Herpetology Notes Lecture 2

Phylogeny

The evolutionary history of a group of organisms depicted in a phylogenetic tree.

Phylogenetic tree

A visual representation of the evolutionary relationships between species, showing the ancestry and history of speciation.

Branches

Represent species or lineages in a phylogenetic tree.

Node

The point where two branches split in a phylogenetic tree, indicating speciation.

Polytomy

A node in a phylogenetic tree where relationships between branches are uncertain, with more than two branches originating from it.

Resolution

When two branches of a phylogenetic tree are consistent with a polytomy.

Terminal units

Individual organisms or groups of species represented at the ends of branches in a phylogenetic tree.

Higher taxon

A group of species represented by a terminal unit in a phylogenetic tree, with the terminal branch representing their common ancestor.

Monophyletic

A group of species descended from a common ancestor, also known as a clade.

Paraphyletic

A group of species in which some descendants are excluded, despite sharing a common ancestor.

Polyphyletic

A group of species that do not share a recent common ancestor.

Actinopterygians

A major group of Osteichthyes (bony fishes) that includes most familiar fish consumed and kept in aquaria, characterized by ray-finned fins.

Sarcopterygians

Another major group of Osteichthyes that includes lungfish, coelacanths, and tetrapods, characterized by lobe-finned fins.

Synapomorphies

Shared derived characteristics that define a particular group, such as the development of bony supports for pectoral and pelvic fins in Sarcopterygii.

Tetrapoda

A group of vertebrates characterized by having four limbs or limb-like structures, with synapomorphies including a separated shoulder girdle from the skull, ankle and wrist joints, and the presence of the stapes bone in the auditory system.

Amphibia

A major clade of tetrapods that includes anurans (frogs and toads), caudates (salamanders and newts), and caecilians (legless amphibians).

Amniota

Another major clade of tetrapods that includes squamates (lizards and snakes), birds, mammals, crocodilians, turtles, and others.