Taxonomy, Species Concepts, and Phylogeny Lecture

Set of question-and-answer flashcards covering taxonomy, species naming rules, several species concepts, phylogenetic terminology, and cladistics principles from the lecture notes.

What is taxonomy in biology?

The science of naming and categorizing biological diversity, now considered a part of systematics.

Who developed the hierarchical system still used for naming species today?

Carolus Linnaeus (1707–1778).

What is the correct way to write a scientific (Latin) name?

Genus name (capitalized) + specific epithet (lowercase), e.g., Homo sapiens.

Which governing body regulates animal names and enforces priority and stability?

The International Code of Zoological Nomenclature (ICZN).

List the main Linnaean ranks from broadest to most specific.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

In binomial nomenclature, what is the ‘specific epithet’?

The second word of a species’ scientific name; it is not the species name by itself.

What requirement must genus and specific epithet follow concerning grammar?

They must agree in gender.

Give an example of a humorous descriptive species name.

Ursus arctos horribilis—literally “bear bear horrible,” the grizzly bear.

Define the typological (morphological) species concept.

Individuals that look alike are considered the same species; relies on a type specimen.

What is Ernst Mayr’s Biological Species Concept?

A species is a reproductive community of populations, reproductively isolated from others, occupying a specific niche.

Name one major problem with the Biological Species Concept.

It is hard to apply to geographically separated or asexual organisms and may underestimate diversity.

What is a ring species example discussed in the lecture?

The Ensatina salamander complex encircling California’s Central Valley.

Describe the Ecological Species Concept (EcSC).

Species are groups of organisms occupying a distinct ecological niche.

Who developed the Evolutionary Species Concept and what is its key addition?

George Gaylord Simpson; it adds a time component by focusing on ancestor-descendant lineages.

Why is the Evolutionary Species Concept criticized?

It lacks explicit, testable criteria for distinguishing species.

State the Phylogenetic Species Concept (PSC).

A species is the smallest diagnosable cluster of organisms with a parental pattern of ancestry and descent (an irreducible basal grouping).

One challenge of the Phylogenetic Species Concept is that it does not easily account for __.

Hybridization or reticulation in phylogenetic trees.

What is homology?

Character similarity due to shared ancestry.

Define convergent evolution.

Independent evolution of similar features in species of different lineages, producing homoplasy.

In phylogenetics, what is an outgroup used for?

To root a tree and determine the polarity (ancestral vs. derived) of characters.

Differentiate monophyletic, paraphyletic, and polyphyletic groups.

Monophyletic: ancestor and all descendants; Paraphyletic: ancestor and some descendants; Polyphyletic: taxa from different ancestors.

What is a synapomorphy?

A shared derived character uniting a clade.

Who founded cladistics and around what year?

Willi Hennig, circa 1950.

What visual representation results from a cladistic analysis?

A cladogram (a type of phylogenetic tree).

Why can every node on a cladogram be given a taxonomic name under cladistics?

Because cladistics emphasizes monophyly and names clades that include an ancestor and all its descendants.

What principle guides naming priority in zoological nomenclature?

The earliest validly published name has priority, promoting stability.

Which two main directives does the ICZN follow?

Priority first, then stability of names.

What does the term ‘character state’ refer to in systematics?

The specific manifestation of a character (e.g., blue vs. green eyes).

Explain the term ‘plesiomorphic character.’

An ancestral character state for the group being considered.

Why do different species concepts often disagree on the timing of speciation?

Each concept uses different criteria (morphology, reproduction, lineage, ecology), leading to varying thresholds for declaring species divergence.