Phylogeny, Eukaryotic Biodiversity, and Animal Diversity

Vocabulary practice flashcards covering taxonomic concepts, phylogenetics, eukaryotic supergroups, animal body plans, and major algal and plant divisions.

Taxonomy

The formal system for naming and classifying living things so that scientists can all speak the same language.

Morphological Species Concept

A practical, widely used, pre-Darwinian concept defining species by physical appearance: what looks different is considered different.

Biological Species Concept

A concept developed by Mayr and Dobzhansky defining species by reproductive isolation, connected populations, and shared derived traits rather than relative differences.

Phylogenetic Species Concept

Defines a species as a population or group of populations sharing a combination of derived traits; they are monophyletic groups (or clades) containing a single common ancestor and all of its descendants.

Phylogeny

The evolutionary history and development of a group of organisms showing how they are related through common ancestry, serving as a hypothesis of ancestor-descendant relationships.

Sister Taxa

Two species or lineages that are more closely related to each other than to any other taxa in a phylogenetic tree.

Nodes

Points on a phylogenetic tree representing theoretical common ancestral populations from which multiple evolutionary lines diverge.

Clade

A monophyletic group of organisms hypothesized to have evolved from a common ancestor.

Homology

Similarity in structure, function, physiology, or development between different taxa due to inheritance from a shared common ancestor.

Analogy (Homoplasy)

Biological traits that look or function similarly but did not arise from a shared ancestor, typically resulting from convergent evolution, parallel evolution, or secondary loss.

Apomorphy

A derived character state that differs from the ancestral state.

Synapomorphy

A derived character state (apomorphy) shared by two or more taxa due to inheritance from a common ancestor, making it phylogenetically informative.

Plesiomorphy

An ancestral character state inherited from an earlier common ancestor.

Autapomorphy

A uniquely derived character state found only in a single lineage or taxon.

Monophyletic

A phylogenetic grouping that includes a common ancestor and all of its descendants.

Paraphyletic

A non-monophyletic group that includes a common ancestor and some, but not all, of its descendants.

Polyphyletic

An assemblage of taxa erroneously grouped together based on homoplasious (analogous) characters rather than common ancestry.

Principle of Parsimony

The methodological rule in phylogenetics that simpler explanations (requiring the fewest evolutionary steps) are preferred over more complex ones.

Opisthokonta

A eukaryotic supergroup containing animals (Metazoa), fungi, and choanoflagellates.

Amoebozoa

A eukaryotic supergroup that includes amoeboid organisms and slime molds.

Archaeplastida

A eukaryotic supergroup containing red algae, green algae, land plants, and glaucocystophytes.

S.A.R.

A massive eukaryotic clade comprising Stramenopiles (diatoms, brown algae), Alveolates (dinoflagellates, ciliates), and Rhizarians (foraminiferans, radiolarians).

Excavata

A eukaryotic supergroup that includes euglenids, trypanosomes, diplomonads, and parabasalids.

Flagella

Cell surface structures present as one or a few long projections that propel the cell by pushing water parallel to their axis in a propeller-like motion.

Cilia

Numerous short cell surface projections composed of microtubule bundles that propel the cell by moving water parallel to the cell surface in a back-and-forth motion.

Isogamy

A form of sexual reproduction where gametes are identical in size and morphology.

Anisogamy

A form of sexual reproduction where gametes differ in size and structure.

Oogamy

A specialized type of anisogamy where fertilization occurs between a large, non-motile egg and a small, motile sperm.

Radial Symmetry

Body organization where two or more planes passing through a central axis divide the body into mirrored halves.

Bilateral Symmetry

Body organization where a single sagittal plane divides the body into right and left mirror halves.

Collagen

A triple-helix structural protein of the animal extracellular matrix that forms connective tissues.

Integrin

A molecule that connects the extracellular matrix (ECM) to the cell exterior.

Cnidaria

A phylum of radially symmetrical predators (including jellyfish, anemones, and corals) characterized by an epithelial-lined, incomplete gut, true tissues, and stinging cnidocytes.

Protostomes

A major clade of Bilateria where the first embryonic opening develops into the mouth, with the anus forming secondarily.

Deuterostomes

A major clade of Bilateria where the embryonic mouth develops secondarily after the anus.

Metamerism

The repeating segmentation of body units found in Phylum Annelida that allows for greater structural and functional complexity.

Ecdysis

The process of molting an outer protective exoskeleton (such as the chitin covering of arthropods) to allow growth.

Phylum Echinodermata

A marine deuterostome phylum characterized by a secondarily derived pentaradial symmetry and a water vascular system.

Notochord

A spring-like cartilaginous rod in chordates that provides structural support and signaling to adjacent tissues.

Phylum Rhodophyta

Red algae characterized by photosynthetic pigments (chlorophyll a, phycoerythrin, phycocyanin, allophycocyanin), cell walls containing cellulose, pectin, agar, and carrageenan, and a complete absence of flagella.

Bryophytes

An informal group of early, small, non-vascular land plants (including mosses, liverworts, and hornworts) that require high humidity or free water for fertilization.