Grundlagen Ökologie & Evolution PDF

Biologie - HS 2024 Grundlagen Ökologie & Evolution GRUNDLAGEN ÖKOLOGIE & EVOLUTION ECOLOGY (MADDY) WHAT IS ECOLOGY & ECOLOGICAL THINKING? Evolution cannot take place without ecology & Ecology only makes sense in connection with evolution!...

Biologie - HS 2024 Grundlagen Ökologie & Evolution GRUNDLAGEN ÖKOLOGIE & EVOLUTION ECOLOGY (MADDY) WHAT IS ECOLOGY & ECOLOGICAL THINKING? Evolution cannot take place without ecology & Ecology only makes sense in connection with evolution! Ecology Scientific study of abundance & distribution of organisms in relation to other organisms & environmental conditions. Abundance / Density Total number of individuals in a population within a defined area Population Individuals of same species living in particular area Species Group of individuals → naturally interbreed & produce fertile offspring Distribution How a species is spread out within a range Range Where the species appears Interspecific interactions crucial for abundance & distribution of both species Environmental conditions constantly determine species-species interactions 3 dimensions of Ecology Seite 1 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution HOW IS ECOLOGY DONE? Observation – looking at correlations between two (or more) variables → ex. butterfly population & temperature Theories – mathematical descriptions of ecological patterns – theories help to generate hypotheses for observations & experiments → hypothesis: proposition that suggests an explanation for some observed ecological pattern/situation Experiments – test of hypothesis by manipulating variables – provide insight into cause-and-effect relationships by showing what outcome occurs when a particular factor is manipulated Synthesis – combination of the three above Seite 2 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution HOW DO ORGANISMS BECOME SUITABLE TO AN ENVIRONMENT? Adjustments Adaptations reversible irreversible & heritable Aquatic life Osmoregulation – mechanism to ensure good water/solute (ex. salt) balance inside the body Hyperosmotic –  solute concentration in body than surrounding water → ex. freshwater fish Hypoosmotic –  solute concentration in body than surrounding water → ex. saltwater fish Q10 – ratio of physiological process at one temp. to its rate at temp. 10°C cooler – tells when temp. can’t be raised anymore → organism would die Optimum environmental conditions – narrow range of best suited environmental conditions → ex. thermal optimum Isozymes – different form of an enzyme Seite 3 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution Terrestrial life → water is crucial to terrestrial life Water potential – water’s potential energy (movement of water in soil) – determined by soil type & water availability – always negative numbers of MPa Field capacity – max. of water held by soil (against gravity) Wilting point – water potential at which plants can’t retrieve water from soil anymore Thermoregulation Ectotherm – body temp. is determined by external environment Endotherm – body temp. is regulated by organism ( than external environment) → high energy costs → mammals & birds Adaptations to variable environments Temporal environmental variations Weather – variation in temp. & precipitation over period of hours/days Climate – typical atmospheric conditions throughout year/s Seasons – weather patterns in a year → driven by amount of solar energy on earth surface Environmental variations – Spatial Environmental Variation → “The faster an individual organism moves – the smaller is the scale of spatial environmental variation.” – Temporal Environmental Variation → “The more quickly an individual organism encounters new environmental conditions – the shorter is the scale of temporal variation.” Seite 4 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution ARE THERE PERFECT ORGANISMS? Trade-off – organism can do very well in one environment & terrible in another Phenotype – observable characteristic of an individual organism → Genotype + Environment = Phenotype Fitness – how many offspring can be produced Phenotypic plasticity – ability of single genotype to produce multiple phenotypes – if environnent doesn’t change → non-plastic perform better Acclimation – change in physiology due to environmental change Thermal niche – tolerance range to thermal stress Microhabitat – specific location within a habitat that differs from the rest of the habitat Allocation of resources – how organisms distribute their energy & materials (ex. nutrients) to different life processes (ex. growth) Seite 5 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution HOW DO ORGANISMS OVERCOME THE STRESS OF HARSH ENVIRONMENTS? Migration seasonal movement of animals Storage adaptive strategy when migration is not possible Dormancy condition in which organisms reduce metabolism Diapause inactive, act dead ex. insects Hibernation reduce energetic costs ex. lowering heart rate & body temperature Torpor short period reduce activity & body temperature WHAT ARE BIOMES? – geographical regions – contain communities composed of organisms with similar adaptations → can be categorized by plants or algae (→ convergent evolution) WHAT DIFFERENTIATES ONE BIOME FROM ANOTHER? Temperature & Precipitation Seite 6 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution 9 terrestrial biomes Biome Pictures Graphs Notable information Tundra Short growth season → no big trees! Boreal forest Dense, evergreen needle trees, short growing season, severe winter Temperate Growth limited by rainforest temperature, tall evergreen trees, much understory Temperate Strong seasonality, seasonal forest deciduous trees & needle trees Woodland / Growth limited by Shrubland drought (summer) & cold temp. (winter) → thick evergreen shrubs Temperate Grass, non-wood plants & grassland drought-resistant shrubs, frequent fires, precipitation varies widely Tropical High biodiversity, rainforest highest biological productivity on earth Tropical Wet & dry periods, seasonal forest / grasses & deciduous trees Savanna Subtropical Extremely dry, desert plants grow far apart (to get as much water as possible) Seite 7 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution WHAT DOES “LIFE HISTORY” MEAN & WHY DOES IT MATTER? → Schedule of an organism’s growth, development, reproduction & survival Fecundity Number of offspring per reproductive episode Parity Number of reproductive episodes Longevity (life expectancy) Life span HOW DO LIFE HISTORY TRAITS SAY ABOUT AN ORGANISMS STRATEGY IN AN ENVIRONMENT? – Variation in one life history trait → correlation to variation in other life history trait → ex. longer life expectancy & clutch size – same life history traits = same environment = convergent evolution CSR system Trade off (a/sexual reproduction) Best life history – No organism has the best of all life history traits → Trade offs (due to finite amount of resources) → Resource can only be used for one thing at a time → Principle of Allocation – Optimal life history: balance between survival & reproduction for the best fitness Seite 8 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution WHEN DO POPULATIONS GROW LIKE CRAZY & WHEN/HOW THEY LEVEL OFF? Population dynamics Exponential population growth Assumptions: – Population growth is constantly changing – Emigration & Immigration rates are constant Birth & death rates per indiv. b & d → r (growth rate) Exponential growth formula → if deaths & births are equal → no change (= 0) Populations grow exponentially when resources are unlimited! → ex. invasive species → but resources will get limited at some point → Exponential growth is not sustainable Seite 9 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution Logistic population growth Logistic equation Logistic population growth formula → K = carrying capacity Density dependence Relationship between population change (r) and population density (N) Carrying capacity Max. amount of indiv. in a population that can survive in a certain environment over time Seite 10 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution WHAT ARE THE VARIOUS TYPES OF NATURAL ENEMIES IN ECOSYSTEMS? Ecological community competition Group of species that occur together & interact in space & time Vertical interactions – Predation – Herbivory – Parasitism – Pathogens Horizontal interactions natural enemies – Competition Predator Parasitoid Parasite Pathogen Lives within their Lives on/within their living host & host but rarely kills it. Type of parasite Kills & eats their prey. consumes their tissue. → Ectoparasite that causes disease Will eventually kill → Endoparasite in host. the host. (inter-/intracellular) Parasites: Seite 11 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution WHAT ARE THE EFFECTS OF NATURAL ENEMIES ON THEIR PREY/HOST/RESOURCE POPULATIONS? – Regulation of population Modes of predation Active hunting – Predators move around & look for prey → Ex. leopard Ambush hunting – Predators wait for prey to pass by → Ex. spiders Year 3 & 4 → density dependant (too many spiders, not enough resources) HOW DO PREY/HOSTS DEFEND THEMSELVES AGAINST NATURAL ENEMIES? → Good defence comes with a cost → defence vs. growth/reproduction → trade-off Behavioural defence – Prey is adjusting it’s behaviour to escape predation → Ex. alarm calling, spatial avoidance & reduced activity Crypsis – = Camouflage Structural defence – Mechanical defence – Reduces predator’s ability to attack/capture/handle the prey Chemical defence – Prey uses chemicals to put off predators Batesian mimicry – Palatable (yummy) species evolve warning colours & then looks like unpalatable species Müllerian mimicry – Several unpalatable species evolve the same pattern of warning colours Aposematism – Prey warns predator → imitates another (unrelated species) → “Don’t come near. I’m dangerous!” Seite 12 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution WHY ARE NATURAL ENEMIES IMPORTANT FOR ECOSYSTEMS? – Trophic cascade effect → “The enemy of my enemy is my friend.” WHAT IS COMPETITION? – Negative interaction between two (or more) species that depend on the same resource → More resources = more population growth Interspecific competition – Competition between individuals of different species Intraspecific competition – Competition between individuals of the same species HOW DO WE PREDICT COMPETITIVE OUTCOMES? Liebing’s Law of the Minimum “A population will increase until the supply of the most limiting resource prevents it from increasing further.” If we know the minimum amount of a resource that is required for populations to grow, we can predict which species will be the best competitor for that resource. Example: Seite 13 von 64 Biologie - HS 2024 Grundlagen Ökologie & Evolution Competitive exclusion principle HOW DO SPECIES AVOID COMPETITION? – Niche differentiation → Very similar (closely related) species have stronger competition (because same resource) Seite 14 von 64