Principles of Biology Biome and Ecosystem

What is the difference between R and K selective? Provide an example of a K specialist species and an R specialist species (find examples outside the textbook). What kind of environment would favor each and why?

The textbook chapter on Biomes and Ecosystems is attached.

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Biomes and Ecosystems “Here is your country. Cherish these natural wonders, cherish the natural resources, cherish the history and romance as a sacred heritage, for your children and your children’s children. Do not let selfish men or greedy interests skin your country of its beauty, its riches or its romance.” —Theodore Roosevelt Learning Objectives Classify the different regions of the biosphere, which includes the Earth’s crust, waters, and atmosphere inhabited by living organisms. Identify how populations have limits to growth based on a population’s carrying capacity. Describe the interactions of living things with each other and the nonliving components around them. Describe how energy is required for life. Explain how and why decreased genetic diversity can be detrimental to a species. Questions Students May Have 1. What is the difference between biotic and abiotic? 2. What is a species with regard to the biological concept? 3. What is the theory of evolution? Populations Populations are only one level of life and a source of variety on the planet. Ecology is the study of the interactions between populations of organisms and their environments; it is studied at the individual, community, and ecosystem level. The population of an organism can vary depending on interactions with other organisms and nonliving items in the environment. / Levels of Life (Cell to Biomes) In science there are living and nonliving components. Living things are described as biotic from bio, meaning life. To be categorized as a living organism, there are some generally agreed upon requirements: Life is organized. Principles of Biology Biome and Ecosystem

A living organism can adapt to changes in the environment or a changing environment. It can regulate a metabolism (obtaining nutrients/resources to survive) and internal environment to maintain homeostasis (e.g., energy regulation to salt concentrations). It can grow. It is capable of reproducing. The species can change over time (Periyasamy, Gray, & Kille, 2013). A single bacterial cell and an elephant can be classified as biotic as they both meet these criteria. Abiotic is the term used to describe nonliving components of the ecosystem. Something that is not living can have some of these characteristics: a crystal can grow in size, but it does not have the ability to acquire a source of nutrition or energy. Examples of nonliving components include climate, fire, rain, wind, and soil. Habitat describes where organisms live (like a home). Habitat includes biotic components like vegetation as well as abiotic components like topography (e.g., mountains, lakes, type and amount of soil). At the microscopic level, organisms can be unicellular, like bacteria, or multicellular, like humans. The cell is the basic unit of life and all living things are either comprised of cells or consist of one cell. The microscopic levels of life include different types of cells. The smallest level of life consists of only one cell. A cell is considered living because it has specific functions that are organized, it responds to environmental changes, it can use membranes to alter the internal environment, it can divide to reproduce, and mutations or errors in reproduction can create changes in the cell’s genetic code.Principles of Biology Biome and Ecosystem

It has been debated as to whether viruses are considered living organisms since the virus is defined by some as having a living part, while the virion (a virus particle) that spreads the virus is nonliving. Early studies found that virions lack metabolism, and these early observations led to viruses being categorized as abiotic (Forterre, 2010). Viruses are acellular, so by definition, they are not considered living. They have genetic material and a protein coat but cannot reproduce without a host. Questions Students May Have What is the difference between biotic and abiotic? Biotic refers to living components of the environment, while abiotic refers to nonliving components of the environment. For example, an apple tree in bloom is living, while the decomposed apple in the compost is not living, or abiotic. A grouping of the same species is called a population. To be defined as a single species from a biological perspective, there are pre- and post-fertilization barriers that separate species (Coyne & Orr, 2004; Meffe & Carroll, 1997). Some pre-fertilization limitations include geographic barriers where / the species would not come in contact with each other (such as those found on different continents), a lack of sexual attraction, or different mating seasons. Post-fertilization barriers include creating hybrids, which are offspring that are unable to survive to adulthood or offspring that are unable to reproduce viable young descendants such as a hinny or mule (offspring of a horse and donkey) (“Mule, in Zoology,” 2013). Hybrids typically do not occur under natural conditions. For example, tigers and lions are found on separate continents, but in zoos there is potential for them to breed, thus creating hybrids called ligers and tigons (Wilson, 2010). The concept of biological species resolves around reproductive isolation mechanisms. These isolation mechanisms are the only way to define a subspecies from the biological species. Alternatives include looking at the similarity of different traits to classify into groups from kingdom, phylum, class, order, family, genus, and species. Traits and/or genetic similarity are the basis for these groupings (Meffe & Carroll, 1997). When there are subspecies, either of these definitions can be debated. Subspecies seem to have the potential to become a separate species, but they can still interbreed (Wilson, 2010). Principles of Biology Biome and Ecosystem

For example, there are subspecies of giraffes that naturally do not breed with each other and have a different spot pattern, but in a captive population they will interbreed and produce offspring that can reproduce. Deoxyribonucleic acid (DNA) of these subspecies of giraffes seems to show distinct differences, but within the scientific community it is still debated (Beheregaray & Caccone, 2007; Chan, Halachev, Loman, Constantinidoe, & Pallen, 2012). Even without the concern of species and subspecies, “86 percent of land species and 91 percent of marine species are still out there waiting for names. At the present rate, it would take more than 1,000 years to catalog them all” (Bakalar, 2014, para. 8). Species are the most specific grouping of organisms. Those that share similar traits have the same genus. Because there can be a variety of common names for the same species, the scientific names of species includes the genus and species. For example, the mountain lion’s scientific name is Puma concolor since it is called a panther or a cougar in other locations. Puma concolor is in the cat family (Felidae), the order of the carnivores (Carnivore), the class of mammals (mammalia), the phylum of animals with a spine (Chordata), and the animal kingdom (Animalia). Questions Students May Have What is a species with regard to the biological concept? A group of reproductively isolated organisms that can reproduce and yield fertile offspring. A community occurs when multiple species coexist in the same geographic place. This includes the interactions of multiple species like a prairie dog creating homes for snakes or ferrets, while at the same time being a food source for some of the species it has created a home for (Cully et al., 2010). Sometimes these relationships are beneficial (may impact one or both species) and at other times they can be harmful to the individual at the organism level, but benefit the population level. These ramifications are further discussed later in this chapter. An ecosystem is a community with abiotic components. Ecosystems are subdivided into terrestrial (on land) ecosystems, such as forests, grasslands, and deserts, or aquatic (in the water) ecosystems, such as fresh and marine systems (i.e., salt water). Principles of Biology Biome and Ecosystem