Evolution and Life in the Ocean - University of Texas at Dallas · 2006. 2. 26. · Evolution and...
Transcript of Evolution and Life in the Ocean - University of Texas at Dallas · 2006. 2. 26. · Evolution and...
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Characteristics of All Living Things
Contain matter in a highly organized state
Capture, store and transmit energy; all organisms require energy
Capable of reproduction
Change through time and adapt to their environment
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Evolution and Life in the Ocean
Life originated in the ocean.
Organisms have evolved over the last 4 billion yearsthrough the process of natural selection.
The environment favors individuals that are welladapted. Microorganisms are the most successful lifeforms.
Sometimes, catastrophic events wipe out many organisms, regardless of adaptation.
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Linnaeus developed the system used to name and classifyorganisms
System is based on a hierarchy: kingdom, phylum, class,order, family, genus and species
Uses scientific names for organisms; a species consists ofthe genus name combined with a trivial name.
Formal names are in Latin; common names are in locallanguages
Classification of Oceanic Life
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The six (or five)kingdoms of organisms
Classification of Living Things
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The Three Domains of Life
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Classification of Oceanic Life
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Classification of the Marine Environment
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Benthic environment - divided by depth into:intertidal zone, sublittoral zone, bathyal zone,abyssal zone, and the hadal zone.
Pelagic environment - divided broadly into:neritic zone and oceanic zone, and morespecifically into the epipelagic, mesopelagic,bathypelagic, abyssalpelagic, andhadalpelagic zones.
Benthic (bottom) and Pelagic(water column) Environments
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Zones Based on Depth of LightPenetration
Photic zone - depth where light issufficient for photosynthesis.
Dysphotic zone - illumination is too weakfor photosynthesis.
Aphotic zone - no light from the surfacebecause it is all absorbed by the waterabove.
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Major Lifestyles
Plankton - free floating organisms;phytoplankton and zooplankton
Nekton - swimmers Benthos - bottom dwellers (on, in or
attached) Epifauna - live on the bottom (attached or
free) Infauna - organisms that live in or burrow in
the sediment
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Physical and Biological Factors
A proper balance of physical and biological factors isimportant for the success of each organism andthe community.
Different organisms have different tolerances for specific factors.
Steno- is a prefix meaning “narrow”. It describes organisms that have narrow tolerances for specificfactors
Eury- is a prefix meaning “wide”. It describes organismsthat have wide tolerances for specific factors
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Limiting Factors
Limiting factor - physical or chemical factorin the environment that can limit or harmorganisms if present at levels that are too large, too small or too extreme.
Any factor required for life can become a limiting factor.
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Physical Factors AffectingMarine Life
Any aspect of the physical environment that affects organisms is aphysical factor.
The most important physical factors for marine organisms are:
light dissolved gases
temperature acid-base balance
salinity hydrostatic pressure
nutrients buoyancy
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Figure 13.9
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Temperature
Temperature - controls distribution, degree ofactivity and reproduction of an organism
Ectotherms - cold-blooded organisms; bodytemperature determined by environmentalconditions (all marine organisms except birdsand mammals)
Endotherms - warm-blooded organisms;maintain near-constant body temperature (birdsand mammals)
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Temperature
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Biogeochemical Cycles
Cycles of elements that are important in lifeprocesses.
Carbon - present in all organic molecules
Nitrogen - found in proteins and nucleic acids
Phosphorus and silicon – found in rigid parts of organisms
Iron and trace metals - used for electron transport
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Figure 13.8
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Physical Factors AffectingMarine Life
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Biological factors also affect organisms in the ocean.
Some biologic factors that affect marine organisms:
• feeding relationships
• crowding
• metabolic wastes
• defense of territory
Biological Factors
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Organisms in the ocean rely on these processes formany life functions.
Diffusion is mixing due to random molecular movements.
Osmosis is diffusion of water through a membrane
Active transport is the transport of a substance against a concentration gradient. Active transport requires energyinput.
Diffusion, Osmosis, and ActiveTransport
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Diffusion, Osmosis, and Active Transport
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Marine Ecology
Ecology: Inter-relationships between the physical andbiological aspects of the environment
Marine organisms live in communities - groups ofinteracting producers, consumers, and decomposerssharing a common living space
Ecosystem - total environment including the biota (all livingorganisms) and the non-living physical and chemicalaspects
Symbiotic relationships are common in the ocean. Mostforms of marine life are actively involved in them
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Organisms Within Communities
Terms for describing organisms and theirenvironments:
Habitat - an organism’s physical location in itscommunity
Niche - an organism’s role in the community
Biodiversity - the variety of species in a given area
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Symbiosis is the close interaction of the lives oftwo species.
Types of symbiotic interactions:
Mutualism - both organisms benefit in these relationships.
Commensalism - one organism benefits, the other is nothelped or harmed.
Parasitism - one organism benefits, but the other isharmed.
Symbiotic Interactions
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Marine Communities
The J-shaped curve represents the growth of a population withoutcompetitors for food or space. The S-shaped curve represents populationgrowth when the population encounters environmental resistance.
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Changes in Marine Communities
Marine communities change through time. Changes canoccur slowly due to climate cycles or seafloor spreading,or quickly due to factors such as volcanic eruption.
A climax community is a stable, long establishedcommunity.
If a climax community is disrupted, it may be restoredthrough the process of succession.
30Competition can occur among members of the same species, orbetween members of different species.
Competition
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Examples of Marine Communities
Rocky intertidal Seaweed Beach Salt marsh and estuary Coral reef Open ocean Deep sea floor Hydrothermal and cold vents
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Intertidal Communities
Generally arranged in distinctive bands orvertical zonation
Zonation reflects amount of time the area issubmerged and ability of organisms to surviveexposure.
Benthic communities also vary based onsubstrate (bottom material). Some organismsare adapted to rocky, sandy, or muddy seabottoms.
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HIGH TIDE
LOW TIDE
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Rocky Intertidal Communities
The most important physical factor in a rocky intertidal community is therise and fall of tides.
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Seaweed Community Seaweed provides protection and high productivity to the
animals that live in the communities
A complex interaction among kelp, sea urchins, and seaotters controls the kelp community
Sea urchins feeding on kelp detach them from theirholdfast and devastate the kelp beds
Sea otters feed on sea urchins and control the size oftheir population
Where sea otters abound, sea urchins are few, kelpbeds thrive and sea otters feed mainly on fish.
Where sea otters are few, sea urchins abound andkelp bed are thin. Sea otters then mainly eat seaurchins.
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Sand and Cobble Beach Communities
Beaches are a demanding physical environment for organisms.
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Salt marshes and estuaries are rich innutrients, but organisms must cope withfluctuating salinity in theseenvironments.
Salt Marshes and Estuaries
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Coral Reefs
More than one millionspecies inhabit coral reefecosystems.
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Open Ocean
Consumers in the open ocean depend on the productivity oforganisms in the water column above.
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The deep-sea floor is dark, cold, and highly pressurized, yet many speciesincluding the blind tripod fish are found in this harsh environment.
The Deep-Sea Floor
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Many chemosynthetic organisms are found near hydrothermal vents andcold seeps.
Hydrothermal Vent and ColdSeep Communities
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A Pacific coast tidepool.
Organisms rely on boththe physical andbiological factors intheir environment forsurvival.