The parasite connection in ecosystems and macroevolution.

In addition to their obvious negative effects ("pathogens"), endoparasites of various kinds play an important role in shaping and maintaining modern animal communities. In the long-term, parasites including pathogens are indispensable entities of any ecosystem. To understand this, it is essential that one changes the viewpoint from the host's interests to that of the parasite.

A mechanism for tooth pattern reversal in sharks: The polarity switch model.

In many shark families the tooth cusps are deflected in a posterior direction. In tooth pattern reversal, one (or a few) tooth families have cusps which are deflected in an anterior direction. This tooth pattern reversal is attributed to a splitting of hypothetical tooth protogerms.