Bio 004,CH14, College of the Desert

• Major changes in the history of life – usually present in the fossil record.

• 1. Origin of new species,

• 2.Origin of evolutionary novelty,

• 3. Diversification after evolutionary breakthrough,

• 4. Diversification after mass extinctions,

Formation of a new species when one or more new species branch from an ancestral species which continues to exist.

A population or group of populations whose members have the potential to naturally interbreed and produce fertile offspring.

• 1. Observable/measurable physical traits.

• 2. Ecological niches/unique adaptations.

• 3. Unique genetic history (DNA).

• Reproductive barrier that impedes mating between species or hinders fertilization of eggs if members of different species should attempt to mate.

• a) Temporal Isolation (different breeding times).

• b) Habitat Isolation (different locations).

• c) Behavioral Isolation (differences in rituals).

• d)Mechanical Isolation (mismatched genitalia).

• e) Gametic Isolation (mismatched gametes).

Reproductive barrier that operates should interspecies mating occur and form hybrid zygotes.

Failure to develop

Failure to fertilize.

• Formation of a new species as a result of a population becoming isolated by a geographic barrier.
• Example: African cichlids at different water depths.

• Formation of a new species as a result of genetic change from the original population; no geographic barrier.

• - Example: Apple maggot flies

When evolution occurs slowly with accumulated series of changes over long periods of time.

When evolution occurs in spurts between which are long periods of little or no evolutionary change.

• Structure that became adapted for one function, later becoming adapted for a different function in a different context.

• Example: Feathers.

• Retention into adult-hood of features that were solely juvenile features in ancestors.
• Example: Axolotl (with gills).

• 250 mya → The super continent Pangaea was formed.
• 180 mya → Pangaea roke up and continents drifted apart again resulting in individual experiments in evolution.

Death of all members of a species

• 90% of marine animals and many terrestrial animals
• Cause: geophysical activity (225 mya).

• Nearly all the dinosaurs.
• Cause: meteorite (65 mya)

Study of diversity and relationships of organisms.

Identification, naming, and classification of species.

• (1707 – 1778) Father of modern taxonomy
• Swedish physician/botanist, developed first, formal taxonomic system.
• "Deus creavit, Linnaeus disposuit.“
• God created, Linnaeus organized.

• 1. Two-part name for each species.
• 2. Hierarchical classification.

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Carnivora
• Family: Canidae
• Genus: Canis
• Species: familiaris

Study of the evolutionary history of a species or group of species.

Branching diagrams depicting hypotheses about evolutionary relationships

• (morphological): Morphological similarities due to shared ancestry.
• (molecular): Molecular similarities in DNA due to shared ancestry.

Similarities between different species occur due to convergent evolution rather than shared ancestry

When similar environ-mental pressures and natural selection produce similar adaptations in organisms from different evolutionary lineages.