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PSYC 385
Timothy Racine

CHAPTER 1 Hierarchical organization – two species that are similar in the details of systemAtend also to be similar in the details of system B • The amount of commonalities become less and the amount of divergence greater Gradual modification – the descendants of the ancestral form, each altering slightly over the generations, have split and split again, giving rise to many distinct branches on the tree of life Phylogeny – a diagram showing the family tree or pattern of ancestral relationships between several different species Natural selection – the process of non-random survival of useful innovations that cumulatively can lead to what seem to be well-designed structures without the involvement of a designer 1. Variation – individual organisms may be similar but not identical to each other 2. Heredity – many of the traits that vary from individual to individual are passed on from parents to offspring 3. Competition – not all individuals successfully mate and reproduce so not all individuals have the same representation in the next generation 4. Natural selection – those who successfully reproduce, those who have adaptive traits, become more common Vestegial structures – anatomical testament to the creature’s evolutionary history; gradual reduction of a part, eventually leading to disappearance, which is now functionless Homologies – similarities stemming from common origin due to similar ways of adaptation to a particular environment • Same structure, different function Analogies – a trait present in two or more different species that does not derive from their common ancestor but instead due to convergent evolution • Same function of a part in different species • Convergent evolution – a similar characteristic evolves independently in different species due to the same selection pressures being at work in each case Gregor Mendel – according to him, each parent provides the offspring with a set of heredity particles (genes); may be passed on discretely over generations CHAPTER 2 Phenotype – the observable characteristics of an individual • The phenotype of an organism is determined by the properties of the proteins in its cells Genotype – the combination of alleles possessed by an individual 3 Principles of breeding 1. There are particles of inheritance passed from parents to offspring, which determine particular phenotypic characteristics 2. Gene often come in alternate forms (alleles) (i.e.Aa) 3. In many sexually reproducing species, individuals have two copies of each gene, with one copy coming from each parent. Genotype influence phenotype. Genes replicate themselves to produce new cells/individuals with the same genotype. Central dogma of genetics – genes affect the properties of proteins, but protiens do not normally affect the properties of genes Somatic cells – only capable of function a (making more phenotype) Germ cells – only capable of function b (making more genotype) Synonymous – redundancy of codes; changes in the sequence of bases that make no difference to the amino acid sequence • The code has considerable robustness to errors in transcription or translation  Genes take up only a small fraction of the total genome Noncoding – non-gene DNA Exons – stretches of codons that are translated into the protein Introns – non-coding sequences inserted within the gene (more intron than exons) Pseudogenes – genes that have ceased to be translated Transposable elements – ability to copy themselves into different parts of the genome as evolution proceeds Gene’s evolvability – ability to generate novel phenotypes; enhanced by the presence of repetitive DNA Polyploidy – organism having more than two copies of the genome  The number of genes tends to rise gradually with increasing phenotypic complexity but its rise is very much slower than the rise in the amount of DNA, introns also rise  When the population size is small, natural selection becomes less efficient at weeding out non- functional but non-lethal characteristics Recombination – a sequence that was originally on chromosomeAends up on chromosome B Mutations: 1. Transitions – chemically similar substitution 2. Transversions – between dissimilar pairs 3. Deletions Gene families – multiple genes descended from a common ancestor by duplication events Locus – a particular site in the genome Polymorphism – two individuals of the same species have different sequences Mendelian diseases – single-gene diseases Association studies – those with phenotypic characteristic of interest and those without it CHAPTER 3 Codominant – heterozygous fully express the phenotype of both of their homozygous parents Incomplete dominance – the phenotype of the heterozygote is intermediate in form between those of the two homozygotes Independent segregation – the phenotypic traits controlled by different genes can become separated from each other through the generations Linkage – tendency of genes to travel together down the generations until broken by recombination Inbreeding – mating with biological relatives • The increased risk of passing on lethal recessive declines with increasingly distant relatedness, by a factor of four Hardy-Weinberg equilibrium – models the change in expected frequencies of alleles over the generations for a polymorphism in a sexually reproducing population, where all genotypes have the same probability of surviving and reproducing – no natural selection 1. Population frequencies of the different alleles do not change over the generations even though sexual reproduction is constantly shuffling the combinations up 2. Mating should be largely random 3. Infinite size of population Genetic drift – fluctuations or random changes in allele frequencies in finite populations Neutral theory of molecular evolution – fixation of a new mutation is more likely in a small population, the number of new mutations arising is greater in larger populations and so these two opposite effects of population size neatly cancel each other out • The amount of divergence between the DNAsequences of any two populations or species basically reflects the time since their common ancestor Molecular clock – hypothesis that neutral genetic changes accumulate at an approximately constant rate through time and that molecular divergence can therefore be used to estimate date of divergence of two lineages Quantitative genetics – investigates the overall relationships between genetic and phenotypic similarity Heritability – the proportion of the observed phenotypic differences that is determined by genetic differences • Problem: does not account for environmental factors Coefficient of relatedness – the probability that the alleles which two individuals have at a locus are identical by descent (derived from the same immediate source) Behavior genetics – the quantitative genetic study of behavioral and psychological traits Falconer’s estimate of heritability – an estimate of the total impact of genetic variation is therefore twice the difference between the phenotypic correlation of MZ twins and the phenotypic correlation of DZ twins ACE models – A: the heritability, C: the effect of the shared environment, E: the effect of non-shared environment • Any phenotypic difference must be attributed to the non-shared environment Dominance effects – where such effects are due to the interaction between the pair of alleles at a locus Epistatic effects – where they are due to interactions between alleles at different loci Narrow-sense heritabilities – heritabilities based on additive effects only Broad-sense heritabilities – estimates that include dominance and epistatic effects CHAPTER 4 Malthus – population grows exponentially but resources increase slower = competition! • Solutions: mortality and mating failure Reproductive success – the number of viable descendants produced  Natural selection is actually changing the frequencies of the underlying alleles Fitness – the number of copies in the next generation that a copy in a generat
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