Biogeography is the study of the distribution of biological organisms. The scale of analysis ranges from very small micro-topography regimes to continental dimensions. Fundamental concepts in this field of study are the nature of barrier formation and response of species to their patterns of travel and migration; in particular, the presence of rivers, mountain ranges, deserts and other natural boundaries are examples of large scale barriers. Besides such major landform barriers there are soil, topographic and meteorological factors that influence the distribution of each species. In the case of smaller scale regimes that are applicable for some bacteria or limited range plant species, there are often very restricted niches; for example, certain bacteriaextremophiles may be limited to such localized features as small geyser pools, and some rare plants may have a single extant colony defined specialized soils such as serpentine and narrow climatic zone. Inherent in the concept of biogeography are the processes of speciation, extinction, dispersal and migration.
Chile has eight ecoregions that occur entirely or partly within its borders on the mainland and three ecorgions offshore:
SpeciesLast Updated on 2014-09-15 11:53:19A species is a group of organisms capable of interbreeding and producing fertile offspring of both genders, and separated from other such groups with which interbreeding does not characteristically occur: however, for asexual organisms, a distinct species may be considered a collection of organisms which have very similar DNA or physical characteristics. Certain species are further subdivided into subspecies.
The early Greeks and Romans had a well established set of taxonomic names for species of animals and plants, based upon the macroscopically observable characteristics of organisms, with Aristotle being the chief architect of this codification; even earlier, the Egyptians and Cretans developed basic symbols and names for species important in farming and culture. It was not until the year 1686 when English naturalist John Ray introduced the concept that species were... More »
Ecoregions of CanadaLast Updated on 2014-09-06 20:21:29
Canada has 50 ecoregions that occur entirely or partly within its borders as listed below and shown in the accompanying figure:
South Avalon-Burin oceanic barrens
Eastern Canadian forests
Newfoundland Highland forests
New England-Acadian forests
Gulf of St. Lawrence lowland forests
Eastern Great Lakes lowland forests
Southern Great Lakes forests
Eastern forest-boreal transition
Eastern Canadian Shield taiga
Torngat Mountain tundra
Low Arctic tundra
Middle Arctic tundra
High Arctic tundra
Davis Highlands tundra
Baffin coastal tundra
Southern Hudson Bay taiga
Central Canadian Shield forests
Western Great Lakes forests
Northern tall grasslands
Midwestern Canadian Shield forests
Northern Canadian Shield taiga
Mid-Continental Canadian forests
Canadian Aspen... More »
Climate change effects on birdsLast Updated on 2014-09-06 19:35:56
Many birds species all over the world are highly sensitive to the effects of climate change. Scientists have found declines of up to 90 percent in some bird populations, as well as total and unprecedented reproductive failure in others, althought the role of any change in climate is typically not determined. Population declines generally have several associative causal factors including habitat loss, habitat fragmentation and pollution.
Specific groups that are at high risk from climate change include migratory birds, mountain birds, island birds, wetland birds, Arctic birds, Antarctic birds and seabirds. Bird species that can move easily to new habitat are expected to continue to do well; however, bird species that thrive only in a narrow environmental range can be expected to decline, and to be outcompeted by invasive species.
With a 0.8°C average... More »
CactusLast Updated on 2014-08-20 18:54:05Cactus is a family of plants that are specially adapted to survive arid conditions, most often having leaves reduced to spines, and succulent characteristics. The scientific family name Cactaceae is applied to this group comprising 121 different genera. This plant family is concentrated in the Americas and has a surprisingly broad latitude range in both the Northern and Southern Hemispheres.
A considerable number of cacti species are threatened, chiefly due to habitat loss to agriculture, trampling by illegal human immigration into the southwestern USA, large-scale desert solar power projects, and overcollecting.
The cactus family is generally considered native to the Americas. A notable exception is Mistletoe cactus, Rhipsalis baccifera, which is thought to have spread, fairly recently, from the American tropics to the subtropics and the deserts of the... More »
Whale Sanctuary of El Vizcaíno, MexicoLast Updated on 2014-07-10 15:39:44
The Whale Sanctuary of El Vizcaino (27° 23'-27° 59'N, 114° 30'-114° 55'W) is a World Heritage Site located in Mexico and comprises two lagoons which lie in the central part of the Baja California peninsula, between the Gulf of California and the Pacific Ocean. Forms part of the Municipality of Mulege, Bajo California Sur State. Accessible via the north-south highway. Both lagoons are situated on the west side of the peninsula, Laguna Ojo de Liebre is connected to the Bahia Sebastian Vizcaino, and Laguna San Ignacio lies east of the town of Punta Abrejos, into which Rio San Ignacio flows.
Federal Decree of 6 December 1971, promulgated on 14 January 1972, declared Laguna Ojo de Liebre a marine refuge zone for whales. On 28 March 1980, the Decree was modified to include the lagoons of Manuela and Guerrero Negro. On 11 September 1972, a Decree... More »
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