“Population ecology”的意思、由来-开放百科全书

The development of population ecology owes much to demography and actuarial life tables. Population ecology is important in conservation biology, especially in the development of population viability analysis (PVA) which makes it possible to predict the long-term probability of a species persisting in a given habitat patch. Although population ecology is a subfield of biology, it provides interesting problems for mathematicians and statisticians who work in population dynamics.

Fundamentals

The most fundamental law of population ecology is Thomas Malthus' exponential law of population growth.^[3]

This principle in population ecology provides the basis for formulating predictive theories and tests that follow:

Simplified population models usually start with four key variables (four demographic processes) including death, birth, immigration, and emigration. Mathematical models used to calculate changes in population demographics and evolution hold the assumption (or null hypothesis) of no external influence. Models can be more mathematically complex where "...several competing hypotheses are simultaneously confronted with the data."^[4] For example, in a closed system where immigration and emigration does not take place, the rate of change in the number of individuals in a population can be described as:

where N is the total number of individuals in the population, B is the raw number of births, D is the raw number of deaths, b and d are the per capita rates of birth and death respectively, and r is the per capita average number of surviving offspring each individual has. This formula can be read as the rate of change in the population (dN/dT) is equal to births minus deaths (B - D).^[3]^[5]

Using these techniques, Malthus' population principle of growth was later transformed into a mathematical model known as the logistic equation:

where N is the biomass density, a is the maximum per-capita rate of change, and K is the carrying capacity of the population. The formula can be read as follows: the rate of change in the population (dN/dT) is equal to growth (aN) that is limited by carrying capacity (1-N/K). From these basic mathematical principles the discipline of population ecology expands into a field of investigation that queries the demographics of real populations and tests these results against the statistical models. The field of population ecology often uses data on life history and matrix algebra to develop projection matrices on fecundity and survivorship. This information is used for managing wildlife stocks and setting harvest quotas ^[5]^[6]

Geometric populations

The population model below can be manipulated to mathematically infer certain properties of geometric populations. A population with a size that increases geometrically is a population where generations of reproduction do not overlap.^[8] In each generation there is an effective population size denoted as N_e which constitutes the number of individuals in the population that are able to reproduce and will reproduce in any reproductive generation in concern.^[9] In the population model below it is assumed that N is the effective population size.^[8]

The raw birth and death rates are related to the per capita birth and death rates:

Assumption 03: b_t and d_t are constant (i.e. they don't change each generation).

Doubling time of geometric populations

The doubling time of a population is the time required for the population to grow to twice its size.^[13] We can calculate the doubling time of a geometric population using the equation: N_t+1 = λ^tN_t by exploiting our knowledge of the fact that the population (N) is twice its size (2N) after the doubling time.^[8]

Half-life of geometric populations

The half-life of a population is the time taken for the population to decline to half its size. We can calculate the half-life of a geometric population using the equation: N_t+1 = λ^tN_t by exploiting our knowledge of the fact that the population (N) is half its size (0.5N) after a half-life.^[8]

Geometric (R) and finite (λ) growth constants

Geometric (R) growth constant

Finite (λ) growth constant

Mathematical relationship between geometric and exponential populations

In geometric populations, R and λ represent growth constants (see 2 and 2.3). In exponential populations however, the intrinsic growth rate, also known as intrinsic rate of increase (r) is the relevant growth constant. Since generations of reproduction in a geometric population do not overlap (e.g. reproduce once a year) but do in an exponential population, geometric and exponential populations are usually considered to be mutually exclusive.^[14] However, geometric constants and exponential constants share the mathematical relationship below.^[8]

Assumption: N_t (of a geometric population) = N_t (of an exponential population).

Take the natural logarithms of the equation. Using natural logarithms instead of base 10 or base 2 logarithms simplifies the final equation as ln(e) = 1.

r/K selection

An important concept in population ecology is the r/K selection theory. The first variable is r (the intrinsic rate of natural increase in population size, density independent) and the second variable is K (the carrying capacity of a population, density dependent).^[15]

An r-selected species (e.g., many kinds of insects, such as aphids^[16]) is one that has high rates of fecundity, low levels of parental investment in the young, and high rates of mortality before individuals reach maturity. Evolution favors productivity in r-selected species. In contrast, a K-selected species (such as humans) has low rates of fecundity, high levels of parental investment in the young, and low rates of mortality as individuals mature. Evolution in K-selected species favors efficiency in the conversion of more resources into fewer offspring.^[17]^[18]

Metapopulation

Populations are also studied and conceptualized through the "metapopulation" concept. The metapopulation concept was introduced in 1969:^[19]

History

The older term, autecology (from Greek: αὐτο, auto, "self"; οίκος, oikos, "household"; and λόγος, logos, "knowledge"), refers to roughly the same field of study as population ecology. It derives from the division of ecology into autecology—the study of individual species in relation to the environment—and synecology—the study of groups of organisms in relation to the environment—or community ecology. Odum (1959, p. 8) considered that synecology should be divided into population ecology, community ecology, and ecosystem ecology, defining autecology as essentially "species ecology."^[1] However, for some time biologists have recognized that the more significant level of organization of a species is a population, because at this level the species gene pool is most coherent. In fact, Odum regarded "autecology" as no longer a "present tendency" in ecology (i.e., an archaic term), although included "species ecology"—studies emphasizing life history and behavior as adaptations to the environment of individual organisms or species—as one of four subdivisions of ecology.

Journals

The first journal publication of the Society of Population Ecology, titled Population Ecology (originally called Researches on Population Ecology) was released in 1952.^[23]

Scientific articles on population ecology can also be found in the Journal of Animal Ecology, Oikos and other journals.

See also

References

1. ^¹{{cite book | last =Odum | first =Eugene P. | authorlink =Eugene Odum | title =Fundamentals of Ecology | edition=Second| publisher =W. B. Saunders Co. | year =1959 | location =Philadelphia and London | isbn = 9780721669410|oclc = 554879 | page =546 p}}
2. ^{{Cite journal|last=Wells |first=J. V. |last2=Richmond |first2=M. E. |title=Populations, metapopulations, and species populations: What are they and who should care? |journal=Wildlife Society Bulletin |volume=23 |issue=3 |pages=458–462 |year=1995 |url=http://www.uoguelph.ca/zoology/courses/BIOL3130/wells11.pdf |format= |deadurl=yes |archiveurl=https://web.archive.org/web/20051104081736/http://www.uoguelph.ca/zoology/courses/BIOL3130/wells11.pdf |archivedate=November 4, 2005 }}
3. ^¹²{{Cite journal | last = Turchin | first = P. | title = Does Population Ecology Have General Laws? | journal = Oikos | volume = 94 | issue = 1 | pages = 17–26 | year = 2001 | doi = 10.1034/j.1600-0706.2001.11310.x | postscript = }}
4. ^{{Cite journal | last = Johnson | first = J. B. | last2 = Omland | first2 = K. S. | title = Model selection in ecology and evolution. | journal = Trends in Ecology and Evolution | volume = 19 | issue = 2 | pages = 101–108 | year = 2004 | url = http://www.usm.maine.edu/bio/courses/bio621/model_selection.pdf | doi = 10.1016/j.tree.2003.10.013 | pmid = 16701236 | postscript = | citeseerx = 10.1.1.401.777 }}
5. ^¹²{{Cite book | last = Vandermeer | first = J. H. | last2 = Goldberg | first2 = D. E. | title = Population ecology: First principles | place = Woodstock, Oxfordshire | publisher = Princeton University Press | year = 2003 | isbn = 978-0-691-11440-8 | postscript = }}
6. ^{{Cite journal | last = Berryman | first = A. A. | title = The Origins and Evolution of Predator-Prey Theory | journal = Ecology | volume = 73 | issue = 5 | pages = 1530–1535 | year = 1992 | doi = 10.2307/1940005 | jstor = 1940005}}
7. ^{{cite journal|last1=Hassell|first1=Michael P.|title=Foraging Strategies, Population Models and Biological Control: A Case Study|journal=The Journal of Animal Ecology|date=June 1980|volume=49|issue=2|pages=603–628|doi=10.2307/4267|jstor=4267}}
8. ^¹²³⁴{{cite web|title=GEOMETRIC AND EXPONENTIAL POPULATION MODELS|url=http://www.afrc.uamont.edu/whited/Geometric%20and%20exponential%20population%20models.pdf}}
9. ^{{cite web|last1=Holsinger|first1=Kent|title=Effective Population Size|url=http://darwin.eeb.uconn.edu/eeb348/lecture-notes/drift/node7.html|date=2008-08-26}}
10. ^{{cite web|title=Bacillus stearothermophilus NEUF2011|url=https://microbewiki.kenyon.edu/index.php/Bacillus_stearothermophilus_NEUF2011|website=Microbe wiki}}
11. ^{{cite journal|last1=Chandler|first1=M.|last2=Bird|first2=R.E.|last3=Caro|first3=L.|title=The replication time of the Escherichia coli K12 chromosome as a function of cell doubling time|journal=Journal of Molecular Biology|date=May 1975|volume=94|issue=1|pages=127–132|doi=10.1016/0022-2836(75)90410-6}}
12. ^{{cite journal|last1=Tobiason|first1=D. M.|last2=Seifert|first2=H. S.|title=Genomic Content of Neisseria Species|journal=Journal of Bacteriology|date=19 February 2010|volume=192|issue=8|pages=2160–2168|doi=10.1128/JB.01593-09|pmid=20172999|pmc=2849444}}
13. ^{{cite web|title=What is Doubling Time and How is it Calculated?|first=Lauren|last=Boucher|date=24 March 2015|website=Population Education|url=https://www.populationeducation.org/content/what-doubling-time-and-how-it-calculated}}
14. ^{{cite web|title=Population Growth|website=University of Alberta|url=http://www.biology.ualberta.ca/courses.hp/bio208/Lecture_Notes_files/Biol208_Lecture19_PopulationGrowth.pdf}}
15. ^{{Cite book| last = Begon| first = M.| last2 = Townsend| first2 = C. R.| last3 = Harper| first3 = J. L.| title = Ecology: From Individuals to Ecosystems| place = Oxford, UK| publisher = Blackwell Publishing| year = 2006| edition = 4th| url = https://books.google.com/?id=Lsf1lkYKoHEC&printsec=frontcover&dq=ecology&cd=1#v=onepage&q=| isbn = 978-1-4051-1117-1| postscript = }}
16. ^{{Cite journal | last = Whitham | first = T. G. | title = Habitat Selection by Pemphigus Aphids in Response to Response Limitation and Competition | journal = Ecology | volume = 59 | issue = 6 | pages = 1164–1176 | year = 1978 | doi = 10.2307/1938230 | jstor = 1938230}}
17. ^{{Cite journal | last = MacArthur | first = R. | last2 = Wilson | first2 = E. O. | title = The Theory of Island Biogeography | place = Princeton, NJ | publisher = Princeton University Press | year = 1967 | postscript = }}
18. ^{{Cite journal | last = Pianka | first = E. R. | title = r and K Selection or b and d Selection? | journal = The American Naturalist | volume = 106 | issue = 951 | pages = 581–588 | year = 1972 | doi = 10.1086/282798}}
19. ^{{Cite book | last = Levins | first = R. | title = Some demographic and genetic consequences of environmental heterogeneity for biological control | journal = Bulletin of the Entomological Society of America | volume = 15 | issue = 3 | pages = 237–240 | year = 1969 | url = https://books.google.com/?id=8jfmor8wVG4C&pg=PA162&q= | publisher = Columbia University Press | isbn = 978-0-231-12680-9| doi = 10.1093/besa/15.3.237 }}
20. ^{{Cite book | last = Levins | first = R. | editor-last = Gerstenhaber | editor-first = M. | title = Extinction. In: Some Mathematical Questions in Biology | year = 1970 | pages = 77–107 | url = https://books.google.com/?id=CfZHU1aZqJsC&dq=Some+Mathematical+Questions+in+Biology&printsec=frontcover&q= | publisher = AMS Bookstore | isbn = 978-0-8218-1152-8}}
21. ^{{Cite journal | last = Hanski | first = I. | title = Metapopulation dynamics | journal = Nature | volume = 396 | pages = 41–49 | year = 1998 | url = http://www.helsinki.fi/~ihanski/Articles/Nature%201998%20Hanski.pdf | doi = 10.1038/23876 | issue = 6706 | deadurl = yes | archiveurl = https://web.archive.org/web/20101231165339/http://www.helsinki.fi/~ihanski/Articles/Nature%201998%20Hanski.pdf | archivedate = 2010-12-31 | df = }}
22. ^{{Cite book | editor-last = Hanski | editor-first = I. | editor2-last = Gaggiotti | editor2-first = O. E. | title = Ecology, genetics and evolution of metapopulations. | publisher = Elsevier Academic Press | year = 2004 | location = Burlington, MA | url = https://books.google.com/?id=EP8TAQAAIAAJ&q=ecology,+genetics,+and+evolution+of+metapopulations&dq=ecology,+genetics,+and+evolution+of+metapopulations&cd=1 | isbn = 978-0-12-323448-3}}
23. ^{{cite web|url= http://www.springerlink.com/content/1438-3896?sortorder=asc&p=93932389f9764a2aadcbe167b466fcef&o=0|title= Population Ecology}}