Mechanisms of Microevolution

Sexual Selection

Australian dragon lizards of the family Agamidae show that sexual selection compared to natural selection has a larger role in the evolution of colour pattern complexity in males. Sexual selection has “led to signal innovation, involving the use of additional and/or novel signal types, which has resulted in increasing complexity in males” (Chen et. al., 2012) and there is a positive correlation between sexual dichromatism and sexual dimorphism in the evolution of colour pattern complexity in males. Particularly males who showed greater colour complexities also had larger bodies and heads (2012).

Genetic Drift

At the end of the Pleistocene period a rise in sea level caused islands to form in the Galapagos region (Jordan & Snell, 2008). The phenotype diversification of Galapagos lava lizards seems to have occurred because of the isolation of species when a larger island mass broke down into smaller islands and seawater became the barrier to gene flow (2008). Less diversification was noticed in species that inhabited smaller islands as compared to larger islands and genetic drift has been considered to be the reason for this (2008).


The same can be considered for species of the Pogona lizards (2008). Their variations could have begun to occur due to isolation of particular groups during periods of evolution caused by geographical changes and land mass shifts leading to drift isolation (2008).

Artificial Selection

The breeding of bearded dragons has led to the discovery of many genetic traits (HereBDragons, 2015). Mutations such as body stripes, eye colour, scale variations and body colour patterns have been noted through breeding (2015). Through captive breeding some of the popular genetic traits have been used for resale in the pet industry (2015).


© 2019 by Daniel Brown.