Ecology: Organisms and Their Environment

• Ecology is the study of interactions between organisms and their environment
• Ecology is an experimental science, not just natural history
• Oikos means home
• The biosphere is the part of Earth that supports life
• The biosphere is the sum of the planet's ecosystems

Organisms and Environment

• An organism is a living creature that can grow and reproduce
• The goal of an organism is to grow and reproduce
• Organisms respond to their environment
• Organisms can adapt to their environment over time via evolution
• Abiotic environment is the physical environment
• The biotic environment involves interactions between organisms
• The environment affects distribution and abundance of organisms

Levels of Inquiry in Ecology

• Organismal ecology studies the physiology, behavior, and evolutionary history of a species
• Organismal ecology looks at how the organism interacts with its environment
• Population ecology studies the factors that affect population dynamics like birth and death rates
• Community ecology studies groups of populations of different species
• Community ecology studies how interactions between species affect community structure like predation and competition
• Community ecology examines how members of a community interact and focuses on the interconnectedness of different species
• Ecosystem ecology studies groups of organisms along with the physical factors they interact with
• Energy flow and chemical cycling between organisms and the environment are part of ecosystem ecology
• Landscape ecology studies many connected ecosystems
• Landscape ecology studies factors controlling exchanges of energy, materials, and organisms across multiple ecosystems, such as dispersal corridors

Nutrient Flow Example

• Mangrove forests, seagrass beds, and coral reefs are connected
• Mangroves provide protection from predators
• Marine organisms use mangroves as a nursery
• Seagrass beds act as a corridor to the coral reef as organisms mature
• This whole system exemplifies landscape ecology

Ecology and Global Systems

• Organisms form populations, mixtures of populations form communities
• A variety of communities form ecosystems
• All ecosystems together make up the biosphere
• Global ecology examines the influence of energy and materials on organisms across the biosphere

Ecology and Environmental Issues

• Ecology offers a scientific foundation for addressing environmental problems
• This is just one component of decision-making that includes social, economic, and political factors
• Environmental science encompasses many disciplines
• Rachel Carson is credited with initiating the modern environmental movement
• Silent Spring was published in 1962

Climate Factors

• Climate is the most significant factor influencing the distribution of organisms
• Climate refers to long-term prevailing weather conditions in a region
• Climate has four components including temperature, precipitation, sunlight, and wind
• Global climate patterns are influenced by latitudinal variations in climate due to unequal heating of Earth's surface
• Direct sunlight at the equator and low angles of incidence at higher latitudes impacts global climate patterns
• Earth's tilt and elliptical orbit also cause seasonal variation in sunlight intensity
• Unequal heating causes air circulation and wind patterns, which then affect ocean currents
• Regional climate is impacted by proximity to water, which moderates the climate
• Regional climate is also affected by elevation and the rain shadow effect
• Topography impacts air movement, affecting local temperature and rainfall
• Latitude affects the accumulation of solar radiation
• Microclimates are localized patterns in climatic conditions
• Microclimates occur due to factors like shade, evaporation, and wind patterns
• Each environment on Earth has small-scale differences in abiotic i.e. non-living -- chemical, physical attributes and biotic i.e. living – interactions with other living organism factors

Global Climate Change

• Earth has warmed an average of 0.8°C since 1900
• Earth is predicted to warm 1-6°C more by 2100
• A major concern is whether species can shift their distributions quickly enough in response to climate changes
• Tree lines are advancing north as an example of climate change
• Some species face a shortage of suitable replacement habitats due to climate change
• A 2015 study shows that the geographic ranges of 67 bumblebee species in the Northern Hemisphere were shrinking

Biomes

• Climate determines the nature and location of Earth’s biomes
• Biomes are major life zones characterized by temperature, precipitation, dominant vegetation types, and physical environment
• Tropical Rain Forests exist, location and climate determine this

Biome Facts

• Tropical Dry Forests exist, location and climate determine this
• Deserts exist, location and climate determine this
• Savannas exist, location and climate determine this
• Chaparral zones exist, location and climate determine this
• Temperate grasslands exists, location and climate determine this
• Northern Coniferous Forests are the largest terrestrial biomes. Factors of location and climate determine this
• Temperate Broadleaf Forests exist, location and climate determine this
• Tundra exists, location and climate determine this

Terrestrial Biomes

• There are no distinct boundaries between biomes
• Areas of integration are called ecotones
• Vertical layering is also important

Disturbances

• Disturbances are seen more often than stability
• Storms, fires, and human activities are examples of disturbances
• Disturbances allow opportunity for new species to colonize
• Disturbances cause biomes to experience patchiness
• Fires are essential for regeneration in some biomes

Aquatic Biomes

• The aquatic biome is the largest part of the biosphere
• The aquatic biomes are characterized by abiotic and biotic factors
• Aquatic Biomes can be marine or freshwater
• Aquatic biomes show less latitudinal variation compared to terrestrial biomes
• Marine biomes have salt concentrations of about 3%
• Oceans cover 75% of Earth's surface

Aquatic Biome Features

• Characterized by physical/chemical environment, geological features, photosynthetic organisms, and heterotrophs
• Stratification in aquatic biomes is defined by light penetration, temperature, distance from shore and depth, open water versus bottom
• Many lakes undergo semiannual mixing of their waters called turnover
• Turnover mixes oxygenated water from the surface with nutrient-rich water from the bottom
• Clear thermoclines exist in some parts of the year
• Some aquatic biomes are freshwater lakes, streams, rivers and wetland.
• Some aquatic biomes are freshwater/marine water, estuaries
• Some aquatic biomes are marine based, intertidal zones, oceanic pelagic biome, coral reefs, and marine benthic zone

Ecology Factors

• Factors of species distribution and ecological interactions are the result of evolutionary interactions through time
• Ecologists question where species occur and why
• Dispersal is when individuals or gametes move away from centres of high population density or from their area of origin
• Dispersal contributes to the global distribution of organisms
• Natural range expansions show the influence of dispersal on the distribution
• Some organisms do not occupy their potential range
• Species distribution may be limited by habitat selection behaviour
• Abiotic factors affecting distribution of organisms include temperature, water, oxygen, salinity, sunlight, wind, and rocks and soil
• Biotic factors that affect the distribution of organisms include predation, herbivory, competition, mutualism, and parasitism
• Sea urchins can limit the distribution of seaweeds

Biogeography

• This is the broad distribution patterns of organisms based on biotic and abiotic factors