Temporal dynamics of aquatic communities and implications for pond conservation [paper summary]

This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Temporal dynamics of aquatic communities and implications for pond conservation”, was published in the journal Biodiversity and Conservation in 2012. You can find this paper online at the publisher, or on Figshare.

Background:  When an area is designated as a site for conservation or special scientific interest that is usually because one or more species of interest have been found or the community as a whole is unique or exceptional. However, the implicit assumption in this approach is that if you come back tomorrow then those species or that community will still be present. If the habitat is dynamic, with frequent population-level extinctions and colonisations, then it may be that this assumption does not hold. Pond ecosystems represent one case where the habitats are small and relatively easily affected by external variables and which may, as a result, vary in their conservation value over time.

What we did: Andrew Hull and Jim Hollinshead have been monitoring ponds in Cheshire (northwest England) for almost 20 years. A set of 51 ponds were surveyed in 1995/6 and again in 2005, meaning that we can test whether or not over this 10-year period there was any change in the conservation value of the ponds. Pond surveys recorded all plant and macroinvertebrate (i.e. invertebrates larger than about 1mm, which was the size of the mesh of the net) species in the ponds and we compared (i) the diversity, and (ii) the conservation value of the ponds between the two surveys. Plants showed similar levels of diversity in both surveys, so highly-diverse ponds in the first survey remained that way in the second. However, invertebrate diversity was not correlated between surveys, meaning that species rich ponds in the first survey did not necessarily remain that way. For both groups there was not correlation between conservation value (calculated based on the rarity of the species in the community) in survey 1 compared to survey 2.

Importance: Ponds are highly variable ecosystems and that is one of the reasons that they support such a wide range of species on a landscape scale. However, it seems that this variability may make it difficult to conserve them adequately, since conservation value is changing over time.  This finding supports the conservation of pond clusters, rather than individual sites, which are more likely to contain a stable species pool.


Image credit: Alison Benbow, CC BY 2.0, http://bit.ly/1l35Tdu

Drones and quadcopters in conservation

I’ve had a bit of a go at using unmanned aerial vehicles (UAVs) in the past (see this little write-up) but with mixed success. Part of the problem is that there has not been any consistent attempt to develop a technology that can be used for environmental or ecological research – just a bunch of scientists trying to MacGyver existing equipment. Now there’s Conservation Drones, who seem to be taking a slight more systematic approach, designing their own drone, spreading the knowledge around, and starting up PhD research projects to develop the tech further. Here’s an early demo of one of their models:

Higher gregarine parasitism often in sibling species of host damselflies with smaller geographical distributions [paper summary]

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Higher gregarine parasitism often in sibling species of host damselflies with smaller geographical distributions”, was published in the journal Ecological Entomology in 2012. You can find this paper online at the publisher, or on Figshare.

Background:  Parasites and the individuals that they attack (called “hosts”) often have a long evolutionary history of interaction. This history often plays-out as an “arms race” where the parasite finds a new way of attacking the host and the host then evolves a defence against that attack, followed by subsequent evolution by the parasite. Not only this, but species of parasites (such as the aquatic mites and protozoa that I work on) that exploit many host species can differentially affect those different hosts. In this study, we were interested in how parasitic protozoa affect closely related damselfly species that differed in their distributions.

What we did: Julia Mlynarek, a PhD student at Carleton University, collected a large number of damselflies from a number of sites around eastern Ontario. The species were grouped into pairs so that we could compare between species from the same genus.  She dissected these to find the number of protozoa (like the one shown above) in guts of each animal. We found that species with smaller geographical distributions tended to have more protozoan parasites than closely related species with larger distributions.

Importance: Explaining how parasites affect their hosts is a big question spanning ecology and evolutionary biology. These results suggest that there might be a combined effect of (i) shared parasites due to evolutionary history, and (ii) varying resistance due to different exposure across geographical ranges.


Image credit: Christophe Laumer, CC BY 2.0, http://bit.ly/1rrvyzt

Leopard dive bomb

Here’s a fascinating example of a leopard hunting by hurling itself from a tree:

Leopards are hugely adaptable creatures and feed in a variety of ways on pretty much anything they can catch and kill from dung beetles to gorillas. Often on the African savannah they will stalk prey around dawn and dusk, pouncing from short range. It isn’t clear whether this was a regular hang out for the leopard or whether it happened to be napping in the tree when lunch walked along…

H/T Richard Conliff at Strange Behaviours

A defense of “denial” and “debate” on climate change

LeedsSkepticsTalkI gave a talk at the Leeds Skeptics last night – part of a mini-tour talking about “Denying the Evidence: Why People Reject Science and What We Can Do About It“. During the Q&A I was asked whether using the term “denier” was an attempt to shut down the debate over climate change. These are two interesting issues which I’ll take one at a time. Continue reading

Yet another post about gender and academic conferences

genderThis is becoming something of a cottage industry recently – it is fairly straightforward to calculate the gender ratio of presenters at academic conferences and to evaluate that ratio against some theoretical baseline. However, these sorts of questions are important to look at because the work is highly complex and so requires a large number of people looking at the diverse kinds of conferences to provide a bigger picture. A number of previous studies have shown a range of different patterns in gender and academic conferences (references at the bottom): Continue reading

Historical changes in the phenology of British Odonata are related to climate [paper summary]

This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Historical changes in the phenology of British Odonata are related to climate”, was published in the journal Global Change Biology in 2007 (my first paper!). You can find this paper online at the publisher, or on Figshare.

Background: A variety of responses to climate change have been detected in a variety of taxa.  Among these is a change in phenology – the timing of the life cycle (like the emergence of an adult dragonfly from its larval case as shown on the right). Since some species use temperature as a cue for when to develop, as the environment warms there is a signal of earlier development in these species. Continue reading