Convergent Evolution

A Monarch Butterfly caterpillar feedsIt’s official: ICR “news” articles are now called Creation Science Updates. Or rather “Update” – they haven’t really mastered this pluralisation thing. The first article of this brave new era is called How Some Insects Can Eat Poisonous Plants, by Brian Thomas.

The chemicals used by milkweeds (including swan plants) and similar as a poison to deter herbivorous insects are known as cardenolides. They work by blocking the sodium pumps in cell membranes, but a handful of organisms are resistant to its effects. The most famous of these is the monarch butterfly, which was already known to have a amino-acid substitution mutation (referred to as “N122H”) in the gene coding for the pump that contributed to the butterfly’s immunity. A new paper in PNASCommunity-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase (pdf) – takes a look at the underlying genetics of all 18 insects known to be resistant, along with a number of their relatives. Continue reading

Arthropod Brains

Fuxianhuia protensa from the Lower Cambrian Chengjiang FaunaThe latest article from Brian Thomas is Cambrian Creature Had Complicated Brain. It relates to a study that found that a Cambrian arthropod, Fuxianhuia protensa, had a “modern” brain (at least for an arthropod). But first, here’s Brian’s conception of the Cambrian explosion:

In the evolutionary scheme, Cambrian fossils represent creatures from an ancient time when they had only recently emerged from unidentified sub-animal life forms. As such, evolutionists expect Cambrian creatures to be more complicated in structure than their supposed precursors, but simpler than their more “highly evolved” descendants.

“Unidentified sub-animal life forms”? Continue reading