Recent controversy about the use of the vertebrate fossil record for external calibration of molecular clocks centers on two issues, the number of dates used for calibration and the reliability of the fossil calibration date. Viewing matters from a palaeontological perspective, we propose three qualitative, phylogenetic criteria that can be used within a comparative framework for the selection of well-constrained calibration dates from the vertebrate fossil record. On the basis of these criteria, we identify three highly suitable new fossil calibration (...) dates for molecular clock estimates: the lungfish–tetrapod split (between 419 and 408 Ma), the bird–crocodile split (between 251 and 243 Ma), and the alligator–caiman split (between 71 and 66 Ma). Together with our previously suggested bird–lizard split (between 252 and 257 Ma), these four fossil dates span a range of very different ages. They are, in our opinion, more suitable for molecular clock calibration than the traditionally used mammal–bird split, which is less well constrained. We plea for closer interactions between paleontologists and molecular biologists in studying the timescale of vertebrate evolution. BioEssays 27:1069–1075, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

This article reports the results of an experiment involving 108 college students with varying backgrounds in biology. Subjects answered questions about the evolutionary history of sets of hominid and equine taxa. Each set of taxa was presented in one of three diagrammatic formats: a noncladogenic diagram found in a contemporary biology textbook or a cladogram in either the ladder or tree format. As predicted, the textbook diagrams, which contained linear components, were more likely than the cladogram formats to yield explanations (...) of speciation as an anagenic process, a common misconception among students. In contrast, the branching cladogram formats yielded more appropriate explanations concerning levels of ancestry than did the textbook diagrams. Although students with stronger backgrounds in biology did better than those with weaker biology backgrounds, they generally showed the same effects of diagrammatic format. Implications of these results for evolution education and for diagram design more generally are discussed. (shrink)

Biologists and historians often present natural history and molecular biology as distinct, perhaps conflicting, fields in biological research. Such accounts, although supported by abundant evidence, overlook important areas of overlap between these areas. Focusing upon examples drawn particularly from systematics and molecular evolution, I argue that naturalists and molecular biologists often share questions, methods, and forms of explanation. Acknowledging these interdisciplinary efforts provides a more balanced account of the development of biology during the post-World War II era.