is What LIFE?
7) Tipler and Barrow
It is a sufficient condition for matter to be called life if it has self-reproduction at some level, and stores information which is preserved by natural selection. "It is only the fact that natural selection occurs with living beings that allows us to distinguish living beings from crystals in terms of self reproduction." "It is a necessary condition for some organisms in any biosphere to satisfy the above sufficient condition." Viruses satisfy the sufficient conditions, but can be crystallized. Cars fit the sufficient conditions, as do memes. Computer viruses, the first man-made life?
What is meant by `species'?
A species is defined as any group of potentially interbreeding individuals. Many rough edges to this definition. Comforting to know that folktaxonomy is close to the scientific taxonomies.
Species and Population
Species
Individuals (plant, animals, microbes) with strong similarities, having close genetic relationship. Group of organisms that can interbreed and produce viable offspring.
Population
Members of a species that live within a given area (in communication and capable of interbreeding).
Biota - Habitat
Biota - Biotic Community.
Assemblage of living entities (plant, animals, microbes)
plant community animal community microbial community
Ecosystem
A group of organisms (Biotic Community) interacting with its nonbiological (Abiotic) surroundings and properties in a manner that perpetuates the grouping.
Self sustaining part of the ecosphere.
Habitat
Area where an individual, a species, or a population exists or can exist.
In part defined by interest of those studying a system (ecologist).
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Ecosystem Structure
Composed of biotic and abiotic components. Biotic Structure
Based in part on the role of organisms in the production and consumption of food.
Biotic Structure
Producers
Utilize raw materials (nutrients) and energy sources to manufacture living tissue (organic matter). Autotrophs (self feeding)
Biotic Structure cont.
Producers
Photosynthetic autotrophs/Photoautotrophs
Most common are green plants (chlorophyll). Includes photosynthetic bacteria.
Heterotrophs - must consume organic matter for source of nutrients.
Consumers - eat living organic matter Scavengers, detritus feeders, and decomposers - eat dead organic matter.
Chemosyntethic autotrophs/Chemoautotrophs.
Most common are sulfur reducing bacteria.
Biotic Structure cont.
Consumers
Primary consumers: those that feed directly on producers. Herbivores. Secondary consumers: those that feed on primary consumers. Tertiary.......
Consumers
Carnivores (secondary and higher consumers). Omnivores: those that overlap primary and secondary consumer groups. Predator - Prey Parasite - Host
"Boundaries" of groups are not unique.
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Consumers -Necrophages
Scavengers - Clean up dead carcasses of larger animals. Detritus Feeders - utilize dead organic matter as source of nutrients. (Worms, termites). Decomposers - Utilizing dead organic matter as source of nutrients and in the process break down organic matter. (Fungi, bacteria).
Full biotic structure
Producers (Autotrophs)
Photosynthetic autotrophs (photoautotrops) Chemosynthetic autotrophs (chemoautotrophs)
Heterotrophs
Consumers
Primary herbivores Secondary carnivores or omnivores Tertiary . . . .
Detritus Feeders and Decomposers
Scavengers Detritus feeders Decomposers
Food chains
A linear pathway by which energy and matter is transferred an in ecosystem from organism to organism by feeding.
Food web
Complex interactions between simpler food chains (Complex food chain).
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Trophic levels
Basic structure of feeding relationships (food chains).
FIRST TROPHIC LEVEL : Producers SECOND TROPHIC LEVEL: All those feeding on producers. Includes Primary consumers and Detritus feeders and decomposers utilizing only material derived from producers. THIRD TROPHIC LEVELS: Those feeding on organism in the second trophic level.
Ecological pyramids
Ecological or biomass pyramids. Structure based on transfer of matter (biomass) along trophic levels. On average about 10% (1 to 20%) of biomass is transferred from one trophic level to another.
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Non-feeding relationships
Mutualism: when two organisms interact in ways that are beneficial to both. Symbiosis: organism living in close union with or without benefit to each other. Competition: those who depend on same food sources.
Habitats and Niches
Habitat:
Area where an individual, a species, or a population exists or can exist.
Niche:
Particular place in food chain, in a habitat, that the organism occupies. Resulting from biotic factors limiting a population.
High
Competition for a single resource leads to resource partitioning and niche specialization.
Light availability
Fundamental Niche Realized
Low Low Nitrogen availability High
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Ecosystems and Biomes
Abiotic Factors
Terrestrial systems:
Temperature average and extremes. Rainfall quantity and distribution. Available light. Wind and Fires. Nutrient availability. Chemistry of soils and available water (pH, salts)..
Abiotic Factors
Aquatic systems:
Salinity of water and pH. Temperature average and extremes. Available light and water depth Nutrient availability. Amount of sediment in water column (turbidity) Texture of bottom Currents
Ecological Succession
A series of biotic communities in the same habitat. Primary, secondary, climax community.
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Pioneer vs. Climax communities
Pioneer community organisms focus on throughput of energy and resources.
Dominated by annual plants. Shallow roots and lots of seeds.
Climax community organisms focus on energy budgets and recycling of resources.
Dominated by perennial plants.
Ecosystems and Biomes
Common abiotic factors act to produce similar ecosystems / biomes. The most important abiotic factor in determining the biome of an area is climate. Microclimates: Conditions in very localized area. Influenced by topography presence of rivers, lakes, etc.
Biomes
Grouping of related ecosystems.
Terrestrial biomes (all land based ecosystems) Aquatic biomes (all water based ecosystem)
Terrestrial ecosystems often defined by climatic variables, hence biomes often reflect climate.
Temperate Rain Forest Tropical Rain Forest
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Biomes - Terrestrial
Deserts Grasslands (Prairies and Savannas) Tropical (Rain Forest and Seasonal) Conifer Forest (Taiga, Boreal, Temperate Rain Forest) Tundra
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Biomes - Aquatic
Freshwater Lake and Rivers Freshwater Swamps, Marshes, Bogs (Wetlands). Estuaries Inter-tidal zone Coastal Marine Open Marine
Ecosystem boundaries
Boundaries between ecosystems are commonly transitional.
Ecotone: transition area between two ecosystems.
Biogeochemical Cycles
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulfur
make up 95 % of matter in organisms.
Ecotone may create unique habitats for organisms not present in the adjacent ecosystems.
Biogeochemical systems/cycles maintain a balance of elements essential to life.
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