module 1 Flashcards
Deffinition of evolution
the change in populations and species over time
patterns in nature that species have changed over time
- species composisitons have changed
Evidence: fossils - species are related
Evidence: resemblances between species(structural developmental and genetic)
why are fossils said to show a pattern that species change over time?
fossils show species composition changed through time
why does homology show species have changed over time?
homology show species share striking similarities
who published the orgin of species
charels darwin
who came across the idea of natural selection first
Alfred Russel Wallace before charels darwin published
who came up with the principles of inheritance?
Mendel
the logical processs of natural selection
individual organisms vary in traits that are haritable by offspring. only a subset of individuals servive the survivors are said to have an advantage.
If traits that produce and advantage are said to be haritable then,
The frequency of individuals carring that trait will increase with respect to individuals not carrying the trait.
natural selection acts on …
individuals
Evolutionary change occurs…
in populations
deffinition of selection pressure:
selection pressure: external factors in a particular enviorment that affect individuals ability to survive.
negitive selection pressure:
negative selection pressure : disadvantage for individuals with particular trait-> leads to a decrease in occurence of that trait
possitive selection pressure:
possitive selection pressure: advantage for individuals with particular trai-> leads to an increase in occurence of that trait.
meaning of fitness in the context of evolution and natural selection
how many offspring an individual produces
adaptation:
adaptation: heritable trait the increases the fitness of an intividual with that trait relative to individuals that do not have that trait
constraints on adaptations
time
trade-offs
historical constraints
adaptive radiation can occur when
evolution occurs rapidly causing new ecological niches to become avalible
female reproduction is limited by
acess to resources
male reproductionn is limited by
acess to females
the two types of displays used to choose a mate
morphological and behavioral
natural selection is the only mechanism of evolution that results in…
adaptations and leads to increased average fitness of the population
allel frequency changes are or are not adaptive
not adaptive
in ____ populations genetic drift can be much more pronounced
small
the founder effect is…
when a subset of the original population immigrate to a new area and establish a new population
populationn bottleneck is
when there is a subben restriction in population size and only a small random selection of alleles survive
drift after population bottleneck leads to
a random subset of alles survive
gene flow
when one population migrates into another population and equelizes allele frequencies
what is a phylogeny?
a depiction of the evolution history of a group of organisms
topology:
the branching pattern of the phylogenetic tree
branch length on a phylogenetic tree represents
the amount of evolution that has taken place along a branch
monophyletic group
share a common ancestor that is exclusive to this group
paraphyly:
one/few taxa not inclided in group descendeed from common ancestor
polyphyly:
common ancestor not exclusive
polytomies:
branching pattern is unresolved
unrooted trees
lack a root and cannot determine order in time of internal nodes
when comparing phylogenetic data
- sample DNA/RNA locus
- remember homologous genes are inherited
- construct an alignment
