L01_what_even_is_ecology.pdf

Principles in Ecology PCB 4043 What even is ecology? Prof. Fahimipour (pronounced “Fa-he-me-poor”) Topics: Scale, organization, interactions [email protected] D: 437 DW | B: 206 Sanson The food that we eat Networks of plants and pollinators provide at least a $0.5 billion per year ser...

Principles in Ecology PCB 4043 What even is ecology? Prof. Fahimipour (pronounced “Fa-he-me-poor”) Topics: Scale, organization, interactions [email protected] D: 437 DW | B: 206 Sanson The food that we eat Networks of plants and pollinators provide at least a $0.5 billion per year service to food production The air you are breathing right now A long game of pacman between plankton controls global oxygen dynamics The fisheries that sustain our economies Billions of people rely on coral reef fish systems for food and tourism The symbionts making your vitamins The E. coli living in your gut make your vitamin K, without which you could not survive Natural predators that protect our crops Reduced pesticide use 50% worldwide Our health in the buildings we occupy We spend 90% of our time indoors exposed to complex microbial ecosystems floating on dust bunnies The medicines we need Something like 25% of our drugs are plant-derived, making biodiversity preservation a medical issue Understanding the emergence of societies Learning how cooperation is advantageous is natural ecosystems Cutting-edge personalized medicine Combating antibiotic-resistance bacterial infections using their natural phage Designing swarming robots and self-driving cars Run algorithms that animals use in collective movements Designing swarming robots and self-driving cars Run algorithms that animals use in collective movements What even is ecology? “The study of the house” Ecology is the study of how organisms interact with each other and with their environment. Direct interactions Indirect interactions Ecologists evaluate competing hypotheses about natural systems with observational data, experiments, and mathematical models. The tangled web of life Circles : Populations of species Lines : Feeding interactions Modern ecology Sees ecosystems as complex systems Connects ecology as a discipline to other complex systems sciences Financial systems The internet The electrical grid Robots, personalized medicine, and all that stuff In complex systems, phenomena can be linked by long chains of cause-and-effect This leads to complicated and often non-intuitive results Ponds with fish have more flowers around them Deformity and Decline in Amphibian Populations: A Case Study (1) There is a high incidence of deformities in amphibians. Amphibian populations are declining worldwide. Amphibians are “biological indicators” of environmental problems: –Skin is permeable; pollutant molecules can pass through easily. –Eggs have no protective shell. –They spend part of their life on land and part in water—exposed to pollutants and UV in both environments. Deformity and Decline in Amphibian Populations: A Case Study (1) Observation of Pacific tree frogs suggested that a parasite (Ribeiroia ondatrae, a trematode flatworm) cause deformities. Small glass beads implanted in tadpoles to mimic the effect of Ribeiroia cysts also produced deformities. Further studies by Pieter Johnson (Stanford): –Deformities in these frogs occurred only in ponds that also had an aquatic snail, Helisoma tenuis, an intermediate host of the parasite. –All frogs with deformed limbs had Ribeiroia cysts. Deformity and Decline in Amphibian Populations: A Case Study (1) Controlled experiment: Experimental groups are compared with a control group that lacks the factor being tested. Johnson et al. conducted a controlled experiment: –Tree frog eggs were exposed to Ribeiroia parasites in the lab. –Four treatments: 0 (the control group), 16, 32, or 48 Ribeiroia parasites. –As the number of parasites increased, fewer of the tadpoles survived, and more of the survivors had deformities. Deformity and Decline in Amphibian Populations: A Case Study (1) Research suggested other factors might also be important. A field experiment to test effects of pesticides and Ribeiroia (Kiesecker 2002): –Six ponds, all with Ribeiroia, three with pesticide contamination. –Wood frog tadpoles were placed in 6 cages in each pond; 3 had mesh size that allowed parasites to enter. Idea: Pesticides decrease the ability of frogs to resist infection by parasites. Deformity and Decline in Amphibian Populations: A Case Study (1) Research suggested other factors might also be important. A field experiment to test effects of pesticides and Ribeiroia (Kiesecker 2002): –Six ponds, all with Ribeiroia, three with pesticide contamination. –Wood frog tadpoles were placed in 6 cages in each pond; 3 had mesh size that allowed parasites to enter. Idea: Pesticides decrease the ability of frogs to resist infection by parasites. “The balance of nature” Suggests there are “stable” ecosystems that are in a state of balance. Every species has a specific important role Gaia hypothesis (James Lovelock and Lynn Margulis) This idea that ecosystems are: Self-perpetuating Self-regulating Systems that maintain the conditions for life “The balance of nature” Suggests there are “stable” ecosystems that are in a state of balance. Every species has a specific important role Gaia hypothesis (James Lovelock and Lynn Margulis) This idea that ecosystems are: Self-perpetuating Self-regulating Systems that maintain the conditions for life The problem is that this is basically completely wrong Modern ecological thinking Ecologists now recognize that: Natural systems do not necessarily return to their original state after disturbance. Random perturbations can play an important role. Different communities can form in the same area under similar environmental conditions. Ecological interactions are more complex than previously thought. One view has not changed: Events in nature are interconnected. A change in one part of an ecological system can alter other parts of that system. Scale is everything Ecologists must select appropriate scales of study: Spatial scales: –Small—e.g., soil microorganisms –Large—e.g., atmospheric pollutants Temporal (time) scales: –Short—e.g., leaf response to sunlight –Long—e.g., species change over geologic time Scale is everything Ecologists study interactions across many levels of organization: Population: A group of individuals of a single species that live in a particular area and interact with one another. Community: An association of populations of different species living in the same area at the same time. Ecological studies often include both the biotic (living) and abiotic (physical) components of natural systems. Scale is everything Ecosystem: A community of organisms plus their physical environment. Landscapes: Areas with substantial differences, typically including multiple ecosystems. All the world’s ecosystems comprise the biosphere—all living organisms on Earth plus the environments in which they live. Answering ecological questions How do ecologists answer ecological questions? No single approach works in all situations, so ecologists use a variety of methods: –Observational studies in the field –Controlled experiments in the laboratory –Experiments in the field –Quantitative models Experiments and big data Mathematics and computation Answering ecological questions The natural world is vast, complex, and interconnected. But we do think it is possible to understand it. Ongoing efforts are sure to be challenging, exciting, and important to the well-being of human societies. We need your help! Ecology is the most important science of this century. Course details Check Canvas regularly for announcements Homework Exams (best 4 out of 5) Policies (review syllabus!) Office hours (by Zoom and in-person) Special instructions for this Friday