Final answer:
Rice, wheat, and maize are the species that account for 80% of the world's weight in crops. These staple crops are extensively planted across the globe, and their genetic diversity is vital for combating diseases and pests. Risks stem from reduced biodiversity due to seed companies focusing on fewer varieties and the heavy reliance on animal pollinators for many crops.
Step-by-step explanation:
The species that account for 80% of the world's weight in crops are rice, wheat, and maize (corn). These uniform strains of these three major crops are extensively cultivated around the globe. Due to their extensive planting, the genetic diversity found in their wild relatives is vital for providing resistance against diseases and pests. Additionally, it is crucial to consider the extreme risk of relying on a single pollinator, as many of these crops depend on animal pollinators.
Maize is currently the most significant staple crop globally. It was developed from a wild grass called teosinte around 9,000 years ago in present-day Mexico and is used widely for human consumption, animal feed, and industrial purposes. When it comes to rice, it is a primary food source in Asia, where it was domesticated between 8,000 and 13,000 years ago. The vast majority of rice cultivated around the world is Oryza sativa, which has over 40,000 varieties.
There are risks involved with contemporary crop species as seed companies tend to focus on fewer varieties for global distribution, thus reducing biodiversity. Practices like breeding new varieties continually are essential for adapting to pest evolution.
Insects play a crucial role in crop production as well. Crops like tobacco and corn have been genetically engineered to produce insecticide proteins that have significantly reduced the use of chemical insecticides.