Chapter 25: Phylogenies and the History of Life

Phylogeny

Branching evolutionary history of organisms.

Phylogenetic tree

Simplified diagram representing evolutionary history.

Systematics

Study of classifying relationships among organisms.

Tree of life

Most universal phylogenetic tree depicting all life.

Taxonomy

Science of naming and classifying organisms.

Taxa

Groups of organisms classified at any level.

Sister groups

Closely related taxa sharing a recent ancestor.

Nodes

Points representing speciation events in trees.

Branches

Lines connecting nodes and taxa in trees.

Conservation priority

Species identified as needing urgent protection.

Fossil record

Historical evidence of past life forms.

Analytical tools

Methods used to reconstruct life's history.

Speciation event

Occurrence when one species diverges into two.

Branch tips

Ends of branches where taxa are located.

Common ancestor

An ancestor shared by two or more taxa.

Proximity of labels

Not indicative of relationships in phylogenetic trees.

Taxa location

Always at branch tips, not within trees.

Rotation of branches

Branches can rotate without altering relationships.

Phylogenetic trees

Hypotheses estimating relationships among taxa.

Data Matrix

Framework for comparing organisms' traits.

Character or trait

Genetic, morphological, or behavioral feature studied.

Character states

Presence (1) or absence (0) of traits.

Outgroup

Related group used to identify ancestral traits.

Ancestral trait

Character existing in a common ancestor.

Derived trait

Modified form of an ancestral trait.

Homoplasy

Similar traits due to independent evolution.

Homology

Similar traits due to common ancestry.

Synapomorphies

Shared derived traits identifying monophyletic groups.

Monophyletic group

Ancestral species and all its descendants.

Clades

Another term for monophyletic groups.

Parsimony

Method minimizing changes to infer relationships.

Evolutionary distance

Average frequency of character changes between taxa.

Maximum likelihood

Statistical method estimating tree based on data.

Bayesian analysis

Probabilistic method using prior information and data.

Convergent evolution

Independent evolution of similar traits in unrelated taxa.

Homologous traits

Similar traits inherited from a common ancestor.

Convergent traits

Similar traits evolved independently in different lineages.

Streamlined bodies

Similar body shapes in dolphins and ichthyosaurs.

Whale evolution

Study of whales' phylogenetic placement in life.

Branch lengths

Represent evolutionary distance in phylogenetic trees.

Reversal in character state

Change back to an ancestral trait state.

Multiple outgroups

Used to better estimate phylogenetic relationships.

Artiodactyls

Even-toed ungulates including hippos and cows.

Astragalus

Pulley-shaped ankle bone in artiodactyls.

Outgroup

A taxon outside the group being studied.

SINEs

Short interspersed nuclear elements in genomes.

Phylogeny

Evolutionary history of species based on traits.

Sister group

Closest relative in evolutionary tree.

Gain event

Evolutionary occurrence of a new trait.

Loss event

Evolutionary disappearance of a trait.

Derived characters

Traits that evolved from a common ancestor.

Fossil record

Total collection of discovered fossils globally.

Fossil

Physical evidence of past organisms.

Intact fossils

Complete remains of an organism.

Compression fossils

Organism remains flattened in sediment.

Cast fossils

Mineral-filled molds of organisms.

Permineralized fossils

Fossils with minerals replacing organic material.

Trace fossils

Evidence of organism activity, like footprints.

Habitat bias

Fossilization likelihood based on organism habitat.

Taxonomic bias

Fossilization favoring organisms with hard parts.

Temporal bias

Recent fossils more common than ancient ones.

Abundance bias

Common species more likely to fossilize.

Radiometric dating

Method for assigning absolute dates to fossils.

Earth's formation

Estimated to have begun ~4.6 billion years ago.

Life's beginning

Estimated to have started ~3.5 billion years ago.

Archaeopteryx

First birdlike dinosaur in the fossil record.

Evolutionary firsts

Indicate appearance of new lineages or innovations.

Precambrian

Interval from 4.5 billion to 541 million years ago.

Hadean Eon

Earliest eon, before life existed on Earth.

Archaean Eon

Eon characterized by the emergence of unicellular life.

Proterozoic Eon

Eon before the Cambrian explosion of multicellular life.

Phanerozoic Eon

Interval from 541 million years ago to present.

Paleozoic Era

Era of ancient life, major animal lineages appeared.

Mesozoic Era

Era known for dinosaurs and gymnosperms dominance.

Cenozoic Era

Era of recent life, mammals and birds dominate.

Holocene Epoch

Current epoch, following the last Ice Age.

Anthropocene Epoch

Proposed epoch reflecting human impact on Earth.

Adaptive Radiation

Rapid production of diverse species from one lineage.

Hawaiian Silverswords

Example of adaptive radiation from tarweed species.

Monophyletic Group

Group consisting of an ancestor and all descendants.

Speciation

Process by which new species arise.

Ecological Diversification

Adaptation of species to various ecological niches.

Niche

Range of resources and conditions a species tolerates.

Permian Period

Last period of the Paleozoic era, major extinction event.

Cretaceous Period

Last period of the Mesozoic era, dinosaurs existed.

Paleogene Period

First period of the Cenozoic era, mammals diversified.

Extrinsic factors

Environmental changes triggering adaptive radiations.

Intrinsic factors

Key trait evolution driving diversification.

Ecological Opportunity

Availability of new resources promoting diversification.

Silverswords

Hawaiian plants diversifying into vacant niches.

Morphological Innovation

Key trait evolution leading to diversification events.

Physiological Innovation

Adaptations in function driving species diversification.

Behavioral Innovation

Changes in behavior leading to evolutionary advantages.

Angiosperms

Flowering plants with over 250,000 known species.

Cambrian Explosion

Rapid diversification of life ~541 million years ago.

Ediacaran period

Time before Cambrian with first multicellular life.

Microfossils

Tiny fossils from early life, less than 1 mm.

Macroscopic fossils

Larger fossils appearing during the Cambrian period.

Filter feeders

Organisms that obtain food by filtering water.

Ecological niches

Roles species play in their environments.