Chart animal phylogeny

Biologists strive to understand the evolutionary history and relationships of members of the animal kingdom, and all of life, for that matter. The study of phylogeny aims to determine the evolutionary relationships between phyla. Currently, most biologists divide the animal kingdom into 35 to 40 phyla. Scientists develop phylogenetic trees, which serve as hypotheses about which species have evolved from which ancestors

Recall that until recently, only morphological characteristics and the fossil record were used to determine phylogenetic relationships among animals. Scientific understanding of the distinctions and hierarchies between anatomical characteristics provided much of this knowledge. Used alone, however, this information can be misleading. Morphological characteristics may evolve multiple times, and independently, through evolutionary history. Analogous characteristics may appear similar between animals, but their underlying evolution may be very different. With the advancement of molecular technologies, modern phylogenetics is now informed by genetic and molecular analyses, in addition to traditional morphological and fossil data. With a growing understanding of genetics, the animal evolutionary tree has changed substantially and continues to change as new DNA and RNA analyses are performed on additional animal species.

What You’ll Learn to Do

• Identify key features scientists use to classify animals
• Interpret the metazoan phylogenetic tree
• List some of the relationships within the modern phylogenetic tree that have been discovered as a result of modern molecular data

Learning Activities

The learning activities for this section include the following:

• Classifying Animals
• Constructing an Animal Phylogenetic Tree
• Modern Revisions of Phylogeny
• Self Check: Animal Phylogeny