Genetic Evolution of what makes a Dog

Evolutionary Genetics

Evolutionary genetics traces back the origins of DNA. This can be impacted by genetic drift, bottleneck effect and founder effect (Bjornerfeldt, 2007).

Genetic Drift is when there are random opportunity genes that can cause adaptions and changes to breed selection.

The Bottleneck Effect is when there is limited population and only a small number can produce offspring.

The Founder Effect is when a group of one species is separated from the rest which can lead to considerable genetic alterations; limiting the gene pool of any group means that there can be health issues and survival implementations.

A mutation, on the other hand, is an error in copying the DNA but this creates genetic diversity. The greater the chance of genetic diversity the greater the chance of success in the species as it has more opportunity to create different outcomes. When the gene pool is limited, there would be less opportunity for mutations and genetic diversity to occur. Meaning this limits the chance the species will be able to adapt to changing environments and be strong enough to survive for future generations.

Genotype and Phenotype

A dogs' DNA is a map of instructions on how to be a dog, which is unique and can vary. Two types of genetic inheritance to note are the genotype and phenotype (The Kennel Club, 2023). Genotype is relating to the same type of characteristics past down to the offspring. For example, a homozygous genotype would be for both parents to have white fur, compared to heterozygous genotype would be one parent having brown fur and the other white. Phenotype refers to the environmental impact on a trait. Phenotype also refers to the expression of the genes, it is like taking a photo, whereas genotype is the genetic makeup.

Epigenetics (Abrantes, 2019) responds to internal or external environmental stimuli by changing the phenotype and genotype without impacting the DNA structure. In other words, there are many forms of Epigenetic responses to stressors which can change the variants in the genes, effectively switching one on or off, which can either damage or benefit the body. Epigenetics tries to prepare the offspring in the very early stages of life to best survive in the environment it will be living in. Epigenetics also explains why some dogs perform better under pressure or stress than other dogs which only demonstrates further that each dog is unique and will require specific behaviour management. Additionally, dogs living amongst humans, caused 'their genetic composition... to change' (Bjornerfeldt, 2007, p.17), otherwise known as the domestication process where genetic changes occurred such as crowed teeth and smaller heads.

Natural selection vs Artificial selection

Dogs reproduced by natural selection before they had a relationship with humans. Natural selection is a way for species to create optimum success in their environment. Whereas, artificial selection occurs when humans wanted specific requirements from dogs. Artificial selection has happened for centuries, for example in 7000 BC there is evidence that Siberian polar bear hunters, 'made sleds that could be pulled by' smaller dogs, while they bred larger dogs 'for hunting polar bear' (Loovers, 2021).

Human requirements in breeding dogs were for friendly temperaments, yet this had an unexpected outcome of possible 'ride-along' genes, which were outcomes that were seemingly unrelated. For example, the dogs with a friendly approach often began to develop floppy ears (Pilot et al, 2016).

In summary, it is important to understand the origins of the domestic dog such as considering the genetic structure puppies can have. This also, allows us to see dogs as individuals with several biological inherited traits or epigenetic changes that may cause difference within a litter of puppies (The Kennel Club, 2023). Moreover, understanding the biological diversity within dogs also comes with understanding the implications of inbreeding from artificial selection and knowing the limitations or advantages (Scandurra et al, 2018). Such as a brachycephalic dog having shorter lifespan compared to other dogs (HSVMA, 2018) or a border collie who has exceptional eyesight and can have enormous impulse control to heard sheep (Fadel, 2016). In other parts of the world where natural selection is still the main foundation of the genetic pool can be subject to effects like the bottleneck effect which could lead to limited genetic diversity (Marsden, 2016).

Citations

Abrantes, R. (2019) Canine Epigenetics. Ethology Institute. Viewed 02/04/2023. Available at: https://ethology.eu/canine-epigenetics/

Bjornerfeldt, 2007. Consequences of the domestication of man’s best friend, the dog (Doctoral dissertation, Acta Universitatis Upsaliensis).

Fadel, F.R., Driscoll, P., Pilot, M., Wright, H., Zulch, H. and Mills, D., 2016. Differences in trait impulsivity indicate diversification of dog breeds into working and show lines. Scientific Reports, 6(1), pp.1-10

HSVMA. 2018. The cost of cuteness. Health and Welfare Issues Associated with Brachycephalic Dog Breeds. Humane Society, Veterinary Medical Association. Viewed: 18/04/2023. Available at: https://www.hsvma.org/brachycephalic#:~:text=The%20lifespan%20of%20dogs%20with,of%20dogs%20(12.7%20years).

The Kennel Club. 2023. Understanding canine genetics. Viewed 01/04/2023. Available at: https://www.thekennelclub.org.uk/health-and-dog-care/health/getting-started-with-health-testing-and-screening/understanding-canine-genetics/#:~:text=The%20combination%20of%20alleles%20a,gene%20expression%20are%20outlined%20below

Loovers, P. 2021. Dogs in the Arctic. The British Museum. Viewed 01/04/2023. Available at: https://www.britishmuseum.org/blog/dogs-arctic

Marsden, C.D., Ortega-Del Vecchyo, D., O’Brien, D.P., Taylor, J.F., Ramirez, O., Vilà, C., Marques-Bonet, T., Schnabel, R.D., Wayne, R.K. and Lohmueller, K.E., 2016. Bottlenecks and selective sweeps during domestication have increased deleterious genetic variation in dogs. Proceedings of the National Academy of Sciences, 113(1), pp.152-157

Pilot, M., Malewski, T., Moura, A.E., Grzybowski, T., Oleński, K., Kamiński, S., Fadel, F.R., Alagaili, A.N., Mohammed, O.B. and Bogdanowicz, W., 2016. Diversifying selection between pure-breed and free-breeding dogs inferred from genome-wide SNP analysis. G3: Genes, Genomes, Genetics, 6(8), pp.2285-2298.

Scandurra, A., Alterisio, A., Di Cosmo, A. and D’Aniello, B., 2018. Behavioral and perceptual differences between sexes in dogs: an overview. Animals, 8(9), p.151