@phdthesis{Figueiredo2021,
  author    = {Figueiredo, Ludmilla},
  title     = {Extinction debt of plants, insects and biotic interactions: interactive effects of habitat fragmentation and climate change},
  doi       = {10.25972/OPUS-23873},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-238738},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The importance of understanding species extinctions and its consequences for ecosystems and human life has been getting increasing public attention. Nonetheless, regardless of how pressing the current biodiversity loss is, with rare exceptions, extinctions are actually not immediate. Rather, they happen many generations after the disturbance that caused them. This means that, at any point in time after a given disturbance, there is a number of extinctions that are expected to happen. This number is the extinction debt. As long as all the extinctions triggered by the disturbance have not happened, there is a debt to be paid. This delay in extinctions can be interpreted as a window of opportunity, when conservation measures can be implemented. In this thesis, I investigated the relative importance of ecological and evolutionary processes unfolding after different disturbances scenarios, to understand how this knowledge can be used to improve conservation practices aiming at controlling extinctions. In the Introduction (chapter 1), I present the concept of extinction debts and the complicating factors behind its understanding. Namely, I start by presenting i) the theoretical basis behind the definition of extinction debts, and how each theory informed different methodologies of study, ii) the complexity of understanding and predicting eco-evolutionary dynamics, and iii) the challenges to studying extinctions under a regime of widespread and varied disturbance of natural habitats. I start the main body of the thesis (chapter 2) by summarizing the current state of empirical, theoretical, and methodological research on extinction debts. In the last 10 years, extinction debts were detected all over the globe, for a variety of ecosystems and taxonomic groups. When estimated - a rare occurrence, since quantifying debts requires often unavailable data - the sizes of these debts range from 9 to 90\\% of current species richness and they have been sustained for periods ranging from 5 to 570 yr. I identified two processes whose contributions to extinction debts have been studied more often, namely 1) life-history traits that prolong individual survival, and 2) population and metapopulation dynamics that maintain populations under deteriorated conditions. Less studied are the microevolutionary dynamics happening during the payment of a debt, the delayed conjoint extinctions of interaction partners, and the extinction dynamics under different regimes of disturbances (e.g. habitat loss vs. climate change). Based on these observations, I proposed a roadmap for future research to focus on these less studies aspects. In chapters 3 and 4, I started to follow this roadmap. In chapter 3, I used a genomically-explicit, individual-based model of a plant community to study the microevolutionary processes happening after habitat loss and climate change, and potentially contributing to the settlement of a debt. I showed that population demographic recovery through trait adaptation, i.e. evolutionary rescue, is possible. In these cases, rather than directional selection, trait change involved increase in trait variation, which I interpreted as a sign of disruptive selection. Moreover, I disentangled evolutionary rescue from demographic rescue and show that the two types of rescue were equally important for community resistance, indicating that community re-assembly plays an important role in maintaining diversity following disturbance. The results demonstrated the importance of accounting for eco-evolutionary processes at the community level to understand and predict biodiversity change. Furthermore, they indicate that evolutionary rescue has a limited potential to avoid extinctions under scenarios of habitat loss and climate change. In chapter 4, I analysed the effects of habitat loss and disruption of pollination function on the extinction dynamics of plant communities. To do it, I used an individual, trait-based eco-evolutionary model (Extinction Dynamics Model, EDM) parameterized according to real-world species of calcareous grasslands. Specifically, I compared the effects of these disturbances on the magnitude of extinction debts and species extinction times, as well as how species functional traits affect species survival. I showed that the loss of habitat area generates higher number of immediate extinctions, but the loss of pollination generates higher extinction debt, as species take longer to go extinct. Moreover, reproductive traits (clonal ability, absence of selfing and insect pollination) were the traits that most influenced the occurrence of species extinction as payment of the debt. Thus, the disruption of pollination functions arose as a major factor in the creation of extinction debts. Thus, restoration policies should aim at monitoring the status of this and other ecological processes and functions in undisturbed systems, to inform its re-establishment in disturbed areas. Finally, I discuss the implications of these findings to i) the theoretical understanding of extinction debts, notably via the niche, coexistence, and metabolic theories, ii) the planning conservation measures, including communicating the very notion of extinction debts to improve understanding of the dimension of the current biodiversity crisis, and iii) future research, which must improve the understanding of the interplay between extinction cascades and extinction debts.},
  subject      = {Aussterbedynamik},
  language  = {en}
}