Critique and makeover: Species richness

Disclaimer: This blog post does not show a conference poster. I hope the lessons are still useful.

This is Figure 7 in a recently published journal article (Wiens 2024; open access, free to read). Click to enlarge!

I don’t think this is an effective figure.

The information is shown purely by text. There is no spatial or colour information displayed.

The box “Clades of same rank” sits closest to information about “Spatial richness,” but the arrow connects it to “Clade-based richness.” This violates our expectations of proximity, that related information is kept together.

Arrows normally indicate causality or time. The only reason they seem to be added here is to fix the problem of showing were “Clades of same rank” belongs. It would look weird to have just one arrow, so everything gets an arrow?

And almost no edges are aligned with any other edge. 

Don’t get me wrong, this is not an easy set of information to organize. The challenge is that there are three big categories, but only one has subcategories. This means that almost any way you slice this, one category will require more space, and you are going to end up with gaps in your figure.

In revising this figure, the overarching goals were to keep the categories equally proportioned and aligned, and to organize the text so that the subcategories were obvious (if possible).

So I messed around in PowerPoint to come up with alternatives.

If we keep to the same style, I suggest this is an improvement:

Now text boxes in a row are the same size and aligned. And the most distracting arrows descending from the title are gone.

Why do we need a background?

While I generally advocate removing boxes, here I think they are useful because they add regularlity. If you remove them, the different amount of text results in irregular shapes.

But again: this is pure text. Why not keep it as such with an organized (but not bulleted) list?

As a PowerPoint slide, this does have a problem in that the right half of the space is going unused. We can fix that by repositioning the title:

We could also fix the empty space on the right by using multiple columns, like the original figure tried to do.

Although as pure text, a tabular presentation might be appropriate for print. Wouldn’t recommend on a slide or poster, though.

But can we make this slightly more visual besides adding superfluous arrows and boxes to text? PowerPoint’s design suggestion threw in a globe for “Spatial richness,” which is appropriate. The other two concepts do not easily lend themselves to a simple icon, but the examples given do!

The example for “Clade-based richness” mentions angiosperms, which are flowering plants. Plenty of flower icons. The example for “Trait-based richness” mentions sex, so male and female icons are used.

At the bottom, a single line points out factors that are common to all three explanations.

This last revision does provide less information than the original. In particular, I gave up on showing the sub-categories in “Clade-based richness.” But this is a summary, not the entire article. I think this would be much better for a slide or on a poster than the original jumble of boxes and lines.

And the moral of the story is: Even figures that have been through a peer review and editorial process can still often be improved!

Reference

Wiens JJ. 2024. Speciation across life and the origins of biodiversity patterns. Evolutionary Journal of the Linnean Society 3(1): kzae025. https://doi.org/10.1093/evolinnean/kzae025