Ecology Exam 1 Review PDF

Test Yourself 1.1 Hierarchical Organization of Ecological Systems ​ Organism ​ Population ​ Community ​ Ecosystem ​ Landscape ​ Biosphere 1.2 Physical and Biological Principles Governing Ecological Systems ​ Law of Conservation of Matter ​ Law of Conservation of Energy ​...

Test Yourself 1.1 Hierarchical Organization of Ecological Systems ​ Organism ​ Population ​ Community ​ Ecosystem ​ Landscape ​ Biosphere 1.2 Physical and Biological Principles Governing Ecological Systems ​ Law of Conservation of Matter ​ Law of Conservation of Energy ​ Dynamic Steady State ​ Adaptation & Evolution 1.3 Roles of Organisms in Ecological Systems ​ Producers (Autotrophs) ​ Consumers (Heterotrophs) ○​ Herbivores ○​ Carnivores (Predators & Parasitoids) ○​ Omnivores ○​ Decomposers & Detritivores ​ Predation & Parasitoidism ​ Parasitism ​ Herbivory ​ Competition ​ Mutualism ​ Commensalism 1.4 Scientific Approaches in Studying Ecology ​ Observational Studies ​ Experimental Studies ○​ Manipulative Experiments ○​ Treatment & Control ○​ Replication & Randomization  ○​ Microcosm Experiments ○​ Natural Experiments ​ Mathematical Models ​ Scientific Method in Ecology ○​ Hypothesis Formation ​ Proximate Hypothesis ​ Ultimate Hypothesis ○​ Predictions & Testing 1.5 Human Influences on Ecological Systems ​ Deforestation ​ Pollution ​ Climate Change ​ Overfishing & Hunting ​ Urbanization ​ Invasive Species 2.1 Earth’s Warming by the Greenhouse Effect ​ Atmosphere ​ Greenhouse Effect ​ Greenhouse Gases (CO₂, CH₄, H₂O, N₂O) ​ Albedo Effect 2.2 Atmospheric Currents and Climate Distribution ​ Climate ​ Weather ​ Unequal Heating of Earth ​ Seasonal Heating ​ Atmospheric Currents ○​ Hadley Cells ○​ Ferrel Cells ○​ Polar Cells ​ Coriolis Effect  ​ Adiabatic Cooling & Heating ​ Latent Heat Release 2.3 Ocean Currents and Climate Distribution ​ Gyres ​ Thermohaline Circulation ​ Upwelling ​ El Niño–Southern Oscillation (ENSO) ○​ El Niño ○​ La Niña 2.4 Geographic Features and Local Climates ​ Mountains (___ Effect) ○​ Windward Side ○​ Leeward Side ​ Bodies of Water ​ Urban Heat Islands ​ Valleys 2.5 How Terrestrial Biomes Are Categorized ​ Biome ​ Categorized by ​ Convergent Evolution 2.6 The Nine Terrestrial Biomes ​ Tundra ​ Boreal Forest ​ Temperate Rainforest ​ Temperate Seasonal Forest ​ Woodland/Shrubland ​ Temperate Grassland ​ Tropical Rainforest ​ Tropical Seasonal Forest/Savanna ​ Subtropical Desert 2.7 Aquatic Biomes (Flow, Depth, and Salinity)  ​ Freshwater Biomes ○​ Streams & Rivers ○​ Ponds & Lakes ○​ Freshwater Wetlands ​ Marine Biomes ○​ Estuaries ○​ Salt Marshes ○​ Mangrove Swamps ○​ Intertidal Zone ○​ Coral Reefs ○​ Open Ocean ​ Photic Zone ​ Aphotic Zone ​ Abyssal Zone 6.1 Evolution & Genetic Variation ​ Mutation ​ Recombination ​ Random assortment 6.2 Evolution Through Random Processes ​ Genetic drift ​ Bottleneck effect ​ Founder effect 6.3 Evolution Through Selection (Nonrandom Process) ​ Stabilizing selection ​ Directional selection ​ Disruptive selection ​ Strength of selection ​ Heritability ​ Artificial selection ​ Natural selection by predators  ​ Reversing the effects of pollution 6.4 Microevolution ​ Operates at what level? ​ Affected by what aspects of natural selection? 6.5 Macroevolution ​ Speciation ○​ Allopatric speciation ○​ Sympatric speciation ​ Phylogenetic trees 7.1 Life History Traits: The Schedule of an Organism’s Life ​ Fecundity ​ Parity ​ Parental investment ​ Longevity ​ r-selected species ​ K-selected species ​ Determinate vs. Indeterminate Growth 7.2 Life History Traits and Trade-offs ​ Growth vs. reproduction ​ Offspring number vs. offspring size ​ Parental investment vs. fecundity ​ Reproductive Strategies ○​ Semelparity ○​ Iteroparity ​ Lack Clutch Hypothesis ​ CSR Theory for Plants ○​ Competitors (C) ○​ Stress-tolerators (S)  ○​ Ruderals (R) 7.3 Reproduction and Senescence ​ Age of Sexual Maturity vs. Life Span ​ Senescence ​ Survival and Evolution ​ Human activity & artificial selection 7.4 Life Histories and Environmental Sensitivity ​ Photoperiod & temperature ​ Predation pressure ​ Resource availability ​ Alternative Life History Strategies ​ Parent-Offspring Conflict & Fitness Trade-offs 8.1 Sexual vs. Asexual Reproduction ​ Sexual reproduction ​ Cost of meiosis ​ Mate guarding ​ Asexual reproduction ○​ Vegetative reproduction ○​ Parthenogenesis ○​ Binary fission 8.2 Evolution of Separate Sexes vs. Hermaphrodites ​ Separate sexes (dioecious species) ​ Hermaphrodites ○​ Simultaneous hermaphrodites ○​ Sequential hermaphrodites ​ Perfect flowers ​ Monoecious species ​ When Hermaphrodites Have a Fitness Advantage ​ When Separate Sexes Have a Fitness Advantage ​ Mixed-mating strategy 8.3 Sex Ratios & Natural Selection ​ Balanced sex ratio ​ Genetic sex determination ​ Environmental sex determination ○​ Temperature-dependent sex determination (TSD) ○​ Sex change in fish ​ Frequency-dependent selection ​ Local mate competition ​ Wolbachia infection 8.4 Mating Systems & Patterns ​ Monogamy ​ Polygamy ○​ Polygyny ○​ Polyandry ​ Promiscuity ​ Female benefits of extra-pair copulations ○​ Good genes hypothesis ○​ Runaway sexual selection ○​ Handicap principle 8.5 Sexual Selection & Reproductive Traits ​ Sexual selection ○​ Intersexual selection (mate choice) ○​ Intrasexual selection (male-male competition) ​ Sexual dimorphism ​ Sexual conflict ​ Impacts of human activity on sexual selection ​ Red Queen Hypothesis Chapter 1 1.1 Hierarchical Organization of Ecological Systems ​ Organism – Individual approach focuses on an organism's morphology, physiology, and behavior to survive (e.g., a wolf’s fur for insulation). ​ Population – Population approach studies variation over time and space in the number, density, and composition of individuals (e.g., wolf population changes over seasons). ​ Community – Community approach examines diversity and relative abundances of different species living together (e.g., wolves, deer, trees in a forest). ​ Ecosystem – Ecosystem approach looks at energy flow and nutrient cycling (e.g., carbon and nitrogen moving through a forest). ​ Landscape – Landscape approach studies the movement of energy, matter, and individuals between ecosystems (e.g., migration of wolves between forests and grasslands). ​ Biosphere – Biosphere approach examines large-scale movement of air, water, and chemical elements across Earth’s surface. 1.2 Physical and Biological Principles Governing Ecological Systems ​ Law of Conservation of Matter – Matter cannot be created or destroyed, only transformed (e.g., decomposed organisms return nutrients to the soil). ​ Law of Conservation of Energy – Energy is neither created nor destroyed, only transferred (e.g., sunlight powers plants, which feed herbivores, which feed predators). ​ Dynamic Steady State – Balance between gains and losses in an ecosystem (e.g., birth and death rates in a population). ​ Adaptation & Evolution – Organisms evolve through natural selection, where the best-adapted individuals have higher fitness and reproductive success. 1.3 Roles of Organisms in Ecological Systems Organisms have different roles based on how they obtain energy: ​ Producers (Autotrophs) – Convert sunlight or chemicals into energy (e.g., plants, algae).  ​ Consumers (Heterotrophs) – Eat other organisms for energy: ○​ Herbivores – Eat plants (e.g., deer). ○​ Carnivores (Predators & Parasitoids) – Eat other animals (e.g., wolves, wasps that lay eggs in hosts). PREDATORS KILL THEIR PREY ○​ Omnivores – Eat both plants and animals (e.g., bears). ​ Decomposers & Detritivores – Break down dead matter (e.g., fungi, bacteria, scavengers like vultures). Organisms also interact in different ways: ​ Predation & Parasitoidism (+/−) – One benefits, the other is killed (e.g., wolf preys on deer, wasp lays eggs in caterpillars). ​ Parasitism (+/−) – Parasites harm but do not usually kill their host (e.g., ticks on deer). ​ Herbivory (+/−) – Herbivores consume plants (e.g., cows eating grass). ​ Competition (−/−) – Two species compete for the same resources (e.g., lions and hyenas fighting over food). ​ Mutualism (+/+) – Both species benefit (e.g., lichen: fungus and algae work together). ​ Commensalism (+/0) – One benefits, the other is unaffected (e.g., barnacles on whales). 1.4 Scientific Approaches in Studying Ecology ​ Observational Studies – Watching nature without interference (e.g., tracking wolf migration). ​ Experimental Studies – Manipulating variables to test hypotheses: ○​ Manipulative Experiments – Actively change conditions (e.g., removing predators from an area). ○​ Treatment & Control – Treatment receives changes, control does not (for comparison). ○​ Replication & Randomization – Ensures results are reliable. ○​ Microcosm Experiments – Small-scale controlled studies mimicking natural conditions. ​ Natural Experiments – Observing real-world changes that already occurred (e.g., deforestation effects).  ​ Mathematical Models – Simulating ecological processes using equations (e.g., predicting species extinction rates). Scientific Method in Ecology 1.​ Hypothesis Formation ○​ Proximate Hypothesis – Explains how something happens (e.g., how wolves communicate using howls). ○​ Ultimate Hypothesis – Explains why something happens (e.g., why wolves evolved to live in packs). 2.​ Predictions & Testing – Using experiments and data to confirm hypotheses. 1.5 Human Influences on Ecological Systems ​ Deforestation – Destroying habitats, leading to biodiversity loss. ​ Pollution – Air, water, and soil contamination harming organisms. ​ Climate Change – Greenhouse gases altering weather patterns and habitats. ​ Overfishing & Hunting – Depleting animal populations, disrupting ecosystems. ​ Urbanization – Expanding cities, fragmenting habitats, and reducing biodiversity. ​ Invasive Species – Non-native species outcompeting local species (e.g., cane toads in Australia). Chapter 2 2.1 Earth’s Warming by the Greenhouse Effect ​ Atmosphere: A 600-km-thick layer of gases surrounding Earth. ​ Greenhouse Effect: Sun’s energy warms the Earth, which re-emits infrared radiation. ​ Greenhouse Gases (CO₂, CH₄, H₂O, N₂O): Trap heat, preventing it from escaping into space. ​ Albedo Effect: Light-colored surfaces (ice, clouds) reflect solar energy, while dark surfaces absorb it. ​ Result: Maintains habitable temperatures; excess gases cause global warming. 2.2 Atmospheric Currents and Climate Distribution ​ Climate: Long-term patterns of temperature and precipitation. ​ Weather: Short-term variation in atmospheric conditions (hours/days). ​ Unequal Heating of Earth: The equator receives more direct sunlight than the poles. ​ Seasonal Heating: Earth's tilt causes varying sunlight exposure, creating seasons. ​ Atmospheric Currents: Large-scale air circulation driven by heat differences. ​ Hadley Cells (0°–30°): Warm air rises at the Intertropical Convergence Zone (ITCZ), cools, and sinks at 30° (creates deserts). ​ Ferrel Cells (30°–60°): Mix warm and cold air, influencing temperate zones. ​ Polar Cells (60°–90°): Cold air sinks at the poles, creating dry, icy conditions. ​ Coriolis Effect: Earth’s rotation deflects wind and water, shaping trade winds. ​ Adiabatic Cooling & Heating: Rising air expands and cools; sinking air compresses and heats. ​ Latent Heat Release: Water vapor condenses into liquid, releasing heat and driving cloud formation. 2.3 Ocean Currents and Climate Distribution ​ Gyres: Large-scale ocean circulation loops driven by trade winds (clockwise in the Northern Hemisphere, counterclockwise in the Southern).  ​ Thermohaline Circulation: Deep-water currents move heat globally based on temperature and salinity, originating from the poles before moving out toward hotter areas. ​ Upwelling: Wind blows over water’s surface, and causes nutrients on the bottom to rise to the top, most effective on coastlines. ​ El Niño–Southern Oscillation (ENSO): ○​ Normal: Trade winds push warm water westward (toward Australia). ○​ El Niño: Trade winds weaken, warm water shifts east, disrupting weather. ○​ La Niña: Opposite of El Niño, strengthens normal conditions. 2.4 Geographic Features and Local Climates ​ Mountains (Rain Shadow Effect): ○​ Windward Side: Moist air rises, cools, and releases rain. ○​ Leeward Side: Dry air descends, creating deserts. ​ Bodies of Water: Regulate temperature, making coastal regions milder because they take longer to heat/cool. Allows warmer winters and cooler summers. ​ Urban Heat Islands: Cities retain heat due to buildings and pavement. ​ Valleys: Trap cold air, leading to frost pockets. 2.5 How Terrestrial Biomes Are Categorized ​ Biome: A geographic region with organisms adapted to similar conditions. ​ Categorized by: dominant plant growth forms, temperature, and precipitation. ​ Convergent Evolution: Similar traits evolve in different biomes (e.g., cacti vs. euphorbs). 2.6 The Nine Terrestrial Biomes 1.​ Tundra: Freezing, treeless, permafrost, mosses/lichens dominate. 2.​ Boreal Forest: Cold, low precipitation, evergreen conifers. 3.​ Temperate Rainforest: Mild, very wet, tall evergreen trees (e.g., Pacific Northwest). 4.​ Temperate Seasonal Forest: Moderate temps, distinct seasons, deciduous trees.  5.​ Woodland/Shrubland: Hot, dry summers, mild winters, drought-resistant shrubs. 6.​ Temperate Grassland: Cold winters, warm summers, grasses, frequent fires. 7.​ Tropical Rainforest: Warm, wet, dense vegetation, highest biodiversity. 8.​ Tropical Seasonal Forest/Savanna: Warm, seasonal rainfall, scattered trees, grasslands. 9.​ Subtropical Desert: Hot, dry, sparse vegetation, plants store water. 2.7 Aquatic Biomes (Flow, Depth, and Salinity) Freshwater Biomes: 1.​ Streams & Rivers: Flowing water, high oxygen in fast-moving parts. 2.​ Ponds & Lakes: Still water, divided into zones ​ Littoral Zone: near the coast, shallow ​ Limnetic Zone: Open water ​ Euphotic Zone: Near surface of water ​ Benthic Zone: Darkness envelops this oppressive space as light itself is unable to proceed into the depths of its viscous blackness. 3.​ Freshwater Wetlands: Standing water, saturated soils, emergent vegetation. Marine Biomes: 4.​ Estuaries: Where freshwater meets saltwater, highly productive. 5.​ Salt Marshes: Coastal, nonwoody vegetation, flood-resistant. 6.​ Mangrove Swamps: Salt-tolerant trees along tropical coasts. 7.​ Intertidal Zone: Rocky/sandy shoreline, extreme tide changes. 8.​ Coral Reefs: Warm, shallow waters, biodiversity hotspots. 9.​ Open Ocean: ○​ Photic Zone: Sunlit surface, supports photosynthesis. ○​ Aphotic Zone: Deep, dark, relies on sinking organic matter. ○​ Abyssal Zone: Cold, high pressure, unique bioluminescent life. Chapter 6 6.1 Evolution & Genetic Variation ​ Evolution requires genetic variation within a gene pool (all genetic material in a population). ​ Sources of variation: ○​ Mutation: Random changes in DNA create new alleles. ○​ Recombination: Mixing of genetic material during reproduction. ○​ Random assortment: Random distribution of alleles during gamete formation. ​ Without variation, selection and evolution cannot occur. 6.2 Evolution Through Random Processes ​ Evolution can happen randomly through: ○​ Genetic drift: Random changes in allele frequency, stronger in small populations. ○​ Bottleneck effect: Drastic reduction in population (e.g., disaster) reduces genetic diversity. ○​ Founder effect: Small group starts a new population, limiting genetic variation. ​ These processes are not guided by natural selection, making them completely random. 6.3 Evolution Through Selection (Nonrandom Process) ​ Selection favors traits that increase survival or reproduction. ​ Types of selection: ○​ Stabilizing selection: Favors the average trait (e.g., medium-sized babies survive best). ○​ Directional selection: Favors one extreme (e.g., faster cheetahs have higher survival). ○​ Disruptive selection: Favors both extremes over the average (e.g., black and white moths survive, but gray ones don’t). ​ Strength of selection: Measured by the difference in the trait’s average before and after selection. ​ Heritability: How much of a trait is due to genetics rather than environment.  ​ Artificial selection: Humans choose traits (e.g., breeding dogs for size). ​ Natural selection by predators: Prey with better camouflage survive. ​ Reversing the effects of pollution: Cleaner environments restore original traits (e.g., lighter moths returning after pollution decreased). 6.4 Microevolution (Population Level) ​ Microevolution: Changes in the frequency of a gene in a population over time ​ Driven by mutation, natural selection, genetic drift, and gene flow. ​ Operates within a single species ​ Example: Antibiotic resistance in bacteria. 6.5 Macroevolution (Species Level & Beyond) ​ Macroevolution: large-scale evolution beyond a single species over unscrupulous amounts of time. Ancestors often change drastically to form new species (e.g snakes losing limbs or chickens evolving from dinosaurs) ​ Speciation: Formation of new species. ○​ Allopatric speciation: Populations become geographically isolated, causing new species to form. ○​ Sympatric speciation: New species form without geographic separation. ​ Phylogenetic trees: Diagrams showing evolutionary relationships among species. Chapter 7 7.1 Life History Traits: The Schedule of an Organism’s Life ​ Life history refers to the patterns and timing of an organism’s development, growth, reproduction, and lifespan. ​ Key Traits: ○​ Fecundity: Number of offspring produced per reproductive event. ○​ Parity: Number of reproductive events in an organism’s lifetime. ○​ Parental investment: Energy/care allocated to offspring. ○​ Longevity: The organism’s lifespan. ​ Organisms follow a fast-slow continuum: ○​ r-selected species (e.g., insects, rodents): Fast growth, early reproduction, many small offspring, short lifespan. ○​ K-selected species (e.g., elephants, humans): Slow growth, delayed reproduction, few large offspring, long lifespan. ​ Determinate vs. Indeterminate Growth: ○​ Determinate growth: Growth stops at sexual maturity (e.g., mammals, birds). ○​ Indeterminate growth: Growth continues throughout life (e.g., fish, many plants). 7.2 Life History Traits and Trade-offs ​ Organisms cannot maximize all life traits due to limited energy (principle of allocation). ​ Common trade-offs: ○​ Growth vs. reproduction: Investing in early reproduction reduces growth and survival (e.g., fast-growing fish reproduce early but die sooner). ○​ Offspring number vs. offspring size: More offspring = smaller size, less survival (e.g., sea turtles lay many small eggs, elephants have few large calves). ○​ Parental investment vs. fecundity: High care = fewer offspring; low care = more offspring (e.g., octopuses lay thousands of eggs but provide no care). ​ Reproductive Strategies:  ○​ Semelparity (one-time reproduction, then death) – e.g., salmon, agave, cicadas (predator satiation strategy). ○​ Iteroparity (multiple reproductive events) – e.g., birds, mammals, many reptiles. ​ Lack Clutch Hypothesis: Birds lay an optimum clutch size based on parental ability to care for offspring. ​ CSR Theory for Plants: ○​ Competitors (C) – Fast growth, early reproduction, moderate seed production (e.g., trees in stable environments). ○​ Stress-tolerators (S) – Slow growth, late reproduction, vegetative reproduction (e.g., cacti). ○​ Ruderals (R) – Fast growth, early reproduction, high seed production (e.g., weeds with wind-dispersed seeds). 7.3 Reproduction and Senescence ​ Age of Sexual Maturity vs. Life Span: ○​ Early reproduction = shorter lifespan (e.g., rodents). ○​ Delayed reproduction = longer lifespan (e.g., elephants). ​ Senescence (Aging): ○​ Gradual decline in survival and reproductive ability over time. ○​ More prominent in iteroparous species, as they must balance long-term survival and reproduction. ​ Survival and Evolution: ○​ Natural selection favors early-life reproductive traits over traits that improve survival later in life because many organisms die before old age. ○​ Salmon and semelparity: High risk of mortality before second breeding season → investing all energy into one massive reproductive event. ○​ Human activity & artificial selection: Hunting large males (e.g., bighorn sheep) causes smaller body sizes and shorter horns over time. 7.4 Life Histories and Environmental Sensitivity ​ Life history traits respond to environmental conditions:  ○​ Photoperiod & temperature: Organisms use day length as a reliable seasonal cue, but some species (e.g., plants) now flower earlier due to climate change. ○​ Predation pressure: ​ Frog embryos hatch early when predators are near. ​ Snails change life history strategies in response to predators. ○​ Resource availability: Poor conditions delay reproduction or reduce offspring size (e.g., fish populations shrink due to overfishing). ​ Alternative Life History Strategies: ○​ Tropical birds: Fewer offspring, longer lifespan. ○​ Temperate birds: More offspring, shorter lifespan. ​ Parent-Offspring Conflict & Fitness Trade-offs: ○​ More parental care = fewer future reproductive opportunities (high care can decrease a parent's fitness). ○​ Offspring survival vs. parental survival: Some species invest heavily in offspring, reducing their ability to reproduce again. Chapter 8 8.1 Sexual vs. Asexual Reproduction ​ Sexual reproduction ○​ Requires two parents, gametes (sperm & egg). ○​ Offspring have genetic variation. ○​ Increases adaptability (Red Queen Hypothesis: continuous evolution against parasites). ○​ Cost of meiosis: Each offspring inherits only 50% of genes, lowering genetic contribution. ○​ Mate guarding: Males often guard females to prevent extra-pair copulation and ensure paternity. ​ Asexual reproduction ○​ Single parent, no gamete fusion. ○​ Offspring are genetic clones (8 gene copies remain in lineages). ○​ Types: ​ Vegetative reproduction (new plants grow from roots, stems, or leaves). ​ Parthenogenesis (offspring develop from unfertilized eggs, e.g., some reptiles & insects). ​ Binary fission (single-cell division in bacteria and protists). ○​ Benefits: Rapid reproduction, no mate needed. ○​ Drawback: No genetic variation, making species vulnerable to changing environments and parasites. 8.2 Evolution of Separate Sexes vs. Hermaphrodites ​ Separate sexes (dioecious species) ○​ Males and females are distinct individuals. ○​ Higher genetic diversity, but requires a mate. ○​ Example: Kalutas (Antechinus spp.), where males die after a short breeding season. ​ Hermaphrodites ○​ One individual has both male & female reproductive organs.  ○​ Types: ​ Simultaneous hermaphrodites (both reproductive organs at once, e.g., earthworms). ​ Sequential hermaphrodites (change sex over time, e.g., blue-headed wrasse, clownfish). ○​ Perfect flowers: Contain both male & female reproductive structures. ○​ Monoecious species: Both sexes on the same plant (e.g., corn). ​ When Hermaphrodites Have a Fitness Advantage ○​ If finding mates is difficult, hermaphroditism is beneficial (self-fertilization). ○​ Small population size or high herbivore activity can favor selfing. ​ When Separate Sexes Have a Fitness Advantage ○​ If inbreeding reduces fitness, separate sexes evolve. ○​ Self-incompatibility genes prevent self-fertilization in some plants. ​ Mixed-mating strategy: Some plants like Orange Jewelweed can self-fertilize or cross-fertilize depending on environmental conditions.​ 8.3 Sex Ratios & Natural Selection ​ Balanced sex ratio (≈ 1:1): Common due to equal parental investment in offspring (Fisher’s Principle). ​ Modifications due to natural selection: ○​ Genetic sex determination (e.g., XX/XY in mammals, ZW in birds). ○​ Environmental sex determination: ​ Temperature-dependent sex determination (TSD): ​ Loggerhead turtles: Warmer = more females, cooler = more males. ​ Jacky dragon lizard: Climate change may skew sex ratios toward females. ​ Sex change in fish: Blue-headed wrasse switches from female to male when necessary. ○​ Frequency-dependent selection:  ​ Rare sex has an advantage (sockeye salmon populations shifting due to overfishing of large males). ○​ Local mate competition: ​ If brothers compete for mates, parents may produce more females (parasitic wasps). ○​ Wolbachia infection: Bacteria can eliminate males in some insect populations, skewing sex ratios. 8.4 Mating Systems & Patterns ​ Monogamy: One male, one female, long-term or seasonal pairing (e.g., swans, wolves). ○​ Favored when both parents contribute to offspring survival. ○​ Mate guarding helps ensure paternity. ​ Polygamy: One individual mates with multiple partners. ○​ Polygyny: One male, multiple females (lions, red-winged blackbirds). ○​ Polyandry: One female, multiple males (seahorses, honeybees). ​ Promiscuity: Multiple partners for both sexes, no strong pair bonds (chimpanzees, some fish). ○​ Increases genetic diversity. ​ Female benefits of extra-pair copulations: ○​ Good genes hypothesis: Choosing genetically superior males. ○​ Runaway sexual selection: Preference for exaggerated traits. ○​ Handicap principle: Costly traits indicate superior fitness. 8.5 Sexual Selection & Reproductive Traits ​ Sexual selection: Evolution favors traits that improve mating success. ​ Two types: ○​ Intersexual selection (mate choice): ​ Traits attract mates (long-tailed widowbird, peacock feathers). ​ Good genes hypothesis: Females select traits indicating good health/genetic quality.  ​ Runaway selection: Traits evolve beyond practicality due to mate preference. ​ Handicap principle: Costly traits signal superior genetics (deer antlers, bright plumage). ○​ Intrasexual selection (male-male competition): ​ Traits help males compete (kangaroo fights, deer antlers). ​ Sexual dimorphism: Males and females look different due to selection (lions’ manes, birds’ plumage). ​ Sexual conflict: ○​ Traits benefiting one sex may harm the other (bedbug traumatic insemination). ​ Impacts of human activity on sexual selection: ○​ Overfishing of large male salmon → Evolution favors smaller, faster-maturing individuals. ○​ Selective hunting → Reduction in secondary sexual traits. ​ Red Queen Hypothesis: ○​ Sexual reproduction provides genetic diversity, allowing species to keep up with evolving parasites. ○​ Roundworm vs. bacteria example: Constant evolutionary arms race. Lazy Review Chapter 1: Ecological Systems and Principles Hierarchy of Ecological Systems ​ Organism → Population → Community → Ecosystem → Landscape → Biosphere, each studying different ecological levels. Principles Governing Ecology ​ Law of Conservation of Matter & Energy: Matter/energy cannot be created or destroyed, only transformed. ​ Dynamic Steady State: Balance of gains/losses in an ecosystem. ​ Adaptation & Evolution: Natural selection favors traits that improve survival and reproduction. Roles of Organisms ​ Producers (plants, algae) convert energy; Consumers eat other organisms (herbivores, carnivores, omnivores); Decomposers break down dead matter. ​ Interactions: Predation (+/−), Parasitism (+/−), Mutualism (+/+), Competition (−/−), Commensalism (+/0). Studying Ecology ​ Observational Studies (no interference), Experimental Studies (manipulation). ​ Scientific Method: Hypothesis (Proximate = how, Ultimate = why), testing with experiments. Human Impact ​ Deforestation, pollution, climate change, overfishing, urbanization, invasive species disrupt ecosystems. Chapter 2: Climate and Biomes Greenhouse Effect ​ Greenhouse gases (CO₂, CH₄) trap heat, affecting global temperature. ​ Albedo effect: Light surfaces reflect heat; dark surfaces absorb. Atmospheric Circulation ​ Hadley (0°–30°), Ferrel (30°–60°), Polar (60°–90°) cells drive wind and climate patterns. ​ Coriolis effect influences wind direction. Ocean Currents & Climate ​ Gyres circulate warm/cool water; thermohaline circulation moves heat globally. ​ El Niño & La Niña alter weather patterns. Geographic Features & Local Climate ​ Mountains (rain shadow effect), water bodies, urban heat islands affect local climate. Terrestrial Biomes ​ Tundra, Boreal Forest, Temperate Rainforest/Seasonal Forest, Grasslands, Deserts, Tropical Rainforest/Savanna—classified by temperature, precipitation, and vegetation. Aquatic Biomes ​ Freshwater: Streams, lakes, wetlands. ​ Marine: Estuaries, coral reefs, open ocean zones. Chapter 6: Evolution and Genetic Variation Genetic Variation & Random Evolution ​ Mutation, recombination, genetic drift, bottleneck effect, founder effect drive evolution. Natural Selection ​ Stabilizing (favors average), Directional (favors one extreme), Disruptive (favors both extremes). ​ Artificial selection (human-driven evolution). Microevolution & Macroevolution ​ Microevolution: Changes within a species. ​ Macroevolution: Speciation via allopatric (geographic separation) or sympatric (same location) mechanisms. Chapter 7: Life History Strategies Life Traits & Trade-offs ​ r-selected species (fast growth, short lifespan), K-selected species (slow growth, long lifespan). ​ Trade-offs: Growth vs. reproduction, offspring number vs. size. Reproduction & Environmental Influence ​ Semelparity (one-time reproduction, e.g., salmon), Iteroparity (multiple reproductive events). ​ Senescence: Aging reduces survival and reproduction. Chapter 8: Reproduction and Sexual Selection Sexual vs. Asexual Reproduction  ​ Sexual: Genetic diversity, costly. Asexual: Fast, but no variation. Evolution of Sex & Sex Ratios ​ Hermaphrodites self-fertilize; separate sexes increase diversity. ​ Sex ratios affected by environmental sex determination, frequency-dependent selection. Mating Systems ​ Monogamy, polygyny (1 male, many females), polyandry (1 female, many males), promiscuity (no pair bonds). Sexual Selection ​ Mate choice (intersexual): Females prefer traits indicating good genes. ​ Male competition (intrasexual): Compete for mates, causing sexual dimorphism (trait differences between sexes). ​ Red Queen Hypothesis: Sexual reproduction helps species adapt against parasites.