2Ecosystems and Ecosystem Management Chapter 6Ecosystems and Ecosystem Management
3Basic Characteristics of Ecosystems Sustained life on Earth is a characteristic of ecosystems, not of individual organisms or populationsStructure (two major parts)Living (Ecological Communities)Non-livingProcesses (two basic kinds)Cycling of chemical elementsFlow of energyChangePredictable – successionUnpredictable change
4Ecological Communities and Food Chains Ecological Communities are defined in two ways:1. A set of interacting species that occur in the same place defined by the way they derive energy: Food chains, food webs, trophic levels (autotrophs)2. A set of all species found in one area. EG. Zoo animals
5Food Chains and Food Webs A Terrestrial Food ChainFour trophic levels:Example:AutotrophsHerbivoresCarnivoresDecomposersPeople are omnivores
9Food Chains and Food Webs Continued… An Oceanic Food ChainInvolve more species and tend to have more tropic levels. See figure 6.6The Food Web of the Harp SealShows how complex a real-life food web truly is.
12The Community EffectSpecies interact directly (symbiosis & competition) and indirectlyCommunity-level interactionsIndirect interactions.Keystone speciesHave large effects on it’s community or ecosystemIts removal changes the basic nature of the communitySee Sea Otter example figure 6.8. Sea otters influence the abundance of sea urchinsHolistic ViewAn ecological community is more than the sum of its parts.
14How Do You Know When You Have Found an Ecosystem? Vary greatly in structural complexity.The watershed is a common, practical delineation.What is a watershed?Common to all ecosystems is energy flow and cycling of chemical elements.
15Ecosystem ManagementEcosystem management is the key to conservation of life on Earth, but it is difficult to know the exact limits of the system and is equally difficult to know all of the interactions that take place within it.If ecosystems cease to function we must supplement with our own actions.Must consider chemical cycling, energy flow, community-level interactions, and natural changes.
17Biological Diversity and Biological Evolution Biological Diversity (biodiversity)The variety of life-forms commonly expressed as the number of species in an areaBiological EvolutionThe change in inherited characteristics of a population from generation to generationOne of the features that distinguishes life from everything else in the universe
18Four Processes that Lead to Evolution MutationNatural SelectionMigrationGenetic Shift
19Mutation A chemical change in a DNA molecule Affects the expressed characteristics when cells or individual organisms reproduce
20Natural Selection 4 Characteristics: Species: Genetic Variability Environmental VariabilityDifferential ReproductionEnvironmental InfluenceSpecies:a group of individuals that reproduce with each other and produce fertile offspring
21Peppered Moth Example Originally White Now more black than white CausesIndustrial PollutionSoot covered treesIndustrial Melanism
22MigrationTwo new species evolve from an original species due to isolationEx: land bridge
23Genetic DriftChanges in the frequency of a gene in a population due to chanceCan be a problem for rare or endangered species
29SpeciesA group of organisms that can reproduce and produce fertile offspring.Ubiquitous speciesWorldwide distributionOverly common in an areaEndemic speciesOrganisms unique to one place only.Indicator speciesThe first native organisms in an ecosystem, to show the effects of environmental problems.
30The Number of Species of Life on Earth No one knows the exact numberAbout 1.4 million species have been identified and namedInsects and plants make up moth of these speciesNumber will increase
31The Competitive Exclusion Principles 2 species that have exactly the same requirements cannot coexist in exactly the same habitatEx) introduction of the gray squirrel into Great Britain
34Professions and Places: The Ecological Niche and the Habitat Habitat: where a species livesEcological Niche: a species professionThe reason more species do not die out from competition is that they have developed a niche, and thus avoid competition
35What is the effect of each species on the other?
36Species Engage in 3 Basic Interactions 1. Competition2. Symbiosis3. Predation-ParasitismEach affect evolution, persistence of a species and the overall diversity of lifeOrganisms have evolved together and therefore adjusted to one anotherHuman interventions upset these adjustments
37SymbiosisThe relationship between two organisms that is beneficial to both and enhances each organisms chances of persistingMutualism, parasitism, commensalismObligate symbionts:a symbiotic relationship between two organisms in which neither by themselves can exist without the otherEx) stomach of a reindeer
43Why Were Introductions of New Species into Europe So Popular Long Ago? Biogeography:The large scale geographic pattern in the distribution of species, and the causes and history of this distribution
44Wallace’s Realms: Biotic Provinces Major biogeographic regions of Earth that are based upon fundamental features of the plants and animals found in those regionsTaxa:Categories that identify groups of living organisms based upon evolutionary relationships or similarity of characteristics (ex: species, families, orders)Biotic Provinces:A geographical region (realm) inhabited by a characteristic set of taxa, bounded by barriers that prevent the spread of those distinctive kinds of life to other regions.
45The main biogeographic realms for animals are based on genetic factors .
46The major vegetation realms are also based on genetic factors
47BiomesA biome is a kind of ecosystem. Similar environments provide similar opportunities for life and similar constraints.RainforestGrasslandsDesserts
48Climate is the most important factor in determining the type of biome that will be found in an area
50Convergent EvolutionThe process by which species evolve in different places of times and, although they have different genetic heritages, develop similar external forms and structures as a result of adaptation to similar environmentsEx) shapes of sharks
51Divergent EvolutionOrganisms with the same ancestral genetic heritage migrate to different habitats and evolve into species with different external forms and structures, but continue to use the same type of habitatsEx) Ostrich
52Island Biogeography Theory of Island Biogeography Adaptive Radiation: Islands have fewer species than continentsThe smaller the island, the fewer the speciesAdaptive Radiation:The process that occurs when a species enters a new habitat that has unoccupied niches and evolves into a group of new species, each adapted to one of these niches.Ecological Island:An area that is biologically isolated so that a species occurring within the area rarely mixes with any other population of the same species