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

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Greetings from… Yunnan, China

The University of Amsterdam wrote a short article about my work in Xishuangbanna Tropical Botanical Garden (XTBG) in Yunnan, China. Unfortunately it’s in Dutch, but I’ll give a short summary here.

Renske field China

In July and August I spent three weeks at XTBG and Kunming Institute of Botany to investigate the colour of palm fruits. XTBG is home to > 300 species of palms, and these show a high interspecific variation in fruit colour, ranging from black to purple to yellow, orange and red. Why does this variation in fruit colour exist? I hypothesise that fruit colour may be adaptive to frugivory – that is, fruit-eating and seed dispersal by animals.

Certain primates are ‘trichromatic’, which means that they can distinguish between red and green (such as humans) whereas other species of primates are dichromatic and can’t distinguish green from red (such as colourblind humans). These trichromatic primates can therefore easily detect reddish fruits against a background of greenish leaves in the rain forest, thereby having an advantage over dichromatic primates – which may have more difficulties finding food under these conditions. To test the hypothesis, I therefore expect that in areas where there is a dominance of trichromatic primates (such as chimpansees, gorillas and howler monkeys), palms with reddish fruits are also more common, as compared to areas dominated by dichromatic primates.

At XTBG I analysed the colour of palm fruits using a constant light source and software to quantify these colours (rather than a subjective classification of ‘green’, ‘red’ or ‘orange’). Together with my collaborators at the University of Amsterdam (my master student Daphne Vink, bachelor student Jorin Veen and Dr. Daniel Kissling) I aim to spend the coming months on analysing these data in a biogeographical context, using distribution and fruit colour data of > 2000 species of palms.

This research is important to better understand why fruits display such a wide range of colours – and to be able to predict how ongoing extinctions of primates may affect the future evolution of colours in the rain forest.

cof

Besides sampling palms, I also presented my previous work at XTBG and Kunming, and had exciting discussions on ongoing work and future collaborations with the members of the Ecology and Biogeography group, led by Prof. Yaowu Xing.

IBC, China

Screen Shot 2017-08-02 at 09.59.26

Last week I attended the XIX International Botanical Congress in Shenzhen, China. With ca. 7000 participants this was by far the largest conference I have ever been to. The organisation was incredible – the whole city (with ca. 16 million people!) was transformed into a ‘save our green planet’ stage to feature the conference, there was a daily newspaper with updates, >1000 talks and the complete Chinese army seemed to be present for security.

China

The venue

My phone informed me that the outside climate felt like 49 degrees, although temperatures ranged from (just) 32 to 37 degrees. This was another highlight of the trip: on all my fieldwork trips to the tropics I have never felt so hot (and humid especially) as in Shenzhen. Fortunately there was no good reason to be outside – inside is where the magic happened: talks ranging from genomics to plants and people to taxonomy and speciation. I gave two talks: one on speciation in tropical palms (work carried out at the University of Amsterdam), and one on the evolution of fruit functional traits in the Annonaceae family, and how these traits may have affected dispersal (work carried out at the Université Paris-Sud).

It was a great meeting, nice to catch up with old friends from all over the world, to taste some of the Chinese culture and to see how China commits to saving our planet, because, as emphasised in several of the talks: we need plants, and plants need us. To save our planet we need to educate the future generations, as well as convince the non-scientific community about the excitement of plants, their incredible diversity and function for humanity.

My trip in China hasn’t finished yet, as I am currently in Xishuangbanna tropical botanical garden in Yunnan. More on that in my next post…

 

 

 

10 things I hate about being a scientist (but I love it)

10 things I hate about being a scientist:

– I hate those days when I realise that what I do is most likely totally useless and will probably never lead to the greater purpose I have in mind for my research;

– I hate the struggle to find the right words (to explain what I do, for example) because jargon is flying through my mind (and watching over my shoulder, correcting me);

– I hate it that some scientists think they are better than others, because they have the ability to make other people cry;

– I hate it that I cannot have a conversation about anything else than science or career anymore. I do not even enjoy talking about anything else anymore, sometimes… ;

– I hate it that my income is very low relative to my non-scientist friends. I’m joking – I do not actually mind that 🙂 ;

– I hate the still existing gender bias in academia;

– I hate meeting great people but then they leave again;

– I hate (and enjoy at the same time) not to know where I will be in a year from now;

– I hate negative reviews because they make me feel even more insecure about my research and where I am trying to get with my life (and career);

– I hate it when coming home after a long day of work and I fall asleep immediately. Where has my life gone?

After all this has been said, I still do not want to do anything else than science, because those short moments I do feel happy about my results and their impact are very rewarding. And if I compare doing science to any other purpose in life, this is probably one with the least egocentric element in it. And who knows – maybe one day I will make the difference and save our planet from extinction….

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.

Proteaceae and their success in open habitats

geb-cover-onstein-et-al-leucospermum-cordifolium

Leucospermum erubescens

In a recent study, published in the journal Global Ecology and Biogeography, we investigate the evolution of leaf morphologies and climatic niches in the Proteaceae family. Proteaceae is a Southern 20131216143659639-page-001Hemisphere family famous especially in Australia and South Africa for their impressive flowers and leaves. They are also tasty – the macademia nut belongs to the Proteaceae as well. Species in the Proteaceae family occur in all kinds of habitats, from montane forests to dry heathlands to tropical rainforests. During their evolution over millions of years, they managed to adapt to these variable and extreme habitats and climates, and their leaves may have helped them doing so. In this study we test whether open (e.g. mediterranean) and closed (e.g. tropical rainforest) habitats have selected for divergent leaf designs. We also show that the combination of certain leaf traits (e.g. small, sclerophyllous leaves with many teeth) in interaction with certain climatic niches (e.g. warm, dry, mediterranean) may increase diversification rates. This could explain some of the spectacular radiations within the family, for example inbanksia-speciosa-9_10-566x800 genus Banksia in Australia, or the Protea in Africa. Last, we show that there is more stochastic evolution of traits and niches in open habitats, which may explain some of the extreme forms and ‘misfits’ we find here. This “disparification” maybe even led to the process of reproductive isolation and speciation, roupala-longipetiolata-4_6-mtvia ecological divergence, and the ~1700 species of Proteaceae we find on Earth.

Onstein, R.E., Jordan, G.J., Sauquet, H., Weston, P.H., Bouchenak-Khelladi, Y., Carpenter, R.J., Linder, H.P. (2016). “Evolutionary radiations of Proteaceae are triggered by the interaction between traits and climates in open habitats.” Global Ecology and Biogeography 25 (10):1239–1251. doi: 10.1111/geb.12481