Final answer:
Hummingbird beaks getting longer is likely an example of natural selection, where longer beaks became advantageous due to environmental changes, such as flowers with deeper nectar reserves. This relationship reflects co-evolution between the bird and flower species, benefiting both partners in a symbiotic relationship.
Step-by-step explanation:
The observation that hummingbird beaks were getting longer over time suggests an evolutionary adaptation in response to changes in their environment. This could be due to a process known as natural selection, where birds with longer beaks may have been better suited to obtain nectar from flowers that also evolved to have longer or deeper floral tubes. As a result, these birds would be more successful at feeding and reproducing, passing on the trait of longer beaks to their offspring.
In the environment, changes such as the availability of specific flowers with deeper nectar reserves could have been occurring, necessitating longer beaks for efficient feeding. This co-evolution between hummingbirds and their preferred flower species is an example of a symbiotic relationship that benefits both the bird, through nutrient acquisition, and the plant, through pollination. If, hypothetically, the hummingbird species were to go extinct, the flowers that have evolved to depend on these specific pollinators might also face a decline or possible extinction due to the lack of effective pollination.