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. The graph shown here compares the average carapace (shell) length of mainland and island tortoises. Summarize the results, then use the data to predict whether the surface area to volume ratio is higher in mainland or island tortoises.

Verified step by step guidance

1. Observe the graph comparing the carapace length of island and mainland tortoises. The graph shows that island tortoises have a significantly larger average carapace length compared to mainland tortoises.
2. Understand the concept of surface area to volume ratio. This ratio is important in biology because it affects the rate of heat loss, nutrient uptake, and waste elimination. A higher surface area to volume ratio means more surface area per unit of volume.
3. To calculate the surface area to volume ratio, use the formula: \( \text{Surface Area to Volume Ratio} = \frac{\text{Surface Area}}{\text{Volume}} \).
4. Predict the surface area to volume ratio for both island and mainland tortoises. Larger animals, like the island tortoises, tend to have a lower surface area to volume ratio because their volume increases faster than their surface area as they grow.
5. Conclude that the surface area to volume ratio is likely higher in mainland tortoises compared to island tortoises, due to their smaller size and the biological implications of the surface area to volume ratio.

Key Concepts

Island Gigantism

Island gigantism is a biological phenomenon where species on islands grow larger than their mainland relatives. This is often attributed to the absence of predators and competitors, allowing these species to exploit available resources more effectively. The reduced need for camouflage and the ability to occupy larger ecological niches contribute to this evolutionary trend.

Surface Area to Volume Ratio

The surface area to volume ratio (SA:V) is a critical concept in biology that describes how the surface area of an object relates to its volume. As an organism grows, its volume increases faster than its surface area, which can affect processes like heat exchange and nutrient absorption. A higher SA:V ratio is typically advantageous for smaller organisms, while larger organisms may have a lower ratio, impacting their metabolic rates and ecological strategies.

Carapace Length in Tortoises

Carapace length refers to the size of the shell in tortoises, which can be an important indicator of their health, age, and ecological adaptations. In the context of island tortoises, larger carapace lengths may suggest adaptations to the unique island environment, such as reduced predation pressure and increased resource availability. Analyzing carapace length can provide insights into the evolutionary pressures faced by these species.