The chapter begins by giving a case study of natural selection and Galapagos Finches. The author states that Galapagos is the place where the human understanding of biology, evolution, and biodiversity was revolutionized by Charles Darwin. From the case study, it is also evident that natural selection is the basis for species evolution. Natural selection and adaptation, natural selection is the process in which critical traits are passed to the next generation of species for survival purposes. Adaptation, on the other hand, refers to the species' acquisition of the essential traits for survival. According to Charles Darwin, advantageous traits are passed from one species to another through DNA. Species distribution to other areas is normally constrained by numerous factors. These factors range from the competition, predation, and physiological stress. Physiological stress refers to environmental factors such as precipitation, temperature, nutrients, and ph. The environmental factors have maximum and minimum levels required for species survival, commonly referred to as tolerance limits. Ecosystem refers to the living and nonliving components. Ecosystem ecology refers to the study of living and nonliving things and their interaction in the environment. Species interactions and diversity. The species' adaptation to ecological niches and environments is mainly influenced by resources limitation. Competition- is one of the main reasons that have caused species to evolve for their adaptation to a specific niche or environment. There are two types of competition that are intraspecific competition and interspecific competition. Intraspecific competition is competition among similar species, whereas interspecific is competition among different species. Predation – predator is any organism that preys on another may it be a plant or animal. Predators include omnivores, herbivores, and carnivores that feed on live prey. Predator-mediated competition is a type of predation competition where predator-prey on other predators to reduce their numbers. For example, lions, leopards, tigers, and cheetahs. Symbiosis – Symbiosis is a biological interaction of species for beneficial purposes. Symbiosis can be in the form of mutualism, parasitism, and commensalism. For example, plants and pollutants coexist harmoniously for beneficial reasons. The survival of the species is enhanced by the symbiotic relationship existing among them. Keystone species- there are species that play a crucial role in controlling and maintaining the population. They include top predators that control herbivores' populations and other species that provide nutrients and food to endangered species. Population refers to the number of species/organisms living in a specific area and with the inherent capability of reproduction. Population ecology studies the dynamics of organisms’ populations and their interaction in a specific geographic location. Population growth – it is the increase in the size of a species' population mainly due to reproduction. Exponential- it refers to the rapid growth of species population without limits. Carrying capacity- it refers to the number of species that a given habitat can hold/support at a given time. It occurs because of limited resources in the environment. Logistic growth- it is the steady drop in population growth when the maximum size is reached. Usually, when the population reaches carrying capacity the growth rate slows and it is this process that is referred to as logistic growth. Different species live in a given geographical environment. These species interact positively and negatively impacting their biological communities. Diversity refers to the number of species in a given geographical area. Abundance refers to the number of a particular group of species living in a given geographical area. Patterns produce community structure.
References
Cunningham, W. P., & Cunningham, M. A. (2008). Principles of environmental science: Inquiry & applications . New York: McGraw-Hill.
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