Question 1
Ecological succession is a process that refers to continuous changes that occur in species making up a community. Succession incorporates an advancement from lower species communities which are less established to higher species communities which are more established. For primary succession, there is an exposure of bare rock or new land formation. The result is the availability of a habitat that can be newly colonized. In volcanic eruptions, for example, magma leads to the formation of new land.
Primary succession comprises of three significant steps. They involve pioneer species, intermediate species and a climax community. Natural forces like weathering help to break down the rock substrate. This process leads to the growth of lichens which are pioneer species serving as soil nutrients. They help to additionally separate the Magna, which is rich in minerals into the soil so that other, less durable organisms can develop and inevitably supplant the pioneer species (Mori et al., 2017). After growing, these pioneer species die, adding to an increasingly developing stratum of disintegrating organic substance that aids in the formation of soil. During succession, this process takes place repetitively. In every stage, there is a movement of new species into a territory and possibly replace their predecessors. This movement is frequently because of environmental changes made by the previous species. This new species that often comprise of grasses are the intermediate species. The community may arrive at a state that is generally steady and quit changing in their composition. This stage is known as the climax community and may exist for hundreds of years.
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Primary succession takes place in basically dormant territories. These regions are those in which the soil is not productive due to such factors as magma streams, or dunes that are newly formed. Secondary succession occurs in areas where a previously existing community has been cleared. This process is exemplified by small disturbances that do not discard all life forms and nutrients from the environment. The clear-cutting of forests is a disturbance that results in secondary succession. Complete forest clearing will destroy most vegetation and make animals flee the zone. The vegetation's supplements eventually decay and are added as nutrients to the soil. Since a disturbed territory has to supplement fertile soil, it may be recolonized more rapidly than the bare rock that starts the process of primary succession.
Before the clearing of forests, tall trees would have dominated the forest vegetation. Their height would have been helpful to the vegetation by enabling them to gain of sun's energy while being a protective covering from excess heat. After the cutting, these trees take time to grow again. In its place, annual plants germinate, followed by spreading grasses. The pioneer species like lichens act as early colonizers because they are involved in the primary succession process. Over numerous years, due to environmental changes brought about by the development of different grasses and other plants, bushes will grow. Eventually, small trees will grow and become tall trees. Without additional disturbances, the trees will dominate the area and form an impenetrable canopy, restoring the community to the state in which it was earlier before the disruption. This succession process takes around 150 years to be complete.
Question 2
The level of ecology being studied by Dr. Marshall is that of the ecosystem. The ecosystems are portions of nature where organisms associate among themselves as well as with their physical environment. A biotic community and its interaction with the environment around it makes up an ecosystem. The communication happens through nutrient recycling and energy exchange. Dr. Marshall's study based on this level because the presence and impacts of endocrine-disrupting chemicals in an obligate riparian songbird is being assessed concerning the environment in which it lives. The hydraulic fracturing that exists in high-intensity areas has an impact on the production of these chemicals.
To study ecosystems, one needs to determine the species they are interested in and the interrelationships that exist between them and their physical environment. Dr. Marshall does this by focusing on the riparian songbird, which is the Louisiana Waterthrush. Next, this researcher identifies the environment in which this bird lives. The ecosystem additionally incorporates an abiotic part—the physical environment (Jacobides et al., 2018). Ecosystems can either be small or big. It is mostly up to the scientist considering the ecosystem to characterize its limits in a way that bodes well for their areas of intrigue. The fracking areas in the Fayetteville and Marcellus Shale Plays were the regions in which the study was carried out. The region had substantial metals related to water-driven fracturing. The area had heavy metals associated with hydraulic fracturing. The interrelationship between this environment and the bird is the production of the endocrine-disrupting chemicals. In the fracking areas, the birds experienced a low reproduction that was associated with small grip sizes, eggs that did not hatch, and nestlings that did not survive. Focusing on these factors makes the focus of Dr. Marshall's study to be that of ecosystems.
Food chains and food webs can also be used for identifying interrelationships between life forms existing in an ecosystem. Dr. Marshall's study is based on the ecosystem level of ecology because of the tests they intend to carry out with Dr. Lin. They have sampled some feathers to be tested for organic compounds that might have the dangerous hydraulic chemicals that disrupt the bird's endocrinal system. Concerning food webs, this bird might have eaten contaminated food that is found in the area. As a result, its reproduction system is negatively affected.
Ecosystem scientists are regularly keen on following the development of matter and energy through ecosystems. Both matter and energy are conserved, neither made nor damaged, yet take various courses through ecosystems. A steady ecosystems state is referred to as equilibrium. In this state, an ecosystem's identity and composition remain commonly stable, notwithstanding vacillations in states of being and the biotic community's biotic makeup. Ecosystems might be taken out of balance by unsettling influences, troublesome occasions that influence their composition. Numerous scientists imagine that the biodiversity of an ecosystem assumes a critical role in stability. Ecosystem resilience and resistance are significant when the impacts of unsettling influences brought about by human activity are studied. If a disturbing factor is sufficiently extreme, it might change an ecosystems past the point of recuperation and drive it into a zone where it has no more resilience. An unsettling influence of this sort could prompt lasting adjustment or loss of the ecosystem. This aspect of ecosystems may be the reason why Dr. Marshall is carrying out her study.
Question 3
Populations have varying capacities in their growth. The biotic potential is the maximum rate for increase of in the presence of unlimited resources ideal environmental. There is a different biotic potential for each species. The reason for this is the differences in the species’ reproduction frequencies, reproductive spans, the offspring sizes and their survival rates. The population of organisms that make up a community experience changes as they respond to the addition or reduction in their numbers. Populations are added through immigration and births and are reduced through emigration and deaths. For every demographic region and species, the highest number of individuals that the assets of an area can indeterminately sustain without becoming depleted is the region's carrying capacity. When applying this term to humans, it means the number of people that can live in a particular area without the degradation of social and cultural environments. It also means that people will preserve the physical environment for future generations.
For exponentially growing individuals, the growth process begins in a slow rate. They then enter a phase of rapid growth that stops when the species' carrying capacity has been attained. The population's size often fluctuates below or above the carrying capacity. Temporarily, the population's size may shoot far above the carrying capacity due to the reproductive lag time (Seroussi & Sochen, 2019). This time is that which is necessary for the decline of the birth rate and the increase of the death rate as the species responds to insufficient resources in the environment. In such a state, the population size may reduce to a lower level that is close to the carrying capacity. The only saving factor is the immigration of these individuals into a region that is more favorable in terms of the available resources. Thus, a region's carrying capacity is never constant since it is affected by environmental factors. This capacity can be lowered by degradation or destruction of resources through things like drought or fires. It can otherwise be increased through social changes or technological advancements.
The colonization of new areas like Europe, Asia, Europe, Polynesia, and Australia as well as infrequent innovations of new weapons and apparatuses permitted ancient people to increase in numbers and become increasingly viable at gathering food for themselves. This change thus allowed the populace to increase. The critical advancements of early agriculture incorporated the taming of a couple of animal and plant species to provide more prominent yields of nourishment for individuals. The improvement of these ancient farming innovations and their related sociocultural frameworks permitted tremendous increments in ecological carrying capacity with regards to humans and their tamed species and allowed for consistent populace growth. Further improvements to the carrying capacity of the Earth concerning the human race were accomplished through other innovative activities like transport and mining. The advancement of the sociocultural frameworks of humans has included many discoveries and developments that expanded the environment's adequate carrying capacity, making it possible for the population size of humans to increase considerably. The innovation of progressively compelling clinical and sanitary advancements has incredibly prompted the decline of death rates in most human populaces.
Question 4
Exponential growth is constant populace enlargement in an environment that has great resources; it is growth that is density-independent. The equation that represents this growth is dN/dT = rN. The development pace of the populace in a given moment is represented by dN/dT; The T value represents time; r is the per capita pace of increment – that is, how rapidly the populace develops per individuals existing in the population; N stands for populace size. At the point when the per capita pace of increment (r) takes a similar positive value irrespective of the populace size, the exponential growth is attained. In exponential growth, the rate of growth for every individual in a population remains proportional to the size of the population. This aspect results in the speedier growth of the population. In physical environments, the exponential growth of populations may occur masses may occur for a given time. However, they eventually are constrained by the availability of resources. Exponential growth, when presented in a graph, takes a J-shaped curve.
Logical growth is constant populace development in a domain where resources are constrained; it is growth that is density-dependent. A sigmoidal or S-shaped curve describes this type of growth. The equation for logistic growth is the following: dN/dT = rN [K - N/K]. The populace size variation is signified by dN/dT. r refers to the per capita increase rate. N stands for populace size and K the value that stands for the carrying capacity. At the point when the per capita pace of increment (r) diminishes as the populace increases towards a most extreme breaking point, at that point, logistic development is accomplished. In logistic growth, a populace's development rate gets smaller as methodologies of population size are most extreme due to the world's limited resources. An S-shaped curve represents logistic growth.
K represents the carrying capacity. This limit is the largest size of the population that can be bolstered or continued by a specific environment. At value K, populace development stops. Ecological conditions vacillate and cause the carrying capacity to vary (Yan & Zhang, 2016). Time intervals in the reaction of the populace to conditions of the environs will result in the population's size wavering around the value K. In essence, the populace will marginally overshoot this value, and people will die because of an absence of resources. As a result, the size of the population will diminish and will result in the undershooting of K. Because there are sufficient resources underneath this value, the populace will begin to develop another time. Therefore, the cycle will be repeated. K is the environment's average population value.
With horticulture's development 10,000 years prior, individuals started to be involved in trade and formed settlements. The sicknesses related to animal taming and city living contributed to expanded rates of death. These developments also led to the increase of birth rates due to availability of reliable nourishment supplies, shared childcare, and division of work. These factors seemed to have balanced one another, hence, slow and lopsided growth presumably proceeded. In any case, the improvement of horticulture, in the same way as other advances in innovation, very likely raised Earth's carrying capacity. Density-independent factors like famines and snowing seasons together with density-dependent elements like ailments contributed to the high and variable rates of death. It took the human populace numerous centuries to reach the 1 billion mark for people, which happened around 1800 CE. At a worldwide development pace of 1.2% in the year 2015, a net number of more than 80 million individuals every year is added. If that development rate were to proceed, the total human populace would twofold in only 58 years.
Question 5
Extinction is a naturally occurring process that takes place during evolution. It results in the death or complete eradication of a species. Annihilation happens environmental factors like natural disasters, global change, and disintegration of environments and humans overexploitation of species for their use lead to the lessening of species. It can also occur due to developmental changes in the members of a species. These changes include a decrease in populace numbers, reduced reproduction and genetic inbreeding. Once in a while, when new animal varieties are formed through the process of natural selection, old individuals become wiped out because of rivalry or natural surroundings changes. Mostly, the species die as a result of ageing.
Background extinction rate, otherwise called the normal extinction rate, alludes to the standard pace of annihilation in Earth's biological and geographical history before people began to be involved in activities that speeded extinctions. This factor is principally the pre-human extinction rates during timeframes between significant occasions of eradication. Researchers estimate background extinction through use of fossil records to initially check what number of distinct species existed in a given place and time and then identify those that were wiped out. When utilizing this technique, they generally centre on the times of calm in the geologic history of Earth—that is, the occasions between the past five mass eradication. The present-day extinction rate is evaluated to be 1,000 to multiple times the background rate of extinction. This rate ranges between one and five animal varieties for each year. This increased rate is due to loss of habitats, climatic changes, deforestation, pollution and overhunting as well as other human exercises. The aggregate of all these activities will probably bring about the loss of species somewhere in the range of 30% and 50% of surviving species by the middle of the 21st century.
The first environmental change is the worldwide homogenization of fauna and flora. Man's propensity for globetrotting has resulted in the movement of limitless species to new environments, regularly unleashing ruin on existing ecological communities and prompting extinctions. Besides, man has added to this occurrence through the utilization of petroleum derivatives for energy, basically mining primary production from an earlier time (Ceballos, Ehrlich & Dirzo, 2017). Thirdly, man is legitimately controlling genomes by molecular techniques and artificial selection processes as they attempt to conserve populations and ecosystems. Indeed, even preservation is affecting development. The technosphere is also enhancing the present mass extinction. This term alludes to the immense, rambling mix of humanity and its innovation, which results in global change and potential mass eradication.
A large number of environmental researchers have stated that the factors that contributed to the Permian Extinction are being seen in the "Anthropocene." Currently, there is global warming, ocean acidification and anoxia. There is also habitat destructions and presence of invasive species in the environment. The distinction between these two extinctions is in their main contributors. Whereas the Permian elimination had the Flood Basalts of Siberia, the Anthropocene has Homo sapiens. The Earth's biodiversity, atmosphere and geology have been changed by human species. In the previous one hundred years, the eradication rate has expanded to over a thousand times its typical rate. Notwithstanding the elimination rate, the global conditions like global warming do not give the perfect environment in which people can live. Biodiversity is likewise decreasing as a direct result of human causes like pollution and overharvesting.
References
Ceballos, G., Ehrlich, P. R., & Dirzo, R. (2017). Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. Proceedings of the national academy of sciences, 114(30), E6089-E6096. https://www.pnas.org/content/114/30/E6089.short
Jacobides, M. G., Cennamo, C., & Gawer, A. (2018). Towards a theory of ecosystems. Strategic Management Journal, 39(8), 2255-2276. https://onlinelibrary.wiley.com/doi/full/10.1002/smj.2904
Mori, A. S., Osono, T., Cornelissen, J. H. C., Craine, J., & Uchida, M. (2017). Biodiversity– ecosystem function relationships change through primary succession. Oikos, 126(11), 1637-1649. https://onlinelibrary.wiley.com/doi/abs/10.1111/oik.04345
Seroussi, I., & Sochen, N. (2019). From Logistic Growth to Exponential Growth in a Population Dynamical Model. arXiv preprint arXiv:1908.00068. https://arxiv.org/abs/1908.00068
Yan, C., & Zhang, Z. (2016). Interspecific interaction strength influences population density more than carrying capacity in more complex ecological networks. Ecological modelling, 332, 1-7. https://www.sciencedirect.com/science/article/pii/S0304380016300965
