Thursday, October 31, 2019

Evolutionary ecology SHOULD be wet and dry

This is a guest post by Erik Sotka
Twitter @eriksotka 

I am part of an NSF-funded Research Coordinated Network on "Evolving Seas" ( Our goal is to summarize what we know, don’t know but should know about the evolutionary responses of marine organisms to climate change. In preparation, I had invited a butterfly-ecologist friend to join the effort. His response was, to paraphrase: “so, NSF pays for folks to get together and chat about how marine biology should proceed…Do I really have anything to contribute?” 

It is not a surprising question. 

The cynical view is that his response reflects an unfortunate bias, in which terrestrial ecologists pay less attention to wet ecosystems (aquatic and marine). Terrestrial papers on population and community ecology are cited 10x more often by aquatic papers than the reverse (Menge et al 2009). Look at the journal Oikos for example: (x-axis; biome of a paper; y-axis: proportion of citations from each biome). 

This bias extends to the principal tools by which we teach the next generation of ecologists as well. Among general ecology textbooks such as Ricklefs 1997, Krebs 2001, Begon et al. 1990, a review found 5 marine examples out of 186 examples, indicating a clear underrepresentation of aquatic studies (Munguia and Ojanguran 2015). 

There’s no reason to think that these biases do not extend to evolutionary ecology. While I didn’t have the time to look at some of our evolutionary journals (e.g., Evolution, Evolutionary Applications), I did survey chapters 9 (Variation) and 11 (Population structure and gene flow) of Futuyma 1997 and counted one (1) marine example out of 61. 

Why does this bias exist? Well, you might suspect that because there are more terrestrial biologists, there are more terrestrial studies. However, while the ratio of terrestrial to aquatic ecologists is 57:43 (Stergiou 2005), the ratio of articles in the top ecological journals is 78:22 (Menge 2009). So, that doesn’t seem to completely explain the pattern.

It seems that the bias is generated by multiple conscious and unconscious decisions made by both terrestrial and marine ecologists. Menge et al. 2009 propose that there is “a tendency for aquatic ecologists to focus more on across-habitat comparisons than do terrestrial ecologists, an increased likelihood that editors and/or reviewers of aquatic papers demand greater citation breadth”, and/or “greater effort by authors to include terrestrial citations to improve chances of acceptance by editors.” 

There is also a “benign neglect” due to the lag in development of marine and terrestrial studies. “Terrestrial ecology as a major subdivision of biology preceded that of aquatic ecology, and especially marine ecology, by several decades.” (Menge et al. 2009). There are likely other reasons, as pointed out by the responses to this Twitter thread earlier this year (

“So what?” you may ask. Unfortunately, the consequence of this asymmetry in literature bias is clear. With less integration, there is less advancement of generalizable theory. There are some really nice summaries of the benefits of integration within Webb 2012 and Dawson 2012.

The notion of integration was one of the gifts that my PhD advisor Mark Hay wisely gave me 2 decades ago. He suggested that I write my publications or give my oral presentations at ESA so that “the spider biologist in Kansas” would be interested. And as the biome-minority at every Gordon Conference, SICB, ESA or SSE meeting I go to, I try to keep this advice in mind.

At the same time, the spider biologist in Kansas would benefit from writing studies that interest a marine evolutionary ecologist in Charleston South Carolina (for example J). This is because integrated studies get *far* more citations at American Naturalist and Evolution journals. American Naturalist articles published between 1980-2019 had ~85% more citations on average if you had both terrestrial and marine in the title or abstract relative to all articles (133.4 vs 71.4). Evolution papers published between 1980-2019 had ~25% more citations on average if you had both terrestrial and marine in the title/abstract relative to Evolution as a whole (80.5 vs 57.5).

So, integrated papers get more citations. Integrated papers avoid missing concepts. Integrated papers move the field forward. We need more interplay between marine and terrestrial evolutionary ecology, and for that, I’m really excited by this RCN on Evolving Seas. 

Menge et al 2009a Front Ecol Environ 7:182
Munguia and Ojanguran 2015 Ecosphere 6:25
Stergiou 2005 MEPS 304:292
Webb 2012 TREE 27:535
Dawson 2012 Frontiers of Biogeography 1.2

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