Next Week: Final 4 presentations - two on Tuesday and two on Thursday… No readings! Today: Are there Laws and/or Foundational Principles of Ecology? 18 of you said yes….

But there’s more to science, and to ecology, than being able to predict things. We seek knowledge, which implies understanding. Ultimately, this means that ecologists must deal with causality (e.g. pattern-process) –> mechanisms The goal of a science is to establish general laws that will facilitate systematic explanation and prediction --Nagel 1961

Oxford Dictionary of Science A law is a descriptive principle of nature that holds in all circumstances covered by the wording of the law. There are no loopholes in the laws of nature and any exceptional event that did not comply with the law would require the existing law to be discarded or would have to be described as a miracle.

According to Webster…. Principle: the ultimate source, origin or cause of something, a fundamental truth, an essential element, constituent, or quality, especially one that produces a specific effect

Why has the development of laws been so difficult in Ecology? 1.Human nature of scientists (ecologists in particular) 2.Logistical difficulties and practical challenges of Ecology 3.Complexity inherent in intermediate scales 4.Unique role that “history” plays in Biology Recap from earlier in the semester…

(1) Back to “Theorists” vs. “Natural Historians”… Ecological patterns, about which we construct theories, are only interesting if they are repeated. They may be repeated in space or in time, and they may be repeated from species to species. A pattern which has all of these kinds of repetition is of special interest because of its generality, and yet these very general events are only seen by ecologists with rather blurred vision. The very sharp-sighted always find discrepancies and are able to say that there is no generality, only a spectrum of special cases. R.H. MacArthur (1968). The Theory of the Niche.

(2) Unique challenges of Ecological Research: Conducting repeatable experiments with identical results is difficult in ecology… Ch. A.S. Hall (1988) lamented that “if physicists had to model electrons that behaved differently when they were hungry, they would probably be not much ahead of ecologists…”. Melvin T. Tyree (1983) noted while conducting experiments in the field that “progress was rather slow because weather conditions could not be arranged to meet experimental requirements”

Physical scientists cannot describe the “intermediate” world very well at all… Wind shear Turbulence Weather Floods Hurricanes Earthquakes (3) Complexity of intermediate scales

Intermediate scales in Ecology Simple (silly) example: Water and productivity. Growth chamber study— Vary water availability in pots (field capacity – wilting) Hold everything else constant 100% predictive power– Productivity = f(water) & mechanism is understood at this small scale and under strictly controlled conditions Scale: many years, 1000 km Law applies at large scale! Intermediate scale?

(4) Contingency and history in biology and ecology Evolutionary Contingency (Beatty 1995): all biology represents the contingent products of evolution. This make ecology (& biology) unique - and immutable laws less likely. Gould’s (1989) metaphor for biology: Biology is a river of evolution with chemistry and physics forming the banks. The banks ultimately constrain processes in the river and what happens upstream (history) affects what happens downstream. But, for any particular reach of the river, there is structure (the underpinning rules?) that shapes the flow of the current…

Ecological State A Ecological State B Independent variable If A goes to B 100% of the time, we have a pattern or a generality… If A goes to B 100% of the time and we know the mechanism, we have a law… But what if if A goes to B 66% of the time and we know the mechanism for this… And it goes to C and D at other times and we know less of these mechanisms…and, we can only predict marginally well when A will go to C or D? Then we have Ecology…where complexity is due to the present and the past… C D

AB Independent variable Underpinning law Evolutionary History Ecological History Abiotic Factors Biotic Factors C D E F H G History and complexity combined Even though predictability may be low, does this mean that there are no underpinning laws?

Lawton (1999) – “General principles that underpin and create pattern” Are there Laws in Ecology? Class re-vote:

A goal of a science is to establish general laws (or rules or principles or understanding?) that will facilitate systematic explanation and prediction? --Nagel 1961 Can we agree that…

Recent seminar indicated that only 10% of the facts taught in lecture courses are retained…and we should teach concepts or principles instead. This means one should have a good idea of what the central concepts/principles of Ecology are. If someone where to ask you to list the most important principles (rules, generalities, concepts) in Ecology, what would you consider them to be?

Assignment: What are the core principles of ecology that underpin and create the patterns and processes we see? Principle: the ultimate source, origin or cause of something, a fundamental truth, an essential element, constituent, or quality, especially one that produces a specific effect Break into groups of 4 – turn these in (legibly written) at the end of class… (include names of people in each group)