Review on climate change and its effect on wildlife and ecosystem

Long-term variations in the abiotic factors such as temperature, rainfall, snow, and wind pattern are referred to as climatic changes (IPCC 2007a). Climate changes create new challenges for humans and wildlife, most common are cloudbursts, dry spells, increasing sea level, thawing permafrost, salinization, increased wildfi res, reduced agricultural yields, water diminish, health problems due to high temperature in cities, and ablation (WWF). Climate change affects individual species and their habitat which alter the structure and function of the ecosystem and services that the natural system provided to society (Diazz, et al. 2019) Most often the climate change is limited but sometimes it spreads commonly and causes the disturbance in food chains, nutrient fl ow, and atmospheric circulation in other regions. Solar energy plays important role in all biological activities. It sustains most of the biomass and supports primary production. It keeps the earth's biological tolerable level. In discussing the effect of climate changes on wildlife it is noted that some species have not been much affected by these changes, while some others go to distinct. In tropical regions, there is great biodiversity because of two main phenomena: phylogenetic niche conservatism and ecological productivity. These two factors play signifi cant roles but accumulating theoretical and experimental studies recommend that the single most important factor is kinetics: the temperature dependency of ecological and evolutionary rates. The relatively high temperatures in the tropics generate and sustain high diversity because ‘the Red Queen runs faster when she is hot’ [1].


Introduction
Long-term variations in the abiotic factors such as temperature, rainfall, snow, and wind pattern are referred to as climatic changes (IPCC 2007a). Climate changes create new challenges for humans and wildlife, most common are cloudbursts, dry spells, increasing sea level, thawing permafrost, salinization, increased wildfi res, reduced agricultural yields, water diminish, health problems due to high temperature in supports primary production. It keeps the earth's biological tolerable level. In discussing the effect of climate changes on wildlife it is noted that some species have not been much affected by these changes, while some others go to distinct.
In tropical regions, there is great biodiversity because of two main phenomena: phylogenetic niche conservatism and ecological productivity. These two factors play signifi cant roles but accumulating theoretical and experimental studies recommend that the single most important factor is kinetics: the temperature dependency of ecological and evolutionary rates. The relatively high temperatures in the tropics generate and sustain high diversity because 'the Red Queen runs faster when she is hot' [1].
Climate change has affected wildlife and the natural environment ecosystem in multiple ways. The dramatic shift in physical atmospheric conditions, climate events, and natural disasters (IPCC 2007a). Spreading wildlife diseases and invasion of exotic species are a few results of climate change that have already been observed.
Citation: Sattar  To sustain the earth's temperature in a tolerable range, the natural greenhouse effect is important. Otherwise, without it, earth temperature may decrease to -18C [2].
Several human activities increase the greenhouse gases that enhance the greenhouse effect which causes global warming. This condition increases the atmospheric and sea surface temperature to cause dangerous climate change. (mcc, 1992). Sea surface temperature is increased by 0.78°C ±0.18°C which intensifi ed within the last couple of decades. (IPCC, 2007a). The average sea surface level temperature will continue to increase further 1.1°C to 6.4°C by the turn of the twenty-fi rst century according to Climate model projections of the intergovernmental panel +of climate change. During the last 20 years rise in temperature is 8 times more than that of the last 100 years and the rate of climate change is very rapid for most species to adapt. The ability of wildlife to adapt to climate change depends critically on the rate of change [3].

S ea level rise
With increasing, sea-level temperature during the past 100 years sea level has risen by 10-25cm and this level will rise further. Sea surface is in equilibrium until atmospheric temperature will increases, leading to thermal expansion of seawater. Besides, the warming atmosphere also melts the glaciers, adding more water to the ocean. (IPCC,2001).
The consequence of rising in sea level have a devastating effect on coastal habitats, it causes erosion, wetland fl ooding, loss of agriculture soil, contamination with salt, loss of habitat for fi sh, bird, and plants. An increase in sea level drives high watermark landward, due to which so many habitats are prohibited from moving inland owing to manmade or natural barriers. This results in loss of habitat like marshes and mudfl ats that are life-threatening to wildlife and wader species (Galbraith, et al.).
The increased sea level is the causative agent for the declining population sizes and decreased variety of shoreline intertidal invertebrates [4]. Changes in sea level can prevent the survival of coastline species .in Florida key islands [5] the Key deer is an example whose habitat will be destroyed due to the rise in sea level. Inland movement of marine-derived nutrients occurs by the tidal infl ow and coastline wetland that supports the land-dwelling biota. Sea level increase is not only the nutrient invasion process but also puts physical pressure on coastline populations capping in lowered yield and diversity in coastline biota [6].
The available space for coastal communities diminishes by increasing sea level which causes coastal erosion. The reduction of coastal vegetation happens due to an insuffi cient infl ux of minerals to landward. Coastal vegetation (climax communities) reverses back to main colonizers due to frequent immersion. Thus, the succession of plant communities will be repeated, and the recovery of each cycle will be slower than the fi rst [7]. as the greenhouse gases are increasing the temperature of the earth also increasing gases [9,10]. This increasing temperature not only causes a change in rainfall or precipitation also locates animals to move towards those places that are more suitable for them [11]. Global warming changes the water's route between oceans atmosphere and land-living, it causes the change in patterns of rainfall and temperature of the local environment that affects all the features of the natural system of earth and the organisms that depend on it [12,13].
There is a complex interaction between global warming and its effects on wildlife. It affects wildlife in different ways. Specifi c differences of species of heat tolerance, food accessibility changes, vulnerability to diseases, and changes in competitive advantages and species will modify their gathering [14]. Global warming changes the water's route between oceans atmosphere and land-living, it causes the change in patterns of rainfall and temperature of the local environment that affects all the features of the natural system of earth and the organisms that depend on it [12,13].
Active species are less affected by global warming than active species because active species spurt fast than inactive species in case of any change in environmental temperature [15]. Species try to move towards higher altitude or poleward when temperature increase because they cannot tolerate high temperature [16]

Phenological shift
In response to variation in temperature, precipitation and photoperiod changes in phenology or seasonal timing of life events have been observed in Africa [17]. The timing of spawning, reproduction and migration in animals have shifted due to phenological events in plants include leaf growth, fl owering, and blooming [18][19][20]. Climate change can also affect wildlife in more complex ways. For example, the breeding is year-round in the African elephant (Loxodonta africana), but subordination males breed in the dry season and dominant males in the wet season. So small changes in precipitation density and drought season can change the breeding rate, ultimately genetic structure also changed in these populations [21]. As the main agriculture in the world is food production, prolonged growing seasons would also increase the cost of crops production. Multiple components of climate change differently affect the probability of species that will be driven to deterioration or extinction. It has been suggested that species that are already vulnerable are at risk of population reduction (Thomas, et al. 2004) because it takes time to adjust according to climate change (Menendez, et al. 2006). While the effect of climate change on species extinction remains controversial but it is the result that stalwartly motivates the conservation community [22]. There is greater apprehension outside the conservative community for inauspicious impacts of climate change on wildlife. The main concern is the "tripping points" that can lead to loss or irreversible shift of ecosystem, their services and functioning to human society and wind-up in a global crisis.

Morphology and behavior
Animals can subsist with environmental fl uctuations by changing their morphology and behavior. Morphological alterations commonly involve changes in the size of the body [23][24][25]. The rise in summer temperatures, for example, has been linked to the reduced body size and increased wing length in North American migratory birds of prey [26].
Warmer temperatures can contribute to faster development rates in ectotherms [27], whose metabolic rate is sensitive to temperatures [28]. but they can also lead to smaller body sizes.
Temperatures have an unswerving effect on the human body. the direct effect of temperatures on growth has been found in [29] and Atlantic cod Throughout the northern hemisphere during recent warming the west coast of the Atlantic morphological responses on the other hand complicated. variable phenotypic alterations may go undetected if genetic change counterbalances environmental impacts [30].
Furthermore, short-term gains may not be adaptive in the long term. Behavioral reactions to climate change can be triggered by temperature changes and emerge before population and species level changes, such as distribution shifts. Changes in the population or changes in the economy [31]. Behavioral seeking shelter or refuge, adjusting feeding periods and so on some are reactions. fl uctuating circadian or circannual cycles and changing site use [32].

Species interactions, emergent properties and biological invasions
The species interactions are altered by primary drivers of species exposure and responses to climate change. As species change their phonologies and distributions because of climatic changes the community characteristics like food web function and form also change that are emergent properties of an ecosystem mediated by species interaction [33]. For example, higher trophic levels are more sensitive to climate change because of changes in predatory demand, search, and encounter rate. However, functional responses vary, depending on body size [34,35], species composition, and abiotic condition [36][37][38][39] To evaluate changes in species interactions, Modeling is used but due to lack of baseline search on biotic interaction, adaptive capacity, community structure, and function, the interaction of climate and non-climate stressor but high discrepancy remains [40][41][42].
Many research and studies estimate that how climate alter the properties of ecosystem either directly or indirectly. [41].
The evaluation of behavioral changes, including phenological, foraging, and reproductive changes are also provided by research [40] such as ratsnake predation on birds in the Southeastern United States by increasing the temperature [43,44]. In the end, Studies suggested that species having local adaptions [36,45]  has the potential to enhance these impacts [47].
Many invasive species fl uctuating community composition, dominance, production, and extinction risk of native species because they are well adapted to changing conditions [48,49]   It is problematic for species to live in those environments that decline specifi c nasties of species with the change in conditions of the environment [58]. The population size of species is intensively affected by the change in species range due to climate change [59]. One-time wetlands were major living places of amphibians, migratory birds, and turtles, but later it changes into woodland and creates a threat to rare animals and plants [16]. The physical series of different species in the world are sifting [60]. Most habitats of species are split at higher elevations, species lose their habitat because they have no alternative habitats at these higher elevations. Habitat loss increases the extinction of these species [61].

Effects on extinction
Climate change reduced source availability like water, food supply, and breeding habitats leads to reduce reproductive abilities decrease fi tness, and lower survivorship [62]. The alteration in structure, environmental favorability of habitat, and resource availability makes them unstable for native fauna and fl ora that leads to extinction (Omas 2004). Climate change can be a major risk factor for habitat specialist amphibians.
Decreased precipitation, increased dryness, and low humidity in the south and central American cause the extinction of several amphibians for example Golden Toads (Bufo periglenes) of Costa Rica has extinct and the Harlequin frog (Atelopus varuns) suffered local extinction by two main events, increased surrounding temperature and cold born fog. Due to warming trends in tropics rainforests, many amphibians' populations are declining [63,64].
Extinction of subpopulation results in loss of genetic variations through bottleneck effect, where certain genes provide phenotypic fl exibility to withstand extreme climate and epidemics will be deleted from the metapopulation [65].
There have been many arguments that which biota is most susceptible to climate change. Some agreed that the most damaging effect of climate change is on high altitudes and high latitudes, primarily due to the lack of alternate habitats for migration [64]. Nonetheless, temperate, and polar species are well adapted, physiologically, morphologically, behaviorally, and biochemically against extreme climate conditions throughout their evolutionary history [66]. Species present in low latitudes are farthest from polar regions and they have to migrate long distances and cross many barriers if the climate change. This distance may serve as inevitable restrictions that stop the migration of these species in search of their suitable thermal environment [67]. Therefore, climate-imposed extinction is non-random for example the population of Edith's checkerspot butterfl y (Euphydryas editha) of North America provides evidence for non-random extinction (Hughes, 2000) Several arctic birds who nest on ice suffered population decline due to two factors imposed by global warming. First, decreasing ice sheets limits space to builds their nests, and second, the low ice cover reduced food for hatchlings [5]. Polar bear's subpopulation declined by rising spring temperature in Hudson Bay and the Canadian wildlife service linked health deterioration of polar bears during the past two decades [68].

Wildlife disease and pest infestation
All over the globe deterioration of wildlife and pest attack has been linked to climate changes. Causative agents of wildlife diseases opportunistically use climate changes in their favor.
These agents may be ectoparasite, endoparasite arthropods, or disease vectors. Many factors are highlighted that can enhance the Wildlife diseases and pest densities parallel to climate change [69]. The commotion of pathogens is also increased by cold and high temperature [70], for example mosquitos climate change moreover pathogens and pets benefi t from this condition. (Harvell 2002) Most often disease agents like fungi, viruses, and bacteria are the carrier of disease agents. Thence, an increased range of pests potentially causes pandemics [71].
In southern Alaska, British Columbia, and some parts of the northwest United States the pine bark beetle benefi ted from hotter and longer summer and double its turnover rate, resulting in huge tree mortality due to disastrous infection [72,73]. Remarkably parasites expand their distribution not only in warm climates as well as higher than normal wet conditions. For example, Hawaiian honeycreepers are susceptible to Avian malaria due to the warming climate of the Islands. Avian malaria has been liable for local eradication of Hawaiian honeycreepers from swamps (lowlands). Rising temperature in the Hawaiian Islands has expanded the distribution of Anopheline mosquitos, allowing them to move into higher altitudes and attacking into previously mosquito-free areas occupied by the birds [74].
Further high temperature also enhances the duration of the breeding season in some organisms that allowing contact of infected and susceptible hist so that the effi ciency of pathogens to transmission has increased. For example, in some reptiles' number of copulations among mating pairs increases, allowing the parasite to spread easily [75]. Several endemic amphibian fauna are extinct in mountain areas due to the virulence of fungus achieved by two factors. Firstly, clouds cover the mountain habitat in the daytime from heating and secondly prevented loss of heat in the nighttime [51, [76][77][78][79][80][81][82][83][84][85][86].

Conclusion
Climate change is a growing threat to wildlife, ecosystem, and ecosystem services all over the world. Climate change has the potential to infl ict severe damage on the health of wildlife as well as human.