2.D.1-Environmental Influences

Transcription

1 2.D.1-Environmental Influences Big Idea 2: Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis. EU 2A- Growth, reproduction and maintenance of the organization of living systems require free energy and matter. EU 2B- Growth, reproduction and dynamic homeostasis require that cells create and maintain internal environments that are different from their external environments. EU 2C- Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. EU 2D- Growth and dynamic homeostasis of a biological system are influenced by changes in the system s environment. EU 2E- Many biological processes involved in growth, reproduction and dynamic homeostasis include temporal regulation and coordination. complex biotic and abiotic interactions involving exchange of matter and free energy A. Cell activities are affected by interactions with biotic and abiotic factors. 1. Cell density 2. Biofilms 3. Temperature 4. Water availability 5. Sunlight complex biotic and abiotic interactions involving exchange of matter and free energy B. Organism activities are affected by interactions with abiotic and biotic factors. [See also 4.A.6] 1. Symbiosis (mutualism, commensalism, parasitism) 2. Predator prey relationships complex biotic and abiotic interactions involving exchange of matter and free energy C. The stability of populations, communities and ecosystems is affected by interactions with biotic and abiotic factors. 1. Water and nutrient availability 2. Availability of nesting materials and sites 3. Food chains and food webs 4. Species diversity End 5. Population density 6. Algal blooms decrease stability Biological Systems A. Species: Group of organisms that can interbreed and produce fertile offspring B. Population: Group of organisms of the same species who live in the same area at the same time. 1

2 Biological Systems C. Community: Group of populations living and interacting with each other in an area. D. Ecosytem: a community and its abiotic environment. E. Ecology: the study of relationships between living organisms and between organisms and their environment Exchanging Energy A. Autotrophs: synthesizes its organic molecules from simple inorganic substances 1. Chemoautotroph 2. Photoautotroph B. Heterotroph: obtains organic molecules from other organisms Exchanging Energy C. Consumer: ingests other organic matter that is living or recently killed D. Detritivore: ingests non-living organic matter. E. Saprotroph: lives on or in nonliving organic matter, secreting digestive enzymes into it and absorbing the products of digestion A. Nonliving chemical and physical components 1. For Plants: a) Temperature b) Water c) Sunlight d) Wind e) Soil ph f) Salinity g) Mineral nutrients h) Periodic disturbances 2. For Animals: a) Temperature b) Water c) Breeding sites d) Food Supply e) Territory Abiotic Influences B. Living components 1. For Plants: a) Predators b) Parasites c) Competitors 2. For Animals: a) Competitors b) Predators c) Mates d) Food Supply Biotic Influences Symbiosis A. Close association between two species B. Strong selection factor (Coevolution) C. Types 1. Mutualism- Both species benefit 2. Commensalism- One species benefits other is not harmed or helped 3. Parasitism- One species benefits, other is harmed (form of predation) 2

3 Predator-Prey Relationships A. Population dynamics closely linked B. Slight lag time for effect Food Chains A. Energy flow through one pathway. B. Rules for Food Chain Models 1. Arrows indicate the direction of energy flow. 2. Real examples should be used from natural ecosystems. 3. Each food chain should include a producer and consumers, but not decomposers. Food Chains 4. Named organisms at either species or genus level should be used. 5. Common species names can be used instead of binomial names. 6. General names such as tree or fish should not be used. Food Web A. A food web shows passage of energy through a community B. Light is the initial energy source for almost all communities. Trophic Structure A. Trophic Levels- organisms that are the same number of steps from the energy input into the system B. Primary Producers (autotrophs) C. Primary consumers D. Secondary and tertiary consumers E. Saprotrophic bacteria and fungi (decomposers) recycle nutrients. Trophic Structure F. Energy losses include 1. Material not consumed or assimilated 2. Heat loss through cell respiration. G. Energy enters and leaves ecosystems, but nutrients must be recycled. 3

4 Ecological Pyramids A. Only 5-20% of energy is transferred between trophic levels B. Pyramid of Energy (productivity) 1. Shape shows loss of energy per level 2. Units are Energy per unit area per unit time (kj/ m 2 /yr). Ecological Pyramids C. Pyramid of Biomass 1. Dry weight of organic material at each trophic level. 2. The only inverted pyramid. 3. Measurement techniques? (return of specimens, destruction of habitat) D. Pyramid of Numbers Species Diversity A. Biome Diversity 1.Consists of richness (number of species) & abundance 2.Number of species in a community increases as we move from the poles to the equator A. Habitat- where an organism lives B. Niche 1. Role an organism plays in its community 2. Use of biotic and abiotic factors 3. Species cannot coexist with identical niches C. Fundamental Nicheniche species occupies if independent of interactions. D. Realized niche- niche species occupies when interactions are present. The Niche Ex: Barnacle sp. on the coast of Scotland Interspecific Interactions A. Between populations of different species B. Strong selection factor (Coevolution) C. Types 1. Predation 2. Parasitism 3. Commensalism 4. Mutualism 5. Herbivory 6. Competition Interspecific Competition A. Interference- actual fighting over resources B. Exploitative- consumption or use of similar resources C.Competitive Exclusion Principle 1.Lotka and Volterra (1920s) 2.Two species with needs for the same limiting resources cannot coexist in the same place D.Gause experiment- Tested hypothesis with paramecium 4

5 Competition Evidence A. Niche (resource) Partitioning- Shift of niches so they no longer directly compete. B. Character Displacement- Species tend to diverge in characteristics that overlap Population Density A. # of individuals per unit of area B. Distribution can be uniform, random, or clumped. C.Measured by 1.Direct counts 2.Indirect indicators 3.Sample size estimate Ex: Anolis lizard sp. perching sites in the Dominican Republic Ex: Darwin s finch beak size on the Galapagos Islands Sampling A. Random Quadrat Sampling: Used to compare the population size of two plant or two animal species. B. Random Transect Sampling: Used to correlate the distribution of plant or animal species with an abiotic variable. C. Mark and Recapture Sampling A. Energy flows, but matter is recycled. [See also 2.A.1] B. Changes in regional and global climates and in atmospheric composition influence patterns of primary productivity. C. Organisms within food webs and food chains interact. [See also 2.D.1] D. Food webs and food chains are dependent on primary productivity. 5