Monday, October 23, 2017

Biodiversity and contemporary evosystem services


Part 1

Bursting a thought-bubble


The Eco-Evo Evo-Eco blog site has had a number of interesting contributions (e.g. rapid evolution and big apple) about “evosystem services” – broadly defined as all the benefits to society from evolutionary processes (Faith et al 2010). Our bioGENESIS group introduced this term to set up a contrast with the conventional term “ecosystem services”. After all, why should we (we asked) refer only to benefits from healthy ecosystems, when we equally could be talking about the benefits from healthy evosystems?


That nice thought-bubble could be all there is to the story. But evosystem services critically adds something more. While every ecosystem service is also an evosystem service, “evosystem services” also captures the idea that the core product of evolution, biodiversity (the variety of life), itself is an evosystem service. As Faith et al (2010) argued, biodiversity has (typically global) “option value” – it provides a contribution to society in maintaining options – maintaining the potential for unanticipated future benefits. Thus, while global biodiversity is not an ecosystem service, it is perhaps the most fundamental evosystem service (for more discussion, see Faith 2017).


As an evosystem service, biodiversity and its option value therefore is a nice interplay of past, present and future. Past evolution creates a storehouse of “features”; presently we place some value on the benefit of having biodiversity’s maintenance of options, knowing that future generations then will continue to discover unanticipated benefits and uses.


The “past” does not have to be that long ago


Faith et al (2010; for discussion, see Faith et al 2017) also discussed evosystem services from rapid or contemporary evolution. Contemporary evosystem services then are all the benefits from rapid evolution. These benefits include option values from biodiversity. The evosystem services work of Bellon and colleagues (e.g. Bellon et al. 2015) illustrates this well. They describe the evosystem services in global food systems arising through “on-farm conservation”: management of crops to produce and maintain biodiversity and its option values, as a global public benefit.


The new home of bioGENESIS, Future Earth, focusses on human-earth system science and sustainability. We wondered initially how evolution and biodiversity conservation fit into conventional “earth system science” (for discussion, see e.g. Faith and Richards, 2012). It is clearer now that there is a good fit. Evolution is a key Earth System process, and one way to look at the human-earth system is that this system operates with a time-lag – evolution in the past has created biodiversity and, from humanity’s point of view, this is a rich heritage or “storehouse” that society now continues to harvest over time. Of course, humanity also is rapidly foreclosing its options through human-caused loss of biodiversity. How we deal with all that is central to sustainability.


This evolutionary perspective on human-earth systems is even more interesting because evolution can be rapid, it may well be directly or indirectly influenced by humans (Hendry et al. 2017), and it may or may not promote human well-being. Such contemporary evolution importantly not only may support ecosystem services, but also support global biodiversity option values, as illustrated by the work of Bellon and colleagues (and discussed in Faith et al 2017).


Biodiversity “option values” do not always get the attention they deserve (see below, and see my review in Faith, 2017). So, it is not surprising to see more discussion in the context of contemporary evosystem services. Rudman et al (2017a) provided useful perspectives, but provided a narrow definition of “contemporary evosystem services” as “the maintenance or increase of an ecosystem service resulting from evolution that occurs quickly enough to alter ecological processes”. As our bioGENESIS response paper in TREE (bioGENESIS members, Faith, Magallón, Hendry, and Donoghue, 2017) pointed out, this definition unfortunately implies that ecosystem services are the only benefits from contemporary evolution, overlooking the role for contemporary evolution in providing the “maintenance of options” contributed by biodiversity.


Wrapped up in that discussion (and in Rudman et al 2017b, which is a reply to our response) are two concerns about how our broad definition extends beyond ecosystem services to include biodiversity option values–


1. It could be claimed that our definition of “evosystem services” is so broad that it is intractable, and so a focus on ecosystem services, in the definition of contemporary evosystem services, makes it more measurable and operational.

2. It could be claimed that biodiversity option values can’t really be a contemporary evosystem service, because the benefits are in the future and not a product of contemporary evosystem


I’ll discuss these in turn.



1.  Reading Hendry labels

I can see why a more constrained definition of contemporary evosystem services might be tempting. Rudman et al’s blog contribution about their TREE paper (the “MS” below) presented more on their rationale. They found support in Andrew Hendry’s recollection that we:


 “intended specifically to make evosystem services synonymous with ecosystem services - to make clear the importance of studying evolutionary diversity even when interested in ecosystem services. [A Hendry 4/9/2017: Stated more correctly, ecosystem services ARE evosystem services.] Thus, the original intent of the term was exactly that which authors of the present MS criticize - that it is all inclusive and, as the authors argue, therefore unhelpful).”


As I noted above, synonymising evosystem services and ecosystem services might have been one useful way to increase appreciation of evolution, but our Faith et al 2010 paper promoted that idea that evosystem services critically adds something more:  


“‘Evosystem services’ provides us with a useful handle in reflecting values that are not very naturally accommodated by the concept of ecosystem services, including the capacity for future evolutionary change and the continued discovery of useful products in the vast biodiversity storehouse that has resulted from evolution in the past. In this sense, ‘evosystem services’ and ‘ecosystem services’ are complementary. Together, the two capture a wider variety of the values that we associate with ecosystems and biodiversity…..Because the pursuit of some ecosystem services can sometimes entail the loss of biodiversity, it is important to make sure that other uses arising from biodiversity also are measured. We think those other uses are extensive— they include not only known uses from known species, but also yet-to-be discovered uses from known and still unknown elements of biodiversity..”


I think the Andrew Hendry blog quote above therefore does not capture the whole story – in fact, in his early blog post here on evosystem services, Andrew noted that not only are ecosystem services a product of evolution but also that –

“evosystem services are so much more because they recognize that biodiversity has current or potential future values to humans that we don’t know about yet and can’t yet envision.”


So, all that supports the little diagram that appears in our TREE response (re-drawn below):




Rudman et al (2017a) had characterised our broad interpretation of evosystem services as “a concept too meta-scale to measure”. But the individual arrows in this figure are measurable. For example, the assessments of on-farm conservation sometimes measure the option values of contemporary evosystem services (blue dotted arrow). Similarly, the maintenance of options resulting from past evolution (blue dashed arrow) is measured using “phylogenetic diversity” (PD).


2. Definitions, and stories about definitions


In their reply to our response in TREE, Rudman et al. (2017b) defended their ecosystem service-focussed definition, arguing that our notion of biodiversity option value did not correspond to something produced by contemporary evolution. They properly referred to Faith 2017 as providing our definition of option value, but then quoted it this way:


“’option value refers not only to the unknown future benefits from known units of biodiversity, but also to the unknown benefits from unknown units.’ Using this definition, Faith et al. focus on the importance of maintaining genetic diversity to maintain ‘future options’ provided by living variation. …. we would not classify these option values as contemporary evosystem services because they are not the product of current rapid evolution”


Faith (2017) did not state that definition, which would on its own have given the impression that the benefits were in the future and so could not be a product of contemporary evolution. This can be cleared up by looking at the full paragraph in Faith (2017) from which Rudman et al’s quoted sentence was plucked:


“the best argument for what we call the option value of biodiversity is that we see many currently beneficial units, and maintaining a large number of units (biodiversity) for the future will help maintain a steady flow of such beneficial units (see also the “storehouse” analogy in Faith et al 2010).  In accord with this idea, the Millennium Ecosystem Assessment (MEA; 2005a: 32) described option value as: “the value individuals place on keeping biodiversity for future generations”. Option value refers not only to the unknown future benefits from known units of biodiversity, but also to the unknown benefits from unknown units. Biodiversity option value therefore links "variation" and "value": providing a fundamental relational value of biodiversity reflecting our degree of concern about benefits for future generations.”


Thus, the sentence prior to the one quoted by Rudman et al points to a version of the actual definition. Individuals (or society) gives some value to that benefit biodiversity provides in maintaining options for the future. As Faith (2017), and our response to Rudman et al (2017a), made clear, the value/benefit is now (“the value individuals place on keeping biodiversity for future generations”) and, as illustrated in Bellon’s work, this benefit may be produced by contemporary evolution.


Part 2


The pre-history of a term


The discussions about evosystem services and biodiversity option value, arising from the Rudman et al papers and bioGENESIS responses, have been constructive. But this also recalls for me the widespread resistance (reviewed in Faith 2017) to the idea that biodiversity has its own direct benefit, maintenance of options, that goes beyond any benefits through support of ecosystem services. Indeed, Faith (2017) traces a popular re-writing of the history of “biodiversity” in which the ecosystem services movement supposedly forged links for the first time from “biodiversity” to human well-being (with biodiversity supposedly only having intrinsic value prior to that).


Faith (2017) also laments that this story-line sometimes is propped up by re-casting “biodiversity” as practically any aspect of ecology that supports ecosystem services. A special case of that problem concerns PD (see above), proposed as a measure of biodiversity and its option value at the regional/global scale (Faith 1992). But now many ecosystem services papers state that Faith (1992) defined PD as the phylogenetic diversity of a community.


An antidote to what I call “the histrionics of a term” (roughly, the over-the-top re-written history of the term after it was invented) is to not only carefully trace the actual history, but also to examine what I call the “pre-history” of a term (“roughly, the history of the term before it was invented”; see Faith 2017).


For the term “biodiversity”, this pre-history exploration is not yet complete. But early papers (well before the coining of the term “biodiversity” around 1985), using terms like “biotic diversity”, reveal rich discussions of anthropocentric values related to the value of variety in maintaining options for the future (see Faith, 2017).


Unmarked landmarks 


Uncovering a “pre-history” can be fun. I have relied on Web of Science and also some previous excellent reviews (including Mazur and Lee, 1993 and Farnham 2007). It appears that a suite of uncovered papers collectively can document an emerging idea well, but any one of the papers may not have been cited much. Indeed, some of the early significant papers are “unmarked landmarks” that raise mysteries.


I really liked a little 1974 paper in Science that reported on an important discussion meeting where participants called for “an Ethic of Biotic Diversity” in which “diversity is viewed as a value in itself and is tied in with the survival and fitness of the human race”. The paper warned that extinction “threatens to narrow down future choices for mankind” (see Faith 2017).


The pdf of that “news and comment” page in Science only had the signature “C.H.”:




Based on Web of Science I attributed the paper to C Haskins (Web of Science now reports it as having exactly one citation - mine). However, I later noticed that Mazur and Lee (1993) referred to the same paper, but with attribution to a different “C.H.”, “Constance Holden”. This seemed plausible; a little detective work revealed that Constance Holden may have been the staff journalist for the “News and Comment” section. Back in Web of Science, I found no less than 15 “News and Comment” papers by Constance Holden in 1974 – all signed “C.H.”


Each paper had a title beginning with a subject:  e.g., “Sex therapy -”, “Ethiopia -”, “Cliometrics -”, “Methadone -”.  Of all of these, the most cited was: “Sex therapy – making it as a science and an industry”. But nowhere could I find a Constance Holden paper on anything like “Biotic diversity – making it as a science and an industry”, which would have been a great read in 1974.


I think I will stick with the C. Haskins attribution

(and raise this challenge to the reader – can you nominate other papers as “unmarked landmarks” that deserve to go from (say) 0 citations to 1 or more?).


Meanwhile, I noted recently that Mazur and Lee also cited another relevant paper for my pre-history of biodiversity - Iltis (1972). H. H. Iltis, who died this past year, was professor emeritus of botany at the University of Wisconsin–Madison. He was best known for his discoveries in the domestication of corn, but also wrote broadly about environmental matters. His 1972 paper called for society to “preserve sufficient diversity of species and of ecosystems” because “we will never reach a point where we shall know which organisms are going to be of value to man and which are not.” Again, we see an early paper that neatly captures the fundamental link between biodiversity and maintaining options for the future.*


*see also the Iltis (1967) Bioscience paper that is 50 years old this year. He argues “life's diversity is threatened with imminent destruction, that in 20 or 30 years it will be all but over for this exuberant biotic wealth”.


Iltis (1972) is another unmarked landmark paper -  Web of Science reports it has been cited only 6 times. In any case, while my pre-history task is not complete, we already can say that by 1972 (45 years ago), biotic diversity itself was promoted as a benefit to be valued by society, and the nature of this benefit to society was the maintenance of options.


I like the phrase “maintenance of options” as a reference to biodiversity’s contribution to people.. As our TREE paper (Faith et al, 2017) on contemporary evosystem services noted, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES 2017) recently recognised “maintenance of options” as a distinct category of “nature’s contributions to people” (NCP).   NCP is a useful shift from conventional ecosystem-services speak. While IPBES (2017) stated that its list of 18 NCP “are generally closely associated with the concept of ‘ecosystem services’”, the “maintenance of options” NCP is the important departure. I hope that IPBES assessments now will implement measures for both the blue-dotted and blue-dashed lines in our figure.


Some references

Bellon, M.R. et al. (2015) Assessing the effectiveness of projects supporting on-farm conservation of native crops: evidence from the high Andes of South America. World Development 70, 162–176

Faith, D.P. (1992) “Conservation evaluation and phylogenetic diversity,” Biol. Conserv.  61: 1–10.

Faith, D.P. (2017) A general model for biodiversity and its value. in The Routledge Handbook of Philosophy of Biodiversity (Eds. J Garson, A Plutynski, S Sarkar)

Faith, D.P. et al. (2010) Evosystem Services: an evolutionary perspective on the links between biodiversity and human-well-being. Current Opinion in Environmental Sustainability 2, 66-74

Faith D P and Richards Z T (2012) Climate change impacts on the tree of life: changes in phylogenetic diversity illustrated for Acropora corals. Biology 1(3), 906-932

Faith D. P., Susana Magallón, Andrew P Hendry, and Michael J Donoghue (2017) Future Benefits from Contemporary Evosystem Services. Trends in Ecology and Evolution Volume 32, Issue 10, October 2017, Pages 717-719.

Farnham, T. J. (2007) Saving Nature's Legacy: Origins of the Idea of Biological Diversity, Yale University Press, 276 pages.


Hendry A.P. et al. (2017) Human influences on evolution, and the ecological and societal consequences. Phil. Trans. R. Soc. B 372:20160028

Iltis, Hugh H. (1967) To the Taxonomist and Ecologist Whose Fight Is the Preservation of Nature. BioScience17, 886-890.



Mazur, Allan and Jinling Lee (1993), Sounding the Global Alarm: Environmental Issues in the US National News. Social Studies of Science, 23, 681-720

Rudman, S.M., M. Kreitzman, K.M.A. Chan and D. Schluter (2017a).  Evosystem Services: Rapid Evolution and the Provision of Ecosystem Services. Trends in Ecology & Evolution. Doi: 10.1016/j.tree.2017.02.019.

Rudman, S.M., M. Kreitzman, K.M.A. Chan and D. Schluter (2017b). Contemporary evosystem services: A reply to Faith et al. Trends in Ecology & Evolution. Doi: 10.1016/j.tree.2017.07.006

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