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Macroevolution
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,
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Speciation
Formation of a new species when one or more new species branch from an ancestral species which continues to exist.
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Species
A population or group of populations whose members have the potential to naturally interbreed and produce fertile offspring.
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Classification of Species Based Upon
1. Observable/measurable physical traits. 2. Ecological niches/unique adaptations. 3. Unique genetic history (DNA).
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Prezygotic Barrier
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).
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Postzygotic Barrier
Reproductive barrier that operates should interspecies mating occur and form hybrid zygotes.
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Hybrid inviability
Failure to develop
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Hybrid sterility
Failure to fertilize.
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Allopatric Speciation
- Formation of a new species as a result of a population becoming isolated by a geographic barrier.
- Example: African cichlids at different water depths.
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Gradualism
When evolution occurs slowly with accumulated series of changes over long periods of time.
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Punctuated Equilibrium
When evolution occurs in spurts between which are long periods of little or no evolutionary change.
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Paedomorphosis
- Retention into adult-hood of features that were solely juvenile features in ancestors.
Example: Axolotl (with gills).
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Continental Drift
- 250 mya → The super continent Pangaea was formed.
- 180 mya → Pangaea roke up and continents drifted apart again resulting in individual experiments in evolution.
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Extinctions
Death of all members of a species
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Permian Extinction
- 90% of marine animals and many terrestrial animals
- Cause: geophysical activity (225 mya).
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Cretaceous Extinction
- Nearly all the dinosaurs.
- Cause: meteorite (65 mya)
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Systematics
Study of diversity and relationships of organisms.
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Taxonomy
Identification, naming, and classification of species.
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Carolus Linnaeus
- (1707 – 1778) Father of modern taxonomy
- Swedish physician/botanist, developed first, formal taxonomic system.
- "Deus creavit, Linnaeus disposuit.“
- God created, Linnaeus organized.
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Two Features of the Linnaean System
- 1. Two-part name for each species.
- 2. Hierarchical classification.
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Hierarchical Classification
- Domain: Eukarya
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Carnivora
- Family: Canidae
- Genus: Canis
- Species: familiaris
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Phylogeny
Study of the evolutionary history of a species or group of species.
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Phylogenetic Tree
Branching diagrams depicting hypotheses about evolutionary relationships
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Homologies
- (morphological): Morphological similarities due to shared ancestry.
- (molecular): Molecular similarities in DNA due to shared ancestry.
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Analogies
Similarities between different species occur due to convergent evolution rather than shared ancestry
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Convergent Evolution
When similar environ-mental pressures and natural selection produce similar adaptations in organisms from different evolutionary lineages.
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