Section 2

Phylogeny

The study of the evolutionary history and relationships among organisms.

Phylogenetic Trees

Illustrate evolutionary relationships among species, showing their common ancestors and divergence over time.

Branch Points on Phylogenetic Trees

The point where two species diverge, representing a common ancestor.

Location of Species on Phylogenetic Trees

Indicates how closely related species are to each other, with more closely related species being closer on the tree.

Most Closely Related Group to Animals

Fungi are the closest relatives to animals.

Most Closely Related Group to Plants

Green algae are the closest relatives to plants.

Most Closely Related Group to Brown Algae

Ciliates are the closest relatives to brown algae.

Application of Science to Phylogenetic Trees

Scientists test different phylogenetic hypotheses using genetic, morphological, and fossil evidence.

Purpose of Classification Systems

Classification helps organize biodiversity into meaningful categories for study.

Limitations of Classification Systems

Limited by the artificial nature of categories and the continuous process of evolution.

Process of Classification

Organisms are grouped based on shared characteristics including physical traits, genetics, and evolutionary history.

Structures Used in Classification

Bones, DNA sequences, embryonic development patterns, and biochemical pathways.

Evidence for Common Ancestry

Universal genetic code and similarities in DNA sequences suggest all living things descended from the same common ancestors.

Assumption About Similar Cell Types in Organisms

Two organisms with the same type of cell or tissue likely share a common ancestor.

Taxonomy

The science of naming, describing, and classifying organisms based on shared characteristics.

Levels of Taxonomic Classification

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

Parts of a Scientific Name

Consists of a genus name (capitalized) and a species name (lowercase), written in italics or underlined.

Scientific Name Formatting Rules (Handwritten)

The name is underlined.

Scientific Name Formatting Rules (Printed)

The name is italicized.

Biological Species Concept Definition

A species is a group of organisms that can interbreed and produce fertile offspring under natural conditions.

Conditions for Same Species

Individuals must be capable of interbreeding and their offspring must be fertile.

Three Domain Classification System

Includes Domain Bacteria, Domain Archaea, and Domain Eukarya.

Characteristics of Domain Bacteria

Unicellular prokaryotes with peptidoglycan cell walls.

Characteristics of Domain Archaea

Unicellular prokaryotes that often live in extreme environments.

Characteristics of Domain Eukarya

Organisms with eukaryotic cells, including protists, fungi, plants, and animals.

Prokaryote Domains

Bacteria and Archaea.

Closest Domain to Eukarya

Archaea.

Study of Evolutionary History Focus

The relationships among organisms and how they evolved over time.

Study of Evolutionary Process Focus

The mechanisms that drive evolutionary change, such as natural selection.

Define Biodiversity

The variety of life forms on Earth, including species, genetic, and ecosystem diversity.

Earliest Evolving Cells

Prokaryotes.

Importance of Cyanobacteria

First organisms to perform oxygenic photosynthesis, leading to the oxygenation of Earth’s atmosphere.

Origin of Eukaryotic Cells

Nucleus evolved from membrane infolding; mitochondria from ancestral prokaryotes; chloroplasts from engulfed photosynthetic bacteria.

What are Protists?

A diverse group of mostly unicellular eukaryotic organisms that do not fit into the categories of plants, animals, or fungi.

Characteristics of Plants

Multicellular, autotrophic organisms that perform photosynthesis.

Characteristics of Fungi

Absorptive heterotrophs that secrete enzymes to digest food externally.

Characteristics of Animals

Multicellular, ingestive heterotrophs that consume other organisms for food.