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GG Gazette Chapter 5 Population By Joseph and Amir What is a population?! Have you ever wondered why and how population grew? Well, Erik Bailey from Iowa sent us a letter regarding this topic. His letter reads: Dear Editor, Although I have been a reader of your gazette since the first edition, I have been curious on the subjects you address in your articles. My biggest question on my mind has been what is population? Please reply back soon! Erik Bailey Dear Erik, It’s amazing how we at the gazette have also been wondering about how a population grows and what factors restricts it! Editor Joseph S. 2008 Population, as you know, is the number of a specific species. There are three very important characteristics which population has. Population consists of geographic distribution, density, growth rate, and age structure. Geographic distribution is a term that describes the area inhabited by a population. Population density is the number of individuals per unit area. This number varies depending on the different kinds of species and its ecosystem. Population Growth The population of each species can vary from each year. There is a possibility the population of a species can rapidly grow when factors are met. There are three major factors that can affect the size of a population: the number of births, deaths and the number of individuals that enter or leave the population. Immigration is term for the movement of which travel into a different location. When individuals leave their current locations for another, this is called emigration. Exponential Growth Above: A graph of exponential growth at 7% per year over a 50 year span. Exponential growth occurs when the individuals in a population reproduce at a constant rate. To begin with, the numbers of individuals in exponentially growing populations’ increase slowly reaching its limit as it grow abundantly over time. Under several of ideal conditions with unlimited resources, a population will grow exponentially. | Capital Gazelles GG Gazette Chapter 5 Population By Joseph and Amir Logistic Growth Limiting Factors Nomad animals are introduced into a completely new environment. They begin to reproduce their lands, but as the availability for resources lessen in the area, the growth of their population decreases. It is possible for it to completely come to an end. A limiting nutrient is an example of a more general ecologist concept: a limiting factor. In the context of populations, a limiting factor is a factor which causes population to decrease. There are two different limiting factors which we will discuss, density- dependent and density independent limiting factors. This is an example of Logistic growth, the pattern in which a population’s growth slows or stops after following a period of exponential growth. The steady number of the number of individuals or species when concisely decreasing is called carrying capacity. . Below: In the graph below is an example of a graph for logistic growth. The line which stabilizes is called the carrying capacity. 2008 A limiting factory that depends on population size is called a density-dependent limiting factor. It becomes limiting only when the number of organisms per unit area reaches a certain level. Competition, predation, parasitism, and disease are some densitydependent limiting factors. When population in an area overflows, the resources for each individual decreases, this leads into fights for the remaining resources which is competition. and sea urchins, sea otters and killer whales are examples of predator-prey interactions that can affect the population growth of their species. Parasites are also a limit in the growth of a species’ population. Parasites are similarly to predators in a variety of ways. For example, parasites take nourishment of animal bodies, often leading to the spread of disease or death. A density-independent limiting factor is different from dependent as these factors do not involve the species of a population but human nature. Unusual weather, natural disasters, seasonal cycles, and certain human activities such as forest cutting are all examples of densityindependent limiting factors. These listed examples can easily vanquish a population. The numbers in population in nature are often manipulated by predations. There are many examples of predator and prey relationships. The sea otters | Capital Gazelles GG Gazette Chapter 5 Population By Joseph and Amir Human Population Growth some countries have high growth rates while other countries grow more slowly. Like many other living organism populations, the size of the human population tends to increase with time. For many thousands of years, the human population has always grown at a steady rate, but as it increased more rapidly. Future Population Growth Below: Will we exceed these extremes? Scientists have indentified a variety of other social and economic factors that can affect human populations. This scientific study of human populations is called demography. Demography examines the characteristics of human populations and attempts to explain how those populations will change over time. 2008 Scientists have predicted that the worldwide human population will grow rapidly in the future to come. They look at each age structure of every country, and calculate. By the year 2025, the world’s population will exceed 7.8 billion, and will continue to grow to 9 billion by 2050. Will our world as we know it be crowded to every bit and corner we still remain? Will there be a massive increase in population that will be devastating? We will never know! -Your Editors Joseph and Amir Birthrates, death rates, and the age structure of a population help predict why | Capital Gazelles