By Natasha Cadenhead
How do academics forage at morning tea? Do sweets go extinct faster than savouries? Which cake should you eat? How much should you eat? How close should you be to the coffee? The exit?
Yesterday we hosted a structured decision making themed morning tea for staff and students in the School of Botany at The University of Melbourne. Each month one of the research groups in the school provides tea, coffee and delicious baked goods for everyone else. It’s a great chance to get to know people you pass in the hallways every day and learn about research going on in other groups.
Some canny Qaecologist suggested we theme our morning tea around structured decision making. Being a part of The Centre of Excellence for Environmental Decisions (CEED) and the NERP Environmental Decisions Hub, this seemed fitting! We created a decision tree to allow guests to maximise their chosen objectives and enable optimal foraging patterns. If their only objective was maximum intake of coffee, they should linger around the tables close to the source of coffee. If adhering to dietary requirements, the tree could direct them to those tables that could meet their needs. After a sugar hit? Or more of a savoury start to the day? The decision tree could help you attain your goal.
Figure 1. Our decision tree, with potential objectives up the top and the choices below. Want to maximise your coffee intake whilst eating some gluten free sweets? You could head to table B for the cashew slice or polenta pear cake!
Depending on an individual’s objectives the decision tree directed you to an appropriate table, where you would then be faced with a range of resources, of differing detectability. Sometimes plates were hidden beneath fern fronds, other times, highly-visible, sparkly cupcakes were the most obvious and easily detected resource on a table. QAECO members wandered about with clipboards, monitoring which food items were headed for extinction. Qaecologist Bonnie Wintle set up a online-monitoring system to keep track of resource depletion in real time – how much of which cakes were being eaten. We predicted the rarer, savoury species, such as a (rather delicious) onion tart, would become extinct more quickly than, say, the over-abundant carrot sticks.
We compared extinction rate in identical foods with different detectabilities. Using some flashy, highly-visible, pink choc chip cookies, and the notoriously shy, brown choc chip cookies, expertly camouflaged beneath a fern frond. We expect the more easy-to-detect cookie species to go first, even though they taste exactly the same. This is an example of the kind of sampling bias than can negatively impact species distribution models (and you can watch a video about this by Qaecologists José and Guru here). The distance to coffee of two competing cakes was also monitored, the theory being that the cakes at the more easily accessible/desirable site (the table close to coffee) would reach extinction faster than those further away. You can see in the final results in the picture below that the outcomes largely matched our predictions!
Figure 2: Bar graph of the species facing extinction at the end of morning tea. The red line indicates extinction of the species. You can see here that the rare onion tart (Tartiaceae delicious) went extinct first, followed closely by cakes nearest to the coffee table and the highly detectable pink cookies.
Mick McCarthy gave a brief overview of structured decision-making and some of the other work that we do, as well as introducing our (rather large) group with a show of hands, before everyone made one more not-so-formally-structured decision (i.e., grabbed whatever food was left) and headed back to work.
There were definitely some confounding effects on the results of our rate-of-extinction monitoring. Social structure governed foraging patterns (people hanging out at tables were their friends were present) and dispersal barriers (large groups of people to manoeuvre though!) played a large part in food choice. By and large, we saw what we expected: rarer species went extinct first, as did more easily accessible and detectable ones. More importantly, we shared our research with other members of the Botany school in a fun, interactive way that (may) have piqued their interest in structured decision making and quantitative ecology. Or maybe they just enjoyed free cake. Because everybody loves cake.
