bio 111 test one

theory

an explanation of a phenomenon that is supported by a massive body of evidence. the evidence comes from many observations and repeatedly testing hypotheses.

pre-darwin view

earth is only ~ 6,000 years old inhabited by perfect non-changing organisms (or types) that God created. "Typological Thinking"

natural theology

the study of nature to learn God's plan

Carolus Linneaus

Swedish physician/botanist, founder of taxonomy. developed binomial naming system in Systema natural. Grouped similar species.

Georges Cuvier

french anatomist. developed paleontology - study of fossils. "Catastrophism"

James Hutton

Scottish geologist. concept of gradualism - present day geologic features are the result of very slow continuous processes (ex. erosion)

Charles Lyell

scottish geologist. theory of uniformitarianism - geologic processes have not changed. earth is very old. slow processes over long periods of time can result in big changes.

Thomas Malthus

English, essay on human population growth and its ability to outgrow resource supplies.

Alfred Wallace

English, came up with the same theory of natural selection independently and nearly at the same time as Darwin

Charles Darwin

English, resident naturalist on HMS Beagle. Collected plants/animals throughout the trip (5y.)

descent with modification

evolution

tree of life

organisms evolved from a common ancestor

artificial selection

selective breeding of domesticated plants and animals extra variety of dog breeds

natural selection

Darwin's mechanism for evolution - change of relative frequencies of traits in a population. Results in adaptation to environment

homologies

similarity in characteristics of related animals

convergent evolution

distantly related organisms can resemble one another, "analogous" features evolved independently to adapt to similar environments

nonrandom mating

geographically proximal organisms are more likely to mate with each other than with geographically distant indviduals

relative fitness

contribution made by an individual to the gene pool

directional selection

drive the variation of the population towards one end of the phenotypic spectrum

disruptive selection

selects against intermediate phenotypes

stabilizing selection

favors intermediate phenotypes over extreme phenotypes

sexual selection

certain individuals are more likely to acquire mates and reproduce than others. a form of natural selection

sexual dimorphism

variability in phenotypes between sexes

intrasexual selection

competition for mates between individuals of the same sex

intersexual selection

mate choice, "choosy" sex select mates based on certain characteristics, "good genes" may be correlated with displays

gene flow

change in allele frequency due to a gain (immigration) or a loss (immigration) of alleles in population

genetic drift

chance changes in allele frequency due to chance combinations of alleles in gametes, small population size

genetic bottleneck

a sudden reduction in the diversity of alleles in a population ex. disease outbreak or natural catastrophes

founder effect

a change in allele frequency when a new population is established

genetic drift

1. affects small populations
2. changes allele frequencies randomly
3. can lead to a loss of genetic variation
4. can cause increased levels of harmful alleles

mutations

introduction of novel alleles due to point mutations, nucleotide mutations, chromosome-level mutations, gene duplications, lateral gene transfer (between organisms)

typological thinking

species are unchanging (immutable) and independent of other species (Plato, many religions), some species are higher (more complex, important) than other species (aristotle)

population thinking

species are not static but can change through time, transitional features

vestigial features

reduced or incompletely developed structure in an organism that has no (or reduced) function

fitness (in context of evolution)

ability of an individual to survive and reproduce relative to other individuals in the population

selection (in context of evolution)

differential reproduction as a result of heritable variation

adaptation (in context of evolution)

heritable trait that increases the fitness of an individual in a particular environment relative to other individuals lacking the trait

Hardy-Weinburg conditions

1. no mutations
2. random mating
3. no natural selection
4. large population size (no genetic drift)
5. no gene flow

DNA

a nucleic acid. generally occurs as a double helix

gene

a section of DNA

a locus

the physical location for a gene on a chromosome

allele

form of a gene

heterozygous

having two different alleles of a gene

homozygous

having two copies of the same allele of a gene

gene pool

all the alleles of all the genes in a population

genotype

genes present in a given individual

phenotype

detectable traits of an individual, typically associated with a genotype

allele frequency equation

p+q=1

genotype frequencies equation

p^2 + 2pq + q^2 = 1

speciation

splitting event that forms two or more species from an ancestral species, genetic isolation followed by genetic divergence

species

an evolutionary independent population or group of populations

genetic exchange

population or group of populations that can interbreed with each other naturally to produce viable, fertile offspring

genetic isolation

can't produce natural viable, fertile offspring with other species

prezygotic reproductive barriers

impede mating or fertilization

postzygotic reproductive barrier

impede zygote from completely developing in fertile adult

types of prezygotic barriers

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

types of postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

allopatric speciation

gene flow stops due to geographic separation

sympatric speciation

gene flow stops without being geographically separated

phylogeny

the evolutionary history of a group of organisms

branch of phylogenetic tree

represents a population through time

Node (fork) of phylogenetic tree

a point within the tree where a branch splits into two or more branches

outgrip in a phylogenetic tree

a taxon that diverged prior to the taxa that are the focus of the study; helps to root the tree

polygamy of a phylogenetic tree

a node that depicts an ancestral branch dividing into three or more (rather than two) descendant branches; usually indicates that insufficient data were available to resolve which taxa are more closely related

tip (terminal node) of a phylogenetic tree

endpoint of a branch; represents a living or extinct group of genes, species, families, phyla, or other taxa

character (phylogenetic tree)

any genetic, morphological, physiological, or behavioral characteristic to be studied

ancestral trait (phylogenetic tree)

a characteristic that existed in an ancestor

derived trait (synapomorphy)

is modified form of the ancestral trait that is found in a descendant/lineage

cladistics (phylogenetic tree)

infer (generate) phylogenetic trees (cladograms) based on synapomorphies

molecular homologies

align sequences based on similarities

molecular homoplasies

similarities that arise by chance (25%)

cladistics

groups organisms by common descent

clade

a group of species that includes an ancestral species and all its descendants

monophyletic

a valid clade, signifying that it consisted of the ancestor species and all its descendants

paraphyletic

group does not contain all descendants from the common ancestor of the members

polypheletic

group contains members that descended from different ancestors

maximum parsimony

tree that requires the fewest evolutionary events (appearances of shared derived characteristics) is most likely

maximum likelihood

given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events

arbitrary (branch length)

estimates evolutionary relationships among populations

genetic difference (branch length)

horizontal branch lengths show the extent of genetic difference among populations

time since divergence

horizontal branch lengths show the extent of evolutionary time between nodes

fossils

traces of living organisms

habitat bias of the fossil record

environments where a) fossilization processes could occur and b) the organism dies

taxonomic/tissue bias of fossil record

soft-bodied organisms and tissues are not likely to leave fossils

temporal bias of fossil record

recently formed fossils are more common that older fossils due to destructive geologic processes

abundance bias of fossil record

rare species will be rare in the fossil record, while common or widespread species will be overrepresented in the fossil record

cambrian explosion

a burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 542 to 525 million years ago.

adaptive radiation: rapid speciation

rapid proliferation of many descendent species from a single lineage, bc of new resources and new ways to exploit resources

adaptive radiation distinctive features

1. monophyletic group
2. spectated rapidly
3. diversified ecologically into many niches

niche

"an organism's address and occupation" - where it is found and what it does (what resources it uses)

end-cretaceous extinction

"background" extinction
"mass" extinction
rapid (<1 my) extinction of about 60% of lineages throughout tree of life, rapid changes in environment

cretaceous mass extinction

60-80% loss of all species including dinosaurs, in fossil record ~65 mya

permian mass extinction

90% loss of multicellular species win fossil record ~251 mya

polyploidy

the presence of extra sets of chromosomes due to accidents during cell division - can lead to speciation

autopolyploid

an individual with more than two chromosome sets, derived from one species

allopolyploid

a species with multiple sets of chromosomes derived from different species

hybrid zone

geographic area where interbreeding between two populations results in hybrid offspring