population ecology biology discussion
Many dire predictions have been made about the worldâs population leading to a major crisis called the âpopulation explosion.â In the 1968 book The Population Bomb, biologist Dr. Paul R. Ehrlich wrote, âThe battle to feed all of humanity is over. Humans, however, have the ability to alter their environment to increase its carrying capacity sometimes to the detriment of other species (e.g., via artificial selection for crops that have a higher yield). Many of these tools were originally designed to study human populations. This is one way movement of individuals into a population. Each of these measures, especially birth rates, may be affected by the population characteristics described above. Concepts of animal population dynamics can be applied to human population growth. A speciesâ life history is genetically determined and shaped by the environment and natural selection. It includes length of life and survivorship factors as well. The United Nations estimates that future world population growth may vary from 6 billion (a decrease) to 16 billion people by the year 2100. These organisms also may have relatively few offspring and provide significant parental care. In addition, the demographic characteristics of a population can influence how the population grows or declines over time. FigureÂ 1. It involves a periodic departure and return of the individuals of a population and occurs only in mobile organisms during unfavourable periods. The treeâs height and size allow it to dominate other plants in the competition for sunlight, the oakâs primary energy resource. On the other hand, when N is large, (K-N)/K come close to zero, which means that population growth will be slowed greatly or even stopped. Answer the question(s) below to see how well you understand the topics covered in the previous section. Croll et al., âThe Population Biology and Control of, Martin Walker et al., âDensity-Dependent Effects on the Weight of Female, David NoguÃ©s-Bravo et al., âClimate Change, Humans, and the Extinction of the Woolly Mammoth.â, G.M. FigureÂ 14. Today, the threat of infectious disease, while not gone, is certainly less severe. As is shown in the FigureÂ 2Â below, smaller organisms tend to be more densely distributed than larger organisms. The worldâs human population is growing at an exponential rate. Was it due to a meteor slamming into Earth near the coast of modern-day Mexico, or was it from some long-term weather cycle that is not yet understood? To model the reality of limited resources, population ecologists developed the logistic growth model. Age distribution is an important characteristic of population which influences natality and mortality. Territorial birds such as penguins tend to have uniform distribution. Biotic Potential and Environmental Resistance 6. In addition to measuring simple density, further information about a population can be obtained by looking at the distribution of the individuals. They engage in interspecific competition: that is, they share the environment with other species, competing with them for the same resources. Additionally, a 2017 study indicates the woolly mammoth genome began to accumulate excess defects as the population size collapsed to a mere 300 individuals living on an isolated island  The exact role this genomic “meltdown” may have played is unknown, but it did occur just prior to the extinction of this species. biology 668 Key questions in population ecology from a theoretical perspective. First, energy expended on mating may reduce an animalâs lifespan, but by this time they have already reproduced, so in the context of natural selection this early death is not of much evolutionary importance. It depends upon the population density and environmental factors. Chapter 20: Population Ecology. The best example of exponential growth is seen in bacteria. What type of population change do you think stage 4 represents? Thus, all species have an energy budget: they must balance energy intake with their use of energy for metabolism, reproduction, parental care, and energy storage (such as bears building up body fat for winter hibernation). Population ecology constitutes organisms of the same species living in the same place and same time. Age structure diagrams for rapidly growing, slow growing and stable populations are shown in stages 1 through 3. FigureÂ 8. The statistical study of population dynamics, demography, uses a series of mathematical tools to investigate how populations respond to changes in their biotic and abiotic environments. Second, when resources such as sperm (and the energy needed to replenish it) are low, an organismâs behavior can change to give them the best chance of passing their genes on to the next generation. 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