Phenotype Climate Change

Introduction

Climate change has become a major issue throughout the world lately. The rate of climate change is still increasing and more people are becoming aware of this undeniable fact. The shifts that are being observed in phenology, i.e. life cycle events of plants and animals could be explained by climate change. Individuals can change their phenotype in response to different environmental conditions through a mechanism called phenotypic plasticity. Shifts in the three major phonological life history events; timing of reproduction, timing of migration, and timing of winter rest are being linked to climate change. As most species use temperature as a cue, their phenotype will shift to an earlier date, as a result of global warming. Secondary

By using four decades of individual-level life history data the effects of several variables, e.g. population mismatch, beech crop and breeding density could be investigated. Data showed that as the mismatch is increasing, the selection for early laying becomes stronger. Early individuals tend to produce two clutches. In addition the mean clutch size and mean probability of zero fledglings doesn’t change. However birds will produce more offspring in years where the population is early, in contrast to birds producing less offspring in years where the population is late. As a result of global warming a general decrease in population size was hypothesized. However the relationship between the mismatch and population growth is showing a stable correlation. The main reason is the chance of reaching the breeding phase next year is very small, if many offspring’s are being produced. Of the used variables in the data, only breeding density had a significant effect on the population size. In general the loss of fitness is being counteracted by fitness gains due to relaxed competition. By using a simulation model the population size in the future was prediction under the effect of the climate change and adding the density-dependent variable or leaving it out. This model showed that depending on the level of climate change, the population size

In addition studies show different conclusion as a result of geographical variation in the change of climate. Still the phonological shifts in many species are inevitable. More studies that will link phonological shifts to the viability of a population are needed in the future. As mismatches in phenology will occur frequently and the mismatches occurring becoming even larger, it is highly likely there will be a consequence for the viability of populations. The rate of climate change is still increasing, nevertheless generating predictions about the future is difficult and therefore predicting what will happen to species unable to keep up with climate change gives uncertainty. Making comparison between populations set in different places might give insight to the exact mechanism and even give possible solutions. For example a great tit population in the UK still shows phenotypic plasticity and their breeding phenology is changing with a similar rate as their food, indicating the phenotypic plasticity for that population is still adaptive. Incorporating observational studies with genetics could give more information why this is the case. Another approach is to study underlying mechanism of the changes in phenology, by controlling the environmental conditions for example with climate cages for birds. A disadvantage of this approach is it is in