exam 1 Flashcards
Jean Baptiste Lamarck
influenced Darwin’s idea. A french nationalist who first proposed that species change over time
typological thinking
organisms are fixed and do not change
what is Lamarck’s idea that evolution changes over time?
- proposed the formal theory of evolution in 1809
- simple organisms originate at the base of the chain by spontaneous generation
- organisms evolve by moving up the chain
horizontal gene transfer
when a cell can duplicate a gene and transfer it to the cell next to them (this is how bacteria spreads)
biological fitness
a species ability to produce surviving, fertile offspring compared to other individuals in a population
acclimation
when an individual experiences a change in phenotype due to an environmental stressor
- ex: goosebumps, sneezing, coughing, etc
fitness trade off
a compromise between traits in terms of how they performed in the environment
evolution
a process changing allele frequencies
genetic drift
allele frequencies in a population change randomly
gene flow
when individuals leave a population to join another and reproduce
mutation
continuously introduces new alleles, thus modifying allele frequencies
population genetics
the study of processes that change a populations allele frequencies
Hardy Weinberg equlibrium
- p^2 + 2pq + q^2 = 1
- random mating
- no genetic drift, gene flow, or mutations
modern synthesis
an era in the early 1500s where evolutionary biologists, mathematicians, and geneticists collaborated to quantify evolution
natural selection occurs when…
heritable variation leads to different survival and reproduction
directional selection
- favors one phenotype over another
- the scale tips in favor of one phenotype that will survive and reproduce more, while the losing phenotype will decrease in population
allele fixation
when the favored trait becomes 100% of the population
purifying selection
when the disadvantageous traits decline in frequency
stabilizing selection
favors the intermediate phenotypes (the medium option)
disruptive selection
favors the extreme phenotypes
balancing selection
there is no phenotypic preference. this happens when no single allele has a distinct advantage
speciation
a process where a group of organisms inside a population become reproductively isolated, and leads to form a new species
ways speciation can occur
- isolation of populations
- divergence in traits of separated populations
- reproductive isolation of populations
- genetic isolation
what defines a species?
- can interbreed
- produce fertile offspring compared
- have at least 97% genetic similarity
allopathic speciation
- they become separated (perhaps geologically by rivers, mountains, glaciers, etc) and there is no contact between the two populations
- no gene transfer
sympatric speciation
- geographical events don’t matter and there’s continuous contact between the two populations
- may live in the same environment, but there are micro environments
prezygotic barrier (temporal)
two species mate at different times of the year
prezygotic barrier: ecological
two species occupy different habitats
prezygotic barrier: behavioral
two populations have different mating behaviors
prezygotic barrier: mechanical
physical differences prevent copulation/pollination
postzygotic barrier: hybrid viability
hybrids are reproduced but fail to develop to reproductive maturity
postzygotic barrier: hybrid infertility
hybrids fail to reproduce functional gametes
postzygotic barrier: hybrid breakdown
F1 hybrids are fertile, but F2 generation fails to develop properly
divergent evolution
individuals in one species with a common ancestor develop enough genetic variation that it leads to two species
convergent evolution
two unrelated species develop similar genetic traits from living in the same environment
coevolution
- two separate species living in the same environment net develop alongside each other
- a change in genetic information in one will induce a change in genetic info in another
sexual selection
- when one sex prefers certain characteristics in the opposite sex
- non random mating
- males compete for a mate
intersexual selection
one sex (typically males) display a certain trait or behavior with the goal to attract a mate
intrasexual selection
individuals of the same sex compete with one another for a mateo
carotenoids
the pigment that causes colorful feathers or beaks. it protects tissues and helps the immune system fight diseases. animals must eat plants to get it
genetic bottleneck
a sudden decrease in population size in large populations. could be caused by disease outbreaks or natural castephroies
chromosome level mutations
change in the number/compositions of chromosomes
founder effect
- when a small subset of a population is used to establish a new colony
- reduction in genetic variation
