Chapter 17

Exercise 1. Improving the reader’s experience

Consider this graph that was produced to show Indian trade balances with prominent partners (link to tweet here)

Identify at least two things that could be changed to make this graph more effective.

Exercise 2. Graphics for talks and theses/papers

This exercise is to think about effective figures for different purposes. Let’s return to Figure 6.5, which shows means (and SEs) for content of salmon with different feeding regimes (see details in Box 6.4):

… Your task is to produce two versions of this figure. Think about information that would be on and around the figure, and the need for titles and captions.

  1. What would you need to do for that figure to appear in a thesis or a manuscript?

  2. How would you design the figure for a conference talk or seminar?

Exercise 2. Reporting interactions

This exercise focuses on a marine ecological experiment reported by Brothers and Blakeslee (2021) looking at the interplay between parasitism and habitat structure in affecting survival of flatback mud crabs, Eurypanopeus depressus, in the Gulf of Mexico.

The parasite was an introduced barnacle, Loxothylacus panopaei, which alters crab behaviour and alter risks of predation. The predators are other crabs, another mud crab, Panopeus herbstii and the stone crab Menippe mercenaria.

The research question of interest was whether the parasite effect depends on habitat complexity.

The question was addressed with a laboratory experiment. The important details for you

  • Mud crabs were infected or uninfected with the parasite

  • They lived in simple (gravel) or complex (oyster shell) habitats

  • Experimental units were large tanks (“mesocosms”), each with 10 crabs

  • 3 replicate tanks for each combination of parasitism and complexity

  • Number of surviving crabs recorded daily for 5 days

The task:

Produce a graph or panel of graphs showing what happened, focusing on the research question. You can use the data file provided (crab example for graphing.csv); the file shows mean and s.e. of the proportion of crabs surviving at a given time. Feel free to use all the data or one particular time, e.g. 24 or 48h.

crab <- read.csv("../data/crab example for graphing.csv")
crab
##    Complexity  Parsitism Time Proportion.alive std.error
## 1      Simple Uninfected    0             1.00      0.00
## 2      Simple Uninfected   24             0.50      0.06
## 3      Simple Uninfected   48             0.27      0.13
## 4      Simple Uninfected   72             0.20      0.10
## 5      Simple Uninfected   96             0.07      0.07
## 6      Simple Uninfected  120             0.07      0.07
## 7      Simple   Infected    0             1.00      0.00
## 8      Simple   Infected   24             0.04      0.04
## 9      Simple   Infected   48             0.00      0.00
## 10     Simple   Infected   72             0.00      0.00
## 11     Simple   Infected   96             0.00      0.00
## 12     Simple   Infected  120             0.00      0.00
## 13    Complex Uninfected    0             1.00      0.00
## 14    Complex Uninfected   24             0.44      0.17
## 15    Complex Uninfected   48             0.17      0.03
## 16    Complex Uninfected   72             0.17      0.07
## 17    Complex Uninfected   96             0.08      0.04
## 18    Complex Uninfected  120             0.04      0.03
## 19    Complex   Infected    0             1.00      0.00
## 20    Complex   Infected   24             0.38      0.08
## 21    Complex   Infected   48             0.21      0.05
## 22    Complex   Infected   72             0.07      0.06
## 23    Complex   Infected   96             0.04      0.03
## 24    Complex   Infected  120             0.03      0.03

• Hand drawn or using software – you’ll need a single page to share with the class

Extension question

If the research question was on the value of habitat complexity and whether the parasite changes this value, how would you draw the graph differently?

Brothers, C. A. & Blakeslee, A. M. H. (2021). Alien vs predator play hide and seek: How habitat complexity alters parasite mediated host survival. Journal of Experimental Marine Biology and Ecology, 535.