Final answer:
A long-term drought would likely lead to increased migration for some bird subpopulations due to food scarcity, and reduced nesting success due to habitat changes. The drought may also give an advantage to birds with traits suited for the available food, leading to a shift in the population under the influence of natural selection.
Step-by-step explanation:
In what ways might a 10-year drought affect the subpopulations of a bird species? A long-term drought is likely to have several effects on bird subpopulations, particularly if there are changes in the food sources available. Given the situation described, we can infer the following:
- Increased migration: Birds that are unable to adapt to the scarcity of their preferred seeds are likely to migrate in search of more suitable feeding conditions.
- Reduced nesting success: If the drought leads to a scarcity of nesting materials or suitable nesting sites, this could result in reduced reproductive success.
- Enhanced feeding opportunities are unlikely because the change in seed availability benefits only those birds with large and broad beaks that can consume the harder, larger seeds.
- Improved habitat diversity is also unlikely, as sustained drought generally leads to habitat degradation, not diversification.
Assuming the population stays isolated and the drought continues, birds with large and broad beaks will likely have an advantage in natural selection due to their ability to consume the available large seeds. Subpopulations with these traits may increase, while others may decline or be forced to migrate. This change in population dynamics could result in a decrease of biodiversity in the community due to the specialized feeding requirements favoring certain birds over others.