evolution Flashcards
biological evolution definition
heritable change in a population across one or more generations determined by genes caused by environment
requires genetic diversity
abiotic and biotic factors play a role in deciding if a trait will succeed in a particular environment
DOES NOT CREATE NEW TRAIT it selects and advantages those already existing
microevolution vs macro
micro: small changes, but still same species
macro: lots of small changes leading to different species (or big change)
ecological selection vs sexual
eco: survival is determined more by ecology than sexual reproduction
sex: survival determined more by sexual characteristics than eco
natural selection encompasses both
morphological vs physiological vs behavioural
morpho: how it looks
physio: its function
behavioral: its in the name
fossil
evidence of past life and their era of living
info about morphology or mammal usually and parts that dont decompose easily and only external
gives info on when they went extinct through the stratigraphic layers
homologous features
similar structure, but different functions, hypothesized to come from common ancestor
analogous structures
structures of organisms with seperate ancestries that adapt in similar ways because they have similar environments, comes from convergent evolution (evolution of features similar in distant groups)
evolution tree
phylogenetic trees (hypothesis)
vestigal structures
loss of fucntion of a feature because of adaptation to different modes of life
horizontal gene transfer
gene trasnfer in bacterias for example, from individual to indvidual, as opposed to vertical gene trasnfer, from generation to generation
population
a population is considered so if it can only reproduce with itself (due to geographic “isolation”)
gene pool
all the alleles present in a population
genetic equilibrium
frequency of alleles and gentype in a population’s gene pool remains constant
a sexually reproducing population will be at genetic equilibrium if all are met:
1-natural selection is not occuring
2-mating is random
3-no net mutation
4- large population (small ones tend to genetically drift)
5-no migration between populations
fitness
ability to survive, find a mate, produce an offspring, and leave genes in next generation
How well adapted to environment
natural selection
adaptive, adapts to the environment
Sexual selection
Non random mat
Direct: two competitors fight
Indirect: attract partner
May have costs, such as energy consuming and attracting predator
Also non random mating that’s not adaptive, when similar genotypes are attached to each other, reduces variability genetic variation
Non adaptive factors leading to evolution
Non random mating that’s not adaptive
Mutations
Genetic drift (bottleneck, founder effect)
Gene flow
Genetic mutation
Random
Must be in gametes to be passed down
In eukaryotes, rates are low
Microorganism more often because of high speed of reproduction (binary fission)
Add variability, if no variability, no evolution
Point mutation: one nucleotide change
Chromosomal mutation: deletion, duplication, usually harmful
Genetic Drift
Change in allele frequencies occurs from a random event that occurs in small population
Small populations more likely to change by random fluctuations
Bottleneck
Sudden decrease in population size cause by adverse environment factors
Reduction in genetic diversity
Founder effect
Individuals leave the original population and start a new one
New population has less genetic variability
Gene flow
Transfer of alleles from one population to another (same species)
Recipient gains alleles, donor may lose alleles
Results from a movement of fertile individual gametes
Ex: horizontal gene flow
Can happen between different species, for example with prokaryotes, can rarely happen with eukaryotes
