Chapter 3.2 Classifying and Naming Organisms (pages 85 92) The Classification of Organisms Taxonomy: the practice of classifying things The continual development of more sophisticated tools for observations and analysis and resulting discovery of new species or reassessment of known ones means that taxonomy remains a practice in development. Taxonomy began approximately 2000 years ago when Aristotle divided the 1000 known organisms into two large groups: plants and animals. He called each group a kingdom. Aristotle further classified animals based on their size and the way they moved. Aristotle classified plants based on their stem characteristics. Aristotle s method of classification had limitations and was changed over time. Life is currently divided into 6 distinct kingdoms and 3 domains: 3 Domains of Life Archaea Bacteria Eukaryota 6 Kingdoms of Life Archaea Bacteria Protista Fungi Plantae Animalia Summary of Classification of Organisms
Domain Kingdom Features of Kingdom Examples of Organisms - single-celled organisms - lacking a membrane bound nucleus - capable of living in extreme environments Archaea Archaea (Kingdom was created in 1990s when advances in genetic analysis showed distinct differences between Archaebacteria and other bacteria.) - deep sea vent bacteria, thermal springs bacteria Bacteria Bacteria - single-celled organims - lack a membrane bound nucleus - e. coli, samonela Protista - have cells containing a nucleus (eukaryotic) - unicellular and multicellular organisms - autotrophs and heterotrophs - algae and protozoans Fungi - have cells containing a nucleus (eukaryotic) - secrete digestive enzymes into food source and absorb molecules that are released - heterotrophs; do not contain chloroplasts - mushrooms, moulds, yeasts Eukarya Plantae - have cells containing a nucleus (eukaryotic) - mostly multicellular; specialized tissues - autotrophs; produce their food - mosses, ferns, coniferous trees, flowering plants Animalia - have cells containing a nucleus (eukaryotic) - mostly multicellular; specialized tissues - heterotrophs; ingest their food. - insects, mammals, birds, reptiles The Levels of Classification
A domain is the broadest category for classification. Scientists group organisms within a domain in a hierarchical system; through increasingly more narrow and more precise categories, down to species. Domain Kingdom Phylum Class Order Family Genus Species To distinguish among groups that had similar characteristics Carolus Linnaeus subdivided each category into smaller and smaller groups of more and more similar organisms by using simple physical characteristics to categorize and describe organisms. At each level of organization, there are more and more similarities among members of the group. Group Bobcat s Classification Examples of organisms that can be included in group domain Eukarya lodgepole pine, mushroom, oyster, earthworm, bee, shark, frog, horse, dog, house cat, lynx, bobcat kingdom Animalia oyster, earthworm, bee, shark, frog, horse, dog, house cat, lynx, bobcat phylum Chordata shark, frog, horse, dog, house cat, lynx, bobcat class Mammalia horse, dog, house cat, lynx, bobcat order Carnivora dog, house cat, lynx, bobcat family Felidae house cat, lynx, bobcat genus Lynx lynx, bobcat species rufus bobcat Naming Systems Binomial nomenclature, or a two-name or binomial system is used for naming organisms. The first word of an organism s scientific name is the genus, and the second in the species. The first letter of the genus is always capitalized and the species is in lower case. Both the genus and the species names are italicized, or when hand written, underlined. Scientific name for the bobcat: Lynx rufus Try these! Organism (common name) Genus Species Scientific name Grey Wolf Canis lupus Canis lupus Golden Jackal Canis aureus Canis aureus Common names for organisms can vary from country to country or even from region to region.
The use of a standardized system of naming allows scientists from around the world to be sure that they are talking about the same species when they are communicating, regardless of the different languages they speak. The use of common names can lead to confusion; scientific names are universal. Dichotomous Keys Dichotomous Key: Identification key that uses observable characteristics to identify organisms through a series of steps. Two statements are given at each step. Using a Dichotomous Key One tool that scientists use to assist in the identification and classification of specimens is the dichotomous key. You should note that dichotomous keys are human made and subject to modification. How to Use a Dichotomous Key A dichotomous key, as its name suggests, is a two-step key. Either the specimen has the trait you are looking at or it doesn t have this trait. In other words, at each decision point within a key, there will be two descriptions, one after the other on the left hand side of the page. You decide which statement best applies to the specimen that you are examining, and read what is written to the right of the description. You will notice that at the end of each description is either the classification of the specimen or directions to go onto another step in the key. If it is a number, look for it below in the key for the next decision. Key to the Kingdoms in the Domain Eukarya Description 1a. Organism is unicellular, colonial or multicellular; lacks complex tissues or systems 1b. Organism is unicellular or multicellular; once considered to be part of the Kingdom Plantae because it is sessile (does not move) 2a. Organism uses photosynthesis to make its own food; it is sessile but is complex with specialized cells 2b. Organism does not use photosynthesis: it is a heterotroph 3a. Organism absorbs nutrients after digesting them externally; it has cell walls made of chitin 3b. Organism ingests food and digests it internally; it is complex and has specialized cells Kingdom or Next Step in Key Kingdom Protista Go to step 2 Kingdom Plantae Go to Step 3 Kingdom Fungi Kingdom Animalia
What to Do: Use the Key to the Kingdoms of Eukarya in your notes to classify the following organisms. List the steps that you followed in the key to arrive at your decision. Organism # 1 Organism #2 Organism #3 Organism #4 Organism #1 Steps: 1a Kingdom: Protista Organism #2 Steps: 1b 2b Kingdom: Plantae Organism #3 Steps: 1b 2b 3a Kingdom: Fungi Organism #4 Steps: 1b 2b 3b Kingdom: Animalia
Chapter 3.3 Studying Organisms in Ecosystems (pages 93 108) Life on Earth is not evenly distributed; the patterns of distribution are largely due to abiotic factors. Most organisms obtain their energy directly or indirectly from sunlight. Every organism requires certain levels of abiotic conditions such as temperature, humidity, salinity (saltiness) and moisture. Organisms can tolerate fluctuation in these levels but only within a certain range there is always a level that is best for the organism. It is the abiotic factors that affect the distribution of Earth s organisms. Climates and Biomes Climate: the average weather conditions in a particular region over a period of time (usually 30 years or more) Temperature and precipitation are the main determining factors in the climate of an area. The spherical shape of the Earth results in the uneven distribution of the Sun s energy across its surface. This uneven distribution of energy (more intense at the equator and dispersed at the poles) causes Earth s major climate zones. The unequal heating of the atmosphere sets up conditions that produce global air and water movements that interact with physical features (mountains, lakes, oceans) to produce various patterns of precipitation. Biome: a region with a distinct climate; particular plants and animals adapted to life in the conditions are found in each biome. Biomes have particular biotic and abiotic characteristics. Terrestrial Biomes Terrestrial biomes have been plotted according to mean annual temperature and precipitation. The pattern of precipitation influences the types of soil that form in the different biomes. The precipitation and soil, along with topography, altitude, latitude, and temperature, determine the types and abundance of organisms that can survive in the biome. Question 1. Which biome do you expect to find the greatest diversity of life in, which biome has the least diversity of life? How did you make this prediction? you would expect to find the greatest diversity of life in the tropical regions around the world. These areas get a constant amount of solar energy and precipitation. The tundra and desert regions have the lowest biodiversity. These regions get low precipitation and are extremely hot or extremely cold.
The same type of biome can occur in different regions in the world. Question 2. Although the same biome may be found on different continents, what similarity do biomes often share? Biomes are often found at similar latitudes (distance north or south of the equator). Question 3. Latitude effects the distribution of biomes on a global scale. What has the same effect on the distribution of biomes on a local scale? Altitude (elevation) has a similar effect on the distribution of biomes, but on a local scale. Habitats Within a biome there can be a tremendous amount of variation. A biome may be broken down further into vegetation zones, which may be further divided into different habitats. Each habitat has its own set of organisms and abiotic conditions. Question 4. What biome does the majority of Alberta occupy? Alberta mainly occupies the Tiaga biome. Grasslands are found in the southern regions and Tundra borders the province to the north. Habitat: place or area with a particular set of characteristics, both biotic and abiotic. Each species is in the specific habitat that its physical, physiological and behavioural adaptations equip it to survive and reproduce in. Range: the geographical region where an organism is found. Question 5. What factors affect an organism s range (the geographical region where it is found)? The range of an organism is generally determined by its habitat requirements. A species will only be found where its habitat is present determined by biotic and abiotic factors. Question 6. Distinguish between a species habitat and range. Will a species be found everywhere throughout a range? Why or why not? The range is the entire geographical region
that the organism may be found in, the organism will inhabit specific areas within this range that offer the biotic and abiotic conditions that the organism is best suited for. Habitats and Niches within Ecosystems Ecological niche: the role that the members of a species play in a community and the total range of biotic and abiotic requirements that its members need in order to survive. (ie. temperature range, type of tree it inhabits, size and type of insect it eats) Question 7. How might an organism having an very narrow niche (eats 2 varies of plants for food source) put it at a higher risk of becoming endangered than an organism that eats a wide variety of vegetation? If the food source becomes scarce the organisms population may suddenly drop. An organism with a varied diet can easily adapt to a shortage in one food source. Question 8. How is it possible for two species to successfully share the same habitat; for example, different species of warblers are known to occupy the same spruce tree. Different species occupy different niches within the same habitat. For example the Cape May warbler lives and eats in the top part of a spruce tree, the Yellow-Rumped warbler lives and eats in the bottom half of a spruce tree. Question 9. What would happen to the different species of warblers is they all tried to occupy the same area of the same tree? The warblers would be in competition with each other. Whichever species was best adapted to live and eat in the area of occupation would out-compete the other species. Aquatic Biomes Zones in a lake have different physical properties, such as differing temperatures and amounts of light. This results in a variety of habitats and niches within the ecosystem. Question 10. How do varying amounts of light and temperature result in a greater biological diversity within a lake ecosystem? The varying levels of light and temperature creates a variety of niches within the lake ecosystem. Each animal is specially adapted to live in a habitat with a specific amount of light and a specific temperature range. This allows for more organisms to co-exist within
the same habitat, hence there is a higher biodiversity. Factors Limiting Growth in Ecosystems Populations cannot grow in an unlimited fashion for a sustained period of time. The growth, survival, and distribution of populations are controlled by limiting factors. Limiting factors: biotic and abiotic conditions that limit the number of individuals in a population. Abiotic Limiting Factors The abiotic components of an ecosystem limit the distribution and size of the populations that live there. For example, plants have an optimum set of abiotic requirements such as moisture and humidity levels, light levels, and temperature range. Their populations are controlled by these abiotic requirements. Question 11. Explain, with reference to abiotic limiting factors, why growing tomatoes in a greenhouse increases production. Less fluctuation in temperature, humidity and soil moisture control, control amount of direct sunlight by covering/ uncovering areas of greenhouse, amount of nutrients (fertilizer) in the soil. Question 12. What are two abiotic factors that can limit the growth of a greenhouse full of tomatoes. Nutrients available through the soil; space restrictions (bound by pot size and surrounding individuals); the amount of carbon dioxide in the air; incoming solar radiation (as plants get larger, there will be less light available to shaded plants); and the amount of water available to the plants. Biotic Limiting Factors A population may grow rapidly, then level off it no longer increases in size but remains fairly constant; the number of births is equal to the number of deaths. Biotic factors such as competition for resources, predators, and parasites play a role. Competition - The availability of resources can limit population size When there is no longer an abundance of food available for each member of a population, the members must compete with each other for the limited food supply. Members of different populations and species also compete for limited resources. Intraspecific competition: members of the same species population compete with each other for the limited resource. Question 13. What are some other resources that members of the same population may compete for? They may also compete for water, sunlight, soil, nutrients, shelter, mates, and breeding sites. Predation involves the consumption of one organism by another. The consumer is referred to as the predator and the consumed organism is referred to as the prey.
The predator-prey relationship can have a significant impact on communities. What to do: read the two paragraphs on the left side of page 103 of the text. Answer the questions that follow. Question 14. Identify and explain the limiting effects of introducing Arctic foxes to the Aleutian islands. The introduction of the foxes limited the populations of seabirds almost to the point of extinction. Answers should also include the impact of the loss of the seabirds, as their guano no longer fertilized the grasslands. The loss of the seabirds and their guano led to the loss of the grasslands and all the organisms that depended on the grassland habitat for survival. Question 15. The term invasive species is given to a foreign organism that out competes other species. List as many invasive species that you are aware of in Canada, do you know how the foreign species got here? Zebra mussels in the Great Lakes brought into the lakes in ballast water from large ships. Lamprey in the Great Lakes Brought into the lakes in the ballast water from large ships. Canadian Thistle brought to Canada by European immigrants. Sea Lamprey in the Great Lakes: http://www.youtube.com/watch?v=x- KJZ22- wtq Asian Carp in the US: http://www.youtube.com/watch?v=dlfe8xfgx24 Parasites Parasitism: an interaction in which one organism (parasite) derives it nourishment from another organism (host), which is harmed in some way. Question 16. How is parasitism similar to predation? How is it different? Parasitism is similar to predation because one organism benefits from the interaction and the other organism does not. In parasitism, however, the host is not always permanently harmed or entirely consumed. Question 17. Use a flow chart or explain how an increase in a host population causes fluctuations in the population of a parasite. Increase in host population increase in parasite population limited ability for host species to survive or reproduce decrease in host population decrease in parasite population