# How to interpret a phenotypic frequency density plot I just read a paper that ran an evolutionary agent-based simulations aimed to test how genetic preparedness and social learning affect survival in various environmental conditions (changing environment, danger level, etc.). The full paper is here.

I'm a psychology student, and quite new to this area of literature. About the graph, I get that density refers to the population density of different strategies at the end point of the simulation, but what does x-axis stand for?

I cannot find any specific mention about the x-axis in the paper, so I presume the graph is a standard one that does not need elaboration. Could someone explain to me how to interpret the graph?

• It would be easier to read if a key was provided, rahter than a description of the colours – user51670 May 22 '19 at 20:44

## 1 Answer

Judging from the first section of the Results part of the paper, it looks like the x-axis represents a continuum between two divergent phenotypes. At one end is parental learning, and at the other end is social learning. The density (y axis) represents the proportion of the population that displays a given balance between the two extremes.

Generally, density plots are a normalised way of presenting observations, such that the overall area underneath each density plot is equal, regardless of the number of actual observations making up any given plot.

• The paper (and the graph) shows 4 strategies - just observational learning, horizontal learning, vertical learning, and hori + vertical learning. Then do you think x-axis stands for the proportion of each strategy used by agents? So for hori + vertical learning ("advanced learning"; orange graph), 1 would mean an agent who has exclusively used advanced learning strategy? – Simonet May 21 '19 at 1:05
• It could be that, sorry I only read some of the paper quickly and missed that point. – Jonathan Moore May 21 '19 at 9:45
• The strategies change depending on the scenario – user51670 May 22 '19 at 20:45