|Examples of informal doublets|
Friday, February 22, 2013
Human Selection - Domestication and Flowers
Domesticate, as defined by the Merriam-Webster dictionary, is to adapt (an animal or plant) to life in intimate association with and to the advantage of humans. From our evolution course we know that adaption means a characteristic that increases the Darwinian fitness of an individual compared to individuals without the trait. (We recall that Darwinian fitness is the ability of an individual to survive and reproduce in its environment.) Thus, domestication is the change in an organism to make it better suited to life with humans.
Moving away from definitions, if you take a look around you, you will see myriad domestic organisms. For example, your pet dog or cat or rabbit are domesticated animals. The houseplants that you forget to water are domesticated. The daffodils and tulips planted in your mother’s garden, the magnolia tree that stands by the backdoor, and the aromatic lavender patch along the pathway are all domesticated plants known as ornamentals. According to Gessert’s paper, “Flowers of Human Presence: Effects of Aesthetic Values on the Evolution of Ornamental Plants,” certain plants were domesticated based on the selection for aesthetics. These included characteristics such as color, pattern, size, form, and texture (and aroma, which ties into a plants aesthetic value). Humans chose these traits not for the "good" of the plant but because they appear visually (and olfactory) stimulating.
The selection for visual aspects of flowers has caused convergent evolution.
Species in the Tea, Ranunculus, Nightshade, Rose, and Poppy Families all exhibit informal doublets – many petals of varying sizes and shapes. Species in each of these families were selected for the similar flower trait. Thus, these flowers resemble each other due to convergent evolution of the selected upon trait.
Does knowing the aesthetically pleasing flowers in your garden are the product of human selection make you view them any differently? I would view them with a new appreciation for what natural genetic diversity and human selection can accomplish. However, due to the prescribed nature of care some of these domesticated varieties demand, it makes me wonder if we’ve upset the natural balance. Would these varieties ever exist in nature without the help of humans’ heavy hands? And does this matter? Are we becoming so focused on the exterior beauty that we forget functionality? These are questions for future blog posts. (365 words)
Gessert, George. (1993) Flowers of Human Presence: Effects of Esthetic Values on the Evolution of Ornamental Plants, Leonardo 26.1 (37-44).
Image from George Gesset, 1993