Evolution exam 1 terms

Organic evolution

Small changes in gene frequency in a population over time are sufficient to explain historical and current patterns of organismal diversification

Homology

Possession by two or more species of a trait inherited from an equivalent trait in a common ancestor.

What is the age of the earth?

~4.6 billion years old

Covergence

Trait adapted to similar function but different origin

Homoplasy

Classification based not on shared ancestry

What were darwin’s 4 postulates?

1. variation amoung individuals

2. Variation is heritable

3. Only fraction of offspring survive

4. Individuals w/ favorable traits will produce more offspring than others

Heritability (h²)

Proportion of variation in character that is caused by action of genes

Monoplyly

Paraplyly

Polyphyly

Synapomorphy (Synopomorphic character)

Derived character state shared by two or more taxa

Parsimony

Fewest changes in phylogenetic tree

Outgroup

Information about ancestral state

Reversal

Removal of a trait from a phylogenetic tree

Molecular clock

Used to date evolutionary events.Molecules evolve at a constant rate such that the amount of divergence is equivalent to the time since two species diverged

Darwinian evolution

Slow and gradual process causes selection for beneficial mutations leading to adaptation. Sufficient mutations need a long time to accumulate.

Biological species concept (BSC)

Species are groups of actually potentially interbreeding natural populations that are reproductively isolated from other such groups.

Phylogenetic species concept (PSC)

Species have separate evolutionary characteristics. Any character can be defined as a species.

Morphospecies concept

Species are grouped based on degree of morphological similarity

What three components need to happen to get speciation?

1. fragmentation and isolation of populations

2. Divergence

3. Reproductive isolation

Allopatric speciation

Evolution of genetic and reproductive barriers between populations that are geologically separated. Gene flow is eliminated.

Vicarient speciation

A type of allopatric speciation that is a sudden geological event which causes change in different species

Peripatric speciation

A type of allopatric speciation in which a large group in which a small subgroup moves to a different location and becomes a separate species (Founder effect)

Parapatric speciation

Reproductive isolation between populations that are continuously distributed in space

Primary integration

A type of parapatric speciation in which an environmental barrier that is strong and sudden to differentiate species contracts gene flow via selection

Secondary contact

A type of parapatric speciation in which a group is originally allopatric becoming two different species but then hybridization occurs and the group becomes parapatric after they aren’t selected

Sympatric speciation

Divergence leading to speciation occurs in presence of substantial gene flow

What was the earliest life form?

The ribozyme

What are the 4 eons?

Hadean (4.6 BYA), Archean (3.6 BYA), Proterozoic (2.5 BYA), Phanerozoic (540-current day)

What are the three sites with the best fossil preservation?

Ediacaren Fauna (Australia), Burgess shale (Canada), and Chengjiang (China)

Punctuated stasis

Predicts that there’s no change until species evolve

Gradualism

Slow accumulation of differences which causes different species

Caldogenesis

Evolutionary change that produces speciation

Anagenesis

Evolutionary change that does not involve speciation