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Insular biogeography [1] or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern of the species–area relationship occurring in oceanic islands.
Foster's rule, also known as the island rule or the island effect, is an ecogeographical rule in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. For example, it is known that pygmy mammoths evolved from normal mammoths on small islands.
Frank W. Preston, an early investigator of the theory of the species–area relationship, divided it into two types: samples (a census of a contiguous habitat that grows in the census area, also called "mainland" species–area relationships), and isolates (a census of discontiguous habitats, such as islands, also called "island" species–area ...
Size comparison of the giant gymnure (moonrat) Deinogalerix from the Late Miocene of Gargano, Italy, with a European hedgehog. Island gigantism, or insular gigantism, is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically in comparison to its mainland relatives.
The Theory of Island Biogeography has its roots in Wilson's work on the ants of Melanesia.MacArthur synthesized Wilson's ideas about competition, colonization and equilibrium into a simple graphical representation of immigration and extinction curves, from which one can determine the equilibrial species number on an island. [3]
The original drawing of the line in Wallace's paper. One of the earliest descriptions of the biodiversity in the Indo-Australian Archipelago dates back to 1521 when Venetian explorer Pigafetta recorded the biological contrasts between the Philippines and the Maluku Islands (Spice Islands) (on opposite sides of the Wallace's Line) during the continuation of the voyage of Ferdinand Magellan ...
Oceanic islands arise due to volcanic activity or reef growth, and usually subside over time due to erosion and changing sea levels. [1] When islands emerge, they undergo the process of ecological succession as species colonize the island (see theory of island biogeography). New species cannot immigrate via land, and instead must arrive via air ...
The edge effect in scanning electron microscopy is the phenomenon in which the number of secondary and/or backscattered electrons that escape the sample and reach the detector is higher at an edge than at a surface. The interaction volume spreads far below the surface, but secondary electrons can only escape when close to the surface (generally ...