The evolution of plants on Madagascar: who eats their fruits now that the giant lemurs have gone extinct?

I’m happy to announce that my proposal to make an outreach video about our work on Madagascar has been funded by the European Society for Evolutionary Biology (ESEB Outreach fund) and iDiv’s Female Scientists Career Fund.

Details will follow, but in short:

We aim to improve the understanding of evolutionary concepts (e.g. genetic connectivity, bottlenecks, speciation and extinction) at secondary schools. These concepts will be illustrated using video shootage from our fieldtrip to Madagascar (starring the new Evolution & Adaptation lab members Laura Mendez and Adriana Alzate!), as well as by use of animations. We study the evolutionary fate of Malagasy megafaunal-fruited plants (fruits > 3 cm) since the extinction of their primary seed dispersers: giant lemurs and elephant birds. Are these plants genetically adapting to new, smaller-bodied frugivores, or have they gone through genetic bottlenecks and are possibly facing extinction? The video will address these questions guided by the scientific and conservation activities performed by (female) researchers on Madagascar.

 

Advertisements

See you at Evolution in Montpellier?!

From 19-22 August 2018 I will attend the Evolution conference in Montpellier, France. I will present a poster on “Fruit colour as a driver for the evolution of trichromatic primate diversity” in S-33 Ecological models of macroevolution. Please visit me and / or my poster during the ‘Cocktail Poster Session 5.30pm –7.30pm’ on Tuesday 21st, or any other time!

 

Screen Shot 2018-08-08 at 13.57.14.png

Sneak preview….

The mutualism between fruits and frugivores is prominent in tropical rainforests, but to what extent fruits have influenced the macroevolution and macroecology of frugivores and their functional traits remains underexplored. Here, we hypothesize that trichromatic colour vision (i.e. the ability to distinguish green and red) in frugivorous primates has evolved as an adaptation to detect conspicuously coloured (i.e. reddish) fruits against a background of green foliage. The readily detection of these fruits as critical resources may have provided trichromatic primates a competitive advantage over dichromatic primates that cannot distinguish reds from greens.

Screen Shot 2018-08-08 at 14.06.49.png

To test this hypothesis, we combined global distribution, phylogenetic and colour vision data for >400 primate species with fruit colour data for >1700 palm and >80 fig species. Palms (Arecaceae) and figs (Ficus) are considered keystone resources for frugivores in tropical rainforests worldwide. We used structural equation modelling to show that the regional proportion of food plant species with conspicuously coloured fruits positively affects the diversity of trichromatic primates, but only in Africa. We show that this effect intensifies towards the tropics, following a hump-shaped relationship with food plant species richness. This suggests that the most species-rich places (i.e. rainforests) provide sufficient alternative food sources for primates, decreasing their dependence on conspicuous fruits. Overall, our results indicate that the consumption of palm and fig fruits could have been a driver for the diversification of trichromatic colour vision in African primates, and that food availability is an important determinant of frugivore diversity more generally.

 

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.

I’m looking for a technician!

I am looking for a technician to join the Evolution & Adaptation lab at iDiv as soon as possible. For more information about the position and how to apply (deadline 9th of July 2018), see here. For additional questions please send me an e-mail: onsteinre@gmail.com. The technician will play an important role in the Madagascar palm seed dispersal project, including the possibility to join the fieldwork. Other projects of interest can be developed as well.

Screen Shot 2018-06-19 at 10.24.43

Illustration: William Snyder @deviantart.com (Pleistocene Madagascar). For a nice blog on this by Pedro Jordano see here: https://pedrojordano.net/2016/12/30/megafauna-in-madagascar/

Biological-Technical Assistant

(initially limited until 30. September 2020) Salary: Entgeltgruppe 6 TV-L

         Tasks:

  • Combining (botanical) data sources (such as monographs and floras) to build databases for biodiversity data (using Access or SQL)
  • Measuring functional plant traits from herbaria or fresh sample material
  • General laboratory organization (incl. setting up a new laboratory) and laboratory maintenance
  • Planning and conducting molecular and cell biology experiments
  • Analysis of generated data and preparation of suitable presentations

    Requirements:

  • successful professional qualification as Biological-Technical Assistant or an equivalent degree
  • hands-on experience in molecular and cell biology techniques (DNA/RNA isolation, PCR, real-time PCR, cloning) would be preferable
  • experience in building databases would be preferable
  • very good computer skills (MS Windows, MS Office etc.)
  • good spoken and written English skills
  • strong team-player, but can also work independently
  • very good work organization and reliability
  • experienced to work in interdisciplinary and international teams

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….

Screen Shot 2018-06-07 at 10.12.09

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).

Start at iDiv!

After moving all our stuff from our lovely apartment in Amsterdam to our new place in Leipzig, Germany, I am ready to start my job as junior research group leader at the German Centre for Integrative Biodiversity Research (iDiv) today.

Get in touch for questions, (student) projects, etcetera! (e-mail: onsteinre@gmail.com)

Media Release:

Interview: https://www.idiv.de/en/groups_and_people/core_groups/evolution_and_adaptation/interview_ro.html

Screen Shot 2018-06-05 at 12.17.17

 

 

New book: The Biology of Mediterranean-type Ecosystems

Screen Shot 2018-04-19 at 14.36.54

A while ago, David Ackerly, professor at the University of California, Berkeley, asked me to jointly write a case study for a book on ‘The Biology of Mediterranean-type Ecosystems’. Now, several years later, I’m happy to announce that the book is published, and can be ordered here. Editors Karen Esler, Anna Jacobsen, and Brandon Pratt have done a great job. The book integrates a broad range of subjects important to MTEs, including climate, geology, physiology, ecology, and conservation.

Our case study specifically addresses the assembly of the five mediterranean-type floras, considering and comparing the processes of convergence, exaptation and evolutionary ‘predisposition’. As shown in the figure below, we could distinguish three hypotheses (H1-H3) for the occurrence of close relatives sharing functional traits matching a mediterranean climate (MTC). These are illustrated on a phylogenetic tree. Adaptation refers to the evolution of traits in response to MTC, whereas exaptation refers to the evolution of traits under another selective regime, which then become adaptive under MTC.

  • H1: Exaptive or adaptive evolution of traits to MTC in one region, followed by long-distance dispersal to another region.
  • H2: Exaptive evolution of traits and long-distance dispersal prior to appearance of MTC and independent sorting of taxa from each continent into the respective regions.
  • H3: Independent and parallel adaptive evolution of traits from common ancestors in response to MTC after dispersal to the respective regions.

Screen Shot 2018-04-19 at 14.43.58

I’m planning to test these three hypotheses in some of my future work on MTEs.