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Unit 2 Ecosystems and Their Diversity Classifying and Naming Organisms Organisms are sorted into a hierarchical system, starting with the broadest category— domain—and progressing through kingdom, phylum, class, order, family, and genus to the most specific category—species. Group Bobcat’s classification Organisms that can be included in this group domain Eukarya euglena, mushroom, lodgepole pine, earthworm, starfish, bee, shark, horse, oyster, frog, dog, cougar, lynx, house cat, bobcat kingdom Animalia earthworm, starfish, bee, shark, horse, oyster, frog, dog, cougar, lynx, house cat, bobcat phylum Chordata shark, horse, frog, dog, cougar, lynx, house cat, bobcat class Mammalia horse, dog, cougar, lynx, house cat, bobcat order Carnivora dog, cougar, lynx, house cat, bobcat family Felidae genus Lynx lynx, bobcat species rufus bobcat cougar, lynx, house cat, bobcat The classification system that is most commonly used today has three domains and a number of kingdoms. The three domains used to classify organisms are Bacteria, Archaea, and Eukarya. Bacteria Eukarya Archaea • Prokaryotic, unicellular organisms • Lack a membranebounded nucleus • Reproduce asexually • Heterotrophic by absorption • Autotrophic by chemosynthesis or by photosynthesis • Move by flagella • Eurkaryotic, unicellular to multicellular organisms • Membrane-bounded nucleus • Sexual reproduction • Phenotypes and nutrition are diverse • Each kingdom has specializations • Flagella, if present, have a 9 + 2 organization • Prokaryotic, unicellular organisms • Lack a membranebounded nucleus • Reproduce asexually • Many are autotrophic by chemosynthesis; some are heterotrophic by absorption • Unique rRNA base sequence • Distinctive plasma membrane and cell wall chemistry The four kingdoms within the domain of Eukarya are Protista, Fungi, Plantae, and Animalia. Scientists use binomial nomenclature to name organisms. The two-part scientific names include the organism’s genus and species, usually in Latin. The scientific name for lodgepole pine is Pinus contorta Genus Genus species species A dichotomous key is a branched or stepped process that can be used to identify organisms. Studying Organisms in Ecosystems In this section, you will identify biotic and abiotic characteristics and explain how they affect ecosystems explain how ecosystems contain a variety of niches and habitats to support diverse organisms explain how limiting factors can affect the distribution and size of a population research the impacts of an introduced species explain the use of sampling techniques Information Energy from the sun drives air currents that distribute H2O vapour Wind interacts with land features forcing air upwards where it is cooled and loses moisture as precipitation The interior of a continent will experience less rain as well as higher latitudes Biomes are classed by one of the following: – One system uses the climate zone system. Uses annual temperature and precipitation to establish boundaries of climatic zones – The other system defines it on the basis of vegetation structure along with average temperatures and vegetation Abiotic factors such as climate, latitude, elevation, temperature, humidity, moisture, salinity, and light affect patterns of distribution of life. • A habitat is a place or area within a biome or ecosystem that has a particular set of biotic and abiotic characteristics. • Its predominant life forms will characterize the type of ecosystem – forest, desert, coral reef • An organism’s range is the geographical area where the organism is found. The The hoary hoary marmot marmot (Marmota (Marmota caligata) caligata) feeds feeds on on plants plants found found in in high high altitude altitude meadows. meadows. Range Range of of the the hoary hoary marmot marmot The ecological niche of a population is the role that its members play in an ecosystem. The variety of niches and habitats within an ecosystem allow it to support a diversity of organisms. These These two two species species of of ocean ocean barnacles barnacles have have similar similar niches, niches, but but the the two two niches niches differ differ enough enough that that both both species species are are able able to to establish establish populations populations at at different different depths depths of of the the rocky rocky shore. shore. A limiting factor is any biotic or abiotic element that controls the number of individuals in a population. Biotic limiting factors include competition, predation, and parasites. Limiting Limiting factors factors prevent prevent these these bacteria bacteria from from reproducing reproducing infinitely. infinitely. Populations: Populations fluctuate depending on: Density Dependant – As populations grow and reach their carrying capacity, competition increases – This in turn result in decreased birth rate, increased death rate and increased toxin accumulation! Density Independent – These would be our environmental changes – forest fires, floods, drought, volcanic eruptions! Types of Population Curves Under ideal conditions a population will continue to grow exponentially (J-curve) No growth curve can continue to grow indefinitely (S-curve) Carrying capacity of an ecosystem is the largest population an environment can support – it is determined by the factors of predation, competition, migration, and climate changes Occasionally populations will explode due to a time lag – then it will crash dramatically! Organisms can be sampled using transects or quadrats situated randomly in a sample area. From these samples, the density of a population can be estimated. A A 5m 5m ×× 100m 100m transect transect Unit Review What system do scientists use to name organisms? What are the levels in the hierarchical system into which organisms are grouped.? What are the three domains of life? What are some of their characteristics? What is a habitat? How does it differ from a niche? Give three examples each of biotic and abiotic limiting factors. What techniques are used to determine population size? Concept Organizer Chapter 3 Summary An organism’s environment includes biotic and abiotic components. Organisms affect and are affected by their environment. Organisms are part of a population, a community, an ecosystem(s), and Earth’s biosphere. Abiotic factors in the environment affect the distribution of organisms. Biologists use a hierarchical system to group organisms. Naming and categorization must sometimes be changed to accommodate new discoveries. A universal, two-word naming system is used, giving each organism a genus and species name in Latin. Summary (cont’d) Biologists use dichotomous keys to identify organisms. Each step in the key has only two choices. Unequal heating of the Earth creates different climates and distinct biomes that support the growth of certain groups of organisms. Within biomes and ecosystems, there is a great deal of variation in habitats and niches. A population’s growth in a particular habitat is limited by biotic and abiotic factors. Biologists use sampling techniques to estimate population size in large ecosystems. Transects are often used for mobile populations, while quadrats are used for sessile populations, such as plants.