BioMaths Colloquium - 17/06/2016

BioMaths Colloquium Series - 2015/16

17 June 2016 - 3pm Maths Seminar Room

(room 224 Talbot Building 2nd floor)

Predator-prey biomass relationships: a role for predator density dependence?

Dr David Murrell

(University College London, UK)

from: ecol-evo.blogspot.com

Abstract

Recent empirical research has shown that increasing ecosystem productivity leads to an increase in the proportion of biomass at lower trophic levels. Thus as prey species increase in abundance/biomass their consumers also increase but at a much reduced rate. Indeed the general empirical results link predator biomass (P) to prey biomass (N) as P ~ N^k, where k<1 for most ecosystems studied. 

Surprisingly, ecological theory does not provide an immediate answer as to how this relationship may occur. I will consider the potential roles for density dependence operating at the level of the predator/consumer to generate these sub-linear increases in biomass at higher trophic levels. Through analyses of simple ecological models I will outline some criteria for generating the empirical pattern and compare these predictions to the rare cases where the models have been applied to data.

The discussions will continue over biscuits and tea/coffee after the seminar. 

Hope to see many of you!

BioMaths Colloquium - 27/05/2016

BioMaths Colloquium Series - 2015/16

27 May 2016 - 3pm Maths Seminar Room

(room 224 Talbot Building 2nd floor)

Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change

Prof Sergei V. Petrovskii

(University of Leicester, UK)

from: Sekerci & Petrovskii (2015) BUll. Math. Biol.

Abstract

Ocean dynamics is known to have a strong effect on the global climate change and on the composition of the atmosphere. In particular, it is estimated that about 70 % of the atmospheric oxygen is produced in the oceans due to the photosynthetic activity of phytoplankton. However, the rate of oxygen production depends on water temperature and hence can be affected by the global warming. 


In this paper, we address this issue theoretically by considering a model of a coupled plankton–oxygen dynamics where the rate of oxygen production slowly changes with time to account for the ocean warming. We show that a sustainable oxygen production is only possible in an intermediate range of the production rate. If, in the course of time, the oxygen production rate becomes too low or too high, the system’s dynamics changes abruptly, resulting in the oxygen depletion and plankton extinction. 

Our results indicate that the depletion of atmospheric oxygen on global scale (which, if happens, obviously can kill most of life on Earth) is another possible catastrophic consequence of the global warming, a global ecological disaster that has been overlooked.

The discussions will continue over biscuits and tea/coffee after the seminar. 

Hope to see many of you!

Biosciences Seminar Speaker 19 May 2016

Biosciences Seminar Series - Spring 2016
19 May 2016 - 1pm - Zoology Museum

Can sustainable agriculture give us a sustainable food system?

Prof Tim Benton

(University of Leeds, UK)

Image from seedfeedfood.eu

Abstract

Other than at a small scale, it makes little sense to think about sustainable agriculture (the supply of food), without also thinking about the demand for food that drives production within the agri-food system.  I’ll examine notions of sustainability, from an environmental perspective, and some of the wicked problems that arise from agriculture impacting upon many ecosystem services (leading to trade-offs between different aspects of impact).  

Whilst we can get better at managing agricultures’ impacts through changing farming efficiency and thinking about ecosystem services and their provision at a landscape scale, without tackling demand, the drive for “intensification” will dominate production systems.  Thus, ultimately, a sustainable farming system requires sustainable demand.

Hope to see many of you - everyone most welcome to attend!

Biosciences Seminar Speaker 12 May 2016

Biosciences Seminar Series - Spring 2016
12 May 2016 - 1pm - Zoology Museum

Land-use impacts on 'beeodiversity' and biodiversity: from data to models to policy

Dr Adriana De Palma

(Natural History Museum London, UK)

from: Natural History Museum London - www.nhm.ac.uk/our-science/science-news/2015/september/research-into-species-traits-could-help-save-europe-s-dying-bees.html

Abstract

Bees are one of the most important groups of pollinators and are threatened by a number of human impacts, but some key knowledge gaps limit our ability to inform conservation activities. Which species or groups of species are most vulnerable to human land use and agricultural intensification? Do different aspects of bee diversity – taxonomic, functional and phylogenetic diversity – respond similarly to land-use pressures? Are responses consistent around the world? Where has bee diversity been most heavily impacted? 

As part of the PREDICTS project (www.predicts.org.uk), I have collated a global dataset of bee diversity from the published literature and integrated it with information on land use, species' traits and phylogeny in order to answer these questions. Whereas that work was based on spatial comparisons, my current work (on “PREDICTS v2”) directly focuses on the temporal dynamics of biodiversity in response to land-use change. Both projects have the potential to inform policy decisions, but making the link between policy needs and PREDICTS outputs can be difficult; I will outline some of the ways in which the PREDICTS project has been engaging with policy.

Hope to see many of you - everyone most welcome to attend!

Biosciences Seminar Speaker 05 May 2016

Biosciences Seminar Series - Spring 2016
05 May 2016 - 1pm - Zoology Museum

Predicting wildlife dynamics in a changing environment

Dr Ben Collen

(University College London, UK)

Abstract

We live amid a global wave of anthropogenically driven biodiversity loss. Over the past decade, numerous metrics for biodiversity — including species abundance, extinction risk, distribution, genetic variability, species turnover, and trait diversity—have been used to create indicators to track how biodiversity has changed.  These indicators have made it
 clear that broad scale biodiversity loss, however it is measured, is showing 
little sign of abatement and 
that humans must respond to safeguard the provision of natural services on which we all rely. 

Butchert etal 2010 Science

But which metrics provide 
the most informative indicators
 under which circumstances? And how can the growing list of indicators best serve conservation policy decisions? I review the responses of animal populations to a range of human mediated drivers of change, showing where biological science has been effective at tracking recent changes in nature, and where gaps remain. I then examine prospects for predicting future changes, and why they matter to the biosphere and humans. 

I argue that evidence-based modelling can allow the causal relationships between policy actions, biodiversity change and indicators of change to be better understood. Developed correctly, indicators can start to tell us how we can best conserve biodiversity, not simply that we are failing to do so. 

Hope to see many of you - everyone most welcome to attend!

BioMaths Colloquium - 29/04/2016

BioMaths Colloquium Series - 2015/16

29 April 2016 - 3pm Maths Seminar Room 

(room 224 Talbot Building 2nd floor)

Spatio-temporal modelling of gene regulatory networks: The role of molecular movement

Prof Mark Chaplain

(University of St Andrews, UK)

Abstract

Gene regulatory networks (GRN), i.e. DNA segments in a cell which interact with each other indirectly through their RNA and protein products, lie at the heart of many important intracellular signal transduction processes. In this talk, we will present and analyse mathematical models of various GRNs using partial differential equations (PDE) and stochastic PDEs. We will then analyze a mathematical model of a canonical gene regulatory network consisting of a single negative feedback loop between a protein and its mRNA (e.g. the Hes1 transcription factor system). 

The model consists of two partial differential equations describing the spatio-temporal interactions between the protein and its mRNA in a one-dimensional domain. Such intracellular negative feedback systems are known to exhibit oscillatory behavior and this is the case for our model, shown initially via computational simulations. In order to investigate this behavior more deeply, we undertake a linearized stability analysis of the steady states of the model. 

Our results show that the diffusion coefficient of the protein/mRNA acts as a bifurcation parameter and gives rise to a Hopf bifurcation. This shows that the spatial movement of the mRNA and protein molecules alone is sufficient to cause the oscillations. Our result has implications for transcription factors such as p53, NF-kappaB and heat shock proteins which are involved in regulating important cellular processes such as inflammation, meiosis, apoptosis and the heat shock response, and are linked to diseases such as arthritis and cancer.

The discussions will continue over biscuits and tea/coffee after the seminar. 

Hope to see many of you!

Biosciences Seminar Speaker 26 April 2016

Biosciences Seminar Series - Spring 2016
26 April 2016 - 1pm - Zoology Museum

Measuring the rate and nature of evolution 

using comparative methods

Prof Robert Freckleton

(University of Sheffield, UK)

Abstract

The comparative method is one of the most important methods for studying evolution and adaptation with applications in ecology, behaviour and conservation. Modern comparative approaches recognize that phylogenetic relationships create structure in data that can be used to improve statistical inference as well as uncover the signal of different evolutionary processes. 

In this talk I present recent work on applying comparative methods to problems in the analysis of data and modelling evolution. In the first part of the talk I discuss problems with heterogeneous data quality and the analysis of experimental data on multiple species. In the second part of the talk I look at non-Brownian evolution resulting from interactions between species during their evolution. 

I highlight the use of new statistical methods that can  be used to model complex evolution of traits in adaptive radiations and present examples of where these have been applied.

Hope to see many of you - everyone most welcome to attend!