to cell size between species and during development has been investigated at the molecular level, because subcellular scaling can be recapitulated using Xenopus in vitro systems.
Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071.
Daniel L
DL
Levy
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720.
Rebecca
R
Heald
D000663:Amphibians / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development; D000818:Animals; D005075:Biological Evolution; D049628:Body Size; D048429:Cell Size; D059646:Genome Size; D010063:Ovum / Q000166:cytology; D011003:Ploidies; D014981:Xenopus / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development