Ecology: Ecological Organization Levels

Introduction to Ecology

• Ecology examines the interactions between living organisms and their environment, maintaining objectivity
• Ecological study spans genetics, behavior, and evolution
• Natural history, while descriptive, is a foundation but not the same as ecology due to its lack of scientific method
• Environmentalism represents a social or political movement for environmental benefit, distinct from ecology
• Ecologists may also be environmentalists
• Ecological organization levels are: individual organisms, populations, community, ecosystem, landscape, biome, and biosphere
• The spatial and temporal scales increase when descending through the levels of ecological organization

Levels of Ecological Organization

• Individual organisms relate to physiological and behavioral ecology
• Physiological ecology involves morphological and physiological mechanisms for energy gathering and coping with stress
• Behavioral ecology focuses on the determinants of individual behavior and inter-organismal influences
• Populations are groups of interacting individuals of the same species within a defined area with properties like abundance, spatial distribution, age structure, and genetics
• Communities consist of multiple species populations interacting in a shared area, with properties like species composition, diversity, relationships, and trophic structure
• Ecosystems encompass all organisms in an area plus the physical environment (biotic and abiotic)
• Unlike communities, ecosystems include abiotic components
• Landscapes link multiple communities and ecosystems through energy and material exchange
• Biomes are broad regions defined by similar ecosystem types, shaped by geography and climate
• The biosphere, the highest ecological level, is the global ecosystem layer

Approaches to Ecological Research

• Ecological research applies diverse approaches grounded in the scientific method
• Research varies by ecological organization level, uses quantitative or qualitative data, and can be theoretical or experimental
• Experimental studies can occur in the field or lab, and be observational or manipulative
• Temporal and spatial scales must be considered and various methods can be applied

Notable Ecological Studies

• MacArthur studied warbler coexistence in 1950s North American spruce forests, finding reduced competition as they occupied unique niches in trees
• The Experimental Lakes Area conducted whole-lake experiments in the 1960s, determining phosphorus caused eutrophication, which led to banning phosphorus in detergents
• Water quality improved following the ban of phosphorus in detergents
• Margaret Davis analyzed pollen in lake sediment cores, effectively reconstructing past forest communities

The Scientific Method

• The scientific method uses a logical approach across all science branches.
• Observation involves noticing a phenomenon
• An explanatory hypothesis is a testable guess about an observation's cause that may not be directly measurable
• Prediction takes the explanatory hypothesis and deduces a pattern-oriented, measurable statement
• Data gathering involves observing/experimenting to collect data
• The data is statistically analyzed
• A statistical null hypothesis restates predictions for statistical testing
• The data gathered is then graphed and analyzed using correlation or linear regression to see if the pattern observed is true
• Findings are disseminated

Factors Influencing Climate and Biomes

• Uneven solar heating drives earth's climate because of the earth's spherical shape and axial tilt
• The spherical shape yields concentrated radiation at equator vs. poles
• Earth's tilted axis causes seasonal radiation variation
• Uneven heating drives air and precipitation patterns
• Hadley cells form deserts (0-30 degrees) due to rising air at the equator and descending dry air
• Ferrel cells are between 30-60 degrees latitude
• Polar cells span from 60 degrees to the poles

Climate Patterns

• Meeting points of polar and Ferrel cells create moist climates
• The Coriolis Effect alters wind direction due to Earth’s rotation, deflecting winds clockwise in the Northern and counterclockwise in the Southern Hemisphere
• Standard climate diagrams plot time on the x-axis, temperature on the left y-axis, and precipitation on the right, which is used to assess plant growth adequacy
• Tundra biomes are at high latitude, have grasses, mosses, and are cold
• The tundra climate is cold and dry with 200-600mm precipitation
• Ocean proximity moderates temperature, cool temperatures and low precipitation cause a thick organic layer in the soil, and contains a permanently frozen layer in the soil called permafrost
• Permafrost is changing due to climate change
• Increased human influence is occurring through mining
• Boreal forests are ecologically and economically significant circumpolar bands comprising 11% of global land
• The boreal forest climate is cold with adequate precipitation, dominated by evergreen conifers, mammal and animals
• Migratory animals inhabit boreal forests

Geographic Land Divisions

• Ecozones are sub-continental geographic divisions marked by representative biotic and abiotic features, coarser than biomes, and Canada has 15 terrestrial ecozones
• Ecoregions, like Alberta's 10, are finer scaled than ecozones
• Ecoregions represent areas sharing common climates driving similarities in characteristics
• The hydrological cycle involves water exchange among aquatic reservoirs driven by solar energy that powers evaporation and wind
• Oceans covers 71% of Earth and hold 91% of water; 20% of world’s freshwater is in Canada

Ocean Structure

• Oceans are structured by decreasing light and temperature
• Oceans basins are structured horizontally
• The Littoral zone is the intertidal zone and shoreline
• The Neritic zone extends from the coast to the continental shelf margin, with the open ocean beyond the continental shelf
• EMBAH structures the ocean vertically, dividing beyond the continental shelf in epipelagic (0-200m), mesopelagic (200-1000m), bathypelagic (1000-4000m), abyssal (4000-6000m), and hadal (6000m+) zones
• Photosynthetic organisms are limited to the epipelagic zone because 80% of solar energy is absorbed in the first 10m
• Oceans are thermally stratified being heated from the top
• Low ocean salinity occurs near the equator and above 40 degrees latitude
• High ocean salinity occurs in the subtropics
• Circulation is critical for element cycling, productivity, climate regulation, and driving ocean productivity
• Water is mixed slowly in the absence of upwelling
• Oceans have vastness which makes them buffers to overharvesting, pollution, extraction, and warming
• Deep water currents are from thermohaline circulation
• Wind-driven surface gyres are circular patterns influenced by wind and Coriolis forces
• Upwelling brings nutrient-rich deep water to the surface near coasts
• Kelp forests grow in regions along rocky shores where max water temperatures are less than 20°C, create vertical forests, and require currents
• Shallow marine waters permit reefs and kelp beds where 10-100m depth

Marine & Freshwater Ecosystems

• Temperature and coral reefs limit kelp distribution preferring 10-20°C, corals 23-25°C
• Kelp is harvested for food and coral used for decorations that results in overfishing, coral bleaching, and stress
• Intertidal zones' dynamic nature are due to tides, light, temperature, salinity, and wind, and tides can move from centimeters-15m
• Rivers and streams can be defined by length, width, and depth
• Most of Earth's freshwater are in large lakes, and the great lakes of North America contain 20% of the surface water
• Lakes vertically mix from seasonal temperatures, have varied water density best at 4°C, and are like oceans but smaller
• Lakes are divided into the littoral ( shallow with rooted aquatic plants) and limnetic zones (vertical layers of epilimnion, metalimnion, hypolimnion)
• Still waters can be eutrophicated by Humans dumping wastes, which causes introduced species like zebra mussels
• Peatlands, including bogs and fens, cover >5% of the earth, mainly in boreal and subarctic areas.
• Wetlands are characterized by cool temperatures, still waters, anaerobic conditions, variety of plant species, and accumulate of peat

Darwin, Mendel, and Genetics

• Darwin found species diversify to fill niches leading to his natural selection theory observing the Galapagos Islands in 1835
• Natural selection occurs if there are more offspring in each generation that the environment can support, there is heritable variation, and some traits give better odds of survival
• Fitness contributes to future generations
• Natural selection is how adapted organisms are likely to survive passing genetic material
• Evolution is gene frequency change over time
• Natural selection causes differential survival and reproduction with mutation, random mating, fertilization, and recombination
• Mendel added the concept of particulate inheritance and genes that have varied expression in different forms of alleles
• Genetic variation shows how the expression of a gene is the frequency of expression in expression as an organism

Phenotypes and Selection

• Phenotypic variation represents the variation in traits on which selection acts, impacting characteristics like height and speed
• Stabilizing selection favors average phenotypes, like Ural owl eggs with intermediate sizes, leading to higher reproduction and survival rates
• Directional selection sees exceptional phenotypes have better survival and reproduction, as in the peppered moth
• Disruptive selection has average phenotypes with poor survival and reproduction, and splits into two groups
• Common garden experiments determine genetic adaptations from phenotypic plasticity by transplanting different populations and growing types together in common environments

Adaptations

• Clausen, Keck, and Hiesey studied Potentilla glandulosa at varied elevations, and performed a null hypothesis to test if there was no genetic variation
• Plant differences show genetic distinctions and local adaptation
• Ecotypes adapt to local conditions
• Phenotypic plasticity describes varied trait expression responsive to the environment
• Genetic drift refers to random allele frequency alterations, mostly seen in small populations, that cause fixation or deletion of an allele or a sampling error
• The bottleneck effect causes skewed genotype frequency due to a random event
• The founder effect causes loss of genotype diversity as a subset found a new colony

Climate and Tolerance

• Macroclimate denotes the prevailing regional climate and large-scale weather patterns
• Microclimate denotes small-scale climate variation which is due to location factors/landscape
• Local changes like trees moderate soil temperatures
• Water is more stable thermally than air
• Specific heat is the ability to absorb heat
• Albedo is landscape reflectivity, with snow reflecting light and soil absorbing it
• Species thrive in tight ranges of conditions which varies by photosynthetic rates

Processes Influenced by Temperature

• Evaporative cooling (sweating and panting) are used by marsupials and rodents
• Poikilotherms have a varied temperature depending on the environment, and are mostly ectotherms
• Homeotherms maintain constant internal temperatures, and are mostly endotherms
• Low-metabolic ectothermic animals use behavioral temperature maintenance and have varied levels of pigmentation due to different climates
• Endotherms use high metabolic insulation
• Almost all plants are both poikilothermic ectotherms, apart from those who use metabolic flower heating

Coping Mechanisms

• Acclimation describes tolerance of cold and use of cryoprotectants
• Inactivity/avoidance describes those who take shelter in burrows to lower metabolic rates
• Hibernation is a prolonged lowered metabolic state in certain months
• Torpor is a short state of lowered metabolic activity
• There are varied environmental water and solute gradients
• Organisms will either gain or lose water to/from the surrounding
• Evaporation is a factor in terrestrial water loss

Key Variables Influenced by Air

• The rate of evaporative water loss to temperature and air
• Water content of air refers to water vapor density, measured as mg H2O/L or g H20/ m^3
• Saturation vapor density is how much water air can potentially hold depending on its temperature
• It is important to consider water vapor deficit and evaporative water loss
• Aquatic organisms have different levels of osmotic tendencies
• Those that are isosmotic- have equal pressures to surroundings
• Those that are hypo-osmotic have high water and low solute concentration
• Those are hyper-osmotic have low water and a high solute concentration

Water Gradients

• Aquatic environments see water flow based on the water and solute concentration relative to the surroundings
• Terrestrial environments see water flow down gradients that are created by the concentration of solutes
• Water potential gives the capacity for water to do work
• Osmotic pressure causes water potential and drives water across a semi permeable membrane
• A water potential of pure water has more than salt water
• The balance of water includes the water taken from food and drink, the water absorbed from the air, lost due to evaporation, lost to excretion, etc

Plant Adjustments to Water

• Plants only absorb from air and roots and lose via secretion
• Terrestrial creatures have varied water adaptations
• Terrestrial animals satisfy their water needs via eating and drinking
• Desert animals adapt to arid biomes through metabolic water production and fog collection
• The quantity of root development shows the amount of water availability due to the climate
• Aphids also reduce water loss through waxy coatings
• Different tiger beetles also have varied water loss and retain more hydrocarbons to survive

Energy and Nutrient Consumption

• There are organisms that depend on solar radiation, organic molecules, and inorganic molecules
• Energy and nutrient levels are limited by the organisms and mechanism vary through plant versus animal interaction
• Autotrophs depend on inorganic forms of carbon and sources of energy and are primary producers
• They either make use of CO2 for carbon and sunlight energy (photosynthesis) or oxidation of inorganic molecules (chemosynthesis)
• Heterotrophs depend on carbon + carbon

Energy Types

• Finite light creates photosynthesis for energy
• Radiation contains infrared, active radiation, and ultraviolet light depending on energy
• Active radiation is used for high percentage of photosynthesis and damages DNA
• Some light gets absorbed while others will be reflected to produce energy
• High levels of plant photosynthesis use C3
• Calvin cells use RuBisCO and must open stomata
• Concentrations create gradients to help C3
• Photosynthesis can reduce the need to open stoma in different cells using different enzymes
• Angiosperms depend on dry carbon environments and 76% of grasses are C4

Arid Ecosystems

• Those in extremely dry environments depend on crassulacean acid
• Crassulacean acids separate light-dependent production of carbon
• Fixation mainly uses C3
• Low photosynthesis relies on small areas
• Different processes affect energy use
• Maximized efficiency is the maximum rate to photosynthesis
• The compensation point is the level at which photosynthesis occurs
• Plant curves are affected by differing amounts of irradiance due to surrounding regions

Trophic Groups

• Heterotrophs have three categories: detritivores, herbivores, and carnivores
• Detritivore waste is mostly not alive, rich in carbon, and low in nitrogen, limited by heat and moisture
• Herbivores need nitrogen so they eat defense-laden plant mass
• Herbivores are dependent on plant defense which can be chemical or physical through digestion and toxins
• Carnivores depend on nitrogen-rich sustenance
• Mixotrophs eat other sources of C
• Those in trophic levels dependent on various environments and various means of digestion

Energy Limitations

• Type I increases linearly
• Type II starts linear before slowing due to time needed to search during a specific hunt
• Type III graphs as an S-shape, with increased consumption in high density prey and decreased use in low density
• Behavioral ecology is a study of living beings due to environment
• Evolution and genetics affect actions

Foraging

• Organisms that depend on resources influence fitness
• Choices favor ways of getting sustenance
• All species need to eat, reproduce, and get out of reach
• Organics require the right times and quantities for where they forage and the separation of the environment
• Consumption, resources, time, search costs, handling need consideration

Bluegill Foraging

• Smaller organisms forage for consumption
• In plants, there are light levels as levels affecting different elements and fitness
• Fitness affects species
• Kin selection favors the fitness of a relative
• Altruism gives benefits to other people
• All animals interact
• Some, but not all animals are altruistic
• Eusociality is complex and involves reproduction

Community Structures

• There are different reproduction forms

Reproductive Systems

• Inter- and intra-sexual selection affect success
• Different cycles affect reproduction and survival
• Resources influence systems differently and the types of habitats
• Resources are key elements

Niche Concepts

• Environments have biotic and abiotic factors
• Species have to fit into their surroundings
• These concepts can explain interactions
• Various processes may or may not favor specific interactions
• Keystone species influence structure despite being small
• Disturbance is needed
• Species must survive, there must be a balance in community

Succession

• Primary disturbance affects species
• Succession shifts change
• Communities rely on equilibrium

Community Control

• Biological communities are key
• Distribution changes due to succession
• Communities can vary
• Climate increases productivity
• There are energy levels or positions depending on energy needs
• There are various levels
• It shows that there are organisms that affect cycles and food needs

Community Interactions

• Landscapes depend on different things
• There are differing habitats influenced by conditions
• Landscape differs due to habitat
• Geological things define vegetation
• Glaciers define rock
• Glacier activity is key
• The composition of landscapes vary
• Fire is the key to structure

Landscape Structure

• Fire affects certain environments more
• Structures influence processes to see what will flow
• Patch, structure, and dispersal are important
• This all informs us of what a landscape is