General Science Part 1: Understanding Phylogenetic Classification

Flashcards covering the basics of phylogenetic classification, including cladistics, character types, cladograms, phylogenetic trees, and homologous/analogous structures.

What is Cladistics?

A method of classifying living organisms based on common ancestry, focusing on branching patterns of evolutionary trees and relationships between species.

What is a Clade?

A group of organisms that includes an ancestor and all its descendants.

What is a Node?

A point on a cladogram where a single lineage splits into two or more lineages.

What is a Derived Character?

A trait that is present in an organism but absent in the last common ancestor of the group.

What are Morphological Characters?

Physical traits such as bone structures and leaf shapes.

What are Molecular Characters?

DNA sequences, RNA sequences, and protein structures.

What are Behavioral Characters?

Specific patterns of behavior that are inherited.

What is Apomorphy?

A derived trait or character that is unique to a group of species.

What is Plesiomorphy?

An ancestral trait that a taxon retains throughout its evolution.

What is Autapomorphy?

A derived trait that is found only in one taxon and absent in even the closest relative species.

What is Synapomorphy?

A derived trait that is particular to an entire clade.

What is Homoplasy?

A character state shared by at least two organisms but not found in their common ancestor.

In a cladogram with species W, X, Y, and Z, if character A is present in all, character B in X, Y, Z, and character C in Y and Z, which statement best identifies a synapomorphy and its implications?

Character B is a synapomorphy for Species X, Y, and Z, indicating these species share a more recent common ancestor than with Species W.

What do Nodes and Branching order indicate on a cladogram?

Each branch point (node) represents a divergence event. The order of branching indicates the sequence of divergence events.

What is a Phylogenetic Tree?

A diagram that represents evolutionary relationships among organisms, reflecting how species evolved from common ancestors.

What defines a Monophyletic Group?

Includes an ancestor and all its descendants.

What defines a Paraphyletic Group?

Includes an ancestor and some, but not all, of its descendants.

What defines a Polyphyletic Group?

Does not include the most recent common ancestor.

Which of the following pairs of structures is an example of homologous structures, and why? a) The wings of a butterfly and the wings of a bird because both are used for flying. b) The fins of a shark and the fins of a dolphin because both are used for swimming. c) The forelimb of a horse and the wing of a bat because they have similar bone structures d) The eyes of a squid and the eyes of a human , because they both serve the function of vision. e) The flippers of a penguin and the flippers of a whale because both are used for swimming.

The forelimb of a horse and the wing of a bat because they have similar bone structures.

What are Homologous Structures?

Structures in different species that are similar because of common ancestry but may perform different functions.

What are Analogous Structures?

Structures in different species that are similar because of convergent evolution, not common ancestry, and are similar in function.