BIOL 1030 Exam 1

Evolution

decent with modification

Evolution can be viewed as both a ______ and a _______

pattern, process

strata

layers of sedimentary rock with the newest on top

Georges Cuvier

• study of fossils

• older species are less similar to present species

• catastrophism

Catastrophism

• each boundary between strata represents a catastrophe

• georges cuvier

Uniformitarianism

• the mechanisms of change are constant and slow

• Chales Lyell

Thomas Malthus

predicted human population will outpace food production

Jean-Baptiste Lamarck

acquired characteristics

Adaptation

inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Lines of evidence for evolution

1. artificial selection

2. direct observation

3. homologous structures and molecules

4. convergent evolution and analogy

5. fossils

6. biogeography

Artificial selection

humans modifying species by selecting and breeding individuals with desired traits

Direct observation of evolutionary change

the evolution of drug-resistant bacteria

fruit size vs beak size

Homology

similarity resulting from common ancestry

Orthologs

homologous characteristics across 2 species

Paraloags

homologous characteristics within a species

Convergent evolution

evolution of similar features in distantly related groups

analogy

Homoplasy

an analogous trait

Biogeography

the geographic distribution of species

Endemic

species not found anywhere else in the world

population

smallest unit of evolution

microevolution

change in allele frequencies in a population over generations

3 mechanisms that drive microevolution

1. natural selection

2. genetic drift: chance events that alter allele frequencies

3. gene flow: the transfer of alleles between populations

Discrete characters

can be classified on an either-or basis

ex: blood type

Quantitative characters

vary along a continuum within a population

ex: height

Point mutation

change in one base in a gene

silent mutation

no change in amino acid

missense mutation

change in amino acid

nonsense mutation

change to a stop codon

Duplication of small pieces of DNA

increase genome size, less harmful

ex: dogs having better smell than humans

Recombination

shuffle existing alleles into new combinations

population

localized group of individuals capable of interbreeding and producing fertile offspring

gene pool

all the alleles for all loci in a population

fixed locus

all individuals in a population are homozygous for the same allele (only one allele possible)

Allelic frequency

the frequency of all alleles in a population will add up to 1

p+q=1

Dominant allele in hardy-weinberg

p

Recessive allele in hardy-weinberg

q

genotypic frequency

frequency of all genotypes in a population will add up to 1

p²+2pq+q²=1

Hardy-weinberg principle

describes a population that is not evolving

states frequencies of alleles and genotypes in a population remain constant from generation to generation

5 conditions for a nonevolving population

1. no mutations

2. random mating

3. no natural selection

4. extremely large population size

5. no gene flow

Genetic drift

• allele frequencies fluctuate unpredictably from one generation to the next

• tends to reduce genetic variation through loss of alleles

Founder effect

a few individuals become isolated from a larger population

Bottleneck effect

sudden reduction in population size

gene flow

the movement of alleles among populations

“good”

Intrasexual selection

competition among individuals of one sex for mates of the opposite sex

Intersexual selection

individuals of one sex are choosy in selecting their mates

neutral variation

genetic variation that does not offer advantage or disadvantage

Diploidy

maintains genetic variation in the form of hidden recessive alleles

Balancing selection

natural selection maintains stable frequencies or two or more phenotypic forms in a population

heterozygote advantage

frequency dependent selection

Heterozygote advantage

heterozygotes have a higher fitness than homozygotes

Frequency-dependent selection

fitness of a phenotype declines if it becomes too common in the population

Speciation

the origin of new species

Macroevolution

broad patterns of evolutionary change above the species level

Biological species concept

states a species is a group of populations whose members have the potential to interbreed in nature and produce viable offspring

does not apply to fossils or asexual organisms

Reproductive isolation

biological barriers that impede two species from producing viable, fertile offspring

Hybrids

offspring of crosses between different species

Pre-zygotic barriers

no fertilization occurs

1. habitat

2. temporal

3. behavioral

4. mechanical

5. gametic

Post-zygotic barriers

prevent the hybrid zygote from developing into a viable, fertile adult

1. reduced viability

2. reduced fertility

3. hybrid breakdown (2nd gen hybrid cant survive/reproduce)

Morphological species concept

defines a species by structural features

Ecological species concept

views a species in terms of ecological niche

phylogenetic species concept

defines a species as the smallest group of individuals on a phylogenetic tree

hybrid naming

name of the male species in front

Allopatric speciation

gene flow is interrupted when a population is geographically isolated

sympatric speciation

speciation takes place in geographically overlapping populations

caused by gene flow reduction

polyploidy

extra sets of chromosomes due to accidents during cell division

more common in plants than in animals

autopolyploid

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

allopolyploid

species with multiple sets of chromosomes derived from different species

Hybrid zone

a region where members of different species mate and produce hybrids

Hybrid zone reinforcement

strengthening reproductive barriers

Hybrid zone fusion

weakening reproductive barriers

Hybrid zone stability

continued formation of hybrid individuals

punctuated speciation

speciation that occurs rapidly

gradual speciation

speciation that occurs over longer periods of time

Biodiversity

number of species, genera, ect

Taxonomy

the naming of groups of organisms

classification

assigning organisms to hierarchical groups

systematics

study of diversification and relationships

phylogeny

evolutionary history

Carolus Linnaeus

• taxonomy

• binomial nomenclature (Genus species)

Classification order

1. domain

2. kingdom

3. phylum (phyla)

4. class

5. order

6. family

7. genus (genera)

8. species (species)

Clade

branch of phylogenetic tree

Grade

group of organisms on a phylogenetic tree that share similarities but do not always have a common ancestor

Monophyletic

lineage with a single common ancestor

Holophyletic

lineage including all descendants of a single common ancestor (clade)

Paraphyletic

lineage including some but not all descendants of a common ancestor

not a clade

polyphyletic

lineage or trait found in independent lineages

not a clade

Plesiomorphic

ancestral characteristic

Apomorphic

a derived (new) characteristic

Symplesiomorphic

a shared ancestral characteristic

Synapomorphic

a shared derived characteristic

Autapomorphic

an unshared derived characteristic

Prokaryote

lacks a nucleus

lacks other membrane bound organelles

cellular

has DNA, ribosomes, cytoplasm, cellular membrane

viruses

not cellular

not considered living

Thermophilic

extreme temperatures

Acidophilic

extreme pH

Halophilic

extreme salt

Bacteria is _____ ancient than archaea

more

Spherical shape

coccus (s) / cocci (p)

rod shaped

bacillus (s) / bacilli (p)

spiral shaped

spirillum (s) / spirilla (p)

Staphylo-

groups of cocci