Oceanic Islands: Models of Diversity

adaptive radiation Evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. allopatric Occurring in separate, nonoverlapping geographic areas. dioecious In plants, having the male and female reproductive organs borne on separate individuals of the same species. disharmony The nonrandom representation of biota among natural colonists of oceanic islands as compared with mainland systems. Species that are more dispersive will have a higher representation in the biota, the effect being accentuated by the tendency of these few successful colonists to diversify into multiple species through adaptive radiation. ecomorph A local population or group associated with a particular ecological niche; the terms has no systematic or taxonomic significance. endemic/endemism Unique to a given locale; occurs in the site at which it is endemic, and nowhere else. impoverishment On an island, paucity of species relative to adjacent mainland. invasional meltdown The compounded effect on an ecological community of successful and successive invasions of alien species benefiting from the previous introduction of the other. microcosm A small, representative system that has analogies to a larger system. Oceanic islands are often considered microcosms of continental areas because the composition of species on islands, and the processes of formation and decline, are analogous but occur on a very small scale. parapatric Occurring in geographical areas that abut but do not overlap. phylogenetics The study of evolutionary relatedness among various groups of organisms (e.g., species and populations). Phylogenetics, also known as phylogenetic systematics, treats a species as a group of lineage-connected individuals over time. relictualization Survival of species on islands after those on adjacent mainland areas have suffered extinction. sympatric Occurring in the same geographic areas without interbreeding. taxon cycle A hypothesis proposed by E. O. Wilson to describe the common niche expansion among colonizers, and subsequent long term toward differentiation, with isolated species narrowing their niches and restricting their ranges resulting in eventual extinction.