Unit 7 Flashcards
Evolution
The change in gene frequencies within a population over time
Natural selection
traits that enhance survival allow for organisms to better live and reproduce, pushing for traits to be selected and more common
Darwin’s postulates for natural selection
- variation is within populations
- some variations are heritable
- organisms over-reproduce
- different survival based on traits
Evolutionary fitness
the ability an organisms has to survive and reproduce
Reproductive success
how well an organism is able to create offspring that can survive to reproductive age
Directional selection
change in a population’s phenotype or genotype overtime away from what the mean is in the environment
Disruptive selection
causes two extreme versions of a trait
Stabilizing selection
selection where the average and moderate phenotypes are selected for, and the extremes start to go away
Genetic Variation in a population
natural genetic differences among organisms part of the same species and population.. allows for population to better survive
Phenotypic variation in a population
variation in appearances of organisms, can be considered a combination of genotypic and environmental variations.
like genotypic variation, it is important in helping populations survive when changes occur
Artificial selection vs natural selection
artificial selection happens because external factors such as human purposefully influence the traits that are selected, eg. dog breeding
natural selection does not have such interventions
Mutation
change DNA sequences
Genetic drift (bottleneck effect and founder effect)
genetic drift is a random change in the allele frequencies in a gene pool
bottleneck effect is when a large part of the population is destroyed so the gene pool decreases and the consequent generations have lesser genetic variation
founder effect is when individuals from a population are separated from the rest of the population and thus only carry a small unrepresentative section of genes
Migration
movement of individuals or populations across different regions that can also cause gene flow
Gene flow
movement or exchange of genes from different populations
5 conditions for Hardy weinberg equilibrium
- no mutations
- no gene flow
- a very large population
- random mating
- no natural selection
Allele frequency
what the frequency or how common an allele is in a population
Genotype frequency
proportion of different genotypes in a population
Geographical evidence
distribution of species all over the world to understand evolution
Molecular evidence
DNA and protein sequences that show proof of evolution
Extant and extinct organisms
extant organisms are ones that are still alive and exist
extinct organisms are ones that completely died
Fossils
preserved remains of ancient organisms
Sedimentary rock
rocks formed from cementation of sediments
Radiometric dating including Carbon-14 dating
used to determine age of organic materials
Common ancestry
to come from the same species before evolving into different…same origin
Conserved genes
genes that can be found in all organisms
Homologous structures
when organisms that have shared ancestry have structures that are similar but have different functions
Analogous structures
organisms don’t have shared ancestry but have structures that are similar in function.. (don’t always look the same, think wings of bats, birds, butterflies)
convergent evolution
organisms that don’t have a common ancestor and aren’t closely related eventually evolve to have the same or similar features and behaviors
Divergent evolution
when species start from the same source but evolve to be different the ancestors
Bacterial resistance to antibiotics
the bacteria with resistance to antibiotics survive and multiply quickly, spreading to other germs too
Phylogeny
study of evolution through relationships of organisms
Phylogenetic tree
a way to visually show phylogeny and the relationships and closeness between organisms
evolutionary and genetic distance
Cladogram
similar to phylogentic trees but this isn’t about evolution its a way to display relationships based on related characteristics
Molecular clock
measures the unchanging rate of change that an organism’s genome goes through
Shared derived characteristics
shared - character that one or two lineages have in common
derived - character that evolves from a lineage into a clade, individuals of clade are different than other clades
Out-group
distantly related group of organisms that is a reference point for evolutionary relationships of the ingroup
Monophyletic group
a group containg a common ancestor and all of its descendants
Clade
another word for monophyletic group
Common ancestor
species that many other’s have originated from…having a shared origin
Speciation
process through which a new species forms
Morphology
study of organism’s structure and form
Reproductive isolation
barriers between different species that stops them from breeding and making healthy children
includes evolutionary, behavioral, psychological, genetic, physical, etc.
Punctuated equilibrium
evolution happens in little segments where for long periods nothing changes and then in short spurts lots of evolution occurs
Gradualism
evolution where species change slow and steadily
Speciation rate
rate that species can emerge from a starting point
Allopatric speciation
geographical isolation causes a new species to evolve from the original
Sympatric speciation
new species evolving from original group without geographical isolation
Prezygotic reproductive isolation
barriers that stop fertilization from happening, like stops a zygote from being formed
Post zygotic reproductive isolation
barriers after zygote formation that prevent further reproduction such as death as embryos or being born sterile
Extinction
organisms disappearing from existence, all of them die out
Extinction rate
the rate at which extinction happens
Background extinction rate
the normal number of species expected to go extinct over a period of time
How humans cause increase in extinction rate
over-consumption, habitat loss, pollution, hunting, etc.
Genetic Diversity and extinction rate
low genetic diversity means higher chances of going extinct and higher genetic diversity means lower chances of species or populations going extinct
Inorganic compounds
compounds that don’t have carbon-hydrogen bonds
Organic compounds
compounds that have carbon in them
RNA world Hypothesis
life in this world started because of RNA molecules that could copy themselves
RNA as genetic material
RNA is the genetic material for viruses and is important in protein synthesis and other processes
RNA as enzymes
ribozymes are RNA molecules that can catalyze reactions
