Are Structured Life Histories Really Buffered Against Environmental Change?

Lead Research Organisation: University of Exeter
Department Name: Biosciences


Demographic research seeks to understand the links between vital rates of organisms, i.e. patterns of mortality, growth and reproduction, and the growth or decline of their populations. In ecological terms, linking life history data with population dynamics can allow us to manage populations for conservation, pest control or harvesting. In evolutionary terms, links between vital rates and fitness determine the action of natural selection, and have promoted the evolution of an incredible diversity of life cycles and life histories among plants and animals.

The environment in which plants and animals live is an unpredictable place, and it is changing rapidly. How do species protect themselves against this unpredictability and change? How do they evolve to cope? One of the most important and well-supported theories in population ecology, the Demographic Buffering Hypothesis, states that the best way to cope is to buffer the most important parts of the life cycle against this environmental variation. For example, the population dynamics of frogs might be most sensitive to the survival of mature individuals, but less sensitive to the annual production of frogspawn. If this is true, then frogs should evolve to make sure mature individuals are resistant to annual fluctuations in weather and temperature, at the expense of similar resistance in egg production.

The Demographic Buffering Hypothesis has found support in the analysis of annual fluctuations in rates of survival, growth and reproduction in a wide variety of organisms, from plants to mammals to fish and even corals. However its assumption, that "variation" is "bad for" fitness, is flawed. Furthermore, statistical patterns in vital rate variation means that the evidence base could be found simply by inventing life histories that have NOT evolved to be buffered in any way. The goal of this project is to PROPERLY ask whether wild species have evolved so that their mnost important vital rates are buffered against changes in their environment.

Our study resource is a global database of thousands of demographic models of hundreds of species of plants and animals. We aim to convert this database into a searchable web-database, available to scientists and public alike.

Our overarching goal is to try to make sense of the bewildering array of plant and animal life cycles, to find patterns and to use these patterns to (a) design management strategies that will help us to exploit natural resources sustainably, and (b) predict the endangered and invasive plants and animals of the future.

Planned Impact

The key beneficiaries of this work will be: members of the environmental sector who are stakeholders in the conservation or management of natural populations and ecosystems (e.g. Natural England, DEFRA, Environment Agency, National Trust, RSPB); the general public; individuals who benefit from training and education; the academic community who will gain insights into life history variation, measuring fitness, and comparative demography.
The project will adopt novel approaches to understanding the evolution of life history variation, in plants and animals. The theoretical approach will provide insights because it is a change from the dominant discourses in climate change biology. Currently most study is made of life history adaptations to constant schedules of mortality and reproduction. We propose that the study of variation in vital rates, caused by environmental variation, competition and disturbances, will serve to clarify the ecological classification of species, globally. It might also lend significant power to our attempts to predict the weeds, invasives and endangered species of the future.

We engage with the scientific community via standard activities by attending conferences, publishing our research in high-profile journals (preferably as open access), and presenting scientific seminars. In addition to this standard activity we intend to conduct the following activities:
Activity 1: Internationalisation: Engagement with the Max Planck Institute for Demographic Research.
Activity 2: Engagement with Industry. We will invite stakeholders in the environmental sector, particularly population managers (in conservation and pest control), to attend and speak at a workshop on 'Demography and Wildlife Management' to be held at Charles Darwin House, the new London hub of activity for Biological Learned Societies. The workshop will support the development of informed population management strategies.
Activity 3: Human capital - next generation of scientists. Human capital will be developed by training the PDRA, PhD and IT technician.
Activity 4: Public engagement and communication
Public engagement will be a key focus for impact. We intend to conduct the following public engagement activities:
(i) Website. We will create a graphically-rich research and educational website suitable for school students (aged 14-19) to provide information about how life histories evolve, and the importance of demographic resilience in a changing world.
(ii) School visits programme. To facilitate dissemination of concepts of demography and life history, we will travel to classes in the area (which is all of Cornwall) to disseminate our research findings.
(iii) Publicity. The Centre for Ecology and Conservation is successful in promoting its work and regularly gains publicity from the national and international media. We have given public seminars and publicized our work via the popular press. We will continue these activities and maximize opportunities to publicise the role of bioscience in the modern day world.


10 25 50
Description We have developed an online portal that describes the location and life cycles of plants, globally. We have demonstrated that plant life histories are NOT (as was previously thought) buffered against environmental variability. Instead, some plant species are buffered, others are indifferent to environmental fluctuations, and yet others are labile to environmental fluctuations. The main predictor of life history strategy is growth type, with shorter-lived species being more likely to be labile. We have searched for evidence that strategies might be guided by functional relationships between environment and fitness, or by covariances among plant vital rates, but have failed to find any strong links.
Exploitation Route Further publications and use of database to identify invasive and endangered species
Sectors Agriculture, Food and Drink,Education,Environment,Pharmaceuticals and Medical Biotechnology

Description Release of the COMPADRE and COMADRE global databases of pant and animal demography resulted in media coverage, explaining the importance of databses for societal understanding of life history evolution and demography
First Year Of Impact 2015
Sector Agriculture, Food and Drink,Education,Environment
Impact Types Societal

Description NERC International Opportunities Fund
Amount £40,000 (GBP)
Funding ID NE/N006798/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 02/2016 
End 07/2016
Description Global database of animal demographic models 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact none to date 
Description Global database of demographic models of plant populations 
Type Of Material Database/Collection of data 
Year Produced 2015 
Provided To Others? Yes  
Impact Highly cited database paper