Geographical divergence in host use ability of a marine herbivore in alga–grazer interaction
- 113 Downloads
When the selective environment differs geographically, local herbivore populations may diverge in their host use ability and adapt locally to exploit the sympatric host population. We tested whether populations of the marine generalist herbivore Idotea baltica have diverged in host us ability and whether they locally adapted to exploit the sympatric population of their main host species, the bladderwrack Fucus vesiculosus. We fed isopods from three local populations reciprocally with the sympatric and two allopatric populations of the host. The bladderwrack populations varied in their quality as food for isopods suggesting variation in the selective environment. The ability to exploit the main host showed considerable divergence among the isopod populations. There was no significant interaction between host and isopod origin, indicating that the patterns observed in the reciprocal feeding experiment could be explained by differences in overall suitability of the hosts and differences in overall performance of the isopod populations. Isopod population that was sympatric to a bladderwrack population with low phlorotannin content showed high performance on the algae from the sympatric but low performance on the algae from the two allopatric populations. Performance of isopods, especially in this population, decreased quickly with the increasing phlorotannin content of food algae. We therefore hypothesize that the isopods adapted to a low phlorotannin content were unable to utilize high-phlorotannin algae efficiently. Isopod populations sympatric to the high-phlorotannin bladderwrack populations may be generally better adapted to deal with phlorotannins, being thereby able to utilize a range of bladderwrack populations.
KeywordsEvolutionary divergence Local adaptation Herbivory Selective mosaic Phlorotannins
We are grateful to Janne Eränen, Meri Lindqvist and Simo Rintakoski for help in the experiment, Riitta Koivikko and Krista Tulonen for chemical analyses, Fiia Haavisto for preparing the map, and the Archipelago Research Institute (University of Turku) for facilities. This research was financed by the Academy of Finland (Project 53832, BIREME) and the Wihuri Foundation (TH).
- Boecklen WJ, Mopper S (1998) Local adaptation in specialist herbivores: theory and evidence. In: Mopper S, Straus SY (eds) Genetic structure and local adaptation in natural insect populations. Chapman & Hall, New York, pp 64–88Google Scholar
- Borowsky B (1987) Laboratory studies of the pattern of reproduction of the Isopod Crustacean Idotea baltica. Fishery Bull 85:377–380Google Scholar
- Haahtela I (1978) Morphology as evidence of maturity in Isopod Crustacea, as exemplified by Mesidotea entomon (L.). Ann Zool Fennici 15:186–190Google Scholar
- Hay ME, Steinberg PD (1992) The chemical ecology of plant-herbivore interactions in marine versus terrestrial communities. In: Rosenthal GA, Berenbaum M (eds) Herbivores: their interaction with secondary plant metabolites. Academic Press, San Diego, pp 371–413Google Scholar
- Hemmi A, Jormalainen V (2002) Nutrient enhancement increases performance of a marine herbivore via quality of its food alga. Ecology 83:1052–1064Google Scholar
- Hemmi A, Jormalainen V (2004b) Geographic covariation of chemical quality of the host alga Fucus vesiculosus with fitness of the herbivorous isopod Idotea baltica. Mar Biol 145:759–768Google Scholar
- Honkanen T, Jormalainen V, Hemmi A, Mäkinen A, Heikkilä N (2002) Feeding and growth of the isopod Idotea baltica on the brown alga Fucus vesiculosus: roles of inter-population and within-plant variation in plant quality. Ecoscience 9:332–338Google Scholar
- Salemaa H (1987) Herbivory and microhabitat preferences of Idotea spp. (Isopoda) in the northern Baltic Sea. Ophelia 27:1–15Google Scholar
- SAS Institute (1999) SAS/STAT User’s Guide, Version 8. SAS Institute Inc., Cary, NCGoogle Scholar
- Targett NM, Arnold TM (2001) Effects of secondary metabolites on digestion in marine herbivores. In: McClintock JB, Baker BJ (eds) Marine chemical ecology. CRC Press, pp 391–412Google Scholar
- Thompson JN (2005) The geographic mosaic of coevolution. University of Chicago Press, ChicagoGoogle Scholar