Chapter 02 pt 1 Flashcards
what is natural selection?
individuals with the most beneficial characteristics are the most reproductively successful
what does natural selection explain about organisms?
how traits become more prevelent in populations over time
theory of evolution states that:
genetic change of a population over time leads to physical changes
What are the 4 tenets that explain natural selection?
- individuals within a population vary
- many traits are passed from parent to offspring
- populatons should grow exponentially but do not
- individuals with beneficial traits will survive and pass down their triats
what are different selective agents that drive natural selection?
intra and interspecific
intraspecific
mate choice, competition
interspecific
predation, parasitism
fitness
the number of viable offspring an individual produces, and amount of genetic information it passes down
mutation
a heritable chang ein a gene or chomosome, random evolutinary force
microevolution
evolution on a small scale
artificial selection
humans slect animals to breed together based on prefered traits
macroevolution
evolution on a larger scale
sexual selection
process that leads to adaptations that increase reproduction chances
phylogeny
history of the evolution of a species or group
Homologus structures
a trait shared by 2 or more species due to a shared common ancestor
analogous structures
trait shared by 2 or more due to simular natural selection pressures
convergent evolution
simular adaptations due to simular enviornmental contraints
phylogenetic trees
shows the history of evolution of a species or group and can help distinguish between homologies and analogies
taxa
group/ species placed at ENDS of branches
Characters
placed at opposite of taxa names
root
at the bottom of the phylogenetic tree
basal/ ancestral/ primative species
evolved early on in time
derived species
evolved later on in time
nodes
where two branches come togehter, represent a shared common ancestor between two or more species
clade
group made of an ancestor and all its decendants
sister taxa
adjacent branches on a tree that form a clade together, (closely related)
plesiomorphies
primative/ inherited form a common ancestor
synapomorphies
derived traits
what are the 5 mechanisms for evolution?
- natural selection
- mutations
- genetic drift
- gene flow
- assortative mating
natural slection
adaptations
mutations
random heritable change in gene or chromosome
what is unique about mutations?
- ultimate source of genetic variation
- new alleles
- makes good and bad traits
genetic drift
change in genetic variation as a result of random chance
meiosis
creates genetically unique gametes that increase genetic variation
bottleneck effect
traits lost due to shrinking population size
founder effect
small number of individuals go to islands
gene flow
movement of genetic info among populataions bc of migration
imigration
import
emigration
export
assortive mating
individuals mate non- randomly (choose mate like humans)
sexual selection
process that leads to adaptations that increase reproduction chances
what is the ultimate source of genetic variation in the gene pool? and why
mutations, they introduce new alleles into the gene pool
what factors can lead to genetic drift?
immigration, emigration, and the bottleneck effect
what happens to genetic variation when there is gene flow?
- increase genetic variation within a population
- reduced genetic variation among populations
What kind of selection results from assortative (non-random) mating? How does this
differ from natural selection?
sexual selection, this differes from natural selection becasuse they are choosing a mate and leads to choosing adaptations that increase reproductive chances
What are the 4 requirements for natural selection to act on a behavior?
- variaton
- heritability
- limited recources leading to COMPETITION
- fitness consequences
Why is it important to build a phylogenetic tree using homologous traits rather than
analogous traits?
bc homologuous traits are ancestor related like the goal of trees is to show ancestoral relations
What kind of data are used to construct a phylogenetic tree?
homologus and analogous traits
