Monthly Archives: September 2020

Himalayan pollinators talk by Alan Moss now available to view on YouTube

The Missouri Botanical Garden’s annual John Dwyer Public Lecture in Biology for 2020 that I highlighted in a post last month is now available to view on YouTube – follow this link.

The talk by Alan Moss of Saint Louis University is called: “Ecology and Botanical History of the Himalayas: The Amazing Diversity of Bumblebees and Their Wildflowers on Yulong Mountain”.

Highly recommended and very, very interesting!

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Seasonal blog post views are a widespread phenomenon: a response to Leather (2020)

In a recent study [that was never published] in Nature, Leather (2020) argued that “Time of year determines some, but not all, views of my blog posts“. An analysis of an independent data set confirms this observation: the blog post “How to deal with bumblebees in your roof” shows clear seasonal periodicity (see figure above) with peaks during the most active period of Tree Bumblebee nest activity in May and June.

In contrast, posts such as “How does a scientist’s h-index change over time?” show no such periodicity (see online Supplementary Information).

I conclude that Leather (2020) is correct in his assertion that insect-related posts such as these “show a correlation (OK, not tested) with the time of year associated with the appropriate part of the life cycle”. Furthermore, one of the research councils should give us a wodge of cash to explore this phenomenon in more detail*

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*Only slightly tongue-in-cheek – I think that Simon’s results and those above are telling us something quite interesting about the ways in which people engage with insects throughout the year. Check out Simon’s piece for a fuller discussion of the phenomenon.

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Magnolia, Mississippi, and American politics: a guest post

This is a short guest post by Dr Peter Bernhardt who recently retired as a professor at St Louis University and continues to be active in pollination biology.

Each of the 50 American states has its own flag. On Election Day in November 2020 the citizens of the state of Mississippi will vote on whether they want a new flag featuring the flower of their state tree, the southern magnolia or bull bay (Magnolia grandiflora). Of the eight Magnolia species native to the continental United States six have natural distributions including the state of Mississippi.

By voting in the magnolia flag Mississippians drop its 126-year old predecessor, which incorporated an emblem (the stainless banner) adopted by southern states during the American Civil War (1861-1865). This will also mean that Mississippi will be the only state with a flag depicting a flower in which tepals, stamens and carpels are all arranged in a continuous spiral and is pollinated by beetles (see Leonard Thien’s study published in 1974). 

The popularity of M. grandifora far exceeds silviculture in the American south as successful exports stretch over two centuries and its cultigens are found as far as China and Australia.

Politics in America have turned floral in the last months of 2020: kamala, as in vice-presidential candidate Kamala Harris, is an Indian word for sacred lotus (Nelumbo nucifera). 

To which Jeff adds: the flag above is the one that Mississippi citizens will be voting on – follow the link at the start to get the full story of the competition that was run to select a new flag.

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Just published: An empirical attack tolerance test alters the structure and species richness of plant–pollinator networks

The latest paper from Paolo Biella‘s PhD work, on which I collaborated and that I’ve discussed before on the blog, has just been published in the journal Functional Ecology. It’s entitled “An empirical attack tolerance test alters the structure and species richness of plant–pollinator networks“. The paper presents more of Paolo’s work showing how the experimental removal of the floral resources provided by the more generalised plants in a community can significantly (and negatively) affect the patterns of interaction between flowers and pollinators that we observe. It’s another piece of evidence that demonstrates how important it is to not neglect the common plants that attract a lot of flower visitors when considering how to manage a habitat.

If anyone has trouble accessing the PDF, drop me a line and I will send it to you.

Here’s the reference:

Biella, P., Akter, A., Ollerton, J., Nielsen, A. & Klecka, J. (2020) An empirical attack tolerance test alters the structure and species richness of plant-pollinator networks. Functional Ecology DOI: 10.1111/1365-2435.13642

Here’s the abstract:

Ecological network theory hypothesizes that the structuring of species interactions can convey stability to the system. Investigating how these structures react to species loss is fundamental for understanding network disassembly or their robustness. However, this topic has mainly been studied in‐silico so far.

Here, in an experimental manipulation, we sequentially removed four generalist plants from real plant–pollinator networks. We explored the effects on, and drivers of, species and interaction disappearance, network structure and interaction rewiring. First, we compared both the local extinctions of species and interactions and the observed network indices with those expected from three co‐extinction models. Second, we investigated the trends in network indices and rewiring rate after plant removal and the pollinator tendency at establishing novel links in relation to their proportional visitation to the removed plants. Furthermore, we explored the underlying drivers of network assembly with probability matrices based on ecological traits.

Our results indicate that the cumulative local extinctions of species and interactions increased faster with generalist plant loss than what was expected by co‐extinction models, which predicted the survival or disappearance of many species incorrectly, and the observed network indices were lowly correlated to those predicted by co‐extinction models. Furthermore, the real networks reacted in complex ways to plant removal. First, network nestedness decreased and modularity increased. Second, although species abundance was a main assembly rule, opportunistic random interactions and structural unpredictability emerged as plants were removed. Both these reactions could indicate network instability and fragility. Other results showed network reorganization, as rewiring rate was high and asymmetries between network levels emerged as plants increased their centrality. Moreover, the generalist pollinators that had frequently visited both the plants targeted of removal and the non‐target plants tended to establish novel links more than who either had only visited the removal plants or avoided to do so.

With the experimental manipulation of real networks, our study shows that despite their reorganizational ability, plant–pollinator networks changed towards a more fragile state when generalist plants are lost.

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