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| '''Relative species abundance''' is a component of [[biodiversity]] and refers to how common or rare a species is relative to other species in a defined location or community.<ref name=Hubbell01>Hubbell, S.P. 2001. The unified neutral theory of biodiversity and biogeography. Princeton University Press, Princeton, N.J.</ref> Relative species [[abundance (ecology)|abundances]] tend to conform to specific patterns that are among the best-known and most-studied patterns in [[macroecology]].
| | Acclaimed to boost metabolisms and help in weight loss targets, Pure Yacon Syrup gives unimaginable benefits to help in wholesome living. In case you have almost any questions with regards to wherever along with how to employ [http://ww4w.ca/live-your-life-the-yacon-way/ Raw Yacon Syrup], you can e mail us with our own web-site. Whether you want to shed weight or simply have interaction in a wholesome consuming program with raw, all-natural components, why not give it a strive?<br><br>Pure Yacon syrup is derived from the South American root, Yacon, discovered within the Andes Mountains. Rich in prebiotics, comparable to inulin and fructooligosaccharides (FOS), the tuberous root was traditionally included into the Peruvian diet. At this time, we now have a new way to enjoy the nutrient wealthy Yacon. By incorporating the Yacon extract into a syrup, now we have a handy strategy to incorporate Yacon into our each day diets.<br><br>The main benefits of including Yacon to our diets embrace weight loss, slimming waist sizes, regulated blood sugar, and healthy digestion. The syrup additionally has metabolism boosting properties which combat excess fat. Pure Yacon Syrup regulates your starvation hormone, making you're feeling full longer. The important thing ingredient and only ingredient to search for is Yacon. There should be no additives, which would subtract from the benefits of the root.<br><br>I like to recommend trying Yacon syrup in your recipes as a sugar substitute. Nice for diabetics and those searching for a low glycemic sugar substitute, pure Yacon syrup is extremely versatile, making it an ideal ingredient to keep in your pantry. Pinterst.com has numerous recipes, together with do-it-yourself salad dressings, meat glazes, barbeque sauces, and popcorn toppings. The syrup also pairs well with bitter greens, kale, and grilled veggies. I personally put it in my coffee and tea every morning in place of the Agave nectar I have used for years.<br><br>Though I have a look at it as an entire meals additive and ingredient in my every day cooking, this great syrup has been touted to help in attaining weight loss goals and slimming waist lines. By taking one teaspoon before or at each meal, you may be one step closer to achieving these goals. Seems like a win-win to me!<br><br>I'd love to listen to your opinions about Yacon Syrup and which brands have worked for you. There are numerous bottles for sale on amazon.com - all from different manufacturers. Although they aren't all created equal, the secret is to find a pure model of the Yacon syrup with the only ingredient being Yacon extract. Good luck in your wholesome living endeavors! I hope this new product will likely be as great for you because it has been for our family. |
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| ==Introduction==
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| ===Relative species abundance===
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| [[File:Hollow curve beetles.png|thumb|'''Figure 1'''. Relative species abundance of beetles sampled from the river Thames showing the universal “hollow curve”. (derived from data presented in Magurran (2004)<ref name=Magurran04/> and collected by Williams (1964)<ref name=Williams64>Williams, C.B. 1964. Patterns in the balance of nature and related problems in quantitative ecology. Academic Press, London.</ref>)]]
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| Relative species abundance and species richness describe key elements of [[biodiversity]].<ref name=Hubbell01/> Relative species abundance refers to how common or rare a species is relative to other species in a given location or community.<ref name=Hubbell01/><ref name=McGill>McGill, B.J., Etienne R.S., Gray J.S., Alonso D., Anderson M.J., Benecha H.K., Dornelas M., Enquist B.J., Green J.L., He F., Hurlbert A.H., Magurran A.E., Marquet P.A., Maurer B.A., Ostling A., Soykan C.U., Ugland K.I., White E.P. 2007. Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework. Ecology Letters 10: 995–1015</ref>
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| Usually relative species abundances are described for a single [[trophic level]]. Because such species occupy the same [[trophic level]] they will potentially or actually compete for similar resources.<ref name=Hubbell01/> For example, relative species abundances might describe all terrestrial birds in a forest community or all [[planktonic]] [[copepods]] in a particular marine environment.
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| Relative species abundances follow very similar patterns over a wide range of ecological communities. When plotted as a histogram of the number of species represented by 1, 2, 3, …,''n'' individuals usually fit a hollow curve, such that most species are rare, (represented by a single individual in a community sample) and relatively few species are abundant (represented by a large number of individuals in a community sample)(Figure 1).<ref name=McGill/> This pattern has been long-recognized and can be broadly summarized with the statement that “most species are rare”.<ref>Andrewartha, H.G., Birch L.C. 1954. The Distribution and Abundance of Animals. The University of Chicago Press, Chicago, Illinois.</ref> For example, [[Charles Darwin]] noted in 1859 in the [[Origin of Species]] that “''…rarity is the attribute of vast numbers of species in all classes…''”<ref>Darwin, C. 2004 (1859). The Origin of Species by means of natural selection or the preservation of favoured races in the struggle for life. Castle Books, New Jersey.</ref>
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| Species abundance patterns can be best visualized in the form of relative abundance distribution plots. The consistency of relative species abundance patterns suggests that some common macroecological “rule” or process determines the distribution of individuals among species within a trophic level.
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| ===Distribution plots===
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| [[File:PrestonPlot beetles.png|thumb|'''Figure 2'''. ''Preston plot'' of beetles sampled from the river Thames showing a strong right-skew.<ref name=Magurran04/><ref name=Williams64/>]]
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| [[File:Rank abundance beetles.png|thumb|'''Figure 3'''. ''Whittaker plot'' of beetles sampled from the river Thames showing a slight "s"-shape.<ref name=Magurran04/><ref name=Williams64/>]]
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| Relative species abundance distributions are usually graphed as frequency histograms (“Preston Plots”; Figure 2)<ref name=Preston>{{cite journal | author = Preston, F.W. | year = 1948 | title = The Commonness, and Rarity, of Species | journal = Ecology | volume = 29 | issue = 3 | pages = 254–283 | url = http://www.bgu.ac.il/desert_agriculture/Vegecology/Papers/Preston48.pdf | doi = 10.2307/1930989}}</ref> or [[rank abundance curve|rank-abundance diagrams]] ("Whittaker Plots”; Figure 3).<ref name=Whittaker65>Whittaker, R.H. 1965. Dominance and diversity in land plant communities, Science 147: 250–260</ref>
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| '''Frequency histogram (Preston Plot)''':
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| ::'''''x''-axis''': logarithm of abundance bins (usually log<sub>2</sub> (because this was historically a simple way to approximate the natural log))
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| ::'''''y''-axis''': number of species at given abundance
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| '''Rank-abundance diagram (Whittaker Plot)''':
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| ::'''x-axis''': species list, ranked in order of descending abundance (i.e. from common to rare)
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| ::'''y-axis''': logarithm of % relative abundance
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| When plotted in these ways, relative species abundances from wildly different data sets show similar patterns: frequency histograms tend to be right-skewed (e.g. Figure 2) and rank-abundance diagrams tend to conform to the curves illustrated in Figure 4.
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| ==Understanding relative species abundance patterns==
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| Researchers attempting to understand relative species abundance patterns usually approach them in a descriptive or mechanistic way. Using a descriptive approach biologists attempt to fit a mathematical model to real data sets and infer the underlying biological principles at work from the model parameters. By contrast, mechanistic approaches create a mathematical model based on biological principles and then test how well these models fit real data sets.<ref name=Tokeshi99>Tokeshi, M. 1999. Species coexistence: ecological and evolutionary perspectives. Blackwell Scientific, Oxford</ref>
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| ===Descriptive approaches===
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| ====Geometric series (Motomura 1932)====
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| [[File:Common descriptiveWhittaker.jpg|thumb|'''Figure 4'''. Generic Rank-abundance diagram of three common mathematical models used to fit species abundance distributions: Motomura's geometric series, Fisher's logseries, and Preston's log-normal series (modified from Magurran 1988)<ref name=Magurran88>Magurran, A.E. 1988. Ecological Diversity and Its Measurement. Princeton Univ. Press</ref>]]
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| [[File:Succession.jpg|thumb|'''Figure 5'''. Plant succession in abandoned fields within Brookhaven National Laboratory, NY. Species abundances conform to the geometric series during early succession but approach lognormal as the community ages. (modified from Whittaker 1972<ref name=Whittaker72>Whittaker, R. H. 1972. Evolution and measurement ofspecies diversity. Taxon 21:213–251</ref>)]]
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| I. Motomura developed the geometric series model based on benthic community data in a lake.<ref name=Motomura>Motomura, I. 1932. A statistical treatment of associations, Jpn. J. Zool. 44: 379–383 (in Japanese)</ref> Within the geometric series each species’ level of abundance is a sequential, constant proportion (''k'') of the total number of individuals in the community. Thus if ''k'' is 0.5, the most common species would represent half of individuals in the community (50%), the second most common species would represent half of the remaining half (25%), the third, half of the remaining quarter (12.5%) and so forth.
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| Although Motomura originally developed the model as a statistical (descriptive) means to plot observed abundances, the “discovery” of his paper by Western researchers in 1965 led to the model being used as a [[niche apportionment models|niche apportionment model]] – the “niche-preemption model”.<ref name=Whittaker65/> In a mechanistic model ''k'' represents the proportion of the resource base acquired by a given species.
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| The geometric series rank-abundance diagram is linear with a slope of –''k'', and reflects a rapid decrease in species abundances by rank (Figure 4).<ref name=Motomura/> The geometric series does not explicitly assume that species colonize an area sequentially, however, the model fits the concept of niche preemption, where species sequentially colonize a region and the first species to arrive receives the majority of resources.<ref name=He_Tang>He , F., Tang D. 2008. Estimating the niche preemption parameter of the geometric series Acta Oecologica 33 (1):105–107</ref> The geometric series model fits observed species abundances in highly uneven communities with low diversity.<ref name=He_Tang/> This is expected to occur in terrestrial plant communities (as these assemblages often show strong dominance) as well as communities at early successional stages and those in harsh or isolated environments (Figure 5).<ref name=Whittaker65/>
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| ====Logseries (Fisher ''et al'' 1943)====
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| : <math>S=\alpha\ln{\left(1+{N\over{\alpha\,\!}}\right)}</math>
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| ''where'':
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| :''S'' = the number of species in the sampled community
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| :''N'' = the number of individuals sampled
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| :<math>\alpha\,\!</math> = a constant derived from the sample data set
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| The logseries was developed by [[Ronald Fisher]] to fit two different abundance data sets: British moth species (collected by [[Carrington Bonsor Williams|Carrington Williams]]) and Malaya butterflies (collected by [[Alexander Steven Corbet]]).<ref name=Fisher_etal>Fisher, R.A, Corbet A.S., Williams C.B. 1943. The relation between the number of species and the number of individuals in a random sample of an animal population. Journal of Animal Ecology 12: 42–58.</ref> The logic behind the derivation of the logseries is varied <ref>Johnson, J.L., Adrienne, W.K. & Kotz, S. (2005). Univariate and Discrete Distributions, 3rd edn. John Wiley and Sons, New York</ref> however Fisher proposed that sampled species abundances would follow a negative binomial from which the zero abundance class (species too rare to be sampled) was eliminated.<ref name=Hubbell01/> He also assumed that the total number of species in a community was infinite. Together, this produced the [[logarithmic series distribution|logseries distribution]] (Figure 4). The logseries predicts the number of species at different levels of abundance (''n'' individuals) with the formula:
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| :<math>S_n= {\alpha\,\!x^n \over n}</math>
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| ''where: ''
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| :S = the number of species with an abundance of ''n''
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| :''x'' = a positive constant (0 < ''x'' < 1) which is derived from the sample data set and generally approaches 1 in value
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| The number of species with 1, 2, 3,…, ''n'' individuals are therefore:
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| :<math>\alpha, {\alpha\,\!x^2\over{2}}, {\alpha\,\!x^3\over{3}}, \dots, {\alpha\,\!x^n\over{n}} </math>
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| =====Fisher’s constants=====
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| The constants ''α'' and ''x'' can be estimated through iteration from a given species data set using the values ''S'' and ''N'' .<ref name=Magurran04>Magurran, A.E. 2004. Measuring biological diversity. Blackwell Scientific, Oxford.</ref> Fisher’s dimensionless ''α'' is often used as a measure of biodiversity, and indeed has recently been found to represent the fundamental biodiversity parameter, θ, from neutral theory ([[Relative species abundance#Fisher.E2.80.99s alpha and Hubbell.E2.80.99s theta .E2.80.93 an interesting convergence|see below]]).
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| ====Log normal (Preston 1948)====
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| [[File:Prestonsveil copy.jpg|thumb|'''Figure 6'''. An example of Preston’s veil. Fish species abundances sampled using repeated trawling over a one month (blue bars), two month (gold bars) and one year period (yellow). One year of sampling indicates that the fish community is log-normally distributed. (derived from Magurran 2004<ref name=Magurran04/>)]]
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| Using several data sets (including breeding bird surveys from New York and Pennsylvania and moth collections from Maine, Alberta and Saskatchewan) [[Frank W. Preston]] (1948) argued that species abundances follow a [[Gaussian function|Normal (Gaussian) distribution]], partly as a result of the [[Central Limit Theorem]] (Figure 4).<ref name=Preston/> According to his argument, the right-skew observed in species abundance frequency histograms (including those described by Fisher ''et al.'' (1943) <ref name=Fisher_etal/>) was, in fact, a sampling artifact. Given that species toward the left side of the ''x''-axis are increasingly rare, they may be missed in a random species sample. As the sample size increases however, the likelihood of collecting rare species in a way that accurately represents their abundance also increases, and more of the normal distribution becomes visible.<ref name=Preston/> The point at which rare species cease to be sampled has been termed ''Preston’s veil line''. As the sample size increases Preston’s veil is pushed farther to the left and more of the normal curve becomes visible <ref name=Magurran04/><ref name=Magurran88/>(Figure 6). Interestingly, Williams’ moth data, originally used by Fisher to develop the logseries distribution, became increasingly lognormal as more years of sampling were completed.<ref name=Hubbell01/><ref name=Williams64/>
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| =====Calculating theoretical species richness=====
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| Preston’s theory has an interesting application: if a community is truly lognormal yet under-sampled, the lognormal distribution can be used to estimate the true species richness of a community. Assuming the shape of the total distribution can be confidently predicted from the collected data, the normal curve can be fit via statistical software or by completing the [[Gaussian function|Gaussian formula]]:<ref name=Preston/>
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| :<math> n = n_0 e^{-(aR)^2} \, </math>
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| ''where:''
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| :''n''<sub>0</sub> is the number of species in the modal bin (the peak of the curve)
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| :''n'' is the number of species in bins ''R'' distant from the modal bin
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| :''a'' is a constant derived from the data
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| It is then possible to predict how many species are in the community by calculating the total area under the curve (''N''):
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| : <math>N= {n_0\sqrt{\pi}\over a}</math>
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| The number of species missing from the data set (the missing area to the left of the veil line) is simply ''N'' minus the number of species sampled.<ref name=Magurran04/> Preston did this for two lepidopteran data sets, predicting that, even after 22 years of collection, only 72% and 88% of the species present had been sampled.<ref name=Preston/>
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| ====Yule model (Nee 2003) ====
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| The Yule model is based on a much earlier, [[Galton–Watson process|Galton–Watson model]] which was used to describe the distribution of species among [[genera]].<ref>Yule, G.U. 1924. A mathematical theory of evolution based on the conclusions of Dr. J.C. Willis, FRS. Philos. Trans. R. Soc. London Ser. B 213:21–87</ref> The Yule model assumes random branching of species trees, with each species (branch tip) having the equivalent probability of giving rise to new species or becoming extinct. As the number of species within a genus, within a clade, has a similar distribution to the number of individuals within a species, within a community (i.e. the "hollow curve"), Sean Nee (2003) used the model to describe relative species abundances.<ref name=McGill/><ref name=Nee>Nee, S. 2003. The unified phenomenological theory of biodiversity. ''In'' T. Blackburn and K. Gaston, Editors, Macroecology: concepts and consequences. Blackwell Scientific, Oxford.</ref> In many ways this model is similar to [[niche apportionment models]], however, Nee intentionally did not propose a biological mechanism for the model behavior, arguing that any distribution can be produced by a variety of mechanisms.<ref name=Nee/>
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| ===Mechanistic approaches: niche apportionment===
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| ''Note'': This section provides a general summary of niche apportionment theory, more information can be found under [[niche apportionment models]].
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| Most mechanistic approaches to species abundance distributions use niche-space, i.e. available resources, as the mechanism driving abundances. If species in the same [[trophic level]] consume the same resources (such as nutrients or sunlight in plant communities, prey in carnivore communities, nesting locations or food in bird communities) and these resources are limited, how the resource “pie” is divided among species determines how many individuals of each species can exist in the community. Species with access to lots of resources will have higher carrying capacities than those with little access. Mutsunori Tokeshi <ref>Tokeshi, M. 1990. Niche apportionment or random assortment: species abundance patterns revisited. Journal of Animal Ecology 59: 1129–1146</ref> later elaborated niche apportionment theory to include niche filling in unexploited resource space.<ref name=Tokeshi99/> Thus, a species may survive in the community by carving out a portion of another species’ niche (slicing up the pie into smaller pieces) or by moving into a vacant niche (essentially making the pie larger, for example, by being the first to arrive in a newly available location or through the development of a novel trait that allows access previously unavailable resources). Numerous [[niche apportionment models]] have been developed. Each make different assumptions about how species carve up niche-space.
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| ====Unified neutral theory (Hubbell 1979/2001)====
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| {{main|Unified neutral theory of biodiversity}}
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| The Unified Neutral Theory of Biodiversity and Biogeography (UNTB) is a special form of mechanistic model that takes an entirely different approach to community composition than the niche apportionment models.<ref name=Hubbell01/> Instead of species populations reaching equilibrium within a community, the UNTB model is dynamic, allowing for continuing changes in relative species abundances through drift.
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| A community in the UNTB model can be best visualized as a grid with a certain number of spaces, each occupied with individuals of different species. The model is [[zero-sum]] as there are a limited number of spaces that can be occupied: an increase in the number of individuals of one species in the grid must result in corresponding decrease in the number of individuals of other species in the grid. The model then uses birth, death, immigration, extinction and speciation to modify community composition over time.
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| '''Hubbell’s theta''' | |
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| The UNTB model produces a dimensionless “fundamental biodiversity” number, θ, which is derived using the formula:
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| : ''θ'' = 2''J''<sub>''m''</sub>''v''
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| ''where'':
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| : ''J''<sub>''m''</sub> is the size of the metacommunity (the outside source of immigrants to the local community)
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| :''v'' is the speciation rate in the model
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| Relative species abundances in the UNTB model follow a zero-sum multinomial distribution.<ref name=Hubbell_Lake>Hubbell, S.P., Lake J. 2003. The neutral theory of biogeography and biodiversity: and beyond. ''In'' T. Blackburn and K. Gaston, Editors, Macroecology: concepts and consequences. Blackwell Scientific, Oxford.</ref> The shape of this distribution is a function of the immigration rate, the size of the sampled community (grid), and θ.<ref name=Hubbell_Lake/> When the value of θ is small, the relative species abundance distribution is similar to the geometric series (high dominance). As θ gets larger, the distribution becomes increasingly s-shaped (log-normal) and, as it approaches infinity, the curve becomes flat (the community has infinite diversity and species abundances of one). Finally, when θ = 0 the community described consists of only one species (extreme dominance).<ref name=Hubbell01/>
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| ===== Fisher’s alpha and Hubbell’s theta – an interesting convergence=====
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| An unexpected result of the UNTB is that at very large sample sizes, predicted relative species abundance curves describe the [[metacommunity]] and become identical to Fisher’s logseries. At this point θ also becomes identical to Fisher’s <math>\alpha\,\!</math> for the equivalent distribution and Fisher’s constant ''x'' is equal to the ratio of birthrate : deathrate. Thus, the UNTB unintentionally offers a mechanistic explanation of the logseries 50 years after Fisher first developed his descriptive model.<ref name=Hubbell01/>
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| ==References==
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| {{reflist|2}}
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| {{modelling ecosystems|expanded=other}}
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| {{DEFAULTSORT:Relative Species Abundance}}
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| [[Category:Biodiversity]]
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| [[Category:Environmental science]]
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| [[Category:Population ecology]]
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Acclaimed to boost metabolisms and help in weight loss targets, Pure Yacon Syrup gives unimaginable benefits to help in wholesome living. In case you have almost any questions with regards to wherever along with how to employ Raw Yacon Syrup, you can e mail us with our own web-site. Whether you want to shed weight or simply have interaction in a wholesome consuming program with raw, all-natural components, why not give it a strive?
Pure Yacon syrup is derived from the South American root, Yacon, discovered within the Andes Mountains. Rich in prebiotics, comparable to inulin and fructooligosaccharides (FOS), the tuberous root was traditionally included into the Peruvian diet. At this time, we now have a new way to enjoy the nutrient wealthy Yacon. By incorporating the Yacon extract into a syrup, now we have a handy strategy to incorporate Yacon into our each day diets.
The main benefits of including Yacon to our diets embrace weight loss, slimming waist sizes, regulated blood sugar, and healthy digestion. The syrup additionally has metabolism boosting properties which combat excess fat. Pure Yacon Syrup regulates your starvation hormone, making you're feeling full longer. The important thing ingredient and only ingredient to search for is Yacon. There should be no additives, which would subtract from the benefits of the root.
I like to recommend trying Yacon syrup in your recipes as a sugar substitute. Nice for diabetics and those searching for a low glycemic sugar substitute, pure Yacon syrup is extremely versatile, making it an ideal ingredient to keep in your pantry. Pinterst.com has numerous recipes, together with do-it-yourself salad dressings, meat glazes, barbeque sauces, and popcorn toppings. The syrup also pairs well with bitter greens, kale, and grilled veggies. I personally put it in my coffee and tea every morning in place of the Agave nectar I have used for years.
Though I have a look at it as an entire meals additive and ingredient in my every day cooking, this great syrup has been touted to help in attaining weight loss goals and slimming waist lines. By taking one teaspoon before or at each meal, you may be one step closer to achieving these goals. Seems like a win-win to me!
I'd love to listen to your opinions about Yacon Syrup and which brands have worked for you. There are numerous bottles for sale on amazon.com - all from different manufacturers. Although they aren't all created equal, the secret is to find a pure model of the Yacon syrup with the only ingredient being Yacon extract. Good luck in your wholesome living endeavors! I hope this new product will likely be as great for you because it has been for our family.