BIOB50H3F Ecology Fall 2024 PDF

BIOB50H3F Ecology Fall 2024 Introduce myself… Laboratory of Quantitative Global Change Ecology - How do climate change, land use change, and other disturbances Dr. Péter Molnár...

BIOB50H3F Ecology Fall 2024 Introduce myself… Laboratory of Quantitative Global Change Ecology - How do climate change, land use change, and other disturbances Dr. Péter Molnár alter ecological and epidemiological interactions? MSc: Mathematics University of Munich PhD: Mathematical & Statistical Ecology Climate Change Impacts on Polar Bears University of Alberta Postdoctoral Fellow: Disease Ecology, Global Change Ecology, Conservation Biology Climate Change Impacts on Parasitism & Disease https://www.utsc.utoronto.ca/labs/molnar/ Princeton University Introduce myself… Laboratory of Quantitative Global Change Ecology - How do climate change, land use change, and other disturbances Dr. Péter Molnár alter ecological and epidemiological interactions? MSc: Mathematics University of Munich e.g., how does climate change PhD: Mathematical & Statistical Ecology affect polar bears? Climate Change Impacts on Polar Bears University of Alberta e.g., how does land use change affect interactions between mammal populations and their parasites (e.g., via disease spillovers)? Postdoctoral Fellow: Disease Ecology, Global e.g., how does climate change alter Change Ecology, Conservation Biology the spread of parasitic diseases? Climate Change Impacts on Parasitism & Disease https://www.utsc.utoronto.ca/labs/molnar/ Princeton University Learning Goals BIOB50H3F is an introductory course to Ecology. Students in this course will: - become familiar with fundamental ecological principles and concepts across all ecological levels of biological organization, from the individual level (physiological / behavioral), to populations, communities, and ecosystems - become familiar with classical ecological studies and results that form the foundation for modern ecological studies and applications - learn how to interpret different types of ecological data, including from theoretical, observational, experimental, and modelling studies - learn how to formulate and test ecological hypotheses in various contexts - learn how to formulate, apply, analyze, and interpret basic ecological models for individual, population, and community dynamics - learn how to use spreadsheet programs to implement and evaluate basic population and community dynamics models - learn how to apply ecological principles, concepts, and models to understand applied aspects of ecology, such as disease ecology, climate change impacts, and approaches to conservation biology WHAT IS ECOLOGY? What is Ecology? Early Ecologists Throughout their history, people have tried to understand how nature works. Knowledge passed on over generations (traditional ecological knowledge) and/or acquired by knowledgeable locals (local ecological knowledge) remain important sources of ecological understanding to this day. In the western literature, ecological writings (describing relationships between animals and plants) can be traced back as far back as Aristotle and his students (4th century BC). Leaps in knowledge occurred during the 17th-19th century when naturalists greatly advanced their fields. Carl Linnaeus, 1707- Alexander von Humboldt, Charles Darwin, 1809- 1778 (taxonomy) 1769-1859 (biogeography) 1882 (evolution) What is Ecology? Definition and the Beginnings of Modern Ecology The term “ecology” was coined in 1866 by Ernst Haeckel, from oikos (Greek: “household”, “home”, “place to live”) and logos (Greek: “study of”): “By Ökologie we mean the comprehensive science of the relationships of the organism to its surrounding environment, in which we include, in the broader sense, all "conditions of existence.“ Ecology is the scientific study of the interactions of organisms with their environment and one another that determine their distributions and abundances. An Example of Ecological Interactions (with implications for conservation biology and human food security): A marine trophic cascade After nearly a century of recovering from overhunting, sea otter populations were suddenly in decline over large areas of their range during the late 20th century. Simultaneously, increased predation by orcas was observed, and kelp forests were lost and being replaced by urchin barrens. What is happening? in decline being transformed preferred prey Increased predation Suppresses (small effect) With overfishing, sea lion and seal populations With lots of fish, Suppresses decline, leading indirectly to sea lion and seal (large effect) an increased predation by populations are orcas on sea otters large Suppresses (small effect) Suppresses (large effect) from Estes et al. 1998, Science An Example of Ecological Interactions (with implications for human health): Land Use Change Impacts on Schistosomiasis Epidemics Schistosomiasis (aka snail fever, bilharzia): caused by parasitic flatworms called schistosomes. urinary and/or intestinal infections (abdominal pain, diarrhea, bloody stool, blood in urine). Chronic infections can lead to liver damage, kidney failure, infertility, or bladder cancer. >250M people affected Everything in Nature is Interconnected! In general, organisms within ecosystems are connected in myriads of ways (e.g., through their resource needs), leading to complex interaction webs (cf. Lecture 9 for details). a classical food web without parasites a food web with parasites included ECOLOGY IN THE ANTHROPOCENE The “Great Acceleration” In the Anthropocene, human impact has now grown to the point that it has changed the course of Earth history for millennia. Human actions dominate the planet and have led to a biological world that is rapidly shifting towards an unknown future state. Sociological changes Ecological changes Anthropogenic Impacts on Ecosystems Ecologists are facing numerous new challenges in the Anthropocene, including understanding the impacts of, and devising mitigation strategies for: Land Use Change Climate Change Overexploitation Invasive Species & Ecosystem Homogenization Species Extinctions “Doctor to an Unwilling Patient” “One of the penalties of an ecological education is that one lives alone in a world of wounds. Much of the damage inflicted on the land is quite invisible to laymen. An ecologist must either harden his shell and make believe that the consequences of science are none of his business, or he must be the doctor who sees the marks of death in a community that believes itself well and does not want to be told otherwise. Aldo Leopold (1949), In A Sand County Almanac BUT I’M NOT AN ECOLOGIST… “But I’m not an Ecologist.” - The world is changing and these changes will influence both your personal (e.g., impacts of ecosystem service losses on your well-being) and professional life (e.g., how your company interfaces with ecological sustainability). Understanding ecological connections will help you better understand and navigate these challenges. - The concepts and tools you learn in this course are used in many related fields in an analogous manners: S I R e.g., epidemiology e.g., medicine e.g., demography - Many new approaches to complex biological challenges integrate knowledge from multiple subdisciplines, e.g. One Health: COURSE OVERVIEW Levels of Biological Organization Population (group of individuals of same species, living and interacting Individual with one another in a particular area) Community (an association of interacting populations of different Ecosystem (a community of species, living and interacting in the organisms plus their abiotic Biosphere (all the same area) (physical) environment) world’s ecosystems) Lecture Schedule Lecture 1 – What is Ecology? [Chapter 1] Biosphere Lecture 2 – Organisms & Their Environment [Ch. 3] Individuals Lecture 3 – Individuals: Physiology & Behavior [Ch. 5.1-5.3, 5.5-5.7] Lecture 4 – Population Dynamics 1 (Pop. Monitoring, Pop. Growth) [Ch. 2, 6.1-6.7] Populations Lecture 5 – Populations Dynamics 2 (Pop. Growth, Spatial Dynamics) [Ch. 6.8-6.9, 12.1-12.4] Lecture 6 – Interactions 1: Competition [Ch. 7.1-7.3, 7.5-7.6] Populations, Communities Lecture 7 – Interactions 2: Exploitation (Predation) [Ch. 8] Lecture 8 – Interactions 3: Exploitation (Parasitism & Disease) [Readings TBA] Lecture 9 – Multispecies Interactions & Food Webs [Ch. 10] Communities, Ecosystems Lecture 10 – Biodiversity & Biogeography [Ch. 11, 12.6] Lecture 11 – Communities Through Time [Ch. 13] Lecture 12 – Global Change Ecology (Ecology in the Anthropocene) [Ch. 15]  Think – Pair – Share The geographic range of malaria is expanding. Imagine you are a public health manager, who is tasked with understanding the ecological dynamics of this change, predicting where / when / and in what abundance malaria will be present in different areas around the globe, and devising mitigation strategies.  Think – Pair – Share The geographic range of malaria is expanding. Imagine you are a public health manager, who is tasked with understanding the ecological dynamics of this change, predicting where / when / and in what abundance malaria will be present in different areas around the globe, and devising mitigation strategies. Look at this course’s Lecture Schedule & write down scientific questions (one for each lecture topic) about the ecological dynamics of malaria that you think might help you with these tasks. Lecture Schedule Lecture 1 – What is Ecology? [Chapter 1] Biosphere Lecture 2 – Organisms & Their Environment [Ch. 3] Individuals Lecture 3 – Individuals: Physiology & Behavior [Ch. 5.1-5.3, 5.5-5.7] Lecture 4 – Population Dynamics 1 (Pop. Monitoring, Pop. Growth) [Ch. 2, 6.1-6.7] Populations Lecture 5 – Populations Dynamics 2 (Pop. Growth, Spatial Dynamics) [Ch. 6.8-6.9, 12.1-12.4] Lecture 6 – Interactions 1: Competition [Ch. 7.1-7.3, 7.5-7.6] Populations, Communities Lecture 7 – Interactions 2: Exploitation (Predation) [Ch. 8] Lecture 8 – Interactions 3: Exploitation (Parasitism & Disease) [Readings TBA] Lecture 9 – Multispecies Interactions & Food Webs [Ch. 10] Communities, Ecosystems Lecture 10 – Biodiversity & Biogeography [Ch. 11, 12.6] Lecture 11 – Communities Through Time [Ch. 13] Lecture 12 – Global Change Ecology (Ecology in the Anthropocene) [Ch. 15] Course Administration & Logistics please see syllabus  HOW DO WE LEARN ABOUT ECOLOGY? 1) Observation & Natural History 2) Experimental Ecology & Null Hypothesis Testing 3) Multiple Hypothesis Testing with Best-Fit Comparisons 4) Ecological Modelling Approaches to Ecology: Observation & Natural History Observation & Natural History Natural history is the study of animals, plants, and fungi, particularly focusing on observation and description (rather than experiment or scientific analysis). Alexander von Maria Sybilla Humboldt, Merian, 1647-1717 1769-1859 (entomology) (biogeography) Charles Darwin, 1809-1882 Natural history is the historical foundation of the field of ecology but differs (evolution) from modern approaches, where observations are typically combined with other approaches of scientific analysis. Approaches to Ecology: Observation & Natural History In modern times, observation remains critical to the study of ecology but has shifted away from describing species to describing broad ecological patterns combined with other approaches of scientific analysis. Example: National Ecological Observatory Network (NEON), collecting >175 types of open- access data from 81 locations across 20 different ecological domains following standardized protocols Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Experimental Ecology & Null Hypothesis Testing From the second half of the 20th century onwards, ecologists increasingly began to apply manipulative experiments and statistical hypothesis testing (i.e., researchers develop hypotheses about the mechanisms that lead to observed ecological patterns, and then conduct carefully designed experiments to produce evidence for supporting or rejecting the hypothesis). Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Based on observation (either direct or through knowledge from previous work / the literature), propose a question. Based on your question, propose a null hypothesis (focal factor does not have an effect) and an alternative hypothesis (focal factor has an effect). Design an experiment that alters/manipulates one or more focal factors (including controls with no manipulation for comparison) and can falsify the null hypothesis (i.e., show that the focal Interpretation leads to factor(s) do have an effect). new questions and the process restarts. The process is iterative and Analyze the data to arrive at results, and then an interpretation self-correcting. for the observations Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Example: Lynx-Snowshoe Hare Cycles (cf. Lecture 7 for details) Observation: One of the most famous and best-documented patterns in ecology is the predator-prey cycle of lynx and snowshoe hare. Data go back to the mid-19th century based on records of pelts that were received by the Hudson Bay’s Company. Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Example: Lynx-Snowshoe Hare Cycles (cf. Lecture 7 for details) Ecological theory suggests that “+/- relationships” between consumers and their resource may lead to population cycles in both the consumer and the resource. Predator Prey Questions: + Are the reported lynx-hare cycles driven by predator-prey interactions? - Herbivore Plant + Or are they driven by interactions between hare and their food resources? - Or are there some alternative explanations? Approaches to Ecology: Experimental Ecology & Null Hypothesis Testing Example: Lynx-Snowshoe Hare Cycles (cf. Lecture 7 for details) Experiment: Charlie Krebs & colleagues designed a large-scale field experiment to test whether hare cycles are a consequence of predation or due to competition for limited food supplies. They set up 1km x 1km blocks of forest in Yukon, YT, where they monitored hare densities & survival rates for eight years. Control + food Results: “Predator exclosure doubled and food addition tripled hare density during the cyclic peak and decline. Predator exclosure combined + food with food addition increased density 11-fold. […] Food and - predator predation together had a more than additive effect, which suggests - predator that a three-trophic-level interaction generates hare cycles.” from Krebs et al., 1995, Science Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Multiple Hypothesis Testing with Best-Fit Comparisons In many situations, experiments cannot be repeated (e.g., due to ecosystem idiosyncrasies over time and space), or conducted logistically (e.g., experimental approaches are typically biased towards small species and short timescales), or ethically (e.g., experimentally testing the effects of an increasingly stressful climate on an endangered species). However, large amounts of various types of data are often available or can be can collected by observation only, without manipulation. Similar to real-life sleuths, ecological detectives can use these data to assess the strength of evidence for a suite of hypotheses regarding which ecological processes might operate. Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Multiple Hypothesis Testing with Best-Fit Comparisons provides a considerable philosophical departure from the classical hypothesis testing framework outlined in the previous section: Instead of aiming to falsify a hypothesis that suggests that a particular factor has no effect, the approach aims to evaluate multiple competing hypotheses for their relative support by the data. Advantages: - can make use of large amounts of available information - allows simultaneously working with multiple hypothesis, and thus, our comprehensive understanding of how an ecosystem works - acknowledges uncertainty - can easily accommodate real-world complexities without requiring large-scale experiments Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Example: Sea Lice Epidemics on Salmon In the early 2000s, infestations of young juvenile salmon with a parasitic copepod, commonly known as “sea louse”, began being reported from the Broughton Archipelago, BC. Alexandra Morton Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Example: Sea Lice Epidemics on Salmon Suspicions began to emerge that the sea lice may be originating from one or more fish farms along the salmon migration route. Sampling within the farm is not possible. Experimentally removing the farm is also not possible. So, how can we evaluate the evidence for this hypothesis? from Krkošek et al. 2006, Proceedings or the Royal Society B Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Example: Sea Lice Epidemics on Salmon Multiple hypotheses may explain the presence of sea lice on migrating juvenile salmon. However, each hypothesis suggests a different spatial pattern of sea louse occurrence. H2: sea lice originate from a H3: occur naturally throughout the H1: sea lice occur naturally fish farm along the salmon’s fjord, with additional contributions throughout the fiord migration route from the fish farm Abundance of sea lice Abundance of sea lice Abundance of sea lice fish farm fish farm fish farm Migration distance Migration distance Migration distance from Krkošek et al. 2005, Proceedings or the Royal Society B Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Example: Sea Lice Epidemics on Salmon Results from Krkošek et al. 2006, Proceedings or the Royal Society B Approaches to Ecology: Multiple Hypothesis Testing with Best-Fit Comparisons Example: Sea Lice Epidemics on Salmon Results relative weight of support by the data H1: ‘only natural’ H2: ‘only farms’ H3 ‘both’ The data suggest that sea lice occur naturally throughout the fjord and that there is a particularly strong infection hotspot at the location of the fish farm. from Krkošek et al. 2006, Proceedings or the Royal Society B Approaches to Ecology: Ecological Modelling Ecological Modelling Models play a fundamental role in modern ecology. - Similar to experiment they allow exploring how various factors affect ecological dynamics, but without the need for experimental manipulation. - “Every model is wrong, but some are useful.” (George Box). Models can be used in many ways, including for: - understanding the mechanisms that lead to ecological patterns - testing complex hypotheses against data - estimating missing information (e.g., population numbers) - identifying what we don’t understand about a system - guiding management - providing forecasts - How much realism in included in a model depends on its purpose. - Many types of models are commonly used in ecology. Models may be conceptual or mathematical; mathematical models may be analytical or simulation-based. Approaches to Ecology: Ecological Modelling Type: Analytical Model; Use: Formalize Complex Ideas Example: The Lotka-Volterra Model of Predation about Interactions; Generalize Understanding Predator Prey + - In Lecture 7, we will see how formalizing our conceptual model of a +/- relation among predators in a mathematical model dN dP = rN − aNP = baNP − mP dt dt suggests that predator and prey cycle around a stable equilibrium point that is determined by the growth rate of the prey, the mortality rate of the predator, the capture efficiency of the predator, and the energetic efficiency of the capture- consumption process: N = m / ba P=r a Approaches to Ecology: Ecological Modelling Type: Simulation Model; Example: Sea Turtle Demographics and Conservation Use: Guide Management Strategies In Lecture 4, we will see how a basic demographic model of loggerhead sea turtles has been used to identify key conservation strategies. Approaches to Ecology: Ecological Modelling Type: Simulation Model; Example: Climate Change and Malaria Use: Climate Change Impact Assessment Combining measurements of the temperature sensitivity of mosquitoes and the malaria parasite with a disease transmission model allows estimating how climate warming may alter the global distribution of malaria (cf. Lecture 3 for more details). blue line: R0 as a function of temperature (ignore red line)  ASSIGNED READINGS: Mandatory: Chapter 1 Recommended: Chapter 2 THERE IS NO QUIZ THIS WEEK.