Our response to Heymann & Fuzessy

It was the day before my maternity leave started that I received an invite from the journal Proceedings of the Royal Society B to submit a reply to the comment by Heymann & Fuzessy. They criticized some of the work my co-authors and I published in early 2020, on the relationship between palm fruit colours and the diversity of trichromatic vision (the ability to distinguish red and green) in primates. See here for the original publication. Luckily, the journal allowed me a bit of time to think about a response while nursing my baby.

The main issue that Heymann & Fuzessy raised, was that there is little natural history information on the dependence of primates on palm fruits, especially in Africa. Therefore, they considered the macroecological and macroevolutionary analyses we performed in our original article unreliable. In our response, we argue that our macro analyses, which show a strong relationship between the spatial and temporal diversity of trichromatic primates and that of conspicuous (e.g. reddish) palm fruits (see figure below), are indeed only one piece of the puzzle, and multiple lines of evidence are needed to further resolve the question whether primates evolved trichromatic vision as an adaptation to detect conspicuous fruits. This includes more natural history information – the dataset of Heymann & Fuzessy was limited and incomplete, especially for Africa – , network analyses, co-phylogenetic methods, and macro approaches as we did here, and perform these across a range of taxonomic plant groups that may be important food sources for primates. Good ones to start with could be Moraceae (figs and relatives), Melastomataceae, Annonaceae.

I hope to further address the question on whether palm fruits are important to explain the distribution and diversity of frugivores (including primates) in my future research.

Results from the original study, showing with structural equation models that the proportion of plants with conspicuous fruits in communities have a strong effect on species richness of day-active, frugivorous polymorphic and trichromatic primates in those same places.

Original publication: https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2731

Comment: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1423

Reply: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2981

Looking for two PhD students to join iDiv!

Application details for both positions are now available – see below!

I am looking for two new PhD students to join the Evolution & Adaptation group at iDiv in Leipzig (Germany) from October 2020 onwards. The positions are fully funded (65% of a full time employment, Salary: Entgeltgruppe 13 TV-L) and for 3 + 1 years. There is a budget available for consumables to perform fieldwork, lab work, sequencing, visit conferences, herbaria, collaborators and take courses. The PhD students will become part of the yDiv graduate school. iDiv is a very international place to work in and learn about Biodiversity science more generally, with weekly seminars, and Leipzig is a lovely city with lots of green space and a cultural history to live in.

Below I briefly describe both projects. Feel free to get in touch (onsteinre@gmail.com) to find out more, if you are interested in applying to one of them:

1. Macroecology and macroevolution of plant – frugivore trait matching in the tropics

Application details available from here: 113_iDiv_P3_REO_engl and 112_general_announcement__4thFlexPoolcall_engl. Deadline for application: 10th July 2020.

Background: Mutualistic interactions between fleshy-fruited plants and frugivorous animals are prominent in tropical rainforests. These interactions are facilitated by the evolution of matching traits in both plants and frugivores, such as fruit size and frugivore gape width. Due to ongoing global change (e.g., defaunation) trait matching may have been distorted in certain places, such as highly disrupted regions, leading to co-extinction or rapid evolutionary change in plants/animals that relied on these locally extinct interaction partners. However, which places harbour such mismatches in traits is unknown. Furthermore, it is unclear when these interaction-relevant traits evolved, and whether they have influenced the past diversification dynamics of plants and frugivores. In this PhD project, we aim to understand the impact of frugivory-related plant and disperser trait origin and extinction on the macroecology and macroevolution of fruit-frugivore trait matching, by addressing three main questions: (1) Do frugivory-related plant and animal dispersal syndromes (i.e., sets of correlated traits) differ among biogeographical realms, or mainland/island systems? (2) Is the spatial distribution of frugivory-related plant traits matched by the corresponding animal disperser traits (e.g., fruit size ~ gape width), or are there mismatches due to Late Quaternary extinctions of particular mammalian, avian or reptilian functional groups? (3) Has there been trait matching or mismatching during particular geological time periods, leading to increased (co-)speciation or extinction? To answer these questions, we will focus on three plant clades that are keystone resources for frugivores in the tropics: Arecaceae (palms), Annonaceae (custard apples) and Fabaceae – Mimosoideae (legumes). Furthermore, we will match the plant data to frugivore data, primarily focusing on frugivorous birds and mammals. We will integrate phylogenetic, distribution and functional trait data for these clades and apply macroecological and macroevolutionary methods to answer the research questions. This project will shed light on the biogeography of plant-frugivore interactions to be able to identify places and lineages prone to ongoing (co-)extinctions of their interaction partners. This project is supervised by me, Ingolf Kühn, Isabell Hensen and Irene Bender, but the student will work with several more collaborators for the specific datasets and their expertise on the plant and animal clades.

Tasks:

  • Developing specific research questions and hypotheses within the scope of the project;
  • Assembling/cleaning plant and animal frugivory-related traits, phylogenetic and distribution data from online databases, literature, monographs and herbarium visits (partly already done);
  • Applying macroecological and macroevolutionary methods to test the specific hypotheses;
  • Writing and publishing scientific papers in peer-reviewed journals;
  • Presenting results at national and international conferences;
  • Participation in iDiv’s PhD training program yDiv.

Requirements: Applicants should hold a Master’s or equivalent degree in a related field of research (e.g., biosystematics, (macro-)ecology, (macro-)evolution, environmental sciences). The successful candidate should be innovative, able to work on his or her own initiative, have expertise and experience in phylogenetics or working with phylogenetic data, interest and ability in handling spatial data and functional traits and strong statistical skills (in R). Candidates should be team-oriented and have strong organizational skills, in order to manage this collaborative research project within an international consortium. Excellent English communication skills (speaking and writing) are required. We seek candidates with an independent mind and the ambition to publish in internationally leading journals.

2. Adaptive evolution of plant-frugivore interactions on Madagascar

Application details available from here: 142_iDiv_PhD_Onstein_EA_engl. Deadline for application: 20th July 2020.

Background: Madagascar harbours exceptional biodiversity, but this tropical hotspot also faces increasing threat from human activities and climate change. Plants with large, ‘megafaunal’ fruits are common across the flora of Madagascar, especially within the palm (Arecaceae) family. However, Pleistocene-Holocene extinctions of large-bodied ‘megafaunal’ fruit-eating and seed-dispersing animals (such as giant lemurs) may have hindered the dispersal of taxa with megafaunal fruits. In this project we aim to investigate the molecular, micro- to macroevolutionary consequences of dispersal limitation in palms, specifically focusing on adaptive evolution of a megafaunal-fruited palm, Hyphaene coriacea, using a comparative framework of Madagascar (all megafauna extinct) and mainland Africa (where H. coriacea is still frequently dispersed by elephants). Specifically, we aim to (i) identify candidate genes for fruit and seed traits important for plant-frugivore interactions, (2) pick up genetic traces of selection or adaptation in relation to dispersal by smaller-bodied frugivores, and (3) evaluate the macroevolution of candidate genes or gene families across the palm family. This project integrates the fields of plant evolution, molecular evolution and plant-frugivore interaction ecology. It will be in collaboration with researchers from Hohenheim University (Prof. Philipp Schlüter) and University of Miami (Prof. Mauro Galetti), among others.

Tasks:

  • Collecting genetic samples from H. coriacea individuals and populations on Madagascar and mainland Africa, and measuring their functional traits (part of these samples have already been collected);
  • Collecting ecological information about the seed dispersal effectiveness (e.g., using camera traps) and demography of H. coriacea in the study areas;
  • Using novel genomic and transcriptomic techniques (e.g., RAD-seq, RNA-seq) to infer candidate genes for functional traits and evaluate traces of selection;
  • Writing and publishing of scientific papers in peer-reviewed journals;
  • Presentation of results at international conferences;
  • Participation in iDiv’s PhD training program yDiv.

Requirements: Applicants should hold a Master’s or equivalent degree in a related field of research (e.g. molecular biology, genetics, phylogenetics, population genomics, ecology and evolution). The successful candidate should be innovative, able to work on his or her own initiative, and willing to spend several months in the field (Madagascar/mainland Africa). Therefore, prior experience with tropical natural history, fieldwork and basic living conditions is advantageous. Furthermore, the successful candidate should have prior experience using molecular techniques, preferably with transcriptomics or bioinformatics, incl. the basics of scripting/programming for handling and statistically analysing large genetic/genomic datasets. Candidates should be team-oriented and have strong organizational skills, in order to manage this collaborative research project within an international consortium. Excellent English communication skills (speaking and writing) are required. We seek candidates with an independent mind and the ambition to publish in internationally leading journals.

 

 

New article: Primate colour vision linked to palm fruit colours

Press release by iDiv (Kati Kietzmann)

Read the open access article here

Data for the article can be downloaded here

Colourful fruits may be the reason why primates can distinguish between shades of red, green and blue

Leipzig/Amsterdam. The evolution of colour vision might be closely linked to the availability of food. Researchers from the German Centre for Integrative Biodiversity Research (iDiv), Leipzig University (UL), and the University of Amsterdam (UvA) found that colour vision in African primate species, which is similar to that of humans, is related to the spatial distribution of palm fruit colours. The results of their study have been published in Proceedings of the Royal Society B. They shed new light on the evolution of primates.

In our retina, three kinds of receptors are responsible for the perception of basic colours: red, green and blue. The same holds true for many primate species – in contrast to all other mammals. For nocturnal species, the ability to distinguish different colours would not provide a significant advantage. It is therefore highly probable that so-called trichromatic vision developed in diurnal primates. In addition to greens and blues, they can also distinguish shades of red, making it easier to detect coloured fruit. This could provide a competitive advantage over other fruit-eating animals that cannot distinguish red from green. While this idea had been tested experimentally in a few species, it remained largely unexplored on a larger scale.

A team of researchers from iDiv, UL and UvA has now shown that trichromatic vision in primates is strongly linked to the availability of conspicuous, red palm fruits. Their research involved analysing data on the colour vision and distribution of more than 400 primate species as well as fruit colour data for over 1700 palm species. The result was clear: trichromatic vision in primates is most common in African countries with a high proportion of palm species with very colourful, conspicuous fruits.

This relationship is a win-win situation, benefiting both primates and palms: while primates rely on palm fruits as their primary food source, they are also important seed dispersers in tropical forests, particularly for large fruits. The research shows that the number of diurnal, fruit-eating primates in Africa increases with the proportion of conspicuous palm fruits, with a peak in subtropical regions. The results suggest that the effects of palm fruits on primates are strongest in the transition zones of arid to subtropical regions, where competition for food is also high. For the African primates, the ability to see several colours is thus an advantage when foraging. Palms, in turn, evolved colourful fruits that could be easily spotted by the primates, thus helping to disperse their seed.

The researchers did not only analyse data from the African continent, but also from Asia and the Americas. “Interestingly, in the Americas and Asia some primate species have trichromatic vision, whereas others do not. Here, we did not identify a relationship between colour vision and the proportion of conspicuous palm fruits,” said first author Dr Renske Onstein from iDiv and UL. Furthermore, most primates in the Americas prefer palm fruits with non-conspicuous colours. By contrast, many trichromatic primates in Asia have no interest whatsoever in a fruit’s colour – they enjoy feeding on large amounts of fruit in general.

“In Asia and the Americas, birds and bats could play a more important role as seed dispersers than primates,” explained Dr Daniel Kissling from UvA, senior author of the study. “In contrast, there are relatively few frugivorous birds on the African continent, so palm species may rely more on primates as seed dispersers than other fruit-eating animals.” The analyses show that palm species in Africa are dominated by those with conspicuous fruits, whereas the fruits of American species tend to be more inconspicuous.

Many primate species are now threatened with extinction due to rapid habitat loss and global changes. This may have cascading effects, especially when some plant species rely on primates as their primary seed dispersers. Thus, conservation efforts should also take plant-animal interactions and fruit-colour diversity into account as this is crucial for maintaining tropical biodiversity.

Original publication

Onstein RE, Vink DN, Veen J, Barratt CD, Flantua SGA, Wich SA, Kissling WD (2020). Palm fruit colours are linked to the broad-scale distribution and diversification of primate colour vision systems. Proc. R. Soc. B 20192731. DOI: 10.1098/rspb.2019.2731

http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2019.2731

Chimpanzee (Pan troglodytes) feeding on a wild date palm (Phoenix reclinata). (Picture: M. McLennan / Bulindi Chimpanzee & Community Project)

Screen Shot 2020-02-28 at 09.36.54

PalmTraits 1.0

Functional traits are characteristics of individuals, populations and species that determine their fitness, via their impacts on growth, survival and reproduction. Examples are leaf size, leaf thickness, fruit size, wood density…. Traits are great proxies for the ecology of species, and used extensively in macroecological and macroevolutionary research. PalmTraits 1.0 provides species-level trait data for all ca. 2500 palm (Arecaceae) species worldwide. The database is available from Dryad. The article in which we present the data was published in Scientific Data.

Screen Shot 2019-12-19 at 11.27.35

PalmTraits 1.0, Figure from the publication in the journal Scientific Data

What else did we (I and my collaborators) do with these data? For example, using average fruit size of palm species, we asked questions such as: Do large fruits co-occur with large-bodied animals that disperse these fruits? And: Does fruit size influence speciation rates via the interaction between fruits and fruit-eating and seed-dispersing animals? What happened to palms with large, ‘megafaunal’ fruits since the Quaternary extinctions of large-bodied animals?

Answers to these questions can be found in these publications:

Onstein, R.E. , Baker,W.J., Couvreur, T.L.P. , Faurby, S., Herrera-Alsina, L., Svenning, J.-C. & Kissling, W.D. (2018). “To adapt or go extinct? The fate of megafaunal palm fruits under past global change”. Proceedings of the Royal Society B 285: 20180882. [ABSTRACT] [PRESS RELEASE]

OnsteinR.E. , Baker,W.J., Couvreur, T.L.P. , Faurby, S. , Svenning, J.-C. & Kissling, W.D. (2017). “Frugivory-related traits promote speciation of tropical palms”. Nature Ecology & Evolution 1:1903–1911. [ABSTRACT] [DATA & CODE] [PRESS RELEASE] [BLOG]

However, the data can be used to answer many more questions, related to the ecology and evolution of palms. Species differ not only in their fruit sizes, but also in, for example, fruit colours, leaf structures and sizes, the presence or absence of spines, growth forms, plant height. In combination with distribution data and a phylogeny, we can now answer questions such as: when did these traits evolve? Where do species with these traits occur? Where do we find the most colourful fruits, and why? Where do species occur that have spines? Etcetera…

Palms of Madagascar meeting in Leipzig

In the beginning of February, I organised a kick-off meeting for Laura Mendez‘ PhD project on “Genomic signatures of palms on Madagascar” – 3 days of discussions at iDiv in Leipzig (Germany). The team includes palm, frugivory and Madagascar experts from Kew Botanical Gardens, Aarhus University, University of Amsterdam, Bochum Botanical Gardens and iDiv – all important collaborators on Laura’s PhD project. The discussions ranged from deciding which species she will sample on Madagascar next summer, to clarifying the specific hypotheses and learning about historical demographic modelling techniques using Rad-seq data. A couple of very valuable and ‘fruitful’ days.

IMG_5798From left to right: John Dransfield, Chris Barratt, Daniel Kissling, Laura Mendez, Renske Onstein, Alex Zizka, Adriana Alzate, Wolf Eiserhardt, Wolfgang Stuppy, Jun Lim, Bill Baker.

New article published in Nature Ecology & Evolution

rainforest Borneo2 editBy dispersing the seeds of plants, fruit-eating animals contribute to the possibility of increased plant speciation and thus biodiversity. These are the findings of our study published on Monday, 23 October (2017) in Nature Ecology & Evolution.

The article is available here, and I wrote a blog post on the Nature community website. Other outreach is available from here (in English) and here (in Dutch). In case you do not have access to the pdf, send me an email and I’ll happily send it to you (onsteinre@gmail.com).

My first time in the rain forest was during a gap year after high school, now more than 12 years ago. My parents had inspired me to follow in their footsteps, and when arriving at Bangkok airport, Thailand, I immediately took a bus up north, to see the remaining rain forest and its treasures with my own eyes.

Fruits of the palm Cryosophila warscewiczii

The diversity of plants and animals, the rain forest sounds and smells, as well as the alarming noise of chainsaws, all encouraged me to study biology in the years that followed. Palms, amongst the most charismatic and recognisable elements of rain forests, immediately caught my attention. They appeared in so many shapes and forms, and I found out that in total there are almost 2600 species worldwide. Their fruits in particular intrigued me: ranging from tiny red berries to huge brown ‘megafaunal’ fruits, up to 12 cm in length. Almost all palm species depend on fruit-eating animals such as chimpanzees, elephants or hornbills for their seed dispersal. Interestingly, palms with large, megafaunal fruits are exclusively dispersed by large-bodied mammals (‘megafauna’) that were highly diverse in the past, but have nowadays gone largely extinct. My trip to the rain forest inspired me to ask questions that ultimately led to his study. Why are palms so diverse? Has their intricate relationship with fruit-eating animals perhaps contributed to their diversification?

Although palms are extraordinarily species-rich, it remains unclear which factors are responsible for this diversity. I expected that the historical interaction of megafaunal-fruited palms with megafaunal animals likely reduced their speciation rate as compared to smaller-fruited palms, because of increased gene flow between populations, reducing the chances of geographic speciation. With this study we show that small fruit sizes do indeed increase speciation rates in palms. However, fruit size is not the only important driver of speciation: understory growth form and the colonisation of islands also contribute to increased speciation. The highest speciation rate was found for palms that are dispersed by birds and bats that are able to fly long distances across oceanic barriers, allowing them to colonise isolated islands in South-East Asia and the Pacific.

These results provide important insights for the future of biodiversity. The ongoing extinction of biodiversity worldwide has dramatic consequences for ecosystem functioning and human well-being. Our study emphasises the need to protect not just single species or habitats, but also to restore interactions between species, such as those between fruit-eating animals and their food plants, in areas where these have been lost.

Publication: https://www.nature.com/article…

R.E. Onstein, W.J. Baker, T.L.P. Couvreur, S. Faurby, J.-C.Svenning & W.D. Kissling: ‘Frugivory-related traits promote speciation of tropical palms’, in Nature Ecology & Evolution (23 october 2017). DOI: 10.1038/s41559-017-0348-7

rainforest Borneo edit

IBS conference, Tucson

Last week I attended the 8th Biennial conference of the International Biogeography Society in Tucson, Arizona (U.S.A.). The conference included symposia on modelling large scale ecological and evolutionary dynamics, experimental macroecology and building up biogeography from process to pattern. I presented the first results of my work on what may happen to megafaunal-fruited palm lineages under rapid global environmental change. These species with anachronistic fruits (> 4 cm in length) suffer from dispersal limitation because of recent extinctions of their large-bodied (megafauna) fruit and seed dispersers, such as gomphotheres, ground sloths and glyptodonts. However, we do not know how these palms have survived and evolved in the past – and whether they have suffered from extinction previously, during Quaternary climate change for example. In this talk I showed how over the last 2.6 million years (the Quaternary) these megafaunal-fruited palm lineages have experienced increasing extinction rates, but only in the Americas, and how they have evolved smaller fruits in Southeast Asia and Australasia. These smaller fruits may be adaptations to bird-dispersal in these dynamic island systems.

Paris-Sud

P1090494

frugivory in the Atlantic rainforest, Brazil

I am currently doing a postdoc in the Sauquet lab at the Université Paris-Sud. In collaboration with Daniel Kissling, Hélène Morlon, Thomas Couvreur, Lars Chatrou and Hervé Sauquet, I study “Frugivory, functional traits and the diversification of a tropical angiosperm family: Annonaceae (Magnoliales)”.

For a 1 minute summary of the project- watch this video.

In short –

Frugivory (i.e. fruit-eating and seed dispersal by animals) is ubiquitous in tropical ecosystems, but the role that frugivores have played in the macroevolution of species-rich tropical plant families remains largely unexplored. This project will investigate how plant traits relevant to frugivory (e.g. fruit size, fruit color, fruit shape, understory/canopy growth form, etc.) are distributed within the angiosperm family of custard apples (Annonaceae), how this relates to diversification rates, and whether and how it coincides with the global biogeographic distribution of vertebrate frugivores (birds, bats, primates, other frugivorous mammals) and their ecological traits (e.g. diet specialization, body size, flight ability, etc.). Annonaceae are particularly suitable because they are well studied, species-rich (ca. 2400 species), characteristic in all tropical rainforests, and dispersed by most groups of vertebrate seed dispersers. Using a phylogenetic framework and functional trait and species distribution data we will test (i) how fruit trait variability relates to phylogeny and other aspects of plant morphology (e.g. leaf size, plant height, growth form, floral traits) and animal dispersers and their traits, (ii) to what extent interaction-relevant plant traits are related to diversification rates, and (iii) whether geographic variability in fruit traits correlates with the biogeographic distribution of animal dispersers and their traits.