endemism,)provincialism,)and)disjunc4on)jankowsk/biol413-11-031914-endemis… ·...
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Endemism, Provincialism, and Disjunc4on
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Major kinds of distribu0on pa2erns:
Note: a single species can be part of a disjunct distribu4on within its family, can be endemic to a specific area, and, along with other taxa endemic to the same area, can characterize provincialism for that area
Endemism, Provincialism, and Disjunc4on
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Endemism: the occurrence of taxa with na4ve distribu4ons restricted to a par4cular geographic loca4on (e.g., taxon X is endemic to loca4on Y). Endemism can be variable in scale from a small area (e.g., a species of fish that is endemic to a specific lake) to whole con4nents. Provincialism: geographic overlap of endemism across mul4ple taxa. Alterna4vely, the delinea4on of geographic areas with par4cular bio4c characteris4cs based on the dis4nc4veness of species assemblages. Disjunc0on: two or more related (usually monophyle4c) taxa or popula4ons occurring in geographically separated areas (and absent from the intervening area).
Endemism, Provincialism, and Disjunc4on
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Outline of topics in this sec0on: Endemism Provincialism Disjunc4on
Examples:
Endemism
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Olympic mudminnow (Novumbra hubbsi)
Pygmy rabbit (Brachylagus idahoensis)
Endemism is typically hierarchical (or nested): Kangaroo rats, kangaroo mice, and pocket mice (family: Heteromyidae) are endemic to southwestern North America, Central America, and extreme northwestern South America.
Within Heteromyidae, kangaroo mice (genus: Microdipodops) are endemic to the Great Basin Desert region in western North America
Within Microdipodops, the pale kangaroo mouse (M. pallidus) is endemic to the sandy habitats of the Lahontan Trough in south-‐central Nevada.
Within M. pallidus, there are two separate mitochondrial DNA lineages endemic to the western and eastern por4ons of the range.
Endemism
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Endemics can be classified by their loca0on of origin:
Endemism
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Autoendemics: evolved in an area within their current distribu4on.
Alloendemics: originated somewhere else, dispersed to their current locality and subsequently have gone ex4nct elsewhere. Also known as relicts.
Endemism can be related to long-‐term temporal pa2erns of diversity:
Endemism
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Taxonomic relicts: remnants of, at one 4me, a much more diverse taxon. (e.g., coelacanth)
Biogeographic relicts: taxa that at one 4me had much wider geographic distribu4ons. (e.g., lungfish)
Endemism may have originated recently or long ago:
Endemism
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Neoendemics: endemics of recent origin (e.g., s4ckleback bethic and limne4c species pairs)
Paleoendemics: endemics that originated long ago (e.g., Olympic mudminnow)
Endemic taxa in different groups of organisms tend not to be randomly distributed, but rather tend to co-‐occur in specific areas. Generally, provinces fit into a hierarchy of areas of endemism:
Realms (terrestrial or marine)
Regions (recall Sclater’s zoogeographic regions)
Subregions
Provinces
Districts
Provincialism
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Provincialism: geographic overlap of endemism across mul4ple taxa. Or, the delinea4on of geographic areas with par4cular bio4c characteris4cs based on the dis4nc4veness of species assemblages.
Concordance suggests common historical events have shaped biotas within a given area (e.g., geological, climatological or oceanographic events). Example: 91% of Australian mammal species are endemic to Australia (compared to 19% for the holarc4c). Long term isola4on of Australia from other landmasses has probably driven high degree of endemism.
Provincialism
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Concordance suggests common historical events have shaped biotas within a given area (e.g., geological, climatological or oceanographic events). Example: High degree of endemism in the North American Great Basin.
Provincialism
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Provinces, like regions, may be separated by biogeographic lines
Provincialism
12 (from Miller 1966)
Provinces, like regions, may be separated by biogeographic lines
Provincialism
13 Freshwater fish provinces of Middle America, showing numbers of families, genera, and species of freshwater fishes in each area (from Miller 1966).
Marine provincialism is generally less well developed than terrestrial. Higher connec4vity among marine habitats, plus high dispersal poten4al for many marine organisms during par4cular life stages (e.g., planktonic larvae in fish and invertebrates).
Provincialism
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Spalding et al. (2007) classified the world’s con4nental shelves into a nested system of 12 realms (colours), 62 provinces (numbers), and 232 ecoregions.
Marine provincialism is generally less well developed than terrestrial.
Provincialism
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(Barber et al. 2000)
Provinces may be defined by geographic features and paderns of diversity, irrespec4ve of endemism.
Provincialism
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Fish faunal regions of Canada based on similarity of species between secondary watersheds. (from N.E. Mandrak)
Provinces may be defined by geographic features and paderns of diversity, irrespec4ve of endemism. Recall Amazonian ecoregions, which are divided by large river systems and also delineate range limits across species groups
Provincialism
Disjunc0ons can occur at any spa0al scale
Disjunc4on
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e.g., Lepidosireniformes (lungfishes) in South America, Africa, and Australia.
Disjunc0ons can occur at any spa0al scale
Disjunc4on
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e.g., Cudhroat trout in western North America.
Three poten0al causes of disjunc0on: 1. Vicariance
Disjunc4on
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Flightless birds
Three poten0al causes of disjunc0on: 2. Ex4nc4ons
Disjunc4on
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Tailed frog (Ascaphus truei) Cudhroat trout (Oncorhynchus clarkii)
Both taxa associated with high-‐gradient streams in mesic forests. This habitat disappeared with climate change following glacial retreat (now xeric).
Three poten0al causes of disjunc0on: 3. Long distance dispersal
Disjunc4on
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Galaxias, aka inanga (Galaxias spp.)
Origin likely in New Zealand 23 mya.
The no0on of disjunc0on relies on the idea that taxa are closely related.
Disjunc4on
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e.g., Freshwater crayfish (from Crandall et al. 2000):
Endemism, Provincialism, and Disjunc4on References for this sec0on: Barber, P.H., et al. 2000. A marine Wallace's Line? Nature 406: 692-‐693.
Crandall, K.A., D.J. Harris, and J.W. Fetzner Jr. 2000. The monophyle4c origin of freshwater crayfish es4mated from nuclear and mitochondrial DNA sequences. Proc. Roy. Soc. Lond. B. 267: 1679-‐1686.
Hafner, J.C., et al. 2008. Phylogeography of the pallid kangaroo mouse, Microdipodops pallidus: a sand-‐obligate endemic of the Great Basin, western North America. J. Biogeography 35: 2102–2118.
Lomolino, M.V., B.R. Riddle, R.J. Whidaker, & J.A. Brown. 2010. Biogeography (4th ed., Chapter 2). Sinauer Associates, Inc., Sunderland, Mass.
McDowall, R.M. 2002. Accumula4ng evidence for a dispersal biogeography of southern cool temperate freshwater fishes. J. Biogeography 29: 207-‐219. Miller, R.R. 1966. Geographical distribu4on of Central American freshwater fishes. Copeia 4: 773-‐802.
Rahel, F.J. 2000. Homogeniza4on of fish faunas across the United States. Science 288: 854-‐855.
Spalding, M.D., et al. 2007. Marine ecoregions of the world: a bioregionaliza4on of coastal and shelf areas. BioScience 57(7): 573-‐583.
Taylor, E.B. 2004. An analysis of homogeniza4on and differen4a4on of Canadian freshwater fish faunas with an emphasis on Bri4sh Columbia. Can. J. Fish. Aquat. Sci. 61: 68-‐79.
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