Restricted host use by the herbivorous amphipod Peramphithoe tea is motivated by food quality and abiotic refuge
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There is a growing list of marine invertebrate herbivores known to restrict their host choices to a subset of available species, yet the relative importance of the evolutionary forces that select for specialized feeding habits remain unclear. One such specialist is the gammaridean amphipod Peramphithoe tea (F. Ampithoidae) that restricts its distribution to the brown laminarian seaweed Egregia menziesii in Oregon. A field survey indicated that among available seaweeds in the low intertidal zone of Boiler Bay, Oregon, Egregia housed greater than 90% of P. tea individuals. A set of laboratory-based habitat and feeding choice assays revealed that this specialized host distribution is likely the consequence of choices made by adult P. tea. The restricted host choice is apparently maintained by at least two evolutionary forces. First, a juvenile performance assay indicates that both Egregia and the co-occurring seaweed Alaria marginata, provide high food quality relative to other seaweeds available in the low-intertidal zone. Second, a field transplantation experiment revealed that Egregia protects adult amphipods from becoming dislodged with wave energy more readily than did Alaria. Thus, Egregia’s value as good quality food and refuge from abiotic stress together explain the restricted host use of P. tea. A comparison with previous studies suggests that use of Egregia is not consistent across the geographic range of P. tea, suggesting the possibility that the host preferences of local populations may respond evolutionarily to geographic shifts in seaweed communities.
KeywordsUlva Wave Force Brown Seaweed High Food Quality Brood Pouch
Thanks to Steve Palumbi, and Bruce Menge, Jane Lubchenco and their laboratory for logistical support. I appreciate the thoughtful comments of two anonymous reviewers. This is Grice Publication Number 300 and was supported in part by Andrew W. Mellon Foundation and the National Science Foundation (OCE-0550245).
- Conlan KE, Bousfield EL (1982) The amphipod superfamily Corophioidea in the northeastern Pacific region, family Ampithoidae: systematics and distributional ecology. Publ Biol Oceanogr Natl Mus Can 10:41–75Google Scholar
- Hay ME (1992) The role of seaweed chemical defenses in the evolution of feeding specialization and in the mediation of complex interactions. In: Paul V (ed) Ecological roles of marine natural products. Comstock Publishing, IthacaGoogle Scholar
- Hay ME, Steinberg PD, Fenical W (1992) The chemical ecology of plant-herbivore interactions in marine versus terrestrial communities. Chemical mediation of seaweed-herbivore interactions. Syst Assoc Spec 46:319–337Google Scholar
- Poore AGB, Steinberg PD (1999) Preference-performance relationships and effects of host plant choice in an herbivorous marine amphipod. Ecol Monogr 69:443–464Google Scholar