Martin Wikelski and L

question 19

Multiple Choice

Martin Wikelski and L. Michael Romero (Body size, performance and fitness in Galápagos marine iguanas, Integrative and Comparative Biology 43 [2003]:376-86) measured the snout-to-vent (anus) length of Galápagos marine iguanas and observed the percent survival of different-sized animals, all of the same age. The graph shows the log snout-vent length (SVL, a measure of overall body size) plotted against the percent survival of these different size classes for males and females.
-Currently the only predators of Galápagos marine iguanas are Galápagos hawks. Iguana body size is not correlated with risk of hawk predation, although small iguanas can sprint faster than large iguanas. If predators (for example, cats) that preferably catch and eat slower iguanas are introduced to the island, iguana body size is likely to ________ in the absence of other factors; the iguanas would then be under ________ selection.

• A) increase; directional
• B) increase; disruptive
• C) decrease; directional
• D) decrease; disruptive

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Definitions:

Sociocultural Factors

Are elements that impact an individual's life and behavior, including cultural norms, values, practices, and social contexts.

Physical Growth

The increase in size, height, and weight of an individual, as a result of the body's cells increasing in number and size.

Bogin's Study

A research investigation carried out by anthropologist Barry Bogin that focuses on patterns of human growth and development, often emphasizing the impact of sociocultural factors.

Monozygotic Twins

Identical twins developed from a single fertilized egg, sharing identical genetic material.