Final answer:
Broad spectrum collecting can happen as a result of various natural occurrences such as hydrological changes, pollination, introduction of new genotypes, or selective predation by birds.
Step-by-step explanation:
Broad spectrum collecting typically occurs as a natural occurrence in response to certain changes in the environment. These changes can include hydrological changes, pollination by insects, introduction of new genotypes, or selective predation by birds. For example, the spread of Brazilian pepper in Florida was brought on by hydrological changes draining farmland and flood control projects, allowing the plant to expand its range. Additionally, the northward range expansion of the European green crab along the Atlantic coast of North America was caused by the introduction of new, cold-tolerant genotypes into the established population.