Bio 152: Evolution - Chapters 1-4

biogeography

Distribution of species across geographical locations.

similar

_____ species are usually found near each other.

common ancestry

Idea that species share a common ancestor from which they diverged.

homologous structures

Structures that have deep, underlying similarities; traits whose similarities can be explained by common ancestry.

transitional fossils

Fossils with subsets of traits found in living groups.

nested structure (taxonomic groups)

Taxonomic branches begin from an ancestor and branch out into various species/families; a pattern of groups nested within groups.

biogeography, homologies, transitional fossils, nested structure

What 4 types of evidence did Darwin use to support common ancestry?

polymorphic population

Population with genetic variation (multiple variants within a population)

Evolution

Change in allele frequencies across generations.

Yes (mutations)

Can evolution occur if an allele is fixed?

Natural selection

Mechanism of influence on evolution in which organisms with genetic variants that better equip them for their environment will survive, and these variants will increase in frequency.

Common ancestry, populations evolve, natural selection

What are the three main ideas in evolution?

phylogenetic tree

a branching diagram used to represent evolutionary relationships between different organisms based on their common ancestry.

root

base of a tree, representing the common ancestral lineage of all taxa in the tree

branches

The lines that make up a tree diagram, which represent population lineages linked together by enough gene flow that they tend to remain genetically similar.

Taxon (pl. taxa)

A named group of biological organisms, often shown at the tips of a tree.

lineage splitting

A splitting of a population into genetically separate populations that no longer have gene flow.

Node

Branching parts of tree diagram, which represent lineage splitting and separate sister lineages.

Speciation

Lineage splitting that ultimately leads to taxa that are classified as different species.

geographic isolation

What is one cause of lineage splitting?

branches (NOT lineage splitting events)

Where does trait evolution occur?

clade

All the descendants of an ancestral lineage.

tree topology

A list of all clades in a tree

Tree thinking

Ability to use the metaphor of a phylogenetic tree to convey accurate evolutionary info.

F

(T or F) Some species are more evolutionarily advanced than others.

relatedness

Recency of common ancestry

recent

Organisms that are more related have a more ____ common ancestor.

retained

Fixed traits in a population lineage will be ____ by its descendants.

F

(T or F) We CAN tell how many traits have evolved along a branch.

No

Is degree of similarity a reliable way to evaluate relatedess?

separate ancestry

The alternative hypothesis to common ancestry, which proposes that each living taxon has an independent origin.

nested, hierarchical

Under common ancestry, distribution of traits amongst species tend to have a ____ or _____ pattern.

independently, be lost

Two exceptions to the nesting pattern in the common ancestry model:
1. Trait may evolve ________ a few times.
2. Trait may evolve and later on _______ in some lineages.

common ancestry model

Statistical evidence supports which model of ancestry?

principle of parsimony

The idea that, given multiple hypotheses, the most likely hypothesis is the one that makes the fewest assumptions; in relation to phylogenies, it favors the hypothesis with the minimum number of evolutionary changes (trait gain/loss).

convergent evolution

phenomenon observed in phylogenetic trees where the same trait evolves separately in more than one lineage; NOT homologous traits.

reversal

the phenomenon in which an ancestral trait was lost and then re-evolved along a lineage.

ambiguous

trait homology can be ________

internodes

What is another word for branches?

Eugenics

Attempt to increase the frequency of "desirable" traits in humans using evolutionary principles; fueled by prejudice and discrimination.

Phenotypic plasticity

The ability of organisms to experience changes in phenotypes solely due to the environment.

phenotype

set of all an organism's measurable attributes, including behavioral, physical, biochemical, and physiological characteristics.

genotype

an organism's entire genetic makeup

allele

a variant of a gene in a population

locus

place in the genome where alleles are encoded

haploid

organism with one set of chromosomes; 1 allele per locus

diploid

organism with two sets of chromosomes; 2 alleles per locus

T

(T or F) Different alleles may not result in different phenotypes

Continuous traits

Traits with a range of variation (e.g. height, weight, length)

normal

Continuous traits that are controlled by variation at many loci tend to exhibit a _____ distribution

allele frequency

% of population with a particular allele

1

p + q = ___

x + y/2

p1 (frequency of allele 1) = ____

z + y/2

p2 (frequency of allele 2) = _____

no migration/mutation, random mating, no selection, infinitely large population

What are the 4 assumptions made in the Hardy-Weinberg equation?

selfing

when an organism reproduces with itself, providing both the egg and sperm components.

p^2

Probability of A1A1 in next generation =

q^2

probability of A2A2 in next generation =

2pq

probability of heterozygote (A1A2) in next gen =

no selection, infinitely large populations

Deviation from which 2 Hardy-Weinberg assumptions are important causes of evolution?

genetic variation, reproductive success

Evolution requires ______ and differences in ______.

environment, genetics

phenotypic traits result from interactions with the ____ and ____.

fixation, extinction

Allele frequencies will fluctuate until they go to _____ or ____.