(Re)appreciating the role of life history in
Eco-evolutionary dynamics?
Contents
Individual variation in life history and eco-evolutionary dynamics: Towards more flexible model
frameworks and new applications .......................................................................................................... 2
Movement as a central trait in life history .............................................................................................. 2
How do butterflies respond to environmental stress in natural populations and when are these
responses adaptive.................................................................................................................................. 3
The roles of environmental context and life history in mediating ecological succession ....................... 3
Life-history trade-offs driving pathogen evolution and epidemiology ................................................... 3
Life history and above-belowground interactions .................................................................................. 4
Life-history traits and the properties of meta-ecosystems: a theoretical perspective........................... 4
Individual variation in life history and eco-evolutionary dynamics:
Towards more flexible model frameworks and new applications
Yngvild Vindenes
Individual variation in life histories can arise from a number of mechanisms, and is essential to our
understanding of eco-evolutionary dynamics. Demographic frameworks such as matrix models and
integral projection models represent powerful tools to investigate the joint dynamics of individual traits
and population level parameters. However, most applications of such models assume that all individuals
follow the same average life history, so that at a given age (or size) they will have the same vital rates
(survival, growth and transition rates). While the average life history is a key characteristic of a species,
recent studies have also emphasized the importance of variation in life histories to eco-evolutionary
processes. I will present a flexible general demographic framework for investigating such processes,
that distinguishes between two types of individual-level state variables: Static traits represent underlying
individual properties that remain constant over the lifetime, such as genotype, whereas dynamic traits,
such as age or body size, change over the lifetime. The static and dynamic traits can have different
effects on vital rates (survival, fecundity, and transitions) and may also interact so that a genotype may
give rise to different vital rate effects across the lifetime, for example. This framework allows a wide
range of individual variation in life history to be modeled, as well as different types of inheritance. I
present an empirical example for a population of pike (Esox lucius), where large variation in life history
arises through early-life differences in somatic growth. Using this model, we evaluate the consequences
of ignoring such life history differences for important demographic outputs such as the mean and
variance of the population growth rate, the net reproductive rate, and generation time. We also explore
how projected responses to ongoing climate change (warming) and harvesting may depend on the
individual life history differences.
Movement as a central trait in life history
Dries Bonte
Life histories have received a lot of attention in ecology as they are providing a template to understand
adaptations towards habitat types that differ in their level of productivity and predictability. Especially
the study of trade-offs among some major life history components (age at maturity, lifespan and
reproduction) allowed the development of a quantitative framework to understand how environmental
variation shapes patterns of biodiversity. There is incremental evidence that evolutionary changes in life
histories feedback on ecological processes at contemporary timescales. Insights on the importance and
magnitude of these eco-evolutionary dynamics are typically derived from populations inhabiting
homogeneous environments. The world is, however, spatially structured and individuals move within
and among habitats to maximize fitness. Movement consequently needs to be considered as a central
trait in life histories. I will use an optimality framework to demonstrate how this integration of
movement might substantially change our view on evolutionary trajectories in spatially structured
environments. Because changes in the spatial configuration of habitats affect the costs of movement and
dispersal, adaptations to reduce these costs will increase phenotypic divergence among and within
populations. This phenotypic heterogeneity leads to non-random dispersal and is anticipated to impact
population and community dynamics. I will present empirical evidence on the central role of movement
and dispersal on the spatial distribution of ecological strategies and its impact on population spread,
invasions and coexistence.
How do butterflies respond to environmental stress in natural
populations and when are these responses adaptive
Marjo Saastamoinen
Organisms in the wild are constantly faced with a wide range of environmental variability, such as
fluctuation in thermal conditions or in food quality and quantity. Understanding the processes and the
underlying mechanisms that allow organisms to cope with such environmental variation is one of the
biggest challenges in ecology and evolutionary biology. My research focuses on the influence of
environmental stress during different life stages on the subsequent life-history variation in the Glanville
fritillary butterfly (Melitaea cinxia). Poor conditions during development or during adult stage often
have a negative impact on fitness-related traits, such as reproduction and lifespan. However, in some
cases individuals can use the experienced conditions as cues for the likely environmental condition the
individual will encounter later on in life (i.e. predictive adaptive responses) or of their current state.
Accordingly, individuals can shape their adult morphology, physiology or life history in a way that
allows them to best deal with the current or the predicted conditions later on in life, or even to move
away from these deteriorating environments.
The roles of environmental context and life history in mediating
ecological succession
Matthew Bracken
A central goal of community ecology is to understand the processes that mediate the diversity of
organisms in a location. Here, I explore how environmental context - including elevation, disturbance,
herbivory, thermal stress, and nutrient availability - interacts with life history to determine successional
trajectories, biodiversity, and resilience. I evaluated these processes by clearing 160 experimental plots
on a rocky shoreline in California, USA. Plots were equally divided between two tidal elevations crossed
with two wave exposures, and thermal stress (shaded, unshaded), herbivore access (present, excluded),
and nutrient availability (added, ambient) treatments were factorially applied to plots. I monitored
colonization and growth of seaweed species for 18 months to evaluate how environmental context and
experimental manipulations affected seaweed succession and diversity. In particular, I focus on the
emergence of nested patterns of species occurrence across realistic gradients in diversity and highlight
how species life history traits interact with factors such as herbivores and physical stress to determine
species richness and relative abundance.
Life-history trade-offs driving pathogen evolution and epidemiology
Anna-Liisa Laine
Trade-offs in life-history traits is a central tenet in evolutionary biology, yet their ubiquity and
relevance to realized fitness in natural populations remains questioned. Trade-offs in pathogens are of
particular interest because they may constrain the evolution and epidemiology of diseases. We find
that the life-history trade-offs in pathogens are highly context dependent – influenced both by host
genotype and coinfection status of the host. Hence, trade-offs may be a key mechanism for maintained
variation in pathogen populations and in driving pathogen evolution. Moreover, we find that trade-offs
mediated by pathogen local adaptation influence epidemiological dynamics at both population and
metapopulation levels.
Life history and above-belowground interactions
Gerlinde B. De Deyn
Research over the last decades has demonstrated the importance of above- and belowground biota, both
from the perspective of plant growth suppression and promotion. Many studies revealed intriguing
indirect interactions between aboveground and belowground organisms and suggest that these can
change according to order of arrival of the different biota and plant ontogeny. However most
experiments on above-belowground interactions were of short duration and extrapolation to ecoevolutionary dynamics and changes in life history traits remains difficult. A key challenge therefore will
be to place the findings of the simplified studies on above-belowground interactions in a realistic setting
and derive implications for life history and plant community dynamics. Using the concept of trade-offs
in growth and defense we can however postulate that plants in resource rich environments should grow,
reproduce and disperse fast while plants in resource poor environments cannot grow fast yet live and
reproduce long and invest in structural defences. Does this concept also hold for plants that grow in the
same environment and what are the implications for plant-community dynamics? Recent research shows
that plants selected over eco-evolutionary time in interspecific competition increase their investment in
growth, likely trading-off with reduced defense against specialist herbivores and pathogens. Importantly
in order to understand the costs and benefits of a plant strategy for different life stages and its impact on
plant community dynamics it is required to also include indirect effects trough plant legacies via litter
inputs and plant associated biota. Overall optimal life history strategies are not easy to predict as they
are dependent on community context and resource levels. It is however clear that interactions with
below- and aboveground biota during and afterlife need to be considered in a general frame-work of life
history syndromes.
Life-history traits and the properties of meta-ecosystems: a
theoretical perspective
François Massol
For most biologists, life-history traits are implicitly linked to the study of population demographics in a
single species or, more rarely, to the study of coexistence conditions in ecological communities.
However, the fact that life-history traits have an impact on ecosystem properties is yet to be fully grasped
and acknowledged. Here, I will give some examples of theoretical models which make an explicit link
between life-history traits and the functioning, stability and complexity of ecosystems. My presentation
will mostly be focused on dispersal as a meaningful life-history trait affecting these ecosystem
properties. In the case of dispersal, the mechanism linking trait value to ecosystem properties such as
functioning or complexity is based on the simple fact that organisms that move “carry” their vital rates
and their material/energy content with them as they migrate. Based on recent empirical literature, I will
argue that other, more intricate links between life history and ecosystem properties might be found by
studying the reciprocal feedbacks between ecological stoichiometry and life-history traits as nutritional
constraints can partially determine life-history traits and different trait values can correspond to different
stoichiometric needs and, hence, lead to different equilibrium levels of chemical elements in their
environments. The issue of “scaling up” life histories thus amounts to bridging some gaps between the
metabolic theory of ecology, ecological stoichiometry and population biology.