AgriPop Friday Talks

Friday's Agripop Talk - 29 March 2013

Hey, we've got a busy day ahead -- 2 talks on the same day!

29 March 2013 - 11:00 - Salle Seminaire

Learning trophic networks : apprehending patterns and generalities from real data

David Bohan

Who eats whome and how to find this out without the need to actually observe the act of predation, or without the need of lengthy analysis of the diet -- just come and listen how David uses commonly available distribution and abundance data to infer trophic relationships between carabid beetles and weeds in arable farmlands.

David worked until recently in the UK at Rothamsted, after which he moved to Dijon to take up a IINRA DR1 position.

 

Lindy Mary Corredores Hurtado

29 March 2013 - 15:30 - Salle Ragondin
Bees and their landscape: mapping the distribution of floral resources in agricultural landscapes and their use by wild bees 

Lindy will present us her sampling plan for mapping the distribution of wild flower resources, especially of poppy flowers, and assess their use by domestic bees. Please come all and help out Lindy - she'll be keen to hear your feedback and advise!

And, what better way to finish the week listening to a talk about bees and wild flowers ... just before pub time??? :-) So, see you all there et bon weekend!

AgriPop Friday Talks

Friday's Agripop Talk

21 March 2013 - 11:15 - Salle Ragondin

The structuring processes of passerine’s communities, the share of the stochastic, environment and biotic interactions

Laura Henckel

Actually, it's a thursday talk!

Which mechanisms drive the assembly of communities is a longstanding question in ecololgy. However there is a renewed of interest for this problematic since the last decades due to some original studies : coexistence theory of Chesson (2000), Hubbell’s unified neutral theory (2001), or due to new available tools (ie. phylogenetic). But notwhithstanding the numerous studies, the debate remain open and there is no consensus amoung the various theories. The controversies concern in particular the relative importance of the processes involved (stochasticity, dispersal, biotic interactions or environmental screen).

Because it is difficult to test directly the effect of these processes via a mechanistic model, a wide range of indirect approachs were proposed in recent years. This great diversity of methods can partly explained the divergence of conclusions. Furthermore, it appears that these results are strongly dependent on the scale of analysis (spatial extent and grain), on taxa and even on the characteristic of the study site. Another thing is that a wide part of the studies on community assemblages remain theoretical and most of the others concern micro-organisms or plant communities. For these reasons further studies are needed, combining both a consistent set of methods and a multi-scale approach in a way to strengthen the results and reduce biases or misinterpretation. We therefore use some of these methods in way to understand the assembly processes that structure the passerine community in the particular context of the intensive agro-ecosystems.

This question constitutes both a scientific and societal challenge in the context of the strong decline of farmland birds observed during the past decades due to agricultural intensification.  For this purpose I will use the point count data collected between 2009 to 2012 on the workshop area “Plaine et Val de Sevre”, which are distributed on the whole area (every 1km²) allowing me to conducted a multi-scale approach by varying the grain and the extent of analysis.  A set of different methods will be used to distangle the processes involved (ie. multiple regressions on distance matrix, co-occurrence analysis) and different models will be compared (stochastic vs different determist models) to try to identify which processes are involved and at which scale. This work constitutes a preliminary study for my PhD which will focus more specifically on the environmental factors and in particular on the landscape heterogeneity effect (crop composition and configuration) on farmland birds.

AgriPop Friday Talks

Friday's Agripop Talks

  15 March 2013 - 11:30 - Salle Ragondin

The evolutionary history of Petrels: 

A microevolutionary and macroevolutionary approach 

 

Adriana Iglesias Vasquez

 Tube-nosed seabirds. Yes, exactly. This week's seminar will be about "tube-nosed seabirds in the bird order Procellariiformes" (Wikipedia docet), commonly known as petrels. But you can do much better and these birds have stimulated the immagination of poets -- you might recall:

Up above the sea's grey flatland, wind is gathering the clouds. In between the sea and clouds proudly soaring the Petrel, reminiscent of black lightning.

Glancing a wave with his wingtip, like an arrow dashing cloudward, he cries out and the clouds hear his joy in the bird's cry of courage.

In this cry -- thirst for the tempest! Wrathful power, flame of passion, certainty of being victorious the clouds hear in that bird's cry.

 Much better, isn't it? And, it turns out, petrels are also interesting from an evolutionary point of view, with a clear lack of research about their evolutionary history. And that's the subject of Adriana's PhD thesis:

Evolution in simple words is understood as the change in the form and behavior of organisms among generations. Variation in the organism’s forms occurs at all levels from DNA sequences to macroscopic morphology promoting the diversity of life (Futuyma, 1998). To understand the processes that shape such diversity evolution could be studied from two approaches acting at two levels and on two timescales: microevolution and macroevolution. Microevolution acts rapidly within populations through adaptive and neutral evolution while macroevolution occurs slowly and the patterns it produces are driven by speciation and extinction (Stearns & Hoekstra, 2005).

My thesis research will focus on these two evolutionary scales having as a biological model a group of the Procellariidae family well known as Petrels. The evolutionary history of these seabirds is unclear, as most of evolutionary studies have focused on terrestrial birds, and likely complex,  with two opposed evolutionary forces shaping its genetic structure: phylopatry and mobility. This Friday I will introduce you the three main questions from which I will develop my thesis: 

1. Is there a correlation between neutral genetic variation and morphological traits? 

2. Is the pattern of genetic differentiation concordant across molecular marker types - nuclear and mitochondrial? 

3. What is the mechanism of speciation that better explains the formation of new species of Petrels?

Thus, come this Friday - usual time and place: 11:30 Salle Ragondin.

And the Petrel soars while crying, reminiscent of black lightning, like an arrow piercing the clouds, 

with his wing rips foam from the waves.

...

AgriPop Friday Talks

Friday's Agripop Talks

  08 March 2013 - 11:30 - Salle Ragondin

Spatial depletion models highlight distribution rules of foraging sea ducks

Vincent Tolon

Seaducks? Yes, there are also ducks in the sea, not only in your local lake! And what do they eat? Clams and other shellfish - but no, not exactly as you are just thinking:

Immage downloaded from http://bit.ly/YCSM3G

... but indeed the same ones that we humans enjoy eating. And one problem with similar resources is that, once a forager takes them, they get depleted! So, how to forage for similar resources? Vincent will address this question using a population of seaducks living on the northern coast of France as study system. Here's a summary from Vincent of what he will show us this week:

Understanding distribution rules of foragers in their environment is one of the main topics of behavioural ecology. For predators that prey on non-renewable resources, depletion (i.e. the simple removal of food that other individuals can consume) is a likely mechanism driving population distributions. Since two decades, spatial depletion models (SDMs) have been developed to predict effects of resource depletion on predator distributions. These models commonly predict that predators should first exploit the richest patch, and include other patches when they become as profitable as previously depleted areas. 

SDMs can help determining how the distribution should change in response to resource depletion, and can provide a reference over which more complex distribution rules (e.g. density dependence) can be tested. We located groups of common scoters Melanitta nigra foraging on benthic communities on a French coast used as wintering areas. We first tested if simple “Ideal Free” SDMs can explain theirs seasonal distribution dynamics between and within large ranges (areas of several dozen of km²). We tested such models for different combination of prey type and determined how much the model/data matching can be explained by density variations.

And here also a cool GIF of Vincent's model predictions:

Cool, isn't it? So, come and listen!