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Biological Changes, which Cause Extinction of Species

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Classical community level approach assumes that climate change and habitant destruction affect species dispersal on their biologically occupied area (Thomas et.al, 2004). Species representing terrestrial regions from Mexico to Australia shift toward the pole or to higher elevations with the suitable habitant decline, caused by global warming (Pounds & Puschendorf, 2004). However, species extinction is closely interacts with landscape modifications, species invasions and increasing level of carbon dioxide (Pounds & Puschendorf, 2004). Therefore, process of species’ abundance distribution repeats in the chain of death-birth-immigration until at equilibrium (Rosindell, Hubbell & Etienne, 2011). That is why non-overlapping generation appear when the entire community dies and alien species could be introduced as a cause of extinction of native species (Rosindell et. al, 2011; Pimm & Raven, 2000). Therefore, a dispersal and distribution should be viewed as the replacement condition under which existing species persist and remain fragmented when habitant is lost (Hanski, 1998).

Species-Area Relationship in Climate-Envelope Concept

Climate-envelope modeling assumes that endemic species’ ability to persist in new climatically suitable areas will be affected by hampered loss, fragmentation and invading distribution in response to glacial climate changes (Thomas et.al, 2004). This concept of species-area linear correspondence helps to explain amphibian declines and their disappearance in the mountains, caused by unusually dry weather that increases cloud formation (Pounds & Puschendorf, 2004). Experiments on the Australian frogs showed that elevated body temperature caused by these weather changes can outbreak lethal parasite – chytrid fungus, which thrives under cool, moist conditions, but declines at the low humidity (Pounds & Puschendorf, 2004). However, the other statement, which does not take into account biodiversity hotspots, claims that if destroying of habitant remains constant, non-linear curve of extinction will rapidly reach the peak of fragmented species’ declining (Pimm & Raven, 2000).Survivorship curve considers burning and selective logging far more damaging than clearing alone (Pimm & Raven, 2000). Another investigation suggests that species-area relationship should not be isolated from distribution-abundance relationship when high density increases immigration levels and decreases extinction rate “by boosting population sizes” (Hanski, 1998, p. 47).    

Effect of Genetic Mutations on the Number of Species

Red Data Book criteria show categories of each species assigned to a threat and indicates the most vulnerable projections for the nearest 50 years, during which more than 50% of residing species will extinct on the area of 500-2000 km² (Thomas et.al, 2004).  However, these investigations covered only small population scope, but did not include significant extinction risk, caused by the increasing level of inbreeding of threatened or endangered species (Haski, 1998). Rosindell et. al call this phenomena ‘point of mutation’ when replacement of individuals founds new species (2011, p. 341). The study on the Glanville fritillary butterfly helped to explain the effect of genetic stochasticity, which will be transferred between populations by migration (Haski, 1998). Moreover, isolation of a habitant patch from existing population, caused by increasing of the distance between connected populations, will increase colonization without any local density dependence (Haski, 1998).

However, this assumption should also consider mortality rates, which are based on the classical neutral theory (Parmesan & Yohe, 2003). In a case of butterfly study, mortality as an important cost of migration has been hard to measure on the metapopulation level, which includes wider scope of species (Haski, 1998). Therefore, incidence function model (IFM) was incorporated to explain the risk of local population decreasing with increasing habitant size area (Haski, 1998). This model is based on the calculations of isolated effects of these areas into basic metapopulation models (Haski, 1998). Therefore, calculations are performed in narrow scope of particular species and then it is projected for a wider scope of the same species (Haski, 1998).

Measures, which Help to Minimize the Number of Extinctions

In order to save a substantial percentage of terrestrial species from extinction, green house gas emissions and carbon dioxide build-up should be minimized to realize minimum expected climate change (Thomas et. al, 2004; Pounds & Puschendorf, 2004). Moreover, concentrating budget and ideas on protecting high densities of small-ranged species in hotspots from increasing extinctions will make many species less vulnerable and endangered (Pimm & Raven, 2000).

It should not be forgotten that isolated populations will last forever, since many habitants has become very fragmented (Hanski, 1998). When applied, landscape management should take into account that species may be absent in environments with unfavorable conditions and vice versa (Haski, 1998). Conservation modeling of population dynamics should extend single-species metapopulation models to multispecies communities, because mutation and immigration aspects have cause-effect on species’ dispersal and distribution (Rosindell et.al, 2011).Conservation is considered as a time delay with which species are expected to track changes in the structure of the fragmented landscape and persist to dispersal, because environmental conditions, which make their extinction, is inevitable (Haski, 1998).

Conclusion

Global warming and green house gas emissions are considered the main causes of the species’ fragmentation and their further extinction and dispersal. The issue covers investigation of the endangered species in terrestrial regions from Mexico to Australia. Different approaches of the climate-envelope modeling assume that species’ distributional changes upon their arrival to new climatically suitable areas are not only caused by the area size, but also by their fragmentation number. The latter can be explained with the growing number of the population size owing to the mutation processes. Moreover, when the entire breed dies, non-overlapping generation may appear. However, this could be possible in other favorable or unfavorable environment conditions. Attention should be focused on the preservence of the existing endangered species that can be reached with minimization of the green house gas emissions and subsequent carbon dioxide build-up.

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