Module 1-Chapter 14

Geological Scale Mass Extinction Classification

universal ancestor

The organism or population from which all life on Earth descended.

biodiversity

The variety of all the world's life-forms, as well as their interactions with each other and the ecosystems they inhabit.

domain

The highest hierarchical level in the organization of life, describing the most basic and ancient divisions among living organisms. The three domains of life are Bacteria, Archaea, and Eukarya.

Bacteria

One of the three domains of life (compare Archaea and Eukarya) and also one of the five kingdoms of life. The domain and kingdom Bacteria include familiar disease-causing bacteria.

Archaea

One of the three domains of life (compare Bacteria and Eukarya) and also one of the five kingdoms of life. The domain and kingdom Archaea consist of single-celled organisms best known for living in extremely harsh environments.

Eukarya

One of the three domains of life, including all the living organisms that do not fit into the domains Archaea or Bacteria, from amoebas to plants to fungi to animals.

lineage

A single line of descent.

evolutionary tree

A model of evolutionary relationships among groups of organisms that is based on similarities and differences in their DNA, physical features, biochemical characteristics, or some combination of these. It maps the relationships between ancestral groups and their descendants, and it clusters the most closely related groups on neighboring branches.

clade

A branch of an evolutionary tree, consisting of an ancestor and all its descendants.

node

The point on an evolutionary tree indicating the moment in time when an ancestral group split, or diverged, into two separate lineages. The node represents the most recent common ancestor of the two lineages in question.

most recent common ancestor

he most immediate ancestor that two lineages share.

shared derived trait

A unique feature common to all members of a group that originated in the group's most recent common ancestor and then was passed down in the group.

kingdom

The second-highest hierarchical level in the organization of life; the unit of classification in the Linnaean hierarchy above phylum and below domain. The five kingdoms of life are Bacteria, Archaea, Plantae, Fungi, and Animalia.

protists

An artificial grouping of eukaryotes, defined by not belonging to any of the three kingdoms of Eukarya, composed of mainly single-celled, microscopic organisms grouped together simply because they are not plants, animals, or fungi and include amoebas and algae.

Plantae; the plants

One of the five kingdoms of life, in the domain Eukarya, encompassing all plants, which are multi-cellular photosynthetic autotrophs.

Animalia

The animals. One of the five kingdoms of life, in the domain Eukarya, encompassing all animals, including humans, birds, and dinosaurs.

Linnaean hierarchy

A system of biological classification devised by the Swedish naturalist Carolus Linnaeus in the eighteenth century.

species

1. Members of a group that can mate with one another to produce fertile offspring. 2. The smallest unit of classification in the Linnaean hierarchy.

genus (pl. genera)

The unit of classification in the Linnaean hierarchy above species and below family.

scientific name

The unique two-word Latin name, consisting of the genus and species names, that is assigned to a species in the Linnaean hierarchy.

family

The unit of classification in the Linnaean hierarchy above genus and below order.

order

The unit of classification in the Linnaean hierarchy above family and below class.

class

The unit of classification in the Linnaean hierarchy above order and below phylum.

phylum (pl. phyla)

The unit of classification in the Linnaean hierarchy above class and below kingdom.

Cambrian explosion

The burst of evolutionary activity, occurring about 540 million years ago, that resulted in a dramatic increase in the diversity of life. Most of the major living animal groups first appear in the fossil record during this time.

adaptive radiation

The expansion of a group of organisms to take on new ecological roles and to form new species and higher taxonomic groups.