Ginkgo biloba by Armando Fabrega

Variability and Genetics

Ginkgo biloba has a very complex genome with about 41,840 genes, which is suggestive of it having a large, rich history throughout time. The Ginkgo are also classified as dioecious, which means that the trees have two genders, which in this case is female and male. Genetics determine what the sex of the tree will be, just like in humans. The male-determining gene contains 210 genes. The wild populations of Ginkgo biloba found in Asia are important because they may contain genetic info not found in the local, human selected populations, due to humans primarily selecting male trees due to them lacking the odor that is made by the seeds of female trees.

Evolution

This species is referred to as "the living fossil"  because it goes back over 200 million years, and it is the remaining species of the Ginkoales as all of its sub-members have become extinct. Some features of this species that have helped it survive compared to its sub-members include its resistance to stress due to many genes that produce defences against elements. It also has a strong strategy for reproduction as the wind pollination and seeds were able to persist despite the harsh conditions from the Ice age. Another aspect is the lifespan of these trees, and they can survive for more than thousands of years, helping it survive for many different generations. 

Artificial Selection and Co-Evolution with Humans

One important aspect as to why ginkgo survived was because humans interfered with their possible extinction. They helped preserve ginkgo by planting it in many areas, such as temples, gardens and even in popular cities throughout Asia. These actions were what helped save the species. Artificial selection is what helped form them into what they are commonly seen as today. In cities, usually the males are seen because they do not have a bad scent like the seeds of the females do. They also have a beautiful fan shape, because those are the ones usually selected to clone by humans. They are also used for its medicinal benefits, and the extract is selected for in many areas so it can benefit humans as well.

As for the fan-shaped leaves, humans have selected them over 1,000 years throughout China, Korea, and and Japan, and were mostly selected by gardeners and temple caretakers. They selected them to have beautiful fan-shaped leaves, a bright yellow fall color, resistance to disease and pollution, as well as fast grown and longevity. The fan-shaped preferred by people had these traits:

-Large, symmetrical leaves

-Divided leaf lobes

-Beautiful colors that represent autumn, such as yellow or golden.

Some examples of human-selected variants include:

• Autumn Gold

• Princeton Sentry 

• Jade Butterflies 

• Mariken. 

These features helped make them attractive to humans to decorate their temples with. Other aspects were the tree form and size.

The trees that had the best qualities were planted and cloned more often, which increased their frequency in these areas. 

Symbiosis and Cooperation

Ginkgo has a symbiotic relationship with Coccomyxa, which is an alga that has lived inside ginkgo tissues for many generations.  It is an endophyte that proliferates inside the host cell, and it can cause host cell hypertrophy and necrosis, eventually releasing algae into the surrounding medium.