Marginal distribution (biology): Difference between revisions
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A geographic range edge represents the line beyond which a [[species]] does not occupy. Core populations represent individuals who reside within the center of the [[range]], and peripheral or edge populations represent individuals who reside at the boundary of the range. The inability of a species to expand their range is due to some factor that constrains them from continually adapting to overcome [[biotic]] or [[abiotic]] factors that impose limits on their distribution<ref name=Mott>{{cite journal|last=Mott|first=CL|title=Environmental Constraints to the Geographic Expansion of Plant and Animal Species|journal=Natural Education Knowledge|year=2010|volume=3|issue=10|pages=72}}</ref>. |
A geographic range edge represents the line beyond which a [[species]] does not occupy. Core populations represent individuals who reside within the center of the [[range]], and peripheral or edge populations represent individuals who reside at the boundary of the range. The inability of a species to expand their range is due to some factor that constrains them from continually adapting to overcome [[biotic]] or [[abiotic]] factors that impose limits on their distribution<ref name=Mott>{{cite journal|last=Mott|first=CL|title=Environmental Constraints to the Geographic Expansion of Plant and Animal Species|journal=Natural Education Knowledge|year=2010|volume=3|issue=10|pages=72}}</ref>. In some cases, geographical ranges are entirely unsurprising, such as a physical barrier of an ocean for terrestrial species<ref name=Mott />. In other cases, reasons why species do not pass these boundaries are unknown, however the main determinants of the distribution of a species across its range come down to [[ecological]] and [[evolutionary]] processes <ref>{{cite journal|last=Hardie|first=DC|coauthors=Hutching JA|title=Evolutionary ecology at the extreme of species' ranges|journal=Environ. Rev.|year=2010|volume=18|pages=1-20}}</ref>. |
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==Abiotic Factors== |
==Abiotic Factors== |
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Revision as of 23:14, 21 November 2012
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A geographic range edge represents the line beyond which a species does not occupy. Core populations represent individuals who reside within the center of the range, and peripheral or edge populations represent individuals who reside at the boundary of the range. The inability of a species to expand their range is due to some factor that constrains them from continually adapting to overcome biotic or abiotic factors that impose limits on their distribution[1]. In some cases, geographical ranges are entirely unsurprising, such as a physical barrier of an ocean for terrestrial species[1]. In other cases, reasons why species do not pass these boundaries are unknown, however the main determinants of the distribution of a species across its range come down to ecological and evolutionary processes [2].
Abiotic Factors
Gradients in climactic factors create physiological barriers to dispersal[1]. All species have limits of tolerance to abiotic factors, which can lower their survival and reproductive success and limit range expansion beyond the edge. Changes in temperature may cause a species to change its geographical distribution. With increasing temperatures resulting from global warming, species have been seen to expand their range northward due to increased survival and reproduction as a result of warming[3]. Precipitation can also be a key determinant in limiting the geographic range edges of species. This is often seen in organisms with high water demands, whose survival and reproduction would decrease beyond the edge due to dry conditions, limiting expansion[4]. Moisture of soil or air is also seen to limit range expansion. In terms of soil moisture, limited range expansion for species that forage on soil organisms or for species that reside in soil and rely on it for nutrients are seen[5] . If moisture requirements are not met beyond the species range, they will not be able to expand due to resulting reductions in fitness. There are many other abiotic factors that can determine a species range, including dissolved oxygen, canopy cover, conductivity, alkalinity and pH[6].
Biotic Factors
Interactions between species can cause limitations to a species geographic range. The most obvious interaction that limits range expansion is predation, where prey species do not move beyond their range to avoid predator attack and mortality. Geographic range edges can also be determined by competition, where less competitive species are forced into suboptimal conditions within the range to avoid stress of reduced food and habitat. The geographic range of one species may be linked to another, where the range of one species cannot extend independent of the other. This is seen in mutualistic relationships, where fitness and population growth are reduced outside of the hosts range where the symbiont is not present. Parasitism can also play a role in limiting the expansion of species outside of their range. This occurs when there is a higher presence of infection at the range edges that reduces population growth and survivorship and ultimately reduces further expansion. Higher parasite presence can occur when abiotic conditions are unfavorable at the edge, leading to lower resistance of species to the infection.
References
- ^ a b c Mott, CL (2010). "Environmental Constraints to the Geographic Expansion of Plant and Animal Species". Natural Education Knowledge. 3 (10): 72.
- ^ Hardie, DC (2010). "Evolutionary ecology at the extreme of species' ranges". Environ. Rev. 18: 1–20.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Battisti, A (2005). "Expansion of geographic range in the pine processionary moth caused by increased winter temperatures". Ecological applications. 15 (6): 2084–2096.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Bateman, BL (2011). "Climate-driven variation in food availability between the core and range edge of the endangered northern betting (Bettongia tropica)". Australian Journal of Zoology. 59: 177–185.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Duckworth, G (2010). "Soil moisture limits foraging: a possible mechanism for the range dynamics of the hadeda ibis in southern africa". Diversity and Distributions. 16: 765–772.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Neff, MR (2011). "Effects of broad-scale geological changes on patterns in macroinvertebrate assemblages". Am. Benthol. Soc. 30 (2): 459–473.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)