Overproduction: Excessive production; production in excess of need or stipulated amount.
Variation: Amount, rate, extent or degree of change. There are many species of Iguanas. Variation are many different kinds of one same specie in this case sea iguanas, cactus eating iguanas, big iguanas, etc.
Adaptation: Any alteration in the structure or function of an organism or any of its parts that results from natural selection and by which the organism becomes better fitted to survive and multiply in its environment. The Iguanas adapt to the dry weather by eating the pulp inside the cactus.Not every animal can get to a place and live there normally, they need to adapt to the changes, in this case not every animal can eat cactus pulp instead of water.
Selection: Any natural or artificial process that results in differential reproduction among the members of a population so that the inheritable traits of only certain individuals are passed on, or are passed on in greater proportion, to succeeding generations.
Speciation: The Formation of new species as a result of geographic, physiological, anatomical, or behavioral factors that prevent previously interbreeding populations from breeding with each other. The sea iguanas are are different from the other iguanas because they have to adapt to geographical features such as the sea.
Isolation: A form of disconnection from the rest of the world. The animals in the Galapagos Islands are Isolated from the rest of the world, this has a positive influence since animals from other environments dont affect negatively the environment.