The fate of megafaunal plants on Madagascar: the video

Link to video: https://vimeo.com/390453594

Plants with megafaunal fruits on Madagascar used to rely on megafaunal animals, such as giant lemurs and elephant birds, for their dispersal. Nowadays, these animals are extinct, and this may lead to dispersal limitation of plants with megafaunal fruits, and possibly their extinction. This video uses animations and footage from Madagascar to present our research to understand the consequences of megafaunal extinctions for palms with megafaunal fruits, and whether they need conservation prioritisation.

This video was made in collaboration with TRICKLABOR for the amazing animations. I also obtained an Outreach grant from the European Society of Evolutionary Biology (ESEB) and a grant from iDiv’s Female Scientist Career Fund to make this film project happen.

In the coming years we hope to find answers to the questions proposed in the video

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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 Proceedings of the Royal Society B

Also see the press release from the University of Amsterdam.

Global change, such as climate changes, may have two outcomes with respect to biodiversity: species will adapt, or they will go extinct. In this article, we address this question from a historical perspective, focusing on the Quaternary (the last 2.6 Ma), a period characterised by rapid global changes. We show that in some parts of the world palm trees with very large fruits have adapted to global change, whereas in other parts they seem to have gone extinct.  The results were published in the journal Proceedings of the Royal Society B.

Palmplants crow smaller fruits

Global change – such as climate change, habitat fragmentations or the extinction of large-bodied animals , such as giant sloths, may force species to adapt or go extinct. In particular, plants with very large fruits that rely on large-bodied animals for the dispersal of their seeds may face a problem: can they adapt quick enough, or will global change drive them ultimately to extinction?

During the last 2.6 million years,  Latin American palms with the largest fruits seem to have gone extinct with increasing rates, whereas large-fruited palms in South-East Asian regions seem to be adapting by producing smaller fruits. Small enough to be eaten and dispersed by birds and bats. These were the results of Onstein and her team which consisted of researchers from the Netherlands, UK, France, Sweden and Denmark. They collected data for more than 2000 palm species across the globe.

Fruits need to become smaller

The absence of certain fruit-eaters, such as large hornbills, elephants or giant tortoises, may require plants with large, ‘megafaunal’ fruits to evolve ‘new’ fruits. This is similar to the selection by humans for fruits (such as papayas or mangos) to become bigger and bigger. However, instead of becoming bigger, these fruits naturally have to become smaller, to adapt to the small-bodied animals that are still there to disperse their seeds. A lack of dispersal may, alternatively, lead to their extinction.

‘Although it is difficult to see the long-term results of current global change, global change has been happening in the deep past as well, especially during the last 2,6 million years,’ says Onstein. ‘We therefore use the past as our experimental set-up to understand how current and future global change may affect these palms with very large fruits.’

Onstein thinks that the dramatic changes in climate, habitat fragmentation and megafauna extinctions that have happened in Latin America over the last 2.6 million years may have been the cause of the increasing extinction of palms. In South-East Asian regions, on the other hand, palm dispersal by flying animals such as birds and bats may have been important to escape the dramatic effects of global change. Palms seem to have had enough time to adapt to these flying animals by evolving smaller fruits.

The future of palms

How does the future of these palms with big fruits look like? There are still at least 220 palm species worldwide that bear these massive fruits larger than 4 cm in length. ‘Large-fruited plants have it increasingly difficult to survive in our human dominated world’, says Daniel Kissling, associate professor and senior author of the study. ‘The loss of large animals in tropical rainforests, e.g. due to hunting, illegal trade, and habitat loss, has a massive effect on tropical biodiversity. It leads to a reduced seed dispersal and less regeneration of these tall and massive plants. This has even the potential to significantly erode the carbon storage of tropical rainforest because large-fruited trees also store most carbon.’

The increasing human pressure and hunting of the still existing megafauna will certainly have cascading effects on the plants they feed on. Whether all palms will be able to adapt to the loss of large-bodied animal dispersers has to be seen.

Publication

Onstein RE, Baker WJ, Couvreur TLP, Faurby S, Herrera-Alsina L, Svenning J-C, Kissling WD. ( 2018 ). To adapt or go extinct? The fate of megafaunal palm fruits under past global change. Proceedings of the Royal Society BBiological Sciences, 285, 20180882.

Looking for a PhD student!

I am looking for a PhD student to work on seed dispersal, connectivity and genomics of palms with megafaunal fruits on Madagascar – the position can be started as soon as possible, and the student will be located at the German Centre for Integrative Biodiversity Research (iDiv) in Leipzig, Germany.

Applications are accepted until 30th June 2018. To apply, see here: https://www.idiv.de/about_idiv/career.html 

Or download the advertisement here.

A bit more background….

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Extinct megafauna on Madagascar, image by VELIZAR SIMEONOVSKI

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 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 micro- and macroevolutionary consequences of dispersal limitation for megafaunal-fruited palms on Madagascar, using a comparative framework. Specifically, we aim to (i) identify genomic signatures of dispersal limitation in megafaunal-fruited palm populations, (ii) reconstruct demographic history and identify historical genetic bottlenecks in these species, and (iii) evaluate whether these species may be adapting to dispersal by smaller-bodied frugivores, by evolving smaller fruits with smaller seeds. This project integrates the fields of plant evolution, phylogeography, and plant-frugivore interaction ecology. It will be in collaboration with researchers from Kew Botanical Gardens, UK (Dr. Bill Baker), Aarhus University, Denmark (Dr. Wolf Eiserhardt), the University of Amsterdam, the Netherlands (Dr. Daniel Kissling) and Botanic Garden of the Ruhr-University Bochum, Germany (Dr. Wolfgang Stuppy), among others.

Job description:
  • collecting genetic samples from palm populations on Madagascar, and measuring their functional traits;
  • identifying Malagasy frugivore communities and their functional traits;
  • using novel genomic techniques (e.g. RAD sequencing) to infer connectivity, demographic history and phylogeographical patterns;
  • 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. ecology, (molecular) biology, genetics, phylogenetics, phylogeography). 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). Therefore prior experience with tropical fieldwork and basic living conditions is advantageous. Furthermore, the successful candidate should have prior experience using molecular techniques, preferably with bioinformatics for large genetic/genomic datasets. An interest in acquiring additional necessary skills (e.g. programming) for handling and statistically analyzing large datasets is essential. 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.

Applications are accepted until 30th June 2018, the applicant is expected to start as soon as possible, but latest by September 2018.

For queries on the application process, please contact Dr. Nicole Sachmerda-Schulz (nicole.sachmerda-schulz@idiv.de); for research project questions, contact Dr. Renske Onstein (onsteinre@gmail.com).

Beyond climate: why are there so many species of flowering plants in mediterranean-type ecosystems?

Have you ever wondered why – evolutionary speaking – the mediterranean floras of the world are so species-rich (e.g. the Cape of South Africa and Western Australia)? And why species look so similar in these systems (small, fibrous leaves adapted to deal with drought and low nutrient soils)?

We (Peter Linder and I) may give you a clue in a recently published study: “Beyond climate: convergence in fast evolving sclerophylls in Cape and Australian Rhamnaceae predates the mediterranean climate” in Journal of Ecology.

Although the very similar climatic conditions among mediterranean-type ecosystems were previously thought to drive this patterns of morphological ‘convergence’, it may not be the only important factor.  Furthermore, it seems that these typical morphological characteristics of the plants (i.e. sclerophyllous leaves) may also have influenced their evolutionary fate: well-adapted leaves may reduce your chance to go extinct. Some groups of plants may therefore have evolved a whole bunch of species – all with similar functional traits – and so contributed to the extraordinary species diversity in these mediterranean-type ecosystems.

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Mediterranean-type ecosystem in the Cape of South Africa