Behavioural Genetics class 1: Science behind behaviour

How environment and genetic traits influence the behaviour of an organism

Image credit: www.nature.com

 

 

Structural and biochemical traits are well studied in modern day science. We have enough data regarding genes and its governing characters. Each protein is encoded by the particular gene and is important for the survival of an organism.  But can we study behavioural characters of an organism based on genetic traits? Well, a behaviour is more psychological than genetics.

Behavioural characters are learnt, it is developed by interactions of the organism with its environment but some of the behavioural characters may be inherited genetically which means it is controlled by some genetic factors.

“Due to the interaction of environment and genetic traits, the genetic composition of organism influences behavioural characters of the organism. It clearly indicates that difference in the genetic composition leads to the behavioural difference in the population”. 

Biologist and psychologist have different views on the behavioural development of an organism. As per the psychological view behaviours are developed by environmental interaction but as per biologist, it may be governed by some genetic traits.  However, both groups of scientist are agreed with the theory that behavioural characters are influenced by the inheritance of traits and their interaction with the environment.

Let us take some example, we have to learn walking by interacting or observing other humans. In contrast, the learning process is not involved in feeling happy. When we feel happy we laugh.

In other organisms, the mechanism of learning and inheritance of genetic trait for particular behaviour is well studied.

The honey bee is the best model organism for studying behavioural genetics. It has a specialized social arrangement with a different level of classification based on functionality. Queen, drone and workers have different functions even their genetics compositions are different.


Attend Class: Extrachromosomal inheritance


W. C. Rothenbuhler studied “hygiene” behaviour in two species of honeybee. He picked bees from Americal foul-brood and Van scoy.

The character of hygiene is governed by a pair of recessive alleles. The worker bees from America foul- brood line maintain hygiene by removing dead pupae from their hive while the Van scoy lines bees are non-hygienic. It leaves the dead pupae in the compartment of hives.

Interestingly, when Rothenbuhler crosses both types of bee and observed result in F1 progeny, all the F1 progeny are non-hygienic. When drones from this F1 lines are backcrossed with the queen of hygiene bees, four different types of progeny are observed in F2 progeny,

The image represents the behaviour of hygiene and opening of hives in the bee. u+ gene codes for hygiene-removes dead pupae, u- is for non-hygiene- not removes dead pupae, r+ for opening hives and r- for not opening hives

 

  1. Pure hygienic bees
  2. Bees that did not open hive compartment but removes dead pupae (that hive compartment are opened by beekeepers).
  3. Bees that opened hive compartments but did not remove the dead pupae.
  4. Non-hygienic bees.   

The hygiene characteristic is controlled by two genes one gene that controls the behaviour of uncapping or opening of hive compartment (called as “r)  and another gene controls the character of removal of pupae from the hive (called as “u).

Interactions of both types of gene results in different types of behaviour in the F2 progeny. From the experiment, Rothenbuhler conformed that some of the behavioural characters are controlled by genetic traits.

Another behavioural character which is controlled by the genetic trait is the collection of alfa alfa pollens in honey bees.

Some of the species of bees collected much higher percentage of alfa alfa pollens while some other colonies collect a low percentage of alfa alfa pollens. When both types of colonies are crossed, in an exact 8th generation the tendency of collecting alfa alfa pollen is intermediate between both types of the colony.

Graphical representation of pollen collection behaviour in two different population of bees.

The preference of collecting Alfa alfa pollen follows the pattern of Mendelian inheritance. Scientifically, the collections of alfa alfa pollen behaviour are learned by parental bees but it is inherited in a specific pattern. This results confirmed that both learning and inheritance are involved in the development of complex social behaviour in honey bees.

Another important behavioural character is even governed by the complex interaction between genotype and learning ability. The food source direction and distance is a behaviour which is learned by other bees however it is regulated by a genetic trait.

Italian bees have slower dancing rhyme and travel 100 meters in search of food. While Australian races of bees have fast dancing rhyme and can travel 80 meters in search of food. When the population of both types of bee mixed, both types of bee misunderstood the rhyming and distance behaviours. This change influences the morphological behaviour of bees.

The image represents distance travelled by two different population of bees, before mixing and after mixing of the population.

Some of the behavioural characters are learned but it can influence the morphological characters and inherits in the Mendelian pattern to their progenies. 

In humans, homosexuality is one of the psychological behaviour in which the individual has an attraction with the same type of sex. This behaviour is more genetical than psychological. Most of the homosexual people are suffered from DSD (disorders of sex) which is occurred due to the mutation in some of the genes.

Under-expression or over-expression of some genes result in hormonal imbalance and it misleads the sexual preference of an individual.

Practically it is not possible to study human behaviour because of ethical limitations. But some of the human behavioural characteristics are common with other mammals.  The behaviour of food intake by the infant is phylogenetically common among mammals. As we all know mammals have mammary glands to feed their Child, “rhythmic searching for nipple” is one of the common characters shared by most mammals.

From the results of behaviour patterns of congenital deaf and blind children, it is confirmed that some of the characters are inherited and not learned. Even if they are blind and deaf, expression of anger, laughing during happiness and facial expressions during each condition are as same as normal children.

Predictably, it is possible that these behaviours are governed by some genetic traits and inherited independently or it may be psychological. However, to date, scientist does not have enough data to conclude that behavioural characters are governed by genetic traits or are psychological.   We will discuss behavioural genetics in the Drosophila, dog and other animals in the next article.


Attend class: Immunogenetics


 

Hey readers, you can comment or suggest us, if we missed any point or topic

Article written by: Tushar Chauhan

Article reviewed by: Binal Tailor

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