Behavioral genetics

Question 1

Define “behavioral genetics”

Answer 1

Behavioral genetics is the field of study that examines the role of genetics in animal (including human) behavior

Question 2

Which prominent intellectual is seen as one of the first behavioral geneticists?

Answer 2

Sir Francis Galton

Question 3

Who wrote “Hereditary Genius”?

Answer 3

Sir Francis Galton, in 1869

Question 4

When did Francis Galton publish “Hereditary Genius”?

Answer 4

1869

Question 5

Who introduced the term “psychogenetics”?

Answer 5

Calvin S. Hall

Question 6

Where was the term “psychogenetics” first used?

Answer 6

In Calvin S. Hall’s seminal book chapter on behavioral genetics, from 1951

Question 7

When did “behavioral genetics” gain recognition as a research discipline?

Answer 7

Behavior genetics gained recognition as a research discipline with the publication in 1960 of the textbook Behavior Genetics by J.L. Fuller and W.R. Thompson

Question 8

Who wrote the textbook Behavior Genetics in 1960?

Answer 8

J.L. Fuller and W.R. Thompson

Question 9

What was the focus of Lee Ehrman’s seminal paper in the early 1970’s?

Answer 9

The relationship between genotype frequency and mating success in Drosophila

Question 10

Who wrote a seminal paper on the relationship between genotype frequency and mating success in Drosophila?

Answer 10

Lee Ehrman, in the early 1970’s

Question 11

What is “The primary goal of behavioral genetics”?

Answer 11

The primary goal of behavioral genetics is to establish causal relationships between genes and behavior

Question 12

How is a reductionist approach used in behavioral genetics (with schizophrenia as an example)?

Answer 12

scientists first observe a psychological or behavioral function (e.g., schizophrenia). Next, using known functions of brain systems and neurotransmitter systems, scientists correlate behavior to these brain areas (e.g., excess glutamate release may stimulate excess dopamine in the limbic system leading to schizophrenic symptoms). Once scientists are able to map behavior to biological systems, they can then turn to genetics to understand the development of these biological systems (e.g., an abnormal glutamate gene could be a candidate gene for schizophrenia).

Question 13

Apart from the reductionist method, which methods are often used in behavioral genetics?

Answer 13

Other methods used with human populations involve twin studies and adoption studies. With non-human animals, selection experiments have often been employed.

Question 14

What is a quantitative trait locus

Answer 14

Quantitative trait loci (QTLs) are stretches of DNA containing or linked to the genes that underlie a quantitative trait. Mapping regions of the genome that contain genes involved in specifying a quantitative trait is done using molecular tags such as AFLP or, more commonly SNPs.

Question 15

What is polygenic inheritance?

Answer 15

Polygenic inheritance refers to inheritance of a phenotypic characteristic (trait) that is attributable to two or more genes and can be measured quantitatively. The assumption of polygenic inheritance is that all involved loci make an equal contribution to the symptoms of the disease

Question 16

What is multifactorial inheritance

Answer 16

Multifactorial inheritance refers to polygenic inheritance that also includes interactions with the environment

Question 17

How does polygenic inheritance differ from Mendelian (monogenetic) inheritance?

Answer 17

Unlike monogenic traits, polygenic traits do not follow patterns of Mendelian inheritance (separated traits). Instead, their phenotypes typically vary along a continuous gradient depicted by a bell curve.

Question 18

How can the distribution of phenotypes from n number of interacting genotypes be calculated?

Answer 18

Polygenic inheritance can be explained as Mendelian inheritance at many loci,[6] resulting in a trait which is normally-distributed. If n is the number of involved loci, then the coefficients of the binomial expansion of (a + b)2n will give the frequency of distribution of all n allele combinations. For a sufficiently high n, this binomial distribution will begin to resemble a normal distribution.

Question 19

How is a disease state typically defined for polygenetic traits?

Answer 19

The disease state will become apparent at one of the tails of the distribution, past some threshold value. Disease states of increasing severity will be expected the further one goes past the threshold and away from the mean.

Question 20

Give an example of how polygenetic inheritance can be an insufficient explanation for some diseases.

Answer 20

Turnpenny (2004) discusses how simple polygenic inheritance cannot explain some diseases such as the onset of Type I diabetes mellitus, and that in cases such as these, not all genes are thought to make an equal contribution. In other words, the assumption of normally distributed phenotypes does not hold up.

Question 21

Name one basic assumption of polygenic inheritance

Answer 21

The assumption of polygenic inheritance is that all involved loci make an equal contribution to the symptoms of the disease. This should result in a normal curve distribution of genotypes. When it does not, the idea of polygenetic inheritance cannot be supported for that illness.