¿Cómo funciona la selección artificial y cuál es la historia de los pez dorado?

Darwin proposed artificial selection to persuade the most skeptical individuals by using the process of selection performed by humans in the domestication of animals to illustrate the mechanism of natural selection in evolution.

How artificial selection or selective breeding Works

The fundamental principle of artificial selection is to choose and breed individuals that possess traits preferred by humans. Firstly, individuals that exhibit desired traits are selected, while those that do not meet expectations are completely excluded. Their offspring inherit these desired traits, and the above selective process is repeated. As a result of multiple rounds of selection, the desired traits become increasingly prevalent throughout the population until subspecies are produced that meet human preferences. The significant difference between artificial selection and natural selection is the human favored traits and completed elimination of undesired traits. So the purpose of selective breeding is very clear and the process is very fast.

Artificial selection example: selective breeding pez dorado

Pez dorado are freshwater ornamental fish originated from China. Any type of pez dorado can produce fertile offspring when crossbred with wild carp, indicating that pez dorado and carp do not experience reproductive isolation. They are different subspecies. In ancient times, carp naturally mutated red scales in the wild to make them more noticeable and easily captured. Later, due to the practice of releasing fish for religious reasons among Buddhists, some people would buy red carp from markets and release them into temple ponds, initiating their semi-domestication.

Subsequently, the emperor of the Southern Song Dynasty built a royal garden in Hangzhou to collect red carp from all over the country, which was then imitated by nobles and officials. Through artificial feeding and selection, red carp became thoroughly domesticated. Those with beautiful colors and patterns were selectively bred. During this period, red carp displayed a wider range of colors and patterns, such as orange, gold, white, black and white patches, red and white patches, etc. Their differences from wild carp became even more pronounced. However, they were not yet considered true pez dorado because they lacked a tail with more than two branches.

In the Ming Dynasty, the transition from large ponds to pottery tanks and wooden basins allowed people to conveniently control their traits. One notable change was that people began to select red carp with multiple branched tails and bloated body while completely eliminating normal streamlined fish. As the pez dorado gracefully swam in water, it tail swung in a mesmerizing rhythm, resembling the ethereal gown of a princess swirling across the ball, which transformed the red carp into true pez dorado. During this period, some lost their dorsal fins, some developed red or orange fleshy growths on their heads, and others have large bubbles below their eyes, or protruding eyes. Their colors, patterns and body shape became completely distinct from wild carp.

In the following years, pez dorado with different characteristics were crossbred to obtain even more diverse combinations. By the end of the Ming Dynasty, missionaries had brought pez dorado from China to various parts of the world.

Preguntas frecuentes

Ventajas y desventajas de la selección artificial

Como herramienta evolutiva, la selección artificial permite a los humanos elegir y criar organismos con rasgos específicos para alcanzar sus propios objetivos. Mediante la selección artificial, podemos mejorar el rendimiento de los cultivos, su calidad y resistencia a enfermedades, cultivar mascotas hermosas y amigables, e incluso impulsar avances en medicina y ciencia mediante la cría selectiva de variantes génicas específicas en laboratorios.

Sin embargo, la selección artificial también plantea algunas controversias. Algunas preocupaciones incluyen la posible reducción de la diversidad genética, la disminución de la adaptabilidad de las especies y los impactos irreversibles en el mundo natural debido a la selección artificial.