David Coppedge

David Coppedge writes: Evidence is growing that organisms share existing genetic information horizontally, not just vertically. This has immense implications for neo-Darwinian theory that are not yet fully recognized. If traits can be shared across species, genera and even phyla, they are not being inherited from common ancestors. The findings might also cast stories about convergence and co-evolution in a completely different light. Let’s look at some of the news on this front. Introgression Last month, Current Biology posted a Primer on Introgression by four authors. Introgression refers to “lasting transfer of DNA from one of the species into the genome of the other” by means of hybridization and backcrossing. Basically, it describes “the incorporation of the DNA from one species into Read More ›

This was bound to come up eventually: First, notice the quote marks around “Cambrian explosion,” a subtle hint that the term is controversial. It’s not. They state clearly that it is “marked by the appearance of most major animal phyla.” Panarthropoda is a taxon that combines arthropods with tardigrades and onycophorans. The sentence means that yes, lots of different arthropods appear throughout the fossil record, revealing “extreme morphological disparities,” i.e. outward differences. Yet these Chinese specimens show that the brains are conservative — not that they vote Republican, but that CNS structures throughout the panarthropod collection are similar, not showing extensive evolution. They’re not just conservative; they are “remarkably conservative.” In terms of general body plan, it’s a picture of Read More ›