Tag Archives: Canary Islands

Local and regional specialization in plant–pollinator networks: a new study just published

Euphorbia canariensis pollinators 2016-04-29 17 58 00

A fundamental feature of the natural world is that no species exists in isolation: all organisms interact with other organisms during their lives. These interactions take many forms and the outcome varies with the type of interactions. For example predator-prey interactions are clearly negative for the prey species, but positive for the predator. Other interactions result in positive outcomes for both species, including relationships between pollinators such as bees, birds and flies, and the flowers that they pollinate. An important feature of such interactions is how specialized or generalized it is; that is, how many different pollinators are actually involved in pollinating a particular type of flower, or how many types of flower does a specific pollinator visits.

In a newly published study, I have collaborated with colleagues from Denmark and Brazil to assess how local specialization (within a community) relates to regional specialization (across communities) using two separate data sets from the Brazilian rupestrian grasslands and Canary Island/North African succulent scrub vegetation.

Here’s the citation with a link to the paper (drop me a line if you can’t access it and need a PDF):

Carstensen, D.W., Trøjelsgaard, K., Ollerton, J. and Morellato, L.P.C. (2017) Local and regional specialization in plant–pollinator networks. Oikos (in press) doi:10.1111/oik.04436

The abstract is as follows:

“Specialization of species is often studied in ecology but its quantification and meaning is disputed. More recently, ecological network analysis has been widely used as a tool to quantify specialization, but here its true meaning is also debated. However, irrespective of the tool used, the geographic scale at which specialization is measured remains central. Consequently, we use data sets of plant–pollinator networks from Brazil and the Canary Islands to explore specialization at local and regional scales. We ask how local specialization of a species is related to its regional specialization, and whether or not species tend to interact with a non-random set of partners in local communities. Local and regional specialization were strongly correlated around the 1:1 line, indicating that species conserve their specialization levels across spatial scales. Furthermore, most plants and pollinators also showed link conservatism repeatedly across local communities, and thus seem to be constrained in their fundamental niche. However, some species are more constrained than others, indicating true specialists. We argue that several geographically separated populations should be evaluated in order to provide a robust evaluation of species specialization.”

This is what those two different habitats look like:

If you would like more information on plant-pollinator networks, including details of an edible game for Christmas (!), follow this link to the standingoutinmyfield blog.


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Filed under Bees, Biodiversity, Biogeography, Brazil, Macroecology, Mutualism, Pollination, Tenerife

Spiral Sunday #31 – hola Tenerife!

Tenerife graffiti spiral P1010967.png

In a few hours I’m heading of to Tenerife with students and colleagues for our annual undergraduate field course, following which I’m staying on to be joined by Karin for a further 10 days of field work.  I’ll try to post as and when I can, though it’ll be a packed few weeks.

In the meantime this week’s Spiral Sunday is a piece of Canarian independence graffiti that I photographed a few years ago on the road above Guimar.  As I’ve mentioned before, the spiral is an ancient and important symbol in the Canary Islands.  Adios!

Tenerife graffiti spiral - full P1010968.png

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Filed under spirals, Tenerife

Spiral Sunday #10 – a shrine in Tenerife


To celebrate number ten in my series I thought I would fulfil a promise that I made in Spiral Sunday #1 to tell the story behind the main image of a blue spiral that adorns this blog.

In 2008 I was leading a group of students on a walk in the Anaga region of Tenerife during our annual undergraduate field course to the island.  We were hiking through laurel forest along the trails from the restaurant at Cruz del Carmen,  looking at the forest and cliff vegetation community structure.  During our lunch break I set off alone down a side trail and came across a shallow recess, a sort of low natural grotto, in the vertical bank that defined one side of the track.

The walls of the grotto were green with lichen which made a vivid backdrop to what appeared to be a small consisting of branches, including one set upright that looked like a human figure with arms raised, or could it represent a crucifix?  Around this were scattered coloured pencils (to the right on the main image) and pieces of paper with writing on them, possibly prayers (on the left).

Most striking of all was a drawing of a blue spiral, its colours smudged and faded with the humidity, but still a conspicuous contrast to the lichen.  I took a few photographs, being careful not to disturb the display, then headed back to catch up with the students.

There is a strong local sense of traditional, pre-Spanish identity in this part of Tenerife and it is well known for its local stories such as the “Witches of Anaga“, and it’s possible that this shrine relates to local ritualistic practices.  The spiral is a traditional design used by the original Guanche inhabitants of the Canary Islands and still regularly found on logos, pottery, etc.  Alternatively what I discovered could have been just kids playing in the forest, though that seems unlikely as it’s off the beaten track and not close to any villages.

I’ve occasionally found other ritualistic items on the island (e.g. a child’s doll wrapped in cloth, with folded paper in the bindings) but the Anaga spiral shrine was a particualrly striking discovery.  When we returned with the field course the following year the spiral had disintegrated but the rest of the shrine had been tidied up and more neatly arranged (see lower photograph).  I wonder if it’s still there?





Filed under Biodiversity and culture, Tenerife