Unit 7 Flashcards
Evolution
a change in genetic makeup of a population over time
Natural Selection
Mechanism of evolution where individuals with more favorable phenotypes are more likely to survive and produce offspring, thus passing traits to subsequent generations
Evolutionary Fitness
Measured by reproductive success
Evolutionary dating methods
Radioactive decay, thermoluminescence, paleomagnetism, biochronology, and molecular clock
radioactive decay
measures amount of radioactive decay of chemical elements; decay occurs in a consistent manner over time
Thermoluminescence
measures number of electrons absorbed and trapped inside a rock or tooth over time
Paleomagnetism
compares the direction of the magnetic particles in layers of sediment to the known worldwide shifts in earth’s magnetic field, which have well-established data using other dating methods
biochronology
since animal species change over time, the fauna can be arranged from younger to older.
Molecular Clock
Compares the amount of genetic differences between living organisms and computes age based on well-tested and rates of genetic mutation over time
Artificial selection
humans affect on variation in other species
convergent evolution
occurs when similar selective pressures result in similar phenotypic adaptations in different populations or species
Mutation
a random process that contributes to evolution and genetic variation, which provides phenotypes on which natural selection acts
Genetic Drift
a nonselective process occurring in small populations, such as bottleneck effect and founder effect
bottleneck effect
reduction in population size leads to reduction in gene pool, lowering genetic diversity
Founder effect
new population established from small # of individuals, lowering genetic diversity
Hardy-Weinberg
p^2 + 2pq + q^2 = 1
p + q = 1
Assumptions of Hardy-Weinberg Equilibrium
No selection, no mutations, no migration, large population, and random mating
allele frequencies
provide evidence for the occurrence of evolution in a population
evidence of evolution
biogeographical (location of life)
fossils (order of fossils in rock layers)
morphological (structures)
molecular (DNA or amino acid sequences)
Common ancestry of eukaryotes
membrane bound organelles, linear chromosomes, and genes that contain intros
Phylogenetic trees
shows changes over time calibrated by fossils or a molecular clock
Cladograms
shows relationship between lineages without the need of time
Speciation
may occur when two populations become reproductively isolated from each other
biological species concept
provides a commonly used definition of species for sexually reproducing organisms. It states that species can be defined as a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.
Punctuated equilibrium
when evolution occurs rapidly after a long period of stasis
Gradualism
when evolution occurs slowly over hundreds of thousands or millions of years
Divergent evolution
occurs when adaptation to new habitats results in phenotypic diversification.
Species
individuals that can reproduce fertile offspring
allopatric speciation
speciation because of geographic isolation
sympatric speciation
speciation with no geographic isolation; behavioral isolation
Prezygotic
before sperm meets egg (barriers prevent successful mating)
Postzygotic
after zygote forms and or develops (ex. hybrids)
Niche
the functional role of an organism in an ecosystem
genetic diversity
Increase of genetic variation = more stable resilience
decrease of genetic variation = more risk of extinction
RNA world hypothesis
proposes that RNA could have been the earliest genetic material
organic molecules
consist of Cs and Hs; serve as building blocks for the formation of more complex molecules, including amino acids and nucleotides
Inorganic molecules
consist of CO2 and H2O; was present at the beginning of the earth and synthesized organic molecules because of the presence of available free energy and absence of a significant amount of atmospheric
