Environmental Science Inquiry and Applications Cunningham • Cunningham Principles of Environmental Science Inquiry and Applications Third Edition Cunningham • Cunningham Chapter 3 Lecture Outlines* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Populations, Communities, and Species Interaction Chapter 3

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Outline: Critical Factors and Tolerance Limits Adaptation and Natural Selection Speciation Taxonomy Ecological Niche Species Interaction Population Growth Community Properties and Structure Succession

Critical Factors and Tolerance Limits Critical Factor - Single factor in shortest supply relative to demand is a critical determinant in species distribution. Tolerance Limits refer to minimum and maximum levels beyond which a particular species cannot survive or reproduce. Many species exhibit tolerance limits that are more critical for the young than for the adults.

Tolerance Limits

Adaptation Adaptation - Process where species acquire traits that allow them to survive in their environments. Limited range of physiological modifications. Inheritance of specific genetic traits allowing a species to live in a particular environment. Population-level phenomenon. Evolution

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Figure 03.01

Natural Selection Natural Selection - Describes process where better competitors survive and reproduce more successfully. Small, spontaneous, random mutations occur in every population creating genetic diversity. Limited resources or environmental conditions may exert selective pressure on a population.

Factors Exerting Selective Pressure Physiological stress due to inappropriate levels of a critical environmental factor. Moisture, Light, pH Predation Parasitism, Disease Competition

Speciation Given enough time, mutations may collectively allow a species to become better suited to new environmental conditions. Divergent - Separation of one species into new species. Convergent - Unrelated organisms evolve to look and act alike.

Galapagos Finches

Taxonomic Naming System Binomial - Based on Latin. Kingdom Phylum Class Order Family Genus Species

Ecological Niche Habitat - Set of environmental conditions in which a particular organism lives. Ecological Niche Description of role played by a species in a biological community. Total set of environmental factors that determines species distribution. Generalists - Broad niche Specialists - Narrow niche

Resource Partitioning

Ecological Niche Cont’d Resource Partitioning - Alter behavior or physiology to minimize competition. Allows several species to utilize different parts of the same resource.

Ecological Niche

Weedy Species Opportunistic Species - Quickly appear when opportunities arise. Many weeds. Pioneer Species - Can quickly colonize open, disturbed, or bare ground.

SPECIES INTERACTION Predation Any organism that feeds directly on another living organism is termed a predator. Predation Influences: All stages of predator and prey life cycles. Specialized food-obtaining mechanisms. Specific predator-prey adaptations. Predation can exert selective pressures. Coevolution

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Competition Intraspecific - Competition among members of the same species. Dispersal Territoriality Resource Partitioning Interspecific - Competition between members of different species. Territoriality Defending resource-rich area, primarily against members of own species. Resource Allocation and Spacing

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Epiphytes Ferns and bromeliads: In commensalistic realtionship with the tree

Symbiosis Symbiosis - Intimate living together of members of two or more species. Commensalism - One member benefits while other is neither benefited nor harmed. Cattle and Cattle Egrets Mutualism - Both members benefit. Lichens (Fungus and cyanobacterium) Parasitism - One member benefits at the expense of other. Humans and Tapeworms

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Defensive Mechanisms Batesian Mimicry - Harmless species evolve characteristics that mimic unpalatable or poisonous species. Mullerian Mimicry - Two unpalatable or dangerous species evolve to look alike.

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Keystone Species Keystone Species - A species or group of species whose impact on its community or ecosystem is much larger and more influential than would be expected from mere abundance. Often, many species are intricately interconnected so that it is difficult to tell which is the essential component. Top Predators Multiple Key Players

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POPULATION DYNAMICS Population Growth Exponential Growth - Growth as a percentage of the whole. dN/dt=rN Biotic Potential - Potential of a population to grow in the absence of expansion limitations.

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Boom and Bust Cycles Exponential growth is graphed as a J curve. Carrying Capacity - Number of individuals that can be indefinitely supported in a given area. Overshoot - When a population surpasses the carrying capacity of its environment. Dieback Oscillations

Population Oscillations

Growth to a Stable Population Logistic Growth - Growth slows as the population approaches carrying capacity.

Limiting Factors Environmental Resistance Density-Dependent Factors - Mortality rates increase as the density of the population increases. Disease, Stress, Predation Density-Independent Factors - Effect on mortality rate is independent of population density. Abiotic conditions.

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(r) Strategies Short life Rapid growth Early maturity Many small offspring Little parental care Little investment in individual offspring Adapted to unstable environment Pioneers, colonizers Niche generalists Prey Regulated mainly by extrinsic factors Low trophic level

(K) Strategies Long life Slower growth Late maturity Fewer large offspring High parental care and protection High investment in individual offspring Adapted to stable environment Later stages of succession Niche specialists Predators Regulated mainly by intrinsic factors High trophic level

COMMUNITY PROPERTIES Primary Productivity - Rate of biomass production. Used as an indication of the rate of solar energy conversion to chemical energy. Net Primary Productivity - Energy (amount of biomass) left after respiration.

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Abundance and Diversity Abundance -Total number of organisms in a community. Diversity - Number of different species, ecological niches, or genetic variation. Abundance of a particular species often inversely related to community diversity. As a general rule, diversity decreases and abundance within species increases when moving from the equator to the poles.

Complexity Complexity - Number of species at each trophic level, and the number of trophic levels, in a community. Diverse community may not be complex if all species are clustered in only a few trophic levels. Highly interconnected community may have many trophic levels, some of which can be compartmentalized.

Resilience and Stability Constancy (Lack of fluctuation) Inertia (Resistance to pertubation) Renewal (Ability to repair damage) MacArthur (1955) proposed complex, interconnected communities would be more stable and resilient in the face of disturbance. Controversial

Community Structure Randomly Arranged Individuals live wherever resources are available. Clumped Individuals cluster together for protection, assistance, or resource access. Regularly Arranged

Community Structure

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Edges and Boundaries Ecotones - Boundaries between adjacent communities. Edge Effects - Important aspect of community structure is the boundary between one habitat and others. May produce differently-shaped habitat patches.

Preserve Shape

COMMUNITIES IN TRANSITION Ecological Succession Primary Succession - A community begins to develop on a site previously unoccupied by living organisms. Pioneer Species Secondary Succession - An existing community is disrupted and a new one subsequently develops at the site. Ecological Development

Primary Succession

Ecological Succession Climax Community - Community that develops and seemingly resists further change. Clements Individualistic Community - Species become established according to their ability to colonize and reproduce in a given area. Gleason

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Introduced Species If introduced species prey upon, or compete more successfully than, native populations, the nature of the community may be altered. Human history littered with examples of introducing exotic species to solve problems caused by previous introductions. Mongoose and Rats in Caribbean

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Summary: Critical Factors and Tolerance Limits Adaptation and Natural Selection Speciation Taxonomy Ecological Niche Species Interaction Population Growth Community Properties and Structure Succession