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Title: Outline and explain the three criteria for determining rare species. Post by: judd on Mar 11, 2011 Outline and explain the three criteria for determining rare species. Include examples that fit each of the criteria.
Title: Re: Outline and explain the three criteria for determining rare species. Post by: star on Mar 11, 2011 The three criteria’s for determing rare species: (1) species with a very narrow geographical range; (2) species with specific habitat requirements; (3) species with small population sizes.
(1) Some species occur at only one or a few sites in a geographical region. These species are also especially vulnerable to global climate change. Bird species on oceanic islands and fish species confined to one lake are examples of species confined to one location. Although the Venus -fly trap is locally abundant, it is considered rare because it occurs only in one geographical region. (2) Species in this category occupy one or a few specialized habitats. For instance, salt marsh cord grass only found in salt marshes; however, it is quite common in this habitat. (3) Species with small populations such as large predators or extreme specialists, including the Mediterranean monk seals, are found in small populations although the populations are found over a wide area. They are rare because the populations are small and isolated. They are more likely to go extinct due to their greater vulnerability to demographic and environmental variation and lose of genetic variability. |