Animal Phylogeny

Free Response

Describe at least two major changes to the animal phylogenetic tree that have come about due to molecular or genetic findings.


Two new clades that comprise the two major groups of protostomes are called the lophotrochozoans and the ecdysozoans. The formation of these two clades came about through molecular research from DNA and protein data. Also, the novel phylum of worm called Acoelomorpha was determined due to molecular data that distinguished them from other flatworms.

How is it that morphological data alone might lead scientists to group animals into erroneous evolutionary relationships?


In many cases, morphological similarities between animals may be only superficial similarities and may not indicate a true evolutionary relationship. One of the reasons for this is that certain morphological traits can evolve along very different evolutionary branches of animals for similar ecological reasons.