Exam 1 Flashcards
Mutations in ______ cells are more important
sex
they are passed on to next generations.
Point mutation-
change in one nucleotide
Substitution point mutations can be ________ (silent) or ________ (meaningful)
synonymous
non-synonymous
Silent mutation-
codon from this mutation specifies the same amino acid as the non-mutated codon. No protein change.
Codon-
triplet sequence of nucleotides that specifies a particular amino acid
Non-synonymous (meaningful) point mutation-
missense, different amino acid, different protein.
Large sections of chromosomal mutations-
deletion, duplication, inversion, insertion, translocation.
Gene position may or may not be important in its __________
expression
Trisomy 21 is due to _________. Leads to ___________
- nondisjunction, extra T21 chromosome
- Down Syndrome
Fusion of a chromosome might be a significant effect in __________
speciation
Estimated number of protein coding genes in humans
25,000
Gross generalization: mutation rate per generation is:
10^-5 or 10^-6
mutation rate (_______) is too low to be main force in evolution. Between _____% of us carry a genetic mutation compared to our parents. Although mutation is too low to be main force of evolution, it is the only source of ___________
- .025 to .25
- 5-44%
- new genes in a species.
Mutations increase genetic variability in a _________ and between __________
- population
- populations
Gene flow-
movement of alleles from one population to another due to mating between populations.
Gene flow inhibits speciation because ____________________
two populations blend their traits and they are now more similar and less likely to genetically diverge from each other.
Genetic drift-
random change in allele frequencies
The smaller the population, the more chance of significant ________
mutations
Two inferences we can make about genetic drift:
- All populations evolve every generation by genetic drift
2. magnitude of evolution by genetic drift is greater in a smaller population than a larger population
The ultimate result of genetic drift is ___________, and all other alleles of the gene have been _______________
- fixation of an allele
- eliminated from the population
Bottleneck and Founder effects-
reduction in genetic variability by chance due to reduction in population size (bottleneck) or establishment of a new, founder population.
Natural selection-
differences among individuals in reproductive success
The unit of natural selection is _________; the unit of evolution is ___________
- the individual organism
- the population (or species)
- Adaptation- result of _________
- Individuals are subject to natural selection, whereas populations (or species) _______
- natural selection
- adapt
-Adaptation occurs only if differences among individuals in reproductive success have ____________
some inheritable basis.
Fundamental Theory of Natural Selection-
opportunity for natural selection is directly related to genetic variability in a population (or species)
There must be ____________________ for there to be natural selection.
genetic differences among individuals in a population (or species), and correspondingly phenotypic differences,
Natural selection “acts” directly on __________, and indirectly on ____________
- phenotypic variability
- genetic variability
Natural selection –
differential reproductive success among individuals in a population (or species).
Three “types” of natural selection
stabilizing selection, directional selection, and diversifying selection
Stabilizing selection –
-Result is to reduce variability in the _________, but no change in _______
- selection against individuals at both ends of the phenotypic distribution curve.
- distribution curve
- the mean value
Directional selection – ____________. Result is a change in the _____________.
- selection for individuals at one end of the phenotypic distribution curve.
- mean value of the distribution
Diversifying selection – ____________________. Result is ______________.
- selection against individuals in the intermediate range of the phenotypic distribution curve, and selection for individuals at the ends of the distribution curve
- two modalities in phenotypic distribution
Units of natural selection:
- gene
- individual organism
- group (i.e., population)
- species
For a “unit” to be subject to natural selection, the trait _____________ and there must be __________.
- must be inheritable
- variance within that unit
Units of natural selection
- Gene-
- Individual organism-
- Group (i.e., population)-
- Species-
- meiotic drive: allele is transmitted to offspring at a rate higher than 50%
- classic Darwinian theory
- individuals in the group sacrifice their reproductive success to ensure group survival
- Species differ among themselves in likelihood of speciation; lineages with high speciation rates persist, whereas those with low speciation rates go extinct
Kin selection
1.
2.
also called 3.
- just more natural selection at level of individual organism
- Individual may reduce her/his reproductive success by aiding the reproductive success of her/his “kin”
- altruism
Kin selection is simply part of an organism’s ___________ and can be considered to be natural selection among individual organisms.
inclusive fitness
Inclusive fitness:
an individual’s genetic contribution to the next generation is based on both one’s own reproduction and by reproduction of one’s relatives.
5 concepts of a species:
- Biological species
- Evolutionary species
- Morphological species
- Ecological species
- Recognition species
Biological Species:
Group(s) of actually or potentially interbreeding organisms that are reproductively isolated from other such groups.
