An important topic in the field of population genetics is speciation, the process by which populations become distinct species.
But how can we determine if different phenotypes from the same population actually constitute genetically separated species?
Deer phenotypes can be places into one of two categories: efficiency, which promotes survival over extravagant antler growth, and luxury, which promotes the growth of large, dangerous antlers.
In order to determine the different effects of environment, nutrition, and genetics on antler phenotypes, for example, researchers can relocate wild individuals to controlled captive facilities.
To start the experiment, the captive facility should be equipped with shade cloth, to separate the pens, and box blinds, to facilitate darting. Two feeders should be stationed at the opposite ends of each pen to reduce competition.
To control for the effects of nutrition on antler growth, provide the captive deer with unlimited quantities of a high quality diet.
After being safely sedated and transported it to the data collection area, the deer’s body mass, hind foot length, and total body length is measured.
While the animal is still sedated, the following antler measurements are obtained—the inside spread, basal circumference, and main beam length. A reciprocating saw is used to remove the antlers, the deer is relocated to the captive facility, and sedation is reversed.
The collected antlers are then measured in the laboratory. Each of the tines and abnormal points protruding from the main beam is measured.
Next, the circumference at the smallest points between the G1 and G2 tines, the G2 and G3 tines, and the G3 and G4 tines is collected. Finally, the antlers are weighed.
After performing this experiment for first- and second-generation offspring, box and whisker plots can be generated to compare antlers across regions of origin. Studies like this can help scientists determine if two or more populations have genetically diverged into separate species.