Many species of animals on islands are larger than related species on the mainland. Scientists hypothesize that this phenomenon, called island gigantism, evolved in response to the scarcity of competitors and predators on islands. Reduced competition and predation allow species to exploit more resources and free them from the need to hide in small refuges.
True or false: The body temperatures of island tortoises always closely match the temperatures in their environments.

Verified step by step guidance

1. Understand the concept of island gigantism: Island gigantism is a biological phenomenon where species on islands grow larger than their mainland relatives, often due to reduced competition and predation.
2. Consider the biology of tortoises: Tortoises are ectothermic animals, meaning their body temperature is largely influenced by the external environment.
3. Explore the relationship between ectothermy and environmental temperature: Ectothermic animals, like tortoises, rely on external heat sources to regulate their body temperature, often resulting in their body temperature closely matching the ambient temperature.
4. Evaluate the statement: Given that tortoises are ectothermic, their body temperature is likely to closely match the environmental temperature, unless they engage in behaviors to regulate it differently.
5. Conclude based on the evidence: The statement is likely true, as ectothermic animals typically have body temperatures that align with their surroundings, unless specific behaviors or environmental conditions alter this relationship.

Key Concepts

Island Gigantism

Island gigantism refers to the phenomenon where species on islands evolve to be larger than their mainland counterparts. This is often due to reduced competition and predation, allowing species to exploit available resources more effectively. The lack of predators and competitors can lead to evolutionary changes that favor larger body sizes, which can be advantageous in resource-rich environments.

Thermoregulation in Tortoises

Thermoregulation is the process by which animals maintain their body temperature within certain boundaries, even when environmental temperatures vary. Tortoises, being ectothermic, rely on external heat sources to regulate their body temperature. They may bask in the sun to warm up or seek shade to cool down, meaning their body temperature can closely match the ambient temperature, but not always precisely.

Ectothermy

Ectothermy is a biological feature where an organism relies on external environmental heat sources to regulate its body temperature. Unlike endotherms, ectotherms do not generate significant internal heat and must use behavioral adaptations to manage their thermal needs. This can lead to body temperatures that fluctuate with environmental conditions, as seen in reptiles like tortoises.