User:Duckhunter&evol/sandbox

Speciation
The evolution of a population leading to a distinct species, otherwise called speciation, has occurred in common side-blotched lizard populations. New species are able to emerge from the three different male morphologies. The "rock-paper-scissors" mating strategy has been preserved over millions of years of evolutionary history throughout parts of the United States and Mexico. However, some populations lose one or two polymorphisms, most commonly the sneaker male, leading to a new species. Since the three polymorphisms are the ancestral trait, this leads to new species due to the sneaker male allele being erased from the gene pool. Considering each allele for each color has different heritability, there must be a selective pressure favoring each one. If enough selective pressure is applied, a morphology may become fixed or lost in the population, leading to speciation despite the long period of maintenance.

Reproductive isolation and hybridization can both lead to speciation for populations of the common side-blotched lizard. In some cases, reproductive isolation can result in the loss of male morphologies since only one or two types of the lizards are favored by the females. This ultimately leads to the evolution of the species. In other situations, rapid changes in the environment leads to the hybridization of two male morphologies. Selection would drive the combination of two morphologies into one. The individual blue and orange morphs may be lost, and a single blue-orange morphology would strive in the new environment.

The loss of a morphology, due to any reason, leads to changes of intraspecies and interspecies pressures, further pushing evolutionary change. This changes the social selection since trait preferences are revised. Alleles that were once used to outcompete the lost morphology are no longer beneficial and new traits that are better adapted for the social structure are ideal. These new selective pressures frequently lead to changes in sexual size dimorphism, which serves as a significant indicator of speciation. Larger male and female size regularly follow the loss of a polymorphism. Additionally, the predator-prey dynamic changes after a morphology is lost. New traits are favored to prey on the remaining morphologies or escape the novel predator. Both intraspecies and interspecies changing structures further drive speciation.