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Nov 4

The dynamics of inselbergs – New paper in Biological Reviews

Since the start of my PhD in 2006, I’ve spent several years of my life walking on inselbergs (i.e. ancient isolated mountains with modest topography) mainly in Africa and Australia, studying the organisms that live there. It was an inspiring and productive endeavor, leading to a lot of published case studies. Yet, some broader insights take time to develop. I believe it’s only when you spend enough time working on a system and after endless discussions with local experts that deeper understanding emerges. In 2017, a meeting was arranged at the University of Rostock, home of Stefan Porembski, arguably the most influential inselberg researcher alive today. As a PhD student I eagerly read and re-read his landmark green book on Inselbergs.

Wouldn’t it be great if we could bundle the insights that emerged in the quarter century after this book? Together with Fernando Silveira and Luiza De Paula, two (at the time) young up and coming inselberg researchers from Brazil we started drawing up some first diagrams and distilled general patterns and processes from the different plant and animal groups we studied and from the different regions we studied: from the Atlantic forest to the Kalahari and back. The paper would not have been possible without the geomorphological and biogeographical insights of Tom Van der Stocken and Falko Buschke who helped to streamline the ideas through various phases and input from a running PhD project by Joren Snoeks. We are proud that this journey now resulted in a synthesis paper published in Biological Reviews. The ecological and evolutionary dynamics of inselbergs. Some pictures of inselbergs featured in the paper are provided below.

https://onlinelibrary.wiley.com/doi/full/10.1111/brv.13150

In the paper, we provide a new liberal definition of inselbergs from a biological perspective, stressing the old age (easily tens of millions of years, often more), unique microhabitats, and isolation as the main defining characteristics. Typical inselbergs are much lower than proper mountains (< 800m) and therefore typically lack strong altitudinal zonation. They also provide a template of habitats that is not limited to the exposed rock. The surrounding vegetation fringe is an integral part of the broader inselberg ecosystem. We also stress the importance of the landscape matrix in which inselbergs are embedded, which can be a source of inselberg species. Inselbergs can house a lot of endemics adapted to the often harsh inselberg conditions. But they can also be ecological refuges and evolutionary refugia for species from the landscape matrix, particularly over long time scales of cyclical environmental change. Finally, we argue that although they resemble islands, only a small subset of the organisms that can be found on inselbergs will experience them as islands. Inselberg specialists with poor dispersal abilities will experience them as islands, while for more mobile species, inselbergs and for generalists, inselbergs may simply provide habitat patches in the broader landscape that can be used. The landscape matrix, therefore, is not simply a barrier to dispersal (as is the case for oceanic islands) but provides a pool of species and habitats that interact with species and habitats on the inselbergs. At the end, we provide a list of major knowledge gaps that may inspire the next decade of inselberg research and can help us to understand the role of these amazing features in our landscapes.

Comoé NP, Cote d’Ivoire
Kari Kari Rock, Colombia
Sugarloaf Mnt, Rio de Janeiro
Kubu island, Botswana
Walga Rock, Australia
Walga Rock, Australia

Nov 4

Resolving the cryptic identity of cocoa pollinators – new paper in Basic and Applied Ecology

Since I started the lab at VUB, we have done a number of projects in the tropics looking at small aquatic habitats such as bromeliads and the ecological dynamics of the biota they contain. It did not escape my attention that these habitats were also used by the same types of midges known to be involved in the pollination of cacao. However, to my surprise at the time, the identity of cocoa pollinators was quite controversial. Work from the 80s and 70s identified midges from the genus Forcipomyia as the main pollinators. However, more recent studies reviewed by Toledo-Hernandez and coworkers (2017) reported a much larger diversity of cocoa flower visitors. To resolve this paradox, we believed it was necessary to introduce stricter criteria to define pollinators. It led to the conception of the Barcoding for Chocolate (BFC) project in our lab, pioneered by PhD student Mathil Vandromme. In her doctorate, she carefully caught flower visitors on cocoa flowers in Nicaragua and noted the behavior of the individuals. This way, we could distinguish taxa that just hung around or rested on the flowers from those that entered the petal hoods and came into contact with pollen. These individuals were sequenced for the COI barcoding gene so we could confirm what they were. But Mathil went another step further: she also sequenced small flies that emerged from different potential larval habitats (rotting cacao husks, banana pseudostems, leaf litter, bromeliads). This way, we can pinpoint where the pollinators breed! The first results of this project are now published in a paper in Basic and Applied Ecology.

https://www.sciencedirect.com/science/article/pii/S1439179123000099

In the meantime, a lot has happened. With Eliza Van de Sande, a new PhD project was started, and a number of dedicated students (Fanny Kratz, Sara Vroman) brought back new pollinator samples from Peru, French Guiana, Malaysia, and Côte d’Ivoire. All flower visitors are now also investigated for pollen adherence, too, so we are getting closer to a definitive list of pollinators. Soon we will get a better idea of the diversity of cocoa pollinators globally. For now, the pilot results from Nicaragua clearly point at biting midges and several potential breeding habitats for cocoa pollinators, but the links found in the paper have to be confirmed at much larger scales in more plantations and in different cocoa breeding areas in the world to generate conclusive evidence of which breeding habitats might be promoted through management to improve pollination.

Dec 3

Biodiversity and ecosystem functioning- new paper in Ecology Letters

We tend to assume that if there are more species in a given site that this typically leads to a better functioning ecosystem with for instance a higher production of biomass. In a new paper in Ecology Letters, we show that this is invalid. It’s not how many species that are present that matters, it’s how many species that had an opportunity to be present (the regional species pool) that determines functioning.

This illustrates that we need to conserve regional biodiversity to support our ecosystem services even when local biodiversity is not declining. https://onlinelibrary.wiley.com/doi/10.1111/ele.13874

The paper is lead by James Hagan, an ex MSc student from our department at VUB and Tropimundo alumnus.

Hagan, J., Vanschoenwinkel, B. & Gamfeldt, L. (2021) We should not necessarily expect positive relationships between biodiversity and ecosystem functioning in observational field data. Ecology Letters.

Sep 3

Empirical evidence for bet hedging – new paper in Ecology

Always nice to deal with unfinished business. After more than 15 years, the data of my only unpublished PhD chapter are now finally published. In the end it took us a physical model, a demographic model, two field experiments and three lab experiments to show that fairy shrimp can avoid extinctions by ensuring that their dormant eggs can hatch at various moments in the future and that this is an evolutionary risk spreading strategy.

The paper is out in the journal Ecology

https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3496?fbclid=IwAR08otGgTFz8MjAROKo09WvLrhfJZBXNNhxtSZf65GBUuNxN1qc4o39rAaw#.YRpENxBqPUA.facebook

Pinceel, T., Buschke, F., Geerts, A., Vanoverbeke, J., Brendonck, L., & Vanschoenwinkel, B. (2021). An empirical confirmation of diversified bet hedging as a survival strategy in unpredictably varying environments. Ecology.  (SCI: 5.499), Q1

Sep 3

A process based metacommunity framework – new paper in Ecology Letters

Bram was part of a working group hosted by the German Integrative Biology Institute in Leipzig that had the ambition to better understand how communities interact in space by including a much needed temporal dimension. In a first paper lead by Patrick Thompson, we present a novel framework to understand (and study) how ecological communities can interact in space and how this leads to different temporal dynamics in community data. Instead of trying to infer process from community patterns, this framework explicitly varies three underlying processes (density dependent competition, density independent environmental filtering and dispersal) and shows that by doing this a whole range of possible metacommunity dynamics can be obtained including all currently known and described dynamics as well as a range of dynamics that have remained unconsidered and unstudied.

We believe it can be an important first step to achieve a much needed synthesis in the field of metacommunity ecology.

The study was published as an “Idea and perspectives” piece in the journal Ecology Letters

https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13568

 

 

Sep 3

Rocky outcrops as ecological refuges – new paper in Biological Conservation

In joint work with the University of the Free State, we study how isolated mountains and rocky outcrops can help to preserve biodiversity. As study region we work  in the grassland biome of the Eastern Free State Province in South Africa.  In a first paper, now out in Biological Conservation, we present data on the butterflies present in this region.

We found that butterflies in the landscape matrix between the mountains were a nested subset of species from the mountains and outcrops, and there was little evidence that species with certain traits were limited to either habitat. This suggests that species can retreat to mountain refuges during harsh conditions and recolonise the surrounding matrix once conditions improve.

Ecological refuges such as these mountains and rocky outcrops  can unify land-sharing and land-sparing because their targeted protection would support the persistence of species throughout wider landscapes.

https://www.sciencedirect.com/science/article/abs/pii/S000632072030817X

Aug 18

Where does land use matter most? – new paper in Sci. Tot. Env.

The lab is active in Tanzania in an inter university collaboration with the Nelson Mandela Institute for Science and Technology in Arusha. In one of the first papers of this project, Grite Nelson shows that studies of river quality and integrity should cautiously infer the influence of surrounding land use activities. Water quality and biota responded to land use at differentn scales.  What is more, the spatial buffers used to calculate land use had a strong impact on the detected land use effects. The work stresses the need to standardize approaches to investigate effects of land use on different aspects of river quality.

The paper is out in the journal Science of the Total Environment

https://www.sciencedirect.com/science/article/abs/pii/S004896971934817X

Jul 24

The effects of distant predators – new paper in Journal of Animal Ecology

Two years ago, Beth Turner did a MSc thesis in the lab and performed a field experiment in Nicaragua together with PhD student Mathil Vandromme. The goal was to demonstrate that prey species do not just respond to predators that are present in a certain habitat, but also to predators elsewhere in the landscape. To test this we used landscapes of bromeliads that have a central tank that provides aquatic habitat.  As a predator we used a caged predatory larva of the mosquito Toxorynchites, a ferocious predator of mosquito larvae including members of its own species.

We could confirm that effects of predators in a natural ecosystem can extend beyond the patch in which the predator is present and that the presence or absence of remote predator effects on habitat selection depends on the distance to predators. The notion that perceived habitat quality can depend on conditions in neighbouring patches forces habitat selection studies to adopt a landscape perspective and account for the effects of both present and remote predators when explaining community assembly in metacommunities.

The work has been published in Journal of Animal Ecology

https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2656.13239

 

Dec 21

Workshop: Uncoupling a meaningful life from the destruction of nature

Workshop picture

In a joint VUB Global Minds project between VUB and the University of the Free State, South Africa, we generated course material that can be used to organize workshops for university students (both in developing and in developed nations) to tackle the important question of whether it is possible to lead a meaningful life without destroying nature.  Participants fill out standardized scientific questionnaires that test:

1. Meaning in life (how meaningful do you find your life?)

2. Ecocentricity (how is your life connected to nature?)

3. Ecological footprint (to what extent does your life style impact nature?)

By correlating the scores of participants on these different tests our aim is to raise awareness to what extent these life traits are correlated. What is more, if applied to a large number of participants from different backgrounds and cultures it can also allow to generate more generic insights in how these concepts are connected globally. A first work shop took place at VUB on December 4th.

 The supporting electronic course material can be downloaded  here

and here

Below are some photos from the event 

Nov 19

Bromeliads as habitats for cacao pollinators

In a new paper, we report the presence of cacao pollinators in bromeliad plants and identify factors that influence their abundances.

Bromeliads are common plants in the Neotropics. Being epiphytic, they are often incorrectly considered as parasites and removed from agroforestry systems. However, their water-filled leaf axils provide habitats for a diverse group of aquatic organisms, potentially including cacao pollinating dipterans which could be beneficial to local farmers. Thus far, it is unclear how frequently and abundantly potential pollinators occur in bromeliads in cacao plantations. Therefore, we investigated the aquatic fauna in different types of bromeliads in Nicaraguan cacao agroforestry systems. Our main goal was to study the impact of bromeliad morphology and vertical position on aquatic biodiversity with particular attention for larvae of presumed cacao pollinators. Aquatic biodiversity was higher in larger bromeliads and in bromeliads positioned closer to the ground. Particularly invertebrates without flying life stages were deficient in elevated bromeliads suggesting dispersal limitation. Potential cacao pollinators occurred in 66% of the bromeliads and were most abundant in bromeliads with larger tanks that were located higher in the canopy rather than on the plantation floor. We conclude that larvae of cacao pollinators can be common and relatively abundant inhabitants of tank bromeliads in cacao trees, and it is likely that preserving these habitats could boost local pollinator abundances.

The paper is out now in Hydrobiologia

DSC_3172
Bromeliads growing on the branches of a cacao tree in Nicaragua (photo: Bram Vanschoenwinkel)

 

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