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Extinction Threshold
Extinction threshold is a term used in conservation biology to explain the point at which a species, population or metapopulation, experiences an abrupt change in density or number because of an important parameter, such as habitat loss. It is at this critical value below which a species, population, or metapopulation, will go extinct,Ovaskainen, O. and Hanski, I. 2003:Extinction Threshold in Metapopulation Models, Ann.Zool.Fennic.40:81-97. though this may take a long time for species just below the critical value, a phenomenon known as extinction debt. Extinction thresholds are important to conservation biologists when studying a species in a population or metapopulation context because the colonization rate must be larger than the extinction rate, otherwise the entire entity will go extinct once it reaches the threshold.Groom, M., Meffe, G. K., and Carroll, C.R. 2000:Principles of Conservation Biology, 3rd Ed, Sinauer Associates. Extinction thresholds are realized under a number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conservation Biology
Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an interdisciplinary subject drawing on natural and social sciences, and the practice of natural resource management. The conservation ethic is based on the findings of conservation biology. Origins The term conservation biology and its conception as a new field originated with the convening of "The First International Conference on Research in Conservation Biology" held at the University of California, San Diego in La Jolla, California, in 1978 led by American biologists Bruce A. Wilcox and Michael E. Soulé with a group of leading university and zoo researchers and conservationists including Kurt Benirschke, Sir Otto Frankel, Thomas Lovejoy, and Jared Diamond. The meeting was prompted due to concern over tropical deforestation, disappe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ilkka Hanski
Ilkka Aulis Hanski (14 February 1953 – 10 May 2016) was a Finnish ecologist at the University of Helsinki, Finland. The Metapopulation Research Center led by Hanski, until his death, has been nominated as a Center of Excellence by the Academy of Finland. The group studies species living in fragmented landscapes and attempts to advance metapopulation ecology research. Metapopulation ecology itself studies populations of plants and animals which are separated in space by occupying patches. Career Ilkka Hanski took his bachelor's degree and Licentiate's degree in the University of Helsinki in 1976 and Doctoral degree from the University of Oxford in 1979. Hanski was a graduate student in Oxford from 1976 to 1979. He was appointed as a docent in the University of Helsinki in 1981 and in the University of Joensuu in 1983. He worked in the Academy of Finland from 1978 to 1988 as well as from 1991 to 1992. He worked as an acting professor of zoology in the University of Helsinki f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Threshold
Ecological threshold is the point at which a relatively small change or disturbance in external conditions causes a rapid change in an ecosystem. When an ecological threshold has been passed, the ecosystem may no longer be able to return to its state by means of its inherent resilience . Crossing an ecological threshold often leads to rapid change of ecosystem health. Ecological threshold represent a non-linearity of the responses in ecological or biological systems to pressures caused by human activities or natural processes. Critical load, regime shift, critical transition and tipping point are examples of other closely related terms. Characteristics Thresholds can be characterized as points or as zones. Zone-type thresholds imply a gradual shift or transition from one state to another rather than an abrupt change at a specific point. Ecological thresholds have caught attention because many cases of catastrophic worsening of conditions have proved to be difficult or nearly i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wildlife Conservation
Wildlife conservation refers to the practice of protecting wild species and their habitats in order to maintain healthy wildlife species or populations and to restore, protect or enhance natural ecosystems. Major threats to wildlife include habitat destruction, degradation, fragmentation, overexploitation, poaching, pollution and climate change. The IUCN estimates that 27,000 species of the ones assessed are at risk for extinction. Expanding to all existing species, a 2019 UN report on biodiversity put this estimate even higher at a million species. It is also being acknowledged that an increasing number of ecosystems on Earth containing endangered species are disappearing. To address these issues, there have been both national and international governmental efforts to preserve Earth's wildlife. Prominent conservation agreements include the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the 1992 Convention on Biological Diversity ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endangered Species
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and invasive species. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. Many nations have laws that protect conservation-reliant species which, for example, forbid hunting, restrict land development, or create protected areas. Some endangered species are the target of extensive conservation efforts such as captive breeding and habitat restoration. Human activity is a significant cause in causing some species to become endangered. Conservation status The conservation status of a species indicates the likelihood that it will become extinct. Multiple factors are considered when assessing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Genetics
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as Adaptation (biology), adaptation, speciation, and population stratification, population structure. Population genetics was a vital ingredient in the emergence of the Modern synthesis (20th century), modern evolutionary synthesis. Its primary founders were Sewall Wright, J. B. S. Haldane and Ronald Fisher, who also laid the foundations for the related discipline of quantitative genetics. Traditionally a highly mathematical discipline, modern population genetics encompasses theoretical, laboratory, and field work. Population genetic models are used both for statistical inference from DNA sequence data and for proof/disproof of concept. What sets population genetics apart from newer, more phenotypic approaches to modelling evolution, such as evolutionary game theory and evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Population Size
Small populations can behave differently from larger populations. They are often the result of population bottlenecks from larger populations, leading to loss of heterozygosity and reduced genetic diversity and loss or fixation of alleles and shifts in allele frequencies. A small population is then more susceptible to demographic and genetic stochastic events, which can impact the long-term survival of the population. Therefore, small populations are often considered at risk of endangerment or extinction, and are often of conservation concern. Demographic effects The influence of stochastic variation in demographic (reproductive and mortality) rates is much higher for small populations than large ones. Stochastic variation in demographic rates causes small populations to fluctuate randomly in size. This variation could be a result of unequal sex ratios, high variance in family size, inbreeding or fluctuating population size.Frankham, R., Briscoe, D. A., & Ballou, J. D. (2002) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction Vortex
Extinction vortices are a class of models through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. This model shows the events that ultimately lead small populations to become increasingly vulnerable as they spiral toward extinction. Developed by M. E. Gilpin and M. E. Soulé in 1986, there are currently four classes of extinction vortices. The first two (R and D) deal with environmental factors that have an effect on the ecosystem or community level, such as disturbance, pollution, habitat loss etc. Whereas the second two (F and A) deal with genetic factors such as inbreeding depression and outbreeding depression, genetic drift etc. Types of vortices *R Vortex: The R vortex is initiated when there is a disturbance which facilitates a lowering of population size (N) and a corresponding increase in variability (Var(r)). This event can make populations vulnerable to additional distu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Extinction
Ecological extinction is "the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species". Ecological extinction stands out because it is the interaction ecology of a species that is important for conservation work. They state that "unless the species interacts significantly with other species in the community (e.g. it is an important predator, competitor, symbiont, mutualist, or prey) its loss may result in little to no adjustment to the abundance and population structure of other species". This view stems from the neutral model of communities that assumes there is little to no interaction within species unless otherwise proven. Estes, Duggins, and Rathburn (1989) recognize two other distinct types of extinction: *Global extinction is defined as "the ubiquitous disappearance of a species".Estes et al. The ecology of extinctions in kelp forest communities'' Conservation Biology. 3: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rescue Effect
The rescue effect is a phenomenon which was first described by Brown and Kodric-Brown,Brown JH, Kodric-Brown A. 1977 Turnover rates in insular biogeography: effect of immigration on extinction. Ecology 58, 445– 449. (doi:10.2307/ 1935620) and is commonly used in metapopulation dynamics and many other disciplines in ecology. This populational process explains how the migration of individuals can increase the persistence of small isolated populations by helping to stabilize a metapopulation, thus reducing the chances of extinction.Richards, C. M. (2000). Inbreeding depression and genetic rescue in a plant metapopulation. American Naturalist, 155, 383– 394.Eriksson A, Elı´as-Wolff F, Mehlig B, Manica A. 2014 The emergence of the rescue effect from explicit within- and between-patch dynamics in a metapopulation. Proc. R. Soc. B 281: 20133127. http://dx.doi.org/10.1098/rspb.2013.3127 In other words, immigration can lead to the recolonization of previously extinct patches, promoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allee Effect
The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness (often measured as ''per capita'' population growth rate) of a population or species. History and background Although the concept of Allee effect had no title at the time, it was first described in the 1930s by its namesake, Warder Clyde Allee. Through experimental studies, Allee was able to demonstrate that goldfish have a greater survival rate when there are more individuals within the tank. This led him to conclude that aggregation can improve the survival rate of individuals, and that cooperation may be crucial in the overall evolution of social structure. The term "Allee principle" was introduced in the 1950s, a time when the field of ecology was heavily focused on the role of competition among and within species. The classical view of population dynamics stated that due to competition for resources, a population will experience a reduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otso Ovaskainen
In Finnish mythology, Otso (also known as Karhu, Ohto, Kontio, Metsän kuningas, and Mesikämmen) is a bear, the sacred king of animals and leader of the forest. It was deeply feared and respected by old Finnish tribes. Otso appears in the Finnish national epic, the ''Kalevala''. Due to the importance of the bear spirit in historical Finnish paganism, bears are still considered by many Finns to be kings of the forest, and the bear is even the national animal of Finland. Otso is not a particular individual bear spirit, but rather the collective animistic spirit of all bears. Besides being worshipped by historical Finnish pagans, Otso is also worshipped in modern Finnish neopaganism, and the neopagan organization Karhun kansa is named after the bear. Mythology The story of how Otso was born varies in myths. Some stories tell of how Ukko, the god of weather, threw wool into the sea and how Otso was born from the bits of wool that reached the shore. Other stories tell of how Otso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
