PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29It is naïve to try to break down behaviors into strictly “nature vs. nurture” categories. Human height is an example of an anatomical outcome that is the result of both genetic factors and the environment.Predominantly EnvironmentalInteractionalPredominantly GeneticSpecific language Height Blood typeSpecific religion Weight Eye colorSkin colorIt is also naïve to divide behaviors into innate (like a FAP) or learned.Another cool behavior website! This one is from Dr. Kent Simmons at the University of WinnipegThere are many opportunities for the environment to influence behaviors (see Figure 5.1 in Text).However, what behavioral geneticists try to do is tease apart the influences of genetics and the environment because the evolution of behaviors (or any characteristic!) does not proceed unless there is at least a partial genetic basis.Once in a while we get lucky and can clearly see the behavioral results of a single or small set of genes.This is the case when we compare 2 strains of honeybees (Apis mellifera): hygienic and unhygienic.Most strains of honeybees are hygienic, meaning that if the workers detect that a bee larva has been infected by the bacillus, Paenibacillus larvae, they will uncap the cell and remove the diseased larva.American foulbrood is a bacterial disease that can infect larvae.A Mendelian cross can be done between true-breeding, homozygous hygienic bees and unhygienic bees.When this is done, the F1 generation of heterozygotes are all unhygienic. Thus, the hygienic allele(s) is/are recessive or unexpressed.And then aF1 X F1 cross is performed.When a F1 X F1 testcross is performed on the bees, the following behaviors result:1. ¼ Uncap cells but do not remove larva.2. ¼ Remove dead larva from previously uncapped cells.3. ¼ Not uncap or remove larva.4. ¼ Uncap cells and remove larva.This tells us that there are at least 2 and possibly more genes responsible for the behavior of: 1. uncapping the cell and 2. removing the dead larva.Honey bee larvae infected with American foulbrood become a stringy mass of material that later dries and carries the spores that may infect other larvae.So the bees areshowing all the evidence of a dihybrid testcross.Mutations and Knockout genes have provided some insight into the relationship between genes and behavior.When mutations are deliberately caused, using a mutagenizing technique such as chemicals or x-rays, there is no control over the site or extent of the damage or alteration of the DNA.This technique usually leads toanimals that are sick ordysfunctional and, because themutations are random in nature,it is time-consuming andexpensive.Knockout gene studies, on the other hand, are a more “fine-tuned” approach. In a knockout procedure a specific gene is targeted and disrupted. Then the resulting animals are screened to find out which have the knockout gene in their DNA. These animals are bred to create a strainof animals that are homozygous forthe inactivated gene. The resultinganimals are studied for any behavioralchanges that might occur as a resultof the inactivated gene.These techniques have already yielded examples of mutations at single gene loci that result in major disruptions of normal behavior.Paramecium:SluggishSpinnerParanoiacDrosophila:SpinsterDunceRutabagaAmnesiacFruitlessAs evocative as these studies are, remember that these genes might also be important in developmental processes or in the normal functioning of the central nervous system. So, further research is focusing on exactly which systems are disrupted by a given mutant.Remember too that pleiotropy (a single gene having multiple phenotypic effects) and epistasis (the action of one gene affecting the action of one or more other genes) can complicate what might seem to be a relatively simple gene/behavior relationship.fosB mutantinformationOther techniques have been used to examine putative single gene effects (e.g., mosaics), but most behavioral traits are caused by multiple gene (polygenic) effects.These include some intuitively simple experiments such as cross-fostering.(These pictures actually shows adoption, not cross-fostering, and are part of an urban legend. Click on right picture to read about the myth.)Great Egret chicks regularlycommit siblicideGreat Blue Heron chicks rarely doMock (1984) hypothesized that the small bits of food given by Great Egret parents to their chicks enabled aggressive chicks to monopolize the food and kill their nestmates.So, he did a cross-fostering experiment.Great Egret chicks regularlycommit siblicideGreat Blue Heron chicks rarely doThe result was that Great Blue Heron chicks, given small bits of food by the Egret parents, became siblicidal indicating that the environment can induce siblicide in the Blue Heron species. In contrast, Egret chicks remain aggressive even when given the large pieces of food typical of Blue Heron parents.Other ways to look at multiple gene effects in an intuitive manner are twin and adoption studies.Most behavioral traits are polygenic, so ifyou measure and graph them, it will result in a normal, or Gaussian, distribution.Another way to examine multigenic traits is by quantifying the amount of variance in a population due to genes versus that due to the environment.VP = VG + VEVariance ofphenotypeVariance ofgenotypeVariance ofenvironmentMultigenic effects: Quantitative StudiesWe can measure genetic transmission of traits throughheritability analyses.In behavioral and population genetics, there are 2 basic types of heritability:1. broad sense2. narrow senseHeritability of 1.0Heritability of 0Usually the heritability of a characteristic(including behavioral) is somewhere between0 and 1.0In “Broad-Sense” Heritabilitythe question is:“What proportion of the variancein a trait is attributableto genetic variance?”Broad-Sense Heritability measures thetotal proportion of variance in a trait – that is, genetic variance as opposed to environmental variance.Example:1. Raise mice in identical environments andmeasure their foraging behavior.2. Differences in behavior should be due to geneticdifferences among individuals (genetic variance or “G”).3. Raise mice in dramatically different environments.4. Now differences are due to G + E (E