Introduction
The success of conservation of a species depends on the understanding of the ecological factors driving the continued survival of that population (Bonsall et al. 2014). This will aid in the understanding of the temporal dynamics of the population when looking at the relationship between per capita growth rate and the local density of that population (Bonsall et al. 2014). When populations are fragmented, they rely on dispersal through migration to prevent inbreeding, and run the risk of extinction if they can’t (Bicknell et al. 2014). Populations are classified as metapopulations if they are demographically or genetically isolated from one another (Hanski 1998).
The aim of this study was to 1) determine how the proportion of habitat patches occupied influenced the change in patch incidence and 2) investigate how the extinction and migration rates influence the amount of patches occupied.
Methods and materials
Deterministic equilibrium model
A vensim model was set up according to the following equation where dP is the change in patch incidence, m is the rate of successful migration, P is the proportion of patches and E is the extinction rate of occupied patches: dP/ dt = mP (1-P)-EP
As m and E are the parameters of the population, they are entered as: m= 0,2 and E=0,1 and assumed to remain the same throughout the simulation. The proportion of patches is varied, first assuming that most patches are empty (P= 0,1) and then most patches are occupied (P=1,0). Graphs were then constructed for dP and P.
Stochastic metapopulation extinction model
For this model, it was assumed that the metapopulation consisted of 6 populations with identical extinction probabilities i...
... middle of paper ...
...0-168.
Bonsall, M. B., Dooley, C. A., Kasparson, A., Brereton, T., Roy, D. B., & Thomas, J. A. 2014. Allee effects and the spatial dynamics of a locally endangered butterfly, the high brown fritillary (Argynnis adippe). Ecological Applications, 24(1), 108-120.
Fernández‐Chacón, A., Stefanescu, C., Genovart, M., Nichols, J. D., Hines, J. E., Páramo, F.,& Oro, D. 2014. Determinants of extinction‐colonization dynamics in Mediterranean butterflies: the role of landscape, climate and local habitat features. Journal of Animal Ecology, 83(1), 276-285.
Hanski, I.1998. Metapopulation dynamics. Nature, 396(6706), 41-49.
Hanski, I.1999. Habitat connectivity, habitat continuity, and metapopulations in dynamic landscapes. Oikos, 209-219.
Nee, S., & May, R. M.1992. Dynamics of metapopulations: habitat destruction and competitive coexistence. Journal of Animal Ecology, 37-40.
Reproduction and passing on genetic and behavioral traits to an offspring is a common fundamental to all the species on this planet. When studying forest ecology, it is crucial to study the proportion of individuals surviving at each stage of their growth as the lives and mortality experienced in a species population describes a characteristic of the species in question. In the case of American beech and sugar maple, their attempt to produce seeds is analogous to entering lottery, where every seedling has a potential chance of becoming a canopy but only some will survive and reach the canopy size; thus, becoming the fit ‘winners’. Our information shows that together, based on size class distribution, both the species display a ‘winner takes all’ pattern, which supports our hypothesis. The results showed a greater count for seedlings and short saplings than for tall saplings, sub-canopies and canopies. This is evident for a Type III survivorship curve. In Type III curve all individuals initially having a very low chance of survival. However, once the individuals pass their threshold age and survive, they live an advanced age. Only some individuals out the mast seeding production mature to become fully fit canopy trees. On the other hand, our hypothesis of canopy trees representing the bulk of the biomass was supported as the basal areas decreased going from growth stages of canopy to seedlings. This is evidence that once the individuals survive the bottleneck where there is high mortality of young individuals (seedlings), who are then considered as ‘losers’, will allow for the other larger size class individuals to flourish. Here, having considerable amount of dbh (diameter at breast height) accounts for greater surfac...
Soule, Michael E et al. “Ecological Effectiveness: Conservation Goals for Interactive Species.” Conservation Biology 17.5 (2003) : 1238-1250.
Gotelli, N. J., & Gillman, M.1996. A Primer of Ecology. Trends in Ecology and Evolution, 11(6), 265. Metapopulation Dynamics A Model of Metapopulation Dynamics pp 84
Biodiversity is influenced by landscape fragmentation at various scales of space and time. The extinction of ecosystem types and component species may cause an increased patchiness of the landscape, resulting in lower population sizes and decreased connectivity. As a result, inhabitants may experience decreased dispersal abilities and lowered gene flows between populations.
Mills, Scott L., Daniel F. Doak, and Michael E. Soule. "The Keystone-species Concept in Ecology and Conservation." BioScience 43.4 (1993): 219-25. Apr. 1993. Web. 30 Oct. 2011.
Living things are categorized by being either a prey animal or a predator animal. A prey animal is what a predator eats and the predator animal is what eats the prey. A stable predator-prey relationship would be when there are more sheep than wolves. This is stable because the predators, which are the wolves, will have enough prey animals to eat. An unstable predator-prey relationship would be if there were more wolves than sheep. This relationship is unstable because the predators will not have enough food to eat. The goal of this investigation was to test stable environments and see when they would go unstable. The guided question was “which factors affect the stability of a predator-prey population size relationships?” This supports the background information because it brings up the question of what will disrupt the stability of an environment.
A different scenario takes place when an alien species is transported to a new area. Although direct competition with similar species is still a problem, the new kid in the block may have no natural pests and diseases. Thus, large stands of monocultures can occur. It is generally accepted that one plant species will support 10 species of animals. If one species takes over 99% of a given habitat dozens if not hundreds of species are lost from that area and some populations are stressed enough that extinction is possible.
When environments are diversified and irregular, species can exhibit trade-offs in their ability to utilize local habitats and to exploit patches regionally. When the dispersal rates are low, each species persists only in the habitat type in which they are favored; local diversity is low. In contrary, at the highest rates of dispersal, species that are better at colonizing empty patches can dominate and drive other species extinct, even though those species ...
Willmer, P.. Ecology: Pollinator – Plant Synchrony Tested by Climate Change. Current Biology. Volume 22, Issue 4, 21 Feb 2012, Pages R131 – R132.
The warblers and larger mammal species on these islands are being affected by similar abiotic factors, but in differing ways for the biotic factors. Specifically, species richness is being affected by island biogeography and its associated costs (abiotic) as well as biotic aspects such as competition, predation pressure, and resources. First, looking at figure 1 we see a strong correlation between species richness, represented by number of different species/island, and land area on each associated island for both larger mammals (R2=0.94) and warblers (R2=0.84). This shows us that the island geography, particularly how big it is, has strong correlation to the number of different species on each island. Land area is related to a number of abiotic features such as environmental heterogeneity, disturbance frequency, distribution, and immigration (Brown et al., 2007).
The increase in extinction rates is documented in many different ways, Pearce (2015) gives insight on how the Millennium Ecosystem Assessment, U.N Convention on Biological Diversity, the International Union for the Conservation of Nature, and various other scientists and institutes have contributed methods of counting and graphing extinction rates to the world. However, because of hazy calculations, these numbers are not precise (para. 1-3). Pearce (2015) gives further evidence to these bizarre counting methods
According to Simberloff (1974), taxon cycle determines the rates of immigration and extinction of species, thus influencing the number of species present in the short-term equilibrium. Taxon cycle is also responsible for increased probability in equilibrium disharmony or sympatry in colonizing species as well as competition between species. The influences of taxon cycle on equilibrium is supported by various studies conducted on birds, insects and lizards.
Sodhi, Navjot S., and Paul R. Ehrlich. 2010. Conservation Biology for All. Oxford: Oxford University Press.
The distance that an organism travels can tell us something about their preferred habitat, how they reproduce as well as being a primary determinant of their likelihood to survive. Dispersal between populations influences the likelihood of colonisation and extinction. If extinction occurs in one habitat patch populations may be rescued by individuals from a nearby population. A ...
The Web. 20 May 2014. Shah, Anup. A. Loss of Biodiversity and Extinctions. Global Issues, 19 Jan. 2014.