Ch 19,20,21,22 Flashcards
evolution
descent with modification
mechanisms of evolution
small population, nonrandom mating, mutations, gene flow, natural selection
tools to analyze evolution of a species
fossils, embryology,
evolution explains…
the unity and disunity of life on Earth
Charles Darwin
descent with modification is the original idea of evolution: that organisms differ from their ancestors; natural selection as the mechanism for evolution
Observations from Darwin that led to Natural Selection Theory
- there are many different heritable traits within a population; 2. an organism can produce more offspring than can survive; 3. species are adapted to their environment
Scala Naturae
Aristotle noticed that all organisms fall on a hierarchy of complexity
Linnaeus’ Contribution
binomial format of naming species; adopted a nested classification structure with similar species
Gradualism
species evolve slowly and continuously over time
Uniformitarianism
processes in geography that operated in the past are similar to processes now; things change at the same rate as they did in the past
Biogeography
the study of the geographic distribution of organisms
Lamarck’s Theories
use and disuse, structures that are used extensively grow faster; the idea that an organism could pass adaptations to its offspring
Homology
similarity of structures resulting from common ancestry; homologous structures are similar structures
Vestigial Structures
structures that are remnants of features that an organism’s ancestor used, but organisms now barely do
Convergent Evolution
the evolution of similar features in organisms with different lineages.
Homologous vs Analogous
homologous structures occur in the same lineage; analogous structures occur from convergent evolution in different lineages; homologous usually have other similar characteristics and matching DNA
Malthus said…
that sooner or later a population will be checked by a natural occurance
What is the unit of natural selection?
variation, sometimes caused by mutations
What is the unit of evolution?
population
phylogeny
the evolutionary history of a species
binomial names order
genus then species name
classification hierarchy
domain, kingdom, phylum, class, order, family, genus, species
taxon
a unit name for something at a level of the hierarchy (animalia, mammalia…)
phylogenic trees
each new branch point is where lineages diverge; the closer on the tree, the more closely related
molecular homology
used in combo with structures for phylogeny; analyze similarities in DNA sequences
cladistics
a method of determining phylogeny uses common ancestors
clade
includes an ancestor and all of its descendants
monophyletic
when a phylogenic branch is a clade; has all descendants of an ancestor
paraphyletic
when a group consists of the ancestor and only some of the descendants
polyphyletic
when a group consists of some descendants that don’t share the same ancestor
shared ancestral character
a character that originated in an ancestor of a taxon (backbone)
shared derived character
a trait shared by all in a taxon but not found in their ancestors (hair for mammals)
molecular clock
measuring evolutionary change with genetics; knowing that some genes never change or change at constant rates (approximate only)
why kingdoms changed to domains
used to be two kingdoms: plant and animal; but then they realized there really should be five kingdoms; and those kingdoms fall under the three domains: bacteria, archaea, eukaryote
hardy-weinberg
if a species isn’t evolving: p^2+2pq+q^2=1; p^2 equals the phenotype proportion and p equals the allele frequency
genetic drift
the change in allele frequency based on pure chance because of mating choices or events that happened randomly
gene flow
when alleles move in/out of populations and alter allele frequencies
founder effect
when only part of a population is blown to an island and they become the new gene pool; involves genetic drift
bottleneck effect
when population size drops and genetic drift and allele frequencies change occurs
directional natural selection
favoring variants that are at one extreme of the phenotypes of a gene
disruptive natural selection
favoring variants at both ends of the phenotype extremes; selecting against heterozygous usually
stabilizing natural selection
removes extreme variants and favors heterozygous phenotypes
sexual selection
natural selection where certain phenotypes are more attractive for mating
sexual dimorphism
when characteristics that affect choosing mates arise within a species; a peacock vs a peahans…one has showy feathers, one doesn’t
intrasexual selection
individuals of the same sex competing against each other
intersexual selection
individuals are choosy of mates they want to mate with
counteraction to directional and stabilizing selection
diploidy and balancing selection
diploidy
the idea that recessive alleles are lower frequency but still provide a means for selection and can keep the species going if the selection conditions change
balancing selection
occurs with heterozygous advantage so both alleles are kept or with frequency-dependent advantage where lower allele frequencies are favored in selection
microevolution
changes in allele frequency
macroevolution
changes in organism structures or characteristics or entire population evolution
biological species concept
populations in which organisms can inbreed and produce viable and fertile offspring
reproductive isolation
biological barriers preventing two species to produce an offspring; either prezygotic or postzygotic
prezygotic barriers
geographically seperated, not attracted to mating, not physically possible to mate, mate at different times of the day, won’t fertilize…
postzygotic barriers
the reproduced organism is a hybrid; it might not survive long, or be able to reproduce
hybrid breakdown
when a hybrid is viable and fertile, but its offspring is not
morphological species concept
species characterized by characteristics
ecological species concept
characterized by contribution to an ecosystem
phylogenetic species conept
common ancestors
allopatric speciation
gene flow is interrupted when population is separated and becomes own population/species
sympatric speciation
without geographic separation, a subset of a species is formed
polyploidy
sympatric speciation from when cell division gives an organism an extra set of chromosomes
autopolyploidy
all chromosomes, including extras, are still from the same species
allopolyploidy
chromosome are a mix of two species and it is a hybrid; still extra chromosomes
hybrid zone
environments where two species overlap and could produce a hybrid
hybrid reinforcement
natural selection strengthens prezygotic barriers when hybrids are unfit
