1Grundkurs Ökologie: Einführung (Kapitel 1-7)
Introduction to the Course and Instructor
Speaker Identification: The lecturer is Tomel Chatkes (nicknamed Tommy), the new professor for applied zoology and animal ecology at the institute.
Background: He is a behavioral biologist and a non-native German speaker (English origin).
Laboratory: He leads the Animal Cognition and Ecology Lab, known as the ASLAB.
Research Focus Areas:
Insect behavior.
Chemical ecology.
Collective behavior.
Invasive ants.
Research Examples and Methodologies in ASLAB
Lego and 3D Printing: Lego was historically used for experimental setups, but has increasingly been replaced by 3D-printed components which are more aesthetic while serving the same function.
Effort vs. Reward Study: Using experimental setups to determine if ants prefer food they worked hard to obtain ("schwer erkämpft") over food that was easily accessible ("leicht erkämpft"). Observations indicate ants prefer food they worked more for.
Chemical Recognition: Glass beads treated to smell like ants are used to observe social interactions; an ant might perceive a bead as a "sister" due to the scent.
Marking Techniques: Ants are marked with tiny dots of paint ("Farbtöpfe Tüpse") on the abdomen ("Hinterleib") for individual tracking.
Collective Behavior:
Studying path selection (e.g., why a colony chooses one food source or trail over another).
Researching "collective hauling" of large objects, a process not yet fully understood.
Ant "Toilets": An accidental discovery led to the study of specific locations ants use for waste. By feeding ants sugar solutions with red or blue food coloring, colored "toilets" were identified.
Fieldwork: Research is conducted on invasive species, specifically the Argentine ant (Lenivitima Humele), with the goal of developing control measures in Spain.
Defining Ecology
Historical Definition (Haeckel): Focuses on the interaction of a single organism with its environment. This is considered outdated.
Modern Definition: Ecology is the scientific research into the distribution, abundance, and interactions between organisms and their environment.
Applied vs. Basic Research:
Applied Science: Likely the original form of ecology, established thousands of years ago for survival (e.g., understanding the effects of burning a forest or animal migration after rain).
Basic (Fundamentals) Research: Developed primarily over the last to years.
Relationship: There is no strict separation; it is a gradient where researchers frequently move between both poles.
Recommended Literature
Ökologiebuch: Described as very high-quality and very deep, often deeper than the lecture content.
Essentials Forcology: A shorter version that has been translated into German. It remains deeper than what is covered in the standard lecture but is highly recommended.
Applied Ecology in Practice
Agriculture and Wind Protection
Research into maximizing yields by altering abiotic factors.
Example: Planting trees as windbreaks.
Mixed Effects: Trees may lower temperatures and increase soil moisture (positive), but also compete for nutrients, including , and cast shade (negative). They may also provide habitat for natural enemies of pests (integrated pest control).
Crop Specificity: Wind protections are very helpful for beans (yield increase of approximately ) but only slightly helpful for oats (yield increase of approximately ).
Pest Control and Ant-Aphid Mutualism
Ants herd aphids, which suck plant juices. This juice is high in sugar but low in nitrogen. Aphids filter the nitrogen and excrete the sugar as honeydew.
Ants "milk" the aphids and protect them from natural enemies. They even move aphid eggs into their nests during winter and bring them back in spring.
Meta-analysis Results: Despite ants increasing aphid numbers, they are generally beneficial for yields because they consume other, more significant pests.
Fisheries and Conservation
Sustainability: Determining how many fish can be harvested without causing a population collapse.
Bycatch Reduction: Solving the issue of dolphins being caught in tuna nets.
Ecological Indicators: Tuna, dolphins, and seabirds often form a community. From the surface, birds and dolphins are visible, signaling tuna below.
Success Story: In the 1960s, approximately dolphins were killed annually. By modifying net designs (allowing dolphins to jump out top while tuna remain lower), this number has been reduced to approximately per year.
Environmental Pollution
Microplastics: Research by Matthias Rillig shows that microplastics are detrimental to yields. The shape (films, fragments, or strands) matters more than the material type; small strands are less harmful than larger fragments.
Biological Indicators:
Mussels: Used as early warning systems in European cities; they close their shells when water quality drops, which can be measured via electrodes.
Ants: City ants are less "picky" ("pingelig") about food quality compared to country ants. This behavioral change could signify ecological health.
Nature Conservation
Simulation Models: Used to evaluate Marine Protected Areas (MPAs).
Findings: Protecting large fish is more effective than protecting small fish because large fish produce significantly more eggs.
Patience: Due to high annual variability, the effects of conservation measures may not be visible for many years.
Fundamentals of Ecology
Trophic Interactions and Energy Flow
Concept: Who eats whom and how energy flows through a system.
Flow: Energy enters via primary producers, is consumed by consumers, and eventually enters the pool of dead organic material and decomposers ("Destruenten").
Predictive Modeling: Ecologists quantify these flows to predict ecosystem changes.
Invasive Species and Ecosystem Cascades
The Acacia/Ant/Zebra Case Study:
Acacia trees and Acacia ants live in symbiosis (ants live in hollow thorns and eat food produced by the tree).
Ants protect trees by stinging elephants.
"Big-headed ants" (Großkopfameisen) invade and drive out Acacia ants.
Without ants, elephants eat the Acacia trees, turning forest-like areas into open savanna.
This open landscape favors lions (who hunt better in the open) resulting in a decline in the zebra population.
Population Dynamics
Source and Sink Populations: Some areas (Source) produce a surplus of individuals, while others (Sink) cannot sustain a population without immigration.
Mayfly Example: Ponds without perch (predators) are source populations; ponds with perch are sink populations where larvae are consumed.
Behavioral Ecology and Climate Change
Phenological Shift: Birds are laying eggs earlier due to global warming (e.g., earlier).
Risk: This increases the probability that chicks hatch during a cold period before insects are active. Mass mortality of chicks can lead to population extinction.
Organizational and Technical Branches of Ecology
Autecology (Autoökologie): Perspective of a single species.
Chemical/Molecular Ecology: Study of natural substances and nutrient biosynthesis.
Ecophysiology: Factors affecting metabolism.
Evolutionary Biology: Factors influencing species evolution.
Population Ecology: Study of breeding communities of one species.
Population Genetics: Distribution of alleles.
Epidemiology: Flow of pathogens.
Community Ecology (Synecology):
Study of succession, biodiversity, and energy flows within a community of populations.
Ecological Terminology and Levels
Biocenosis (Biozennosen): The entire community of different species in a specific habitat.
Biotop: The living space for a biocenosis (e.g., a pond).
Habitat: The living space for a single specific species (e.g., a specific sludge layer for a worm).
Ecosystem: Biocenosis $+$ Biotop.
Biome: A community of biocenoses within a large climatic area (e.g., Tundra or Tropical Savanna).
Hierarchical Levels: Ecology spans from the entire biosphere down to individual organisms. To understand a mechanism at one level, one must often study the level below it.
Scale: Temporal scales range from seconds to approximately years.
Key Principles and Patterns in Ecology
Complexity: Ecosystems are non-linear; more of one thing does not always mean more of another.
Long-term Patterns: Long-term studies are essential. For example, acid rain data from a or -year period might suggest an increase, whereas a -year dataset confirms a downward trend.
Distribution Types:
Random (Zufällig): Difficult for humans to perceive without statistics (e.g., lichens on a stone).
Regular/Even (Gleichmäßig): Often seen in nesting sites where individuals maintain distance from neighbors.
Aggregated/Clumped: Groups of individuals (e.g., flowers in a meadow).
Abundance Rule: Generally, as body weight increases, abundance (density per area) decreases.
Isotope Analysis for Trophic Levels
Method: Measuring ratios of Nitrogen isotopes ( vs. ). The heavier variant is preferentially enriched in tissues as one moves up the food chain.
Bat Example: Fieldwork in Costa Rica/Ecuador involved catching bats with mist nets ("Nebelnetze") in the canopy.
Findings: Using biopsies and fecal matter, researchers found that "carnivorous" bats occupy a trophic level of approximately (not ), indicating they still consume significant amounts of insects.
Succession and the Mosaic Cycle
Primary Succession: Occurs after a total wipeout (e.g., volcano, glacier retreat). Steps: Pioneer plants $\rightarrow$ Shrubs $\rightarrow$ Fast-growing trees $\rightarrow$ Slow-growing trees $\rightarrow$ Climax stage.
Mosaic Cycle Theory: The "climax" is not static. Small-scale disturbances (lighting, fire, fallen trees) create a mosaic of different successional stages within one area.
Trophic Pyramids: Biomass and energy decrease at higher trophic levels due to an ecological efficiency of < 1.
Efficiency Calculation Example: If of plant energy yields of herbivore mass, the efficiency is .
Energy Loss Causes: Not everything is eaten; energy is lost through feces, respiration, and growth costs.
Energy Sources for Ecosystems
Autochthonous Biocenosis: Self-sufficient; produces its own energy via photosynthesis (e.g., forests, ocean surface).
Allochthonous Biocenosis: Dependent on external energy; no primary production (e.g., caves, deep sea, fast-moving streams).
Deep Sea Exception: Hydrothermal vents serve as highly productive biocenoses. Sulfur-rich water supports bacteria, which in turn support organisms like Rifthia (giant tube worms) through chemosynthesis.
Types of Evidence in Ecology
Observations: Measuring aspects without intervening. Useful for finding patterns and forming hypotheses (e.g., recording grouse population cycles in Scotland).
Experiments: Systematically varying one variable while keeping others constant to establish causality (e.g., removing parasites to stop population cycles; nitrogen additions to study species richness).
Limitation: Expensive, short-term, and often limited to one variable.
Models: Abstractions (mathematical or simulations).
Quantitative Models: Require reliable data from measurements and experiments.
Agent-based Models: Simulations to identify general patterns (e.g., forest fire behavior based on wind and dryness).