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  • Post date: 9 months 2 weeks ago
    Citation for this post: BibTeX | RIS

    In a in Science, provided evidence that demonstrated a event in a Galapagos finch species. This was, probably, the first such documentation of character displacement in the wild. Ten years after the paper was published, I spoke to Peter and Rosemary Grant about the making of this study, and how this work has progressed since then.

    (Interview conducted over email between 9th September 2016 and 30th November 2016)

    Citation: Grant, P. R., & Grant, B. R. (2006). Evolution of character displacement in Darwin's finches. Science, 313(5784), 224-226.

     

    Hari Sridhar: The motivation for this paper was the character displacement event you observed in  in 2004-2005, what you call "the strongest evolutionary change seen in the 33 years of the study". What has happened in the next 10 years (2006-2016), in this character displacement story?  If you were to extend the x-axis of Figures 2 and 3 to 2016, what would they look like?

    Peter Grant & Rosemary Grant: No change from 2005 to the end of the study in 2012: a straight horizontal line on the graph of time.

     

    HS: Is "no change" the case for the population graph (Fig. 3) as well? Does this continue to be the "strongest evolutionary change" you have detected so far in this system?

    PG & RG: Regarding Fig. 3, numbers of both species rebounded after the drought, fortis more than . Because there was no further change in the fortis trajectory, there was no more strong selection; so the 2004-06 episode of selection plus evolution remained the strongest in 40 years. Incidentally, if you have access to our most recent book you will see the full 40 years of morphological data (). 2012 was the last year of the field study.

     

    HS: What was the spark that ignited the idea for this work and this paper? Were you looking out for it right from the time G. magnirostris established a breeding population on in 1982? Or was it initiated by the dramatic character displacement observed in 2004?

    PG & RG: To answer this question, we have to go back to the early 1970s for the origin of interest in this subject. At that time, I (PG) . Certainly, patterns of variation in nature could be interpreted as the product of competitive interactions between species, but the problem was that each of the patterns could be explained in alternative, non-competitive ways. One of the motivations of our initial work in the Galápagos was the desire to do better. In his , David Lack had pointed out some apparently clear-cut patterns. For example, on the small island of Daphne Major, the medium ground finch (Geospiza fortis) was smaller than elsewhere, and because the (G. fuliginosa) was absent from the island, Lack argued that the medium ground finch had taken over the niche of the missing species. On other, larger, islands both species were present and morphologically very distinct. Since Daphne had probably been colonized from nearby, larger and older , this seemed like an example of the opposite side of the character displacement coin - character release as it has been called. Thus, part of the research we began in 1973 was designed to test the hypothesis of character or competitive release. Then, about a decade later, Daphne was colonized by the large ground finch (G. magnirostris). When it became clear this was not an ephemeral event, and that large ground finches were more efficient at exploiting the large and hard seeds of than the large members of the medium ground finch population, we started to wonder if, one day, large ground finches could have a competitive influence on medium ground finches. This did indeed happen, twenty-two years after the initial colonization.

     

    HS: Please tell us a little about the actual writing of this paper. At what point in the process did you start writing the paper and when and where did you do most of the writing? Did this paper have a relatively smooth ride through peer-review and was Science the first journal you submitted this to?

    PG & RG: It did not take us long to convert the data into a paper, because the results of all analyses were clear and interpretable. We started analysing and writing when staying with our daughter and family in Corvallis, Oregon, and finished it in Princeton. We held back from publishing until we had been able to return to the field in 2006 to check whether the next generation of fortis remained, like their parents, displaced morphologically (see Fig. 2) from the pre-drought position. They had. So we finished the paper and submitted it to Nature. The editor rejected it without review because of “insufficient interest to researchers in a broad range of other disciplines”. Therefore we promptly reformatted the manuscript and submitted it to Science. Here it had a completely different reception. The manuscript was sent out for review, and all three reviewers plus editor were highly enthusiastic about it. The paper was accepted with some minor changes at the end of May and published six weeks later. Almost exactly 10 years later Science published our , where we provided a genomic understanding of what happened during the character displacement episode. But that is another story, and we will be happy to share it if you wish.

     

    HS: Yes, please do tell us more about the follow-up genomics work, and if it was also followed up in any other ways. 

    PG & RG: We continued the fieldwork for seven more years after the character displacement event, to determine the long-term outcome of , and to follow the fate of the new lineage we had discovered. We will be glad to discuss this later. 2012 was the last year of fieldwork. Even before then we had started to synthesize the long-term research in order to write a book about the Daphne study. The book was published in 2014 by Princeton University Press ().

    The genomic work began with a small problem of trying to understand the genetic basis of a beak colour polymorphism in finch nestlings. Beaks are yellow or pink. In 2010, we discovered a paper had been written about the same kind of colour polymorphism in chickens. It was by ’s group at Uppsala. We were put in touch with Leif by a mutual friend - at Arizona State University. That was the start of our collaboration. We found strong evidence of a simple mutation that accounted for the polymorphism in most populations of finches. One thing led to another, and we shifted the focus to the larger questions of finch genome variation and evolution. This work has led to two major papers so far. First, we published  that used genomic data to reconstruct the phylogeny. We also reported discovery of a gene, ALX1, which is a transcription factor affecting the development of beak shape. A mutation in the same gene in humans gives rise to cleft palate. Second, we published  this year on the genomic follow-up to the character displacement paper a decade earlier. In the new paper, we reported the discovery of another gene influencing beak development through transcriptional activity. This is HMGA2, and it comes in two forms in finches. One is present in species with large beaks and the other is present in species with small beaks. These two variants are correlated with beak size among members of the Daphne population of fortis, with heterozygotes being intermediate in average beak size as expected. We found that genotypes associated with large beak size were at a strong selective disadvantage in the drought of 2003-04. The selection coefficient, 0.59, is exceptionally strong for natural selection on a continuously varying trait in a natural population. In fact, variation in haplotypes statistically explained approximately one third of the variation in the shift in average beak size. So, although many genes govern beak size, as we know from heritability estimates, we had discovered a single gene with a major effect on beak size, and it played a large role in character displacement. Interestingly, beak shape did not change during the character displacement episode, nor did the frequency of ALX1 haplotypes.

     

    HS: Please tell us a little more about the work you did to determine the outcome of introgressive hybridization and the fate of the new lineage.

    PG & RG: At the beginning of 2005, fortis were smaller on average than at any time in the preceding 32 years, and the question was whether they would stay that way or gradually change back to their pre-drought size, as happened after the drought of 1977. Offspring of the survivors of the 2004 drought were, on average, almost the same size as their parents, as we expected from the very high heritability of body size and beak dimensions. And in fact, average body size and beak size remained small right up to the end of our field study in 2012. Therefore, character displacement was not ephemeral: it persisted for seven years. 

    Part of the reason for a lack of change after 2005 is introgressive hybridization. G. fortis receives genes from fuliginosa, a smaller species, and scandens, a larger species. Genetic inputs from these two sources appear to have been roughly equal and hence contributed to the maintenance of the status quo.

    Another part of the reason for lack of change is the flourishing of the Big Bird lineage after the character displacement event. We should first explain what the lineage is and how it formed. The lineage was initiated by a particularly large finch (hence the name Big Bird) that arrived on Daphne Major Island in 1981. Microsatellite DNA data suggested it was a fortis x scandens hybrid that had immigrated from nearby Santa Cruz Island. It bred with fortis, and two generations were produced before the drought of 2003-04. Two members of the lineage, a brother and a sister, survived the drought and bred with each other in 2005, as well as in the following years. Remarkably, their offspring bred with each other or with their parents, so did the grand-offspring. In breeding entirely endogamously the lineage behaved like a new species.

    Big Birds occupy the morphological gap between magnirostris and fortis. The gap widened as a result of character displacement in fortis, and thus the Big Birds were less constrained by potential competition for large seeds from large members of the fortis population. The Big Birds have flourished because their diet in the dry season is varied, encompassing the large seeds eaten by magnirostris, the small seeds eaten by fortis, and nectar, pollen and seeds of Opuntia cactus eaten by both of them as well as by scandens, the cactus finch. The Big Birds are thus a central generalist in the Daphne community of finches.

    We have recently taken the eco-morphological study into the realm of genomics by collaborating with Leif Andersson and his molecular genetics group in Uppsala, Sweden. The goal has been to investigate character displacement as a genetic phenomenon. The group discovered two genes that influence the development of beak traits through transcription factors. One of them, ALX1, affects beak shape. The other, HMGA2, affects beak size. Each gene comes in two forms: two haplotypes. In the character displacement event, the haplotype of HMGA2 that is associated with large beaks was at a strong selective disadvantage and declined in frequency. This demonstrates at genetic level what we had previously shown at phenotypic level. Interestingly fortis receives ALX1 and HMGA2 haplotypes from both fuliginosa and scandens. The HMGA2 haplotype from fuliginosa appears to have enhanced the evolutionary response in 2005 to natural selection in 2004.

    To conclude, the community of finches on Daphne Major Island has changed from a 2-species community to a 4-species community. The character displacement episode played a pivotal role in the ecological adjustment of one species to another. It was caused by one of the additional species (magnirostris) and apparently facilitated the expansion of the other addition (Big Birds). The frequency of an important gene affecting beak size underwent a strong change. Introgressive hybridization with fuliginosa and scandens contributed to the evolution of fortis. We are currently using genomics to gain a deeper understanding of the consequences of introgression and the success of the Big Bird lineage.

     

    HS: How was the paper received, both within academia and in the popular press, when it was published? Did it attract a lot of attention?

    PG & RG: The paper was received very favourably in the scientific literature, and that has continued in both scientific papers and in books. We cannot recall any attention given to it in the popular press.

     

    HS:  In concluding your paper, you say "Replicated experiments with suitable organisms are needed to demonstrate definitively the causal role of competition, not only as an ingredient of natural selection of resource-exploiting traits but as a factor in their evolution. Our findings should prove useful in designing realistic experiments, by identifying ecological context (high densities at the start of an environmental stress) and by estimating the magnitude of natural selection." Today, 10 years after this paper was published, could you reflect on whether and to what extent this has happened?

    PG & RG: The adjustment species make when brought into competitive conflict is still studied mainly opportunistically and observationally, not experimentally, by researchers alert to the possibility of character displacement. Three years ago, and . By applying strict criteria to the evidence, they concluded that only six cases (including Darwin’s finches) passed their test. Given so few examples documented in nature, it should be no surprise that experimental tests of the role of competition in character displacement in nature have not been done. The closest to our proposal was a . Microcosms have been investigated experimentally in the laboratory where conditions are strictly controlled and feasible mechanisms demonstrated. However, they do not address the question of applicability to processes in nature, or whether the results can be scaled up from micro- to macro-organisms and environments. Perhaps the best system for research in the field would be annual plants that have recently come into contact and shown evidence of competitive interaction. A promising environment might be alpine or subalpine habitat, where species ranges are shifting under climate change and previously separated species are now encountering each other.

     

    HS: Today, in retrospect, is there anything that you wish you had done differently, or any other data you wish you had collected, at the time of the character displacement event in 2006?

    PG & RG: It would have helped if we had quantified the seed supply before, during, and after the character displacement event by random sampling, just as we had done in every year from 1976 to 1991. However, given our observations, on the difficulty finches experienced in finding Tribulus fruits during the 2003-04 drought, we are quite confident that sampling data would have revealed a very strong decline in availability. 

     

    HS: In the paper, you acknowledge "K.T. Grant, L.F. Keller, K. Petren and U. Reyer" for fieldwork help. Could you tell us a little more about who these people were and how they helped?

    PG & RG: K.T. Grant is our daughter, . She helped us with fieldwork in many years, beginning in 1973 when she was six years old. Her help was crucial in 2005, when she visited Daphne to census the banded finches in order to find out which ones had survived and which ones had not. Rosemary and I could not visit the island that year because I had to have an operation for colon cancer, followed by a three-month course of chemotherapy under a doctor’s supervision. Thalia’s visit to the island was then followed by a longer visit by the other three helpers. (University of Zürich) and (University of Cincinnati) had been post-doctoral fellows with me, and was head of the Ecology Department at the University of Zürich, host on our two long visits to his Department, and a good friend. Their visit was nicely timed, fortunately, as heavy rain fell while they were there. Therefore we know the exact date when the drought ended. As it turned out, Thalia had found almost all the survivors on her short visit, and although our other helpers added very few to the list, their inventory gave us more confidence in our estimate of the true survival. In the next field season in 2006 we did not find a single banded finch that had escaped detection in 2005.

     

    HS: Have you ever read this paper after it was published?

    PG & RG: No, we have never read it, we have only checked some numbers in tables.

     

    HS: Could you tell us why you decided to end fieldwork on this project in 2012?

    PG & RG: We both retired from teaching at Princeton University in 2008. The last of our research money was spent in 2012, and after 40 years of fieldwork it seemed a good time to stop and the write a synthesis, which became the book Rosemary and I published in 2014: “.”

     

  • Post date: 9 months 2 weeks ago
    Citation for this post: BibTeX | RIS

    by Rachel White 

    On the 11th December 2016, some 90 students and ECRs gathered at ACC Liverpool to actively participate in the Early Careers Programme – kick-starting the 2016 Annual Meeting of the  () – the biggest one to date, with over 1200 delegates attending from around the world. The Early Career programme, collaboratively organised by the BES and INNGE, comprised a series of workshops targeted at students and early-career researchers and supported by both panel discussions and presentations during the Annual Meeting itself. The bumper number of early-career sessions included the following: “How to make the most of meeting”, “How to set-up a productive Twitter account”, “Unlocking your potential”, “How to devise a question for a plenary speaker/senior ecologist”, “From PhD to Post Doc/From Post Doc to permanent position”, “Staying employable in and out of academia”, “Communicating effectively from CV to interview”, “How to get published”, “Managing an interdisciplinary career”, and “Building support networks” – phew! See below for a summary of some of these sessions. Tweets can be accessed for these events by searching for .

    Due to its success, this Early Careers Programme will be built upon and repeated at next year’s joint BES Annual Meeting in Ghent, Belgium (Dec 2017) – so do come along if you can!  

     

    The early-career delegates in all their glory!

    Pre-meeting webinar series – A guide to scientific conferences for first-time attendees:

    Before the BES Annual Meeting had even started, we decided to run several webinars targeted at ecologists who had yet to experience a conference environment. The panel of early-career conference veterans included Rachel White (University of Brighton, UK), Pen-Yuan Hsing (Durham University, UK), Simon Tarr (University of Nottingham, UK), Kate Luckett (BES), and Karen Devine (BES).

    Some top pieces of advice included:

    • Plan what you want to get out of the conference in advance. Take the time to look through the programme and select which talks/workshops/socials you want to attend.
    • Take a look through the list of delegates and make a list of people you’d like to speak to. One of the best ways to arrange a meeting with someone at a conference is to email (ideally before the conference start) with a short intro, proposed day and time. Don’t feel down if you don’t receive a reply during the conference – instead email again once home using the conference as starting point.
    • Bring business cards along (you never know when they may come in handy).
    • Socialising and networking is often easiest at poster sessions.
    • Don’t try to attend everything at the conference – be selective.
    • Remember that every single person at the conference has been in your shoes/started in exactly the same place, so be brave and introduce yourself.

    Do also take a look at Dynamic Ecology’s blog post on “” 

    Unlocking your potential session

    This session, a regular feature of the BES Annual Meeting due to its popularity, was organised as a panel discussion and provided an opportunity for attendees to question ecologists representing a breadth of careers and career stages. Speakers were: Sue Hartley (University of York, ), Marc Cadotte (University of Toronto, ), Will Gosling (University of Amsterdam, ), and Emma Sayer (Lancaster University, ). See their key points below: 

    Sue Hartley

    Will Gosling

    Marc Cadotte

    Emma Sayer

    “Make the most of training opportunities during your PhD/Post-Doc” - SH

     “As best as you can, avoid comparing yourself to others” – ES

    “Choose a subject you’re passionate about to build your career around” – SH

    “Make use of BES career development resources” – ES

    “Think carefully about whether you want an academic or research career” – SH

    “Be flexible, resilient, determined, brave, and decisive!” – SH, ES

    “Working on current world problems is attractive to funders and motivating” – SH

    Don’t be afraid to use skills learnt in one area of your work to another – interdisciplinary is good! SH

    “Find yourself a mentor(s)” –SH, ES

    “Try and write your thesis by publications” – SH

    “Get connected – network and be noticed” - SH

    “Start searching/applying for applications early” – ES

    “It is possible to find a work-life balance, but you need to be efficient with your use of time” – MC

    “Do not be modest in applications – sell your achievements” – ES

     

    For more on mentorship schemes, see:

    Top tips - how to ask a good question for plenaries? Keep the question short, focused, ask for examples/priorities, and get them to stick their neck out!

    From Post-doc to Permanent position:

    Permanent positions within ecology certainly do exist, but how can you get one? Rachel White (University of Brighton, UK – ) and Maria Beger (University of Leeds, UK - ) spoke candidly to a number of ECRs during this breakout session. RW obtained her PhD at the Durrell Institute of Conservation & Ecology (DICE) at the University of Kent in 2013 and, after a short post-doctoral position, obtained a permanent lectureship position in ecology and conservation at the University of Brighton in 2014. RW’s top tips were to (1) not undersell/hold yourself back, (2) apply for positions you’re interested in, even if you think you only hit most (rather than all) the position requirements, (3) gain teaching experience during your PhD if you know you want to go down the lectureship career path, (4) continuously build your network of ecological contacts/collaborators. RW also discussed the limitations of not having enough post-doctoral research experience before obtaining a lectureship position, and trying to find ECR funding that she’s eligible for. MB completed her PhD at the University of Queensland in 2008 and after a series of post-docs obtained a Research Fellow position at the University of Leeds in 2012. MB discussed the need for being adaptable and flexible with respect to the geographical location of advertised positions, and clearly discussing with your partner/family just how far and for how long you’re prepared to go. Look for opportunities which provide relocation assistance.

    Communicating effectively from CV to interview:

    During the session, tips were discussed on deciding when to apply for roles, what employers are looking for and the do/don’t guide to interviews. The panel comprised of: Kate Jones (UCL, ), Julia Blanchard (University of Tasmania), and Stefano Allesina (University of Chicago).

    • CV:
      • No page limit
      • Easy to scan = easy to read/understand
      • Not an essay
      • Should be tailor-made for each application
      • Keep a master CV that you add to continuously
      • Having an impact/outreach section on CV shows care
      • Limit listing manuscripts “in prep” to a maximum of two
      • Clearly signpost how you meet all of the criteria
      • If you want to avoid saying you’re an expert in x, instead use phrases like: I have working knowledge of x; x years of experience in y, competent in x…
    • Job application/Interview:
      • You will be Googled. Make sure your future employers see what you want them to.
      • Don’t be afraid to make contact – send pointed emails about your interests to PIs
      • Prepare interview and have a punchy elevator pitch ready
      • Don’t undersell yourself
      • Do email for feedback
    • BES Career development resources -

    How to get published:

    An interactive beginner’s guide to getting published was provided by the BES publications team and editors, including Katie Field (: Functional Ecology @ FunEcology) and Rob Salguero-Gomez (: Journal of Ecology ). Advice was given regarding:

    • How to choose a journal: who do you want to read your work? Choose the journal you and your colleagues/peers read? Don’t be obsessed with impact factors.
    • How to write your manuscript: write it as a story; use clear, accurate and simple language; keywords should be used carefully; statistics always checked clearly before submitting; use recent research to frame yours; use figures and tables effectively.
    • Get informal feedback from a variety of people before submitting.
    • Manuscript decision: A decision of major revision is very common and getting rejected with possibility for resubmission means that the editor has seen merit in your work but considerable revisions needed. Carefully draft letter of response using 3rd person and passive tense. Clearly highlight changes made and original strengths of paper in cover letter.
    • Once published, let people know about it! Twitter, ResearchGate, individual emails.   

    Check out the !

    – so keep persevering !

    Exercise on how to pitch your manuscript to the most suitable journal

  • Post date: 11 months 1 week ago
    Citation for this post: BibTeX | RIS

    In a published in Animal Behaviour in 1977, , , Michael Webber and showed experimentally that whether great tits (Parus major) are selective or not about prey choice depends only on the supply rate of the more profitable prey, and not of the less profitable prey. These findings partially supported a model of optimal foraging that they had developed. Twenty-four years after the paper was published, I spoke to John Krebs about the making of this study and what we have learnt since then about foraging decisions of great tits.

     (Questions sent by email on 10 August 2016; responses received on 10 August 2016)

     Citation: Krebs, J. R., Erichsen, J. T., Webber, M. I., & Charnov, E. L. (1977). Optimal prey selection in the great tit (Parus major). Animal Behaviour, 25, 30-38.

     

    Hari Sridhar: What was your motivation to do the experiments presented in this paper?

    John Krebs: To test a model of optimal prey selection

     

    HS: This paper has four authors. Could you tell us how this group came together and what each member of the group contributed to this study?

    JK: Erichsen designed the apparatus, Charnov did the modelling, Webber and I ran the experiments and the analyses.

     

    HS: Who were the two observers - one who replenished the food and the other who watched the video monitor - during this experiment?

    JK: Sometimes Krebs and Webber, and sometimes Krebs and Erichsen.

     

    HS:  How did you come up with the idea of using a conveyor belt apparatus for this experiment? Would you know whether the apparatus that you used still exists?

    JK: Erichsen had designed the apparatus for another purpose. I doubt that it still exists

     

    HS:  Where and by whom were the four great tits caught? How did you find the fifth bird, which was raised from an age of 12 days?

    JK: They were caught by Krebs at , the fifth was hand raised by Krebs.

     

    HS: Could you share with us what the codes 'bw', 'gbw', 'ro', 'yy' and 'pw' stand for?

    JK: Colour ring codes: blue, white, green, red, orange, yellow, pink

     

    HS: During the writing of this paper, how did the authors share, discuss and edit drafts of the manuscript? Would you remember how long the writing took?

    JK: Don’t know how long it. Krebs wrote the draft and others commented

     

    HS: Did this paper have a relatively easy ride through peer-review? Was Animal Behaviour the first journal you submitted this to? 

    JK: We didn’t submit it elsewhere.  I don’t recall how the referees commented on it

     

    HS: Were these results considered controversial soon after they were published? Did this paper receive a lot of attention from peers?

    JK: The results weren’t controversial. The paper was, I think, well-received.

     

    HS: Did this paper play a role in influencing the future course of your research career?

    JK: It was one of our early papers on foraging theory, which formed a major research focus of my group for the following decade.

     

    HS: Today, 39 years after it was published, would you say that the main conclusions of this study still hold true?

    JK: I have no reason to doubt the results, but corrected the theory, and were unable to repeat the results in toto.

     

    HS: If you were to redo these experiments today would you do them differently?

    JK: Yes.

     

    HS: In the paper you say "it will be impossible to distinguish between 'mistakes' and 'deliberate sampling' until we have devised a specific predictive sampling model". Was such a model developed subsequent to this paper?

    JK: Yes.

     

     

    HS:  You say that "our failure to find this [a step change from no selection to selection for profitable prey] in our experiment is likely to be a general result". Was this statement borne out by future research? 

    JK: See

     

    HS: In the 39 years since it was published, have you ever had to go back and read this paper for any reason?

    JK: I did in the early days but not recently

     

    HS:  Among all the papers you have published, is this one of your favourites? If yes, why? 

    JK: It was one of our early papers testing optimal foraging models.  In hindsight the theory and experiments could have been improved

     

    HS: What would you say to a student about to read this paper today? What should he or she take away from this paper written 39 years ago?

    JK: I would say it is a good example of how to link theory and experiment, but also that by today’s standards it is not a very sophisticated piece of work and much has been done since then to develop both the theory and experimental techniques.

     

  • Post date: 11 months 1 week ago
    Citation for this post: BibTeX | RIS

    In a published in Science in 1999,  and a team of collaborators reported the results of an experiment, replicated in eight European field sites, that showed that loss of plant species diversity leads to reduced above-ground plant biomass. Seventeen years after the paper was published, I spoke to Andrew Hector about the making of this project and what we have learnt since about the diversity-productivity relationship.

     (Questions sent by email on 30 July 2016; responses received on 18 September 2016)

     Citation: Hector, A., B. Schmid, C. Beierkuhnlein, M. C. Caldeira, M. Diemer, P. G. Dimitrakopoulos, J. A. Finn et al. 1999. Plant diversity and productivity experiments in European grasslands. Science 286: 1123-1127

     

    Hari Sridhar: Please tell us a little about the motivation for setting up this multi-country experiment. Whose idea was it? Was it setup specifically to investigate niche complementarity and sampling effects?

    Andrew Hector: Research on the link between biodiversity and ecosystem functioning only coalesced as a field following a conference in the early 90’s put together by Detlef Schulze and Hal Mooney. That meeting spawned several studies. Interestingly, the link between diversity and function but there was only sporadic study of it until the 90s. The multi-country approach of BIODEPTH was facilitated by the European Framework 4 – we had about a dozen groups in 8 countries led by at the NERC Centre for Population Biology at Imperial College Silwood Park.

     

    HS: You joined the BIODEPTH project soon after you completed your PhD. Can you share with us how you got into this project?

    AH: Luckily, I spent much of the previous year working for at Imperial College, monitoring on-going experiments and helping set up new ones, to earn money while I wrote my PhD up. That put me in a good position when the postdoc. came up for BIODEPTH.

     

    HS: Please give us a sense of how this collaboration worked. How did people join this group? Did all of you meet anytime during the making of this study? Did you have regular online meetings?

    AH: BIODEPTH was a success because of the great collaborative spirit - it was a real team effort and everyone in it made an important contribution to its success. The Framework 4 structure had meetings every 6 months and we worked our way around most of the sites.

     

    HS: How did the writing of this paper happen? Did you do most of the writing? How were drafts shared and commented upon?

    AH: The paper was born at one of the regular meetings. It was hard to explain to people how to send the data in for inclusion in the database so we went through the whole process in a mock example and then did a basic statistical analysis there and then. Seeing how quickly it could be done really motivated people to get the data sent in speedily.

     

    HS: Did this paper have a smooth ride through peer-review? Was Science the first place you submitted this to? In what ways did the published version differ from the first submitted draft?

    AH: Yes and no. Science were happy to have it but it had mixed reviews – some scientists were (and still are) quite against the whole idea that diversity can be important for functioning. To some degree, the final paper was a compromise between opposing reviewer opinions.

     

    HS: In the Acknowledgements you thank "P. Heads and E.Bazeley-White" - can you tell us how these people helped? You also thank J. Nelder for advice on statistical analyses" - can you tell us more about this?

    AH: Phil Heads managed the NERC Centre for Population Biology for John (he was one of his ex-PhD students) and Ellen managed the database (she is now at British Antarctic Survey). It was great to have both of them to help support the work. was a very influential statistician. We hired him to hold a short workshop where we could bounce ideas for the analysis off him.

     

    HS: You say you used "standardized protocols to establish experimental assemblages ". Can you tell us a little more about these protocols?

    AH: The details are too technical to go into here. The key point was that each team followed the same approach at the different field-sites to make the data as comparable as possible.

     

    HS: Did this paper attract a lot of attention - in academia and in the media - when it was published?

    AH: Yes. Interestingly, the media did not find the idea controversial - it seems to make sense to people that biodiversity affects how ecosystems work – but some scientists did.

     

    HS: What impact did this paper have on your career and the future course of your research?

    AH: Obviously getting my second publication into Science was a huge break – I was very lucky to have had the opportunity.

     

    HS:  It is now 17 years since this paper was published - would you say that the main conclusions from this study still hold true?

    AH: Yes, in general. We have realized many scientific results are not reproducible (‘the reproducibility crisis’) but the BIODEPTH results turned out to be very reproducible despite being controversial with some people. The experiment has been repeated in , , and elsewhere and all results fall in the range seen in our study.

     

    HS:  If you were to redo these experiments today, would you do anything differently, given the advances in technology, theory and analytical techniques?

    AH: We tried to manipulate both species richness and functional groups and although their effects cannot be totally separated (more groups means more species) it would have been nice to have teased them apart a bit more (although did this for legumes, omitting them from their study). We used random mixtures of species due to some practical constraints. It might have been nice to use mixtures that reflected how species might be lost in reality, but this is hard to predict and depends on what is driving species loss. And, on the other hand, randomization is a key feature of good experimental design and a good place to begin.

     

    HS:  In the paper you say that this was "the most extensive experiment to date in terrestrial ecosystems." Since then, have there been bigger experiments on this topic?

    AH: At single sites yes (Cedar Creek and Jena), and BIODEPTH seems to have been partly responsible for the current popularity of networks (coordinated distributed networks) like Nutrient Network and Drought-Net.

     

    HS: Did the work presented in this paper serve as a motivation for ?

    AH: Yes. Basically we had a pattern, but could not pin down the mechanism. The 2001 paper helped us to do this.

     

    HS:  In your paper you say that "There may also be transient effects at this early stage of the experiment that largely disappear by the following year". Can you tell us whether this has happened in subsequent sampling?

    AH: Sadly, the EU framework 4 only allowed us to keep the 8 sites going for 3-4 years (some ran for longer) but longer term work at Cedar Creek and Jena has shown the effects generally get stronger over time as the experiments go on.

     

    HS: At the time of this study, Trifolium pratense was the only species that had particularly marked effects on productivity. Since then have other important species been discovered?

    AH: Actually, that result has to be taken in the context that red clover was one of the few species grown at all sites. I don’t doubt it has strong effects (it is a nitrogen fixer) but the design could not get at the effects of all species.

     

    HS: What is the status of the plots used in this study? Do they continue to be used for these experiments? Have the sites in which these plots are located undergone any changes since the time of this paper?

    AH: As I said above, sadly we could not keep the study going in the long term but the projects at Cedar Creek and Jena are still going.

     

    HS: At the time you did this study, did you anticipate that it would be cited so much? Do you know what this paper has been mostly cited for?

    AH: I didn’t really think about it but it was a new field and a controversial topic so it is not surprising. It is cited as evidence that biodiversity affects how ecosystems function.

     

    HS: Have you ever read the paper after it was published? When you read it now, what strikes you the most about it?

    AH: Not recently. I remember there is a mistake in it – at one point we say species richness affected diversity (when we meant productivity).

     

    HS: What would you say to a student about to read this paper today? What should he or she take-away from it?

    AH: That it is important to repeat the same study to see how repeatable or variable the result it.

     

    HS: Is this your favourite paper among all the papers you have published? If yes, why? If no, and if you do have another favourite, which is it and why?

    AH: It seems a long time ago now (it was!) but obviously it will always be one I remember. My other current favourites are:

     

     

     

  • Post date: 11 months 4 weeks ago
    Citation for this post: BibTeX | RIS

    In r published in Nature in 1982, showed, experimentally, that female choose mates based on the lengths of their tails. Andersson’s study was, arguably, the first experimental support for . Thirty-four years after the paper was published, I spoke to Malte Andersson about the making of this study and what we have learnt since about mate choice in widowbirds.

     (Questions sent by email on 7 July 2016; responses received on 17 September 2016)

     Citation: Andersson, M. (1982). Female choice selects for extreme tail length in a widowbird. Nature 299: 818-820.

     

    Hari Sridhar: What was your motivation for doing this study ? How and when did you first come to know about long-tailed widowbirds?

    Malte Andersson: My interest in sexual selection and signaling was seeded around 1970, during my doctoral studies of behaviour and ecology of long-tailed skuas in Lapland, Northern Sweden. The long-tailed skua is a relative of auks and gulls, and turns rodent predator in the far North during the breeding season. Inspired by the comparative ethological studies of gulls by ’s group, my aim was to study skua behaviour and its adaptations to an ecological lifestyle very different from that of its phylogenetic relatives. I was aware that both sexes in skuas have a pair of elongated central tail feathers that differ markedly in shape and length among the four Northern hemisphere species. In the field, I found that both sexes raise and expose the tail conspicuously during courtship, and I wondered about its function. Perhaps the elongated feathers are important for species recognition in pair formation? But at their breeding grounds, the species are easy to tell apart for a human observer, based on size, calls, coloration and other aspects. So why should the birds need different tail shapes for that purpose? Species recognition did not seem an entirely plausible hypothesis. On the other hand, catching the same individuals over several years, I found that the central tail feathers became longer and therefore reflected age and perhaps also survivorship. I wondered if that might somehow be relevant.

          About a decade earlier, Peter O’Donald, ’s last doctoral student, had studied sexual selection of color morphs in Arctic skuas. Reading his pioneering papers made me aware of Darwin’s and Fisher’s theory of sexual selection by female choice. I also read widely outside the curriculum, visiting our university library each weak, skimming journals in behavior, ecology and evolution for interesting new studies. I was also influenced by books on evolution, selection and adaptation by , and , which strengthened my interest in evolution. After my dissertation, these research fields, in particular sexual selection, full of interesting theory and unsolved problems, were on my mind. During a visit to East Africa in 1975, I saw long-tailed and Jackson’s widowbirds on their savanna breeding grounds in the Kenyan highlands. Why were male long-tailed widowbirds, with their black plumage, red wing epaulet and, especially, a half meter long unwieldy tail, so different from the females, which resembled dull females of other weaverbirds (Ploceidae)?

     

    HS: This is the first test of Darwin's hypothesis about male sexual ornaments. Why do you think it took so long for it to be experimentally tested?

    MA: Most biologists for a long period were skeptical about Darwin’s ideas on mate choice, and many remained skeptical even after the ‘’ in the mid 1900’s (e.g. , ). And, in spite of early pioneering work by Niko Tinbergen, experimental tests of behavior in the wild gained momentum only in the 1970’s and 80’s. Then, new results made it increasingly clear that field experiments in the natural environment could often provide decisive results and distinguish between hypotheses in behavioral and evolutionary ecology, clarifying the function and adaptive significance of a trait. Controlled field experiments thereafter became more common.

     

    HS:  During this study, what was a typical day in field like?

    MA: Usually going to the field site a while after sunrise, when widowbird males returned to their grassland territories from the night roost. We caught territorial males with a clap-net trap. Before and after catching and manipulating a male, I measured his display activity. After the sun dried out the morning dew from the tall grass, I searched for nests of females breeding in the territory, doing so once a week until the end of the breeding season.

     

    HS:  You started the fieldwork for this study in November 1981. In the same month, you wrote was accepted in the Biological Journal of the Linnean Society. Did this paper, in some way, motivate your study on widowbirds?

    MA: Yes, in a general way, as work on theoretical aspects of sexual selection made me read and think about debated issues of female choice and male ornaments. was one possibility, and it also seemed likely to me that ornaments could indicate phenotypic and genetic fitness, through resource allocation, as portrayed in a figure in the paper you mention. I thought that, in spite of lingering skepsis among many researchers, female choice based on male ornaments was plausible, encouraging me to attempt an experimental test.

     

    HS: Did you do all the fieldwork on your own or did you have help in field?

    MA: In catching the birds and during the experimental manipulations, a field assistant, first Uno Unger, then Kuria Mwaniki, helped me. He held the male in a suitable position, while I cut and glued the tail feathers. This way there was no need for anesthetics, and the bird could be released immediately after being manipulated and ringed.

     

    HS:  How difficult was it to find the nests?

    MA: It was more time-consuming than difficult. Females build their rather large-domed grass nest in the upper third of 0.5 – 0.8 m tall grass in the male’s territory. Females usually flew from the nest when I was several meters away. By systematically searching the grass areas of the territory in parallel walks about 2 m apart, I located the nests, and I repeated the search each week until the end of the breeding season, when no new nests were started.

     

    HS: Walk us through how you came up with the idea of modifying the tail lengths of these birds? Was it tricky to cut and paste the tail feathers back? Did you use a particular brand of glue for this?

    MA: Controlled field experiments was an approach I had used in several earlier studies during work with skuas and lemmings in Lapland. And I was aware of the . So, experimental testing of a conspicuous male ornament, potentially involved in female choice, was not a far-fetched approach. In fact, I had been thinking about this possibility for a long time, but then with the epitome of male ornaments in mind: the train of the peacock. I explored possibilities for doing such a field experiment during a visit to Sri Lanka in 1979, but found that such a study of peacocks in the wild would be difficult for several reasons. The lek sites I found in a national park were in jungle with plenty of elephants and wild buffalo around; not an ideal situation. In addition, manipulating trains of unwilling peacocks in the wild seemed to present some problems of its own.  That made me think again about the African widowbirds, which appeared more manageable.

          When I planned the experiments, rapidly hardening cyanoacrylate superglue was coming on the market. The brand I used was called . Testing with feathers from other birds, I found that the glue hardened quickly enough, in just a few seconds, to be suitable for use in the field for tail elongation. I practiced and improved my skill at feather manipulation at the lab before going to Kenya for the study. During manipulations in the field, the assistant sat in front of me holding the bird, while I cut, trimmed and glued the tail feathers.

     

    HS:  Fig. 1 in this paper is one of the nicest figures I have seen in a scientific paper. Whose idea was it to include the widowbird illustrations perched on the bars in the graph? How was this figure made at that time?

    MA: I thought carefully about how to include, without overloading the figure, as much information as possible. For instance the number of nests for each individual male at the bottom of the bars. The idea of having perched widowbirds with relevant tail lengths on the bars came rather naturally, because this was the way I often saw males in the field. There were many cattle fences in the area, and fence poles were the favorite perch sites for territorial males. I made the first version of the figure, which was then redrawn in ink by a departmental lab assistant, Aino Falk Wahlström, skilled at illustration work.

     

    HS:  One of the unique aspects of your study is the elegant “double control” you used for the experiments. Was this the first time such a design was being used?

    MA: I am not aware of any previous study with such a design, but it may well have been used before. I first planned to use only the color-ringed birds as control, but became worried that the cut-and-glue operation might have an important effect, so added a control for that.

     

    HS:  Your paper presents a lot of natural history information on the widowbird. Was this already known or did it come from your own observations?

    MA: Some of it was known from earlier studies of the South and the East African subspecies (e.g. ). Other aspects I learned during fieldwork.

     

    HS:  Today, do we know more about aspects of this bird's ecology which weren't well-known then, e.g. nest-site choice by females, role of tail length in competition, and territory ownership?

    MA: There has apparently not been much more fieldwork on this species, but several other widowbirds have been studied extensively by observations, experiments and comparative phylogenetic analyses, in particular by my former PhD student (no relative!) and his research group.

     

    HS:  Today, do we know more about why females choose long-tailed males in this species?

    MA: Our knowledge about mate choice in other widowbirds, and of course more generally, has increased vastly in the 34 years since the study was published, but there have been no further studies of mate choice in this species. The reason may be that a number of other widowbirds, whydas and other species also have long tails. Researchers have apparently preferred to study some of these other species rather than the one I already studied. Focusing on another species permits both another independent test of tail function, and can show if ornamental long tail plays a role in female choice more generally among birds. A number of studies of different species have found that it does.  

     

    HS:  Your work was entirely experimental. Have there been studies looking at whether your findings hold true with respect to natural variation in males?

    MA: Not in this species, but in many other birds, studies based on natural variation have found that male mating success correlates with ornament size.

     

    HS: Did this paper create a buzz - within academia and outside - when it was published?

    MA: Yes, it raised much interest among biologists, demonstrating sexual selection by mate choice of a conspicuous ornament, of the kind that long puzzled Darwin, until he arrived at the essentially correct explanation. It also raised interest in general news media, some of which reported that now it has been proved: the length matters.

     

    HS:  How important has this paper been in your career? Has it had a major influence on the course of your future research?

    MA: It had a major influence. Sexual selection is a field full of both fascinating natural history and interesting debated theory. Partly as a consequence of the simultaneous publication of the widowbird study and my theoretical paper in Biological Journal of the Linnean Society, I was invited by editors at Princeton University Press to write . Not anticipating the eruption of coming studies I gladly accepted. That decision kept me busy for a number of years. When the first version of the book manuscript was finished, it was necessary to revise almost every chapter, because so many new important results had been presented in the meantime. And the same procedure had to be repeated again also when the revision was finished, until I could finally deliver a manuscript that was reasonably up to date with the latest findings. Writing the book greatly reduced my available time for widowbird work and other research. Fortunately Staffan Andersson, after presenting his thesis on Jackson’s widowbird, could continue comparative and experimental studies of sexual selection of coloration and other ornamental traits in widowbirds and bishops, which remains a successful ongoing project. After gaining more time for own research when the book was finished, I have worked for instance on various aspects of breeding systems.

     

    HS:  Have you ever gone back and read this paper after it was published? What aspects about it strike you now? What memories does it bring back?

    MA: Yes, I have read the paper in preparing some talks and lectures. A nice aspect is its brevity. The experimental design, planned after a pilot visit to the study site a year before the experiment, made the outcome rather clear and easy to write about, resulting in a short informative paper. Reading it now recalls exciting fieldwork in a beautiful rural part of the Kenya highlands, with cool nights and hot sunny days, helpful and friendly Kikuyu farmers, and the Nyandarua Mountains as a magnificent backdrop under a clear sky. (There were thunderstorms and torrent rains too, but they seem to have thinned out in my memory.)

     

    HS: If you compare this paper to papers you write today, do you find any striking differences, e.g. in writing style?

    MA: Not that I am aware of. I try, but of course fail, to write as simply and briefly as possible, without sacrificing clarity and readability. A researcher that in my opinion wrote lucidly about quantitative evolutionary problems was John Maynard Smith. Authors with such writing style were for instance and .

     

    HS:  Have you had the opportunity to go back to your study site after the paper was published? Has the site changed a lot since the time you worked there, in 1981-82?

    MA: I have not been back since the mid-1980s, but even then, some of the breeding habitat of long-tailed widowbirds was disappearing, being turned into arable fields or plots for growing vegetables, and the nesting grass (Eleusinae) was being cut for thatching of roofs.

     

    HS:  This paper has been cited 793 times (Google scholar) as of today. Did you anticipate that it would generate so much interest? Do you know what your paper has mostly been cited for?

    MA: I had no idea it would raise so much interest. It has probably been cited mostly because it experimentally demonstrated female choice based on a conspicuous male ornament in the wild.

     

    HS:  What would you tell a student who is about to read this paper today? Any caveats? What should he or she take-away from it?

    MA: I spent much time thinking about the experimental design, and exploring the possibility for such a study by a pilot visit to the field site. So the importance of careful planning is probably a useful takeaway. Viewed today, there are many caveats. For instance, there is no paternity determination, as DNA methods were not then available. And the adaptive reasons for female choice of males with long tail could not be studied in this brief experiment. But the successful experimental demonstration of female choice in the wild may have helped encourage subsequent better studies.

     

    HS: Among all the papers you have written, is this your favourite?

    MA: Yes, I believe it is my best paper because it is short and informative, reporting a fairly clear outcome of a controlled, interesting experiment. It demonstrated, in the wild, female choice of mate based on a conspicuous ornament, one of Darwin’s most controversial ideas. Another often cited sexual selection paper is a model () showing that a genetic indicator process of mate choice can work, taking to higher frequencies a female preference and a preferred male ornament that reflects genetic viability. This, together with similar results from other researchers, may have helped generate more interest and more sophisticated modeling and empirical testing of such processes in sexual selection.

     

     

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