The role of sexual selection and population subdivision in pop persistence in a changing world

Principal researcher: Francisco García González.

Period: 2020-2024

Determining whether sexual selection accelerates or hampers adaptation in novel environments is a central question in evolutionary biology. Resolving this question has important implications for understanding the potential of populations to persist in the face of rapid environmental change. Sexual selection can theoretically facilitate or hinder adaptation to new environments, depending on whether it works as a filter reducing mutational loads, or on whether the negative population-level consequences of sexual conflict are reduced under environmental stress. Few empirical studies have formally tested the alignment or misalignment of sexual and natural selection, and strikingly, no study has explored whether a key ecological and demographical factor such as population spatial structure moderates the effect of sexual selection on adaptation. This project will innovatively investigate the interactive influences of sexual selection (including sexual conflict) and population subdivision on the individuals' and the populations' ability to withstand environmental change. The project will take advantage of the power of experimental evolution to address these questions. It will use selection lines of a pest beetle that have been subject to variation in selection arising from reproductive competition and population spatial structure for over eighty generations, and it will measure a wide array of relevant phenotypic and life-history traits (including lifetime reproductive success, behavioural plasticity, resistance to environmental stressors) and population traits (including population viability and realized extinction events) in response to exposure to environmental disturbances. Sex-specificity underlying evolutionary responses, and the genetic basis providing the potential for evolution will be inspected. In addition, this project will also investigate (both within and outside a context of variation in selection histories), whether non-genetic inheritance via transgenerational effects, and in particularly father-offspring transmission of altered environments, play a role in adaptation to changing environments. Results will inform on whether sexual selection, population spatial structure, their interaction, and transgenerational plasticity, accelerate adaptation, or on the contrary, hinder components of viability selection. Alterations of population spatial structure (e.g., through habitat fragmentation) represent key conservation threats and this work will provide useful empirical data on how these changes may impact key evolutionary processes linked to population viability. This work will in this way provide unique insights into evolutionary and ecological factors affecting extinction risk, but the benefits will not be, therefore, circumscribed to the area of evolutionary biology; they will also have repercussions for conservation biology. Additionally, this research will uncover some of the far-reaching evolutionary implications of transgenerational effects for the evolution of phenotypes and, possibly, population viability. Finally, the project will provide excellent research opportunities for students, and it will also yield useful data for pest control. .

Evolutionary ecology of phenotypic plasticity of morphological, life history and behavioural traits

Principal researcher: Laszlo Garamszegi

Period: 2015-2018

The main interest in evolutionary ecology lies on the variation in phenotypic traits, its link with fitness variation and how these are transferred across generations. This individual variation is not fixed in natural populations but flexibly changes across space and time depending on the prevailing environmental conditions. In factsome traits exhibit consistent variation among individuals, and still remain substantially variable at an individual level. Within an evolutionary point of view, such a dichotomy has been conceptually established by the joined action of selection and heritability of traits (microevolution) or by plastic expression according to the changing environmental circumstances (phenotypic plasticity). However, there is conceptual room to consider trait phenotypic plasticity per se an individual-specific characteristic linked to fitness, and thus susceptible to be selected upon. Such an evolutionary mechanism is yet to be quantified. To understand the evolution and ecology of most phenotypic traits in light of the changing environment, it is now becoming crucial to decompose different variance components and relate these to genetics, physiology and fitness, and also to study how fluctuations in the socio-ecological circumstances shape within- and between-individual (co-)variances. Such tasks are notoriously hard to accomplish in wild animal populations, because they typically necessitate the repetitive sampling of the same individuals under standardized conditions over long periods of time or across large geographic distances. In the current proposal, we aim to accomplish this challenging mission by taking advantage from the long-term studies (over 30 years) of wild populations of two closely related passerine species, the collared and pied flycatchers (Ficedula albicollis and F. hypoleuca) breeding in central and southern Europe, respectively. Using our long-term records in combination with targeted within-individual sampling at a shorter time scale, we will characterize different variance components for different types of traits (morphology, life history and behaviour). Exploiting the temporal and spatial resolution of our study, we will be able to investigate how predictable and unpredictable changes in various socio-ecological contexts (e.g. climate, food supply, predation pressure, demographic patterns, levels of competition) can have microevolutionary consequences for between-year, and between- and within-individual variances as well as for phenotypic plasticity. We will apply a rigorous framework based on quantitative genetics and individual-based models to determine which variance components are attributable to genetic and environmental effects, while we will also establish the evolutionary potential for phenotypic plasticity by exploring the proximate and ultimate mechanisms that can mediate the within-individual variance of different traits. The expected results will have major implications on how we understand ecological and evolutionary processes of adaptation, and how the consistency and plasticity of different phenotypic traits play roles in such processes. Ultimately, our findings will be fundamental for our comprehension of the origin and maintenance of biodiversity both at geographical and temporal scales.

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Determinants of variation in host-parasite interactions

Principal researcher: Francisco Valera Hernández:

Period: 2015-2018

Disease occurs non-randomly in space and factors such as climate, physical habitat characteristics, community context, host species identity and parasite species identity may account for such variation. Yet, our understanding on how biotic and abiotic factors determine host-parasite interactions is still limited and we ignore much about the general rules and mechanisms explaining the above-mentioned relationships. Another important gap in our knowledge about emerging infectious diseases is that, while the host specificity between specific hosts and parasites has been frequently revealed, the specificity between parasites and their vectors remains largely neglected even for major host-vector-parasite systems. This shortcoming has been suggested as the major obstacle to dealing with the current emerging infectious diseases crisis.

The main goal of this project is to disentangle the context dependency of local host-parasite interactions and the relative importance of the processes influencing parasitism intensity by following a community ecology-oriented approach encompasing various study systems and spatio-temporal scales. We also aim at uncovering some mechanisms underlying the links between habitat and disease, both between hosts and parasites and between hosts, vectors and haematozoan parasites. The general hypothesis of the project is that environmental conditions strongly influence, either directly and/or indirectly, the occurrence of epidemics and host-parasite interactions. Specifically the project focuses on:

- the effect of spatial and temporal variation in climatic conditions on the ecto and endoparasitic community of several study systems,

- the effect of physical features of the habitat on the ectoparasitic community of an avian guild and on parasite dispersal via its influence on local host density and host community structure,

- the evaluation of the variability and context dependency of local host-parasite interactions,

- the identification of the host-vector-parasite associations in our study systems.

The strength of this project relies on its broad framework that jointly considers the interactions among biotic drivers (e.g. host density), and abiotic/physical drivers of epidemics. This approach is necessary for a complete understanding of disease ecology once the study of hostparasite interactions in isolation has proved insufficient. Moreover, by studying patterns of variation of parasitisation across a range of scales, we can gain insight into the relative importance of different processes involved in the dynamics of diseases. This project will improve the understanding of links between climate, microclimate, habitat structure, species interactions, and parasitism. Highlighting these links and the underlying mechanisms is necessary to predict accurately the likelihood of epidemics in particular locations, what is of major interest fin the current scenario of climate warming. Finally, if the vectorial role of some of our study species is confirmed, this project will have a norteworthy impact because vector and host ecology are studied simultaneously and comprehensively to reveal their effects on the spread of avian haemoparasites

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