Final answer:
Lack's hypothesis suggests that optimal clutch size for birds maximizes survival and reproductive success by balancing the number and size of eggs. However, factors like environmental conditions, parental condition, and predation risk can influence optimal clutch size in a given year.
Step-by-step explanation:
Lack's hypothesis states that the optimal clutch size for birds is the one that maximizes the number of surviving offspring. It suggests that survival and reproductive success are influenced by trade-offs between the number and size of eggs in a clutch. The hypothesis predicts that birds should lay more eggs in environments with high predation pressure and fewer eggs in environments with limited resources. However, there are factors not included in the hypothesis that may influence optimal clutch size in a given year. These factors include:
- Environmental conditions: Weather conditions like temperature and rainfall can affect the availability of food resources and influence the optimal clutch size.
- Parental condition: The health and nutritional status of the parents can influence their ability to provide for a larger clutch size.
- Predation risk: The level of predation risk in a specific year can affect the optimal clutch size. If predation risk is high, parents may lay smaller clutches to reduce the chances of attracting predators.