Ecology Concepts

• This text provides an overview of ecological systems, climate, biomes, evolution, genetic variation, life history strategies, and reproduction, focusing on key principles and processes in ecology.

Hierarchical Organization of Ecological Systems

• Ecology is studied at different levels: organism, population, community, ecosystem, landscape, and biosphere.
• The organism-level approach focuses on individual survival traits like morphology and physiology.
• The population approach studies changes in the number, density, and composition of groups.
• The community approach studies diversity, species abundance, and interactions.
• The ecosystem approach examines energy flow and nutrient cycling.
• The landscape approach regards movements energy, matter, and individuals between ecosystems.
• The biosphere approach examines large-scale movements of air, water, and chemicals across the earth.

Physical and Biological Principles

• Matter is conserved and can only be transformed, for example, nutrients returning to the soil.
• Energy is conserved and only transferred, for example, sunlight powering plants.
• Dynamic Steady State defines balance between gains and losses in an ecosystem.
• Adaptation & Evolution occurs through natural selection, increasing fitness and reproductive success.

Roles of Organisms in Ecological Systems

• Producers (autotrophs) convert sunlight or chemicals into energy, like plants and algae.
• Consumers (heterotrophs) consume other organisms for energy.
• Herbivores eat plants, such as deer.
• Carnivores (predators and parasitoids) eat other animals; predators kill their prey, while parasitoids lay eggs in hosts like wasps.
• Omnivores eat both plants and animals.
• Decomposers and detritivores break down dead matter, such as fungi and vultures.
• Predation & Parasitoidism involves one organism benefiting and the other being killed (+/-).
• In parasitism, parasites harm their host without killing it (+/-).
• Herbivory involves herbivores consuming plants (+/-).
• Competition occurs when two species compete for the same resources (-/-).
• Mutualism is when both species benefit from a relationship (+/+).
• Commensalism is when one species benefits and the other is unaffected (+/0).

Scientific Approaches in Ecology

• Observational Studies are about watching nature without interference.
• Experimental Studies involve manipulating variables to test hypotheses.
• Manipulative Experiments actively change conditions, using comparative controls.
• Treatment groups receive changes while control groups do not.
• Replication and Randomization are incorporated to ensure reliable results.
• Microcosm Experiments are small-scale, controlled studies mimicking natural conditions.
• Natural Experiments are about observing real-world changes such as deforestation effects.
• Mathematical Models simulate ecological processes using equations to predict outcomes like species extinction rates.

Scientific Method

• Proximate hypotheses explain how something happens.
• Ultimate hypotheses explain why something happens.
• Predictions and Testing involves confirmation of hypotheses using experiments and data.

Human Impacts on Ecological Systems

• Deforestation destroys habitats, leading to biodiversity loss.
• Pollution of air, water, and soil harms organisms.
• Climate Change greenhouse gases alter weather patterns and habitats.
• Overfishing & Hunting depletes animal populations, disrupting ecosystems.
• Urbanization expands cities, fragmenting habitats, and reduces biodiversity.
• Invasive Species outcompete local species.

Earth's Warming by the Greenhouse Effect

• The atmosphere is a 600-km-thick layer of gases surrounding Earth.
• The greenhouse effect warms the Earth as the sun's energy is re-emitted as infrared radiation.
• Greenhouse gases include CO2, CH4, H2O, and N2O.
• These trap heat, preventing its escape into space and maintaining habitable temperatures.
• Excess greenhouse gases cause global warming.
• Albedo Effect: Light-colored surfaces (ice, clouds) reflect solar energy, while dark surfaces absorb it.

Atmospheric Currents and Climate Distribution

• Climate is the long-term patterns of temperature and precipitation.
• Weather is the short-term variation in atmospheric conditions.
• Unequal Heating of Earth occurs because the equator receives more direct sunlight that the poles.
• Earth's tilt causes varying sunlight exposure and seasonal heating.
• Atmospheric Currents: Large-scale air circulation is driven by heat differences.
• Hadley Cells (0°–30°): Warm air rises at the Intertropical Convergence Zone (ITCZ), cools, and sinks at 30°, promoting desert formation.
• Ferrel Cells (30°–60°): Mix warm and cold air, influencing temperate zones.
• Polar Cells (60°–90°): At these locations, cold air sinks, creating dry, icy conditions.
• The Coriolis Effect: Earth's rotation deflects wind and water, shaping trade winds.
  • Adiabatic Cooling & Heating: Rising air expands, cools and sinking air compresses and heats.
• Latent Heat Release: Water vapor condenses into liquid, releasing heat and driving cloud formation.

Ocean Currents and Climate Distribution

• Gyres: Large-scale ocean circulation loops are driven by trade winds, rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
• Thermohaline Circulation: Deep-water currents are driven by temperature and salinity, moving heat globally.
• Upwelling: Wind blows over water's surface, causing nutrient-rich water from the bottom to rise, especially on coastlines.
• During Normal conditions, trade winds are pushing warm water westward (toward Australia).
• During El Niño, trade winds weaken and warm water shifts east, disrupting weather.
• During La Niña, conditions opposite to El Niño strengthen normal climatic patterns.

Geographic Features and Local Climates

• Mountains have a Rain Shadow Effect, where moist air cools and releases rain on their slopes.
• The windward side of mountains promotes moist air that rises, cools, and releases rain.
• The leeward side of mountains are dry, with air descending, which creates deserts.
• Bodies of Water regulate temperature, making coastal regions milder with warmer winters and cooler summers.
• Urban Heat Islands: Buildings and pavement retain heat in cities.
• Valleys trap cold air, leading to frost pockets.

Terrestrial Biomes

• Biomes are geographic regions with organisms adapted to similar conditions.
• They are categorized by dominant plant growth forms, temperature, and precipitation.
• Convergent Evolution shows similar traits evolving independently in different biomes: cacti and euphorbs.
• Tundra has freezing conditions, is treeless, its permafrost is its mosses and lichens are its dominant species.
• Boreal Forest is cold with low precipitation, evergreen conifers.
• Temperate Rainforests are mild, very wet, with tall evergreen trees such as the Pacific Northwest.
• Temperate Seasonal Forests have moderate temperatures, distinct seasons and desiduous trees.
• Woodland/Shrubland has hot, dry summers, mild winters, and drought-resistant shrubs.
• Temperate Grassland is considered to have cold winters, warm summers, grasses, and frequent fires.
• Tropical Rainforests feature high temperatures, wet conditions, dense vegetation, and the highest levels of biodiversity.
• Tropical Seasonal Forest/Savanna is warm with seasonal rainfall, scattered trees, and grasslands.
• Subtropical Deserts are hot, dry regions with sparse vegetation.

Aquatic Biomes

• Flow, depth, and salinity define aquatic biomes.
• Freshwater Biomes can be:
• Streams & Rivers because they have flowing water and high oxygen in fast-moving parts.
• Still water divided into zones are Ponds & lakes.
• The littoral zone is near the coast and is shallow.
• The limnetic zone is open water.
• The euphotic zone is the near the surface of the water.
• The bentic zone is dark, due to depths/opacity.
• Freshwater wetland have standing water, saturated soils, emergent vegetation.
• Marine Biomes are:
• Estuaries which are where freshwater meets saltwater, are highly productive.
• Salt Marshes have coastal, nonwoody vegetation, and are flood-resistant.
• Mangrove Swamps have salt-tolerant trees along tropical coasts.
• Intertidal Zones have rocky/sandy shorelines, and experience extreme tide changes.
• Coral Reefs have warm, shallow waters, these are biodiversity hotspots.
• Open Ocean has:
• Photic Zones, a sunlit surface which supports photosynthesis.
• Aphotic Zones, which are deep, dark, and relies on sinking organic matter.
• Abyssal Zone, which has cold temperatures, high pressure, and includes unique bioluminescent life.

Evolution and Genetic Variation

• Evolution depends on genetic variation within a gene pool.
• Sources of variation include:
• Mutation: Random changes in DNA creates new alleles.
• Recombination: Mixes of genetic material during reproduction..
• Random assortment: Random Distribution of alleles occurs during gamete formation.
• Without variation, selection and evolution cannot occur.

Evolution Through Random Processes

• Evolution can occur randomly by:
• Genetic drift: Random changes in allele frequency are impactful in small populations.
• Bottleneck effect: Drastic disasters drastically reduce in population, reducing genetic diversity.
• Founder effect: Small founding groups can initiate new populations, limiting genetic variation.
• These listed processes are not guided by natural selection and are completely random.

Evolution Through Selection (Nonrandom Process)

• Selection favors traits increasing survival or reproduction. -Stabilizing selection favors the average trait. -Directional selection favors one extreme. -Disruptive selection favors both extremes. -The strength of selection is measured by trait's average difference.
• Heritability is the trait % due to genetics rather than environment. -Artificial selection is human-driven. -Natural selection results from predator pressure. -Reversing Effects of Pollution can restore original traits.

Microevolution & Macroevolution

• Microevolution refers to changes happens within a species driven by gene flow, mutation, genetic drift, and natural selection.
• Macroevolution regards large-scale evolution beyond a single species, eventually including speciation.
  • Speciation: Allopatric speciation: Populations become geographically isolated
  • Sympatric speciation: New species form independent of geographic separation.
• Phylogenetic trees illustrates evolutionary relationships among species.

Life History Traits

• Life history is the patterns and timing of development, reproduction, growth, and lifespan.
• Fecundity is the number of offspring produced per reproductive event.
• Parity is the number of reproductive events during an organism's lifetime.
• Parental investment regards energy/care allocated to offspring.
• Longevity specifies the organism's lifespan. -r-selected species exhibit fast growth, short lifespan, the species reproduces early and often and has small offspring. -k-selected species are slow-growing and have delayed reproduction, few offspring, but a long lifespan.
• Determinate growth: Growth stops at sexual maturity.
• Indeterminate growth: Growth continues throughout life.

Life History and Trade-offs

• Limited energy means organisms cannot maximize all life history traits. -There is a trade-off between growth and reproduction: more early reproduction reduces later growth.
• More offspring = smaller size, which results in less survival.
• More offspring = smaller size, less survival (e.g., sea turtles lay many small eggs, elephants have few large calves).
• High parental care = fewer offspring.
• Low care = more offspring.
• Reproductive Strategies:
  • Semelparity: Reproduction that happens only one time during an organisms' life.
  • Interoparitory: Multiple reproductive events during any given organisms life.

CSR Theory for Plants

• Competitors (C): Fast rate of growth and early reproduction.
• Stress-tolerators (S): Slow growth and late reproduction. - Ruderals (R) Fast growth, rate of early reproduction, elevated seed production.

Reproduction and Senescence

• Early reproduction = shorter lifespan.
• Delayed reproducted equal longer lifespans.
• Senescence regards a gradual survival and reproductive decline.
• Senescence is more prominent in with interoparitous species.

Survival and Evolution

• Survival and evolution is dependent upon early life traits. -Investing life energy into breeding leads to the potential for massive loss.
• Hunting, causes size, shorter horns over time.
• Life histories fluctuate relative to environmental conditions. -Use of day length: Organisms use length as a reliable season, with a shift, some species will now flower earlier as result of climate change. -Predator pressure includes hatching development for embyros. -Resource avalibility can affect population. -tropical birds, fewer offspring, longer lives. -temperate have more shorter lival spans.
  • More offspring = high parental success.

Sexual vs. Asexual Reproduction

• Requires 2 parents (sperm/egg)

• Genetic diversity

• Asexual Reproduction -1 parent (gamate fusion) -clones (genes remain) -rapid reproduction, no mates) -no variation

Separate Sexes vs Hermaphrodites

-distinct individuals -hider heratiblity -one has female parts, male parts

• Types:
• Simultaneous hermaphrodites: (both reproductive organs occur at the same time - earthworms). - Sequential hermaphrodites (change sex over time - a change in sex is common relative to species).
• Perfect flowers contain (make and female structures)
• • The most favorable is small population, or high activity.
• Mixed Mating strategies - allows a species to reproduce relative to external conditions.

Natural Selection of Sex Ratios

• Balenced ratios- equall parental investments -Genetic sex - (XX/XY in mammals and birds)
  • Environmental Sex
    • Warmers climates can produce turtles, lizards or fish accordingly.
    • Frequency-dependent selection for mates.

Mating System, Patterns

• Mogamy - has seasonal pairing.
  • Mates stay in close proximity with paternal rights being the most common. Polygamy:
    • Multiple - one male -Female- Female dominance. Promiscusity - both have the same pattern with the inclusion of genetic diversity.
• Females can benefit with selection to mate with superior genetics.

Reproductive Traits

Sexual- improve mating

• 2 types - mates are attached can be attractive and select good health genetics - Male competes in mate/ or animal group, select
  • dimorphisim

Test your knowledge of ecological concepts. Questions cover hypothesis types, environmental processes, and species interactions. Topics include climate patterns and mating systems.