| 1. |
- Nylin, Sören, et al.
(författare)
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Embracing Colonizations : A New Paradigm for Species Association Dynamics
- 2018
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Ingår i: Trends in Ecology and Evolution. - Elsevier : Elsevier BV. - 0169-5347 .- 1872-8383. ; 33:1, s. 4-14
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Tidskriftsartikel (refereegranskat)abstract
- Parasite-host and insect-plant research have divergent traditions despite the fact that most phytophagous insects live parasitically on their host plants. In parasitology it is a traditional assumption that parasites are typically highly specialized; cospeciation between parasites and hosts is a frequently expressed default expectation. Insect-plant theory has been more concerned with host shifts than with cospeciation, and more with hierarchies among hosts than with extreme specialization. We suggest that the divergent assumptions in the respective fields have hidden a fundamental similarity with an important role for potential as well as actual hosts, and hence for host colonizations via ecological fitting. A common research program is proposed which better prepares us for the challenges from introduced species and global change. Parasites are typically assumed to be highly specialized on their hosts and well adapted to them, yet they frequently colonize new hosts - including humans, causing EIDs.This parasite paradox has caused a growing unease with the traditional assumptions in parasitology, which differ markedly from those in the field of insect-plant studies.We report the results of a workshop where parasitologists and insect-plant researchers met to explore the possibility that the two systems may be more similar than the divergent research traditions suggest, so that a common research program can be developed to better prepare us for future challenges.
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| 2. |
- Braga, Mariana P., et al.
(författare)
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Host use dynamics in a heterogeneous fitness landscape generates oscillations in host range and diversification
- 2018
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 72:9, s. 1773-1783
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Tidskriftsartikel (refereegranskat)abstract
- Colonization of novel hosts is thought to play an important role in parasite diversification, yet little consensus has been achieved about the macroevolutionary consequences of changes in host use. Here, we offer a mechanistic basis for the origins of parasite diversity by simulating lineages evolved in silico. We describe an individual-based model in which (i) parasites undergo sexual reproduction limited by genetic proximity, (ii) hosts are uniformly distributed along a one-dimensional resource gradient, and (iii) host use is determined by the interaction between the phenotype of the parasite and a heterogeneous fitness landscape. We found two main effects of host use on the evolution of a parasite lineage. First, the colonization of a novel host allowed parasites to explore new areas of the resource space, increasing phenotypic and genotypic variation. Second, hosts produced heterogeneity in the parasite fitness landscape, which led to reproductive isolation and therefore, speciation. As a validation of the model, we analyzed empirical data from Nymphalidae butterflies and their host plants. We then assessed the number of hosts used by parasite lineages and the diversity of resources they encompass. In both simulated and empirical systems, host diversity emerged as the main predictor of parasite species richness.
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