Lecture 5: Using Phylogenies

These flashcards cover key concepts related to phylogenies, their applications in taxonomy, conservation, medical forensics, and the classification of species.

The scientific discipline concerned with reconstructing the evolutionary history and patterns of descent among groups of organisms, often visualized in diagrammatic forms such as phylogenetic trees, is referred to as ____.

phylogeny

A natural group of organisms in phylogenetics that consists of a single common ancestral species and all of its descendants, thus representing a complete and exclusive branch on a phylogenetic tree, is officially termed a ____ (also synonymous with a clade).

monophyletic group

The formalized method for naming species, wherein each species is assigned a distinct two-part scientific name—comprising a genus name and a specific epithet (always italicized)—in accordance with international codes, is known as the ____ of nomenclature.

binomial system

Shared, derived homologous characteristics that first appeared in the most recent common ancestor of a particular monophyletic group and are subsequently inherited by all its descendant members, providing crucial evidence for classifying and defining that group, are defined as ____.

synapomorphies

Shared biological features (e.g., anatomical structures, genetic sequences) among different species that are attributable to their descent from a common ancestor, such as the similar bone structure in the forelimbs of vertebrates, are termed ____.

homologies

Similar biological features that have arisen independently in unrelated lineages through convergent evolution or reversal, rather than being inherited from a common ancestor (e.g., the streamlined body shapes of sharks and dolphins), are classified as ____.

homoplasies

A species or group of organisms included in a phylogenetic analysis that is closely related to the ingroup (the group of interest) but is known to have diverged earlier than all members of the ingroup, serving as a reference to determine the ancestral state of characters, is known as an ____.

outgroup

The principle applied in phylogenetics stating that, among competing hypotheses, the simplest explanation (i.e., the phylogenetic tree requiring the fewest evolutionary changes or character state transformations) is generally the most preferred, is referred to as the principle of ____.

parsimony

On a phylogenetic tree, two descendant groups or species that share an immediate common ancestor that is not shared by any other group, making them each other's closest evolutionary relatives, are designated as ____.

sister taxa

A group of organisms consisting of a common ancestor and all its lineal descendants, forming a single 'branch' on the tree of life, is alternatively known as a ____.

clade

A group of organisms that includes descendants from multiple ancestors, but conspicuously excludes their most recent common ancestor from the group, rendering it an unnatural grouping based on convergent evolution, is called a ____.

polyphyletic group

A group of organisms that includes a common ancestor but only some of its descendants, intentionally excluding one or more descendant lineages, is termed a ____.

paraphyletic group

On a phylogenetic tree, the point at which a lineage splits into two or more descendant lineages, representing a common ancestor, is called a ____.

node

The ancestral lineage at the very base of a phylogenetic tree, representing the most ancient common ancestor of all other lineages in the tree, is known as the ____.

root

Any observable trait or feature of an organism (e.g., morphological, molecular, behavioral) that can be used to infer evolutionary relationships, and which can exist in different states, is defined as a ____.

character