| 1. |
- Åkesson, Anna, 1985-
(författare)
-
Disturbances in food webs : Importance of species interactions from an ecological and evolutionary perspective
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biodiversity loss is occurring globally at an unprecedented pace. This is not only followed by ethical concerns; it also affects all levels of an ecosystem, with wide-spread implications for ecosystem functioning, services and human well-being. The severe extinction risk for many species is a result of human activities, such as habitat destruction and land-use change, overexploitation and introduction of invasive species. During the past decades, climate change has additionally become an important human-induced driver, causing biodiversity loss and altered species interactions.To mitigate the negative impact on ecosystems, we need to understand how the species building up the systems respond to disturbances. Several structural properties, both at species- and network-level, are known to affect species vulnerability. At the species-level, a species position in the food web, as well as its distribution of prey items, are important factors. At the network-level, diversity and structure of feeding interactions are important measurements related to stability. Additionally, species may both directly and indirectly affect other species, as species are entangled in complex network structures. The loss of a single species could set in motion a cascade of secondary extinctions that may not be predictable based on species’ performance in isolation. Particularly, disturbances of primary producers have a high risk to propagate and augment through the network. Moreover, species interactions have the potential to affect several other ecological processes. For example, altered environmental conditions force species to disperse to more suitable habitats, or to stay and adapt to the new local condition. Such processes can be significantly altered by species interactions. Another example concerns ecosystem service provisioning. Even if a species not being a service provider goes extinct, the event can via direct and indirect effects cause secondary extinctions of service providing species, causing loss of the services.Despite the recognition of the importance of a network context and of species interactions, such aspects are in many cases modeled in a simplified manner or not considered. In this thesis, I use mathematical models to study how species embedded in an ecological network respond to disturbances. I have two primary focus areas. First, I analyze how the interplay between evolution, dispersal and species interactions affect how species respond to climatic change. In paper I, I studied the effects of these eco-evolutionary processes under increasing temperatures, using empirically-motivated parameterizations of a suite of community models with increasing ecological interaction complexity. Second, I analyze how several structural properties affect species persistence following a disturbance. In Paper II, I focus on how network-level properties as well as species-level properties affect consumer species persistence following basal level disturbances. In Paper III, I disentangle the most influential characteristics of groups of basal species, causing a negative impact on consumer species when disturbed. I use the Serengeti savanna food web as case study. In Paper IV, I connect ecosystem services to the species providing them, and analyze how ecosystem service provisioning is affected by anthropogenic threats. I use the Baltic Sea as a case study.In summary, the results of this thesis underscore the importance of studying disturbances within a network context. Species interactions highly influenced the eco-evolutionary dynamics in Paper I, and mitigated some of the negative impacts following climatic change. Several structural network properties, both of the species being disturbed and of the species being affected, influenced species’ vulnerability following disturbance in Paper II-IV. The interplay between species influenced how disturbances percolated through the network. Moreover, Paper IV found that indirect effects mediated by the network of species interactions were of substantial importance for how anthropogenic threats are affecting ecosystem service delivery. in this thesis, I have developed novel methods, as well as extended and showcased new applications for existing ones. As such, this thesis has a broad applicability and expands our basic understanding of the interplay between ecological and evolutionary processes, as well as our understanding of the mechanisms behind how networks of interacting species are affected by disturbances. Further, the results have important implications for conservation efforts.
|
|
| 2. |
- Jakobsson, Martin, et al.
(författare)
-
Ryder Glacier in northwest Greenland is shielded from warm Atlantic water by a bathymetric sill
- 2020
-
Ingår i: Communications Earth & Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 1
-
Tidskriftsartikel (refereegranskat)abstract
- The processes controlling advance and retreat of outlet glaciers in fjords draining the Greenland Ice Sheet remain poorly known, undermining assessments of their dynamics and associated sea-level rise in a warming climate. Mass loss of the Greenland Ice Sheet has increased six-fold over the last four decades, with discharge and melt from outlet glaciers comprising key components of this loss. Here we acquired oceanographic data and multibeam bathymetry in the previously uncharted Sherard Osborn Fjord in northwest Greenland where Ryder Glacier drains into the Arctic Ocean. Our data show that warmer subsurface water of Atlantic origin enters the fjord, but Ryder Glacier’s floating tongue at its present location is partly protected from the inflow by a bathymetric sill located in the innermost fjord. This reduces under-ice melting of the glacier, providing insight into Ryder Glacier’s dynamics and its vulnerability to inflow of Atlantic warmer water.
|
|
| 3. |
- Stålhammar, Anna, et al.
(författare)
-
Resource test-driving for service innovation : How ordinary employees innovate new value propositions
- 2012
-
Ingår i: Proceedings of the 15th QMOD-ICQSS conference. - Poznan, Poland : COMPRINT, Poznan Univ. of Technology.
-
Konferensbidrag (refereegranskat)abstract
- PurposeThe purpose of this paper is to investigate the role of ordinary employees in service innovation. Departing from the service-dominant (S-D) logic, service innovation is conceptualized as a resource integration process leading to the creation of value propositions.MethodologyThe paper reports on a case study of service development at three different organizations. Twenty ordinary employees were interviewed. Ordinary employees are defined as those lacking a formal innovation obligation, e.g. frontline employees. These normally have knowledge of both the customers’ needs and the firm’s ability to realize these.FindingsThe findings suggest that ordinary employees contribute to service innovation by test-driving resource integrations and potential value propositions. Specifically, the findings suggest that ordinary employees use three different ways of test-driving resources: Cognitive test-driving; Test-driving in practice, and Discursive test-driving. Although the findings suggest that these ways of test-driving resources are intertwined, they also suggest that parts of the innovation process are dominated by one of these.Research limitations/implicationsThis article is based on a case study of three organizations, thus limiting the possibility of statistical generalization.Originality/valueThe study is novel in several respects: (i) it introduces the notion of resource test-driving; (ii) it provides a systematic empirical analysis of how ordinary employees contribute to service innovation through test-driving resource integrations and new value propositions; (iii) it offers an S-D logic informed service innovation model; (iv) it contributes to the S-D logic by detailing how resource integration takes place in practice.
|
|
