Biology Species within a given population will differentiate due to a sudden and dramatic geological or climatological change. If a volcano erupted on an island like one of those on Vanuatu, the populations of local geckos would start to differentiate depending on where members of that population were before and after the eruption.

Statement/Hypothesis: If a volcanic eruption led to lava flows on one side of the island, but not on the other side, then the gecko population would differentiate based on the availability of food sources and also based on the remaining predators.

Geological Event: A volcano erupts on a small tropical island, part of the Vanuatu group. The types of observations necessary for the evaluation of the impact of the volcano on local lizard (gecko) species include size (length), coloration and visual patterns, and vocalizations. Behavioral observations would include territories occupied, feeding patterns, and mating patterns.

Characteristics of the Two Environments: Before the volcano erupted, the island of only 300 square miles in area revealed little...

The island had a volcanic soil and some rich mineral veins. Foliage was dense throughout, but with some plant diversity depending on elevation. Moreover, the windward and leeward sides of the island differed in their vegetation and prevalence of certain gecko species. After the eruption of the volcano, the windward and leeward sides of the island shifted dramatically. The leeward side received the majority of the heavy lava flows and was henceforth characterized by treeless terrain over great swathes of land; whereas the windward side remained relatively unchanged.
Changes to the Two Populations: Geckos that were prevalent on the leeward side of the island started to grow larger, as their primary predators were impacted adversely by the lava flows. As species of endemic tree snake lost much of its habitat on the leeward side of the island, resulting in greater survival of young geckos and a longer life span. As a result, the geckos on the leeward side of the island also ceased to engage their defenses as readily, and became bolder as well as bigger. The coloration of…