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Kristin Hultgren

Graduate Student in Ecology
University of California - Davis

Research interests

  I am generally interested in ecology and evolution of antipredator behaviors in crustaceans. For my dissertation, I am focusing on ecology and evolution of camouflage behaviors in the Majoidea (Brachyura) on several scales. Within a species, I am interested in geographic variation in behavior and the implications that this variation can have on local adaptation and community interactions. Among closely related species (Epialtidae, or the kelp crabs) I am interested in the adaptive significance of different camouflage strategies and their effect on habitat use. At a larger scale, I am interested in the evolution of camouflage behaviors among Majoid species.

  Crabs in the Majoidea superfamily (Brachyura), also known as decorator crabs, use specialized hooked setae (pictured above) to decorate. Decoration behavior is limited by the extent and distribution of hooked setae.

  Decorator crabs (Brachyura: Majoidea) attach algae and/or marine invertebrates to various portions of their carapace using hooked setae. Different species often use characteristic "types" of decoration materials; some decorate with organisms such as tunicates (which also then overgrow the carapace), others use algae to match the algal habitats they inhabit. However, decoration behavior is limited by hook morphology and distribution. In the Epialtidae family (kelp crabs), some species with few hooks decorate little and instead are thought to use a form of color camouflage. The diversity of camouflage strategies in the Majoidea superfamily makes them an ideal group with which to investigate the ecology and evolution of camouflage strategies.

While most Majoid crabs rely on decoration for camouflage, some crabs (especially in the Epialtidae, or kelp crabs) also rely on color change to camouflage. Pictured above is Pugettia producta on the intertidal algae Egregia.

Geographic Variation in Decoration Selectivity
  As part of a collaboration with the laboratory of Dr. Keiji Wada (Nara Women's University, Japan), I investigated geographic variation in decoration behavior of Micippa platipes and Tiarinia cornigera in Japan.

Micippa platipes, shown here decorated with algae, is a commonly-encountered decorator crab in the intertidal area of Japan's east coast.

Alternate Camouflage Strategies in the Epialtidae (Kelp Crabs)
  I am currently investigating utilization of two alternate camouflage strategies-- color change and decoration-- by closely related species in the Epialtidae family. My research has shown that while both camouflage strategies protect crabs against predation, species differ in their utilization of each strategy. In Bodega Bay, CA, where several species coexist, utilization of decoration or color change camouflage may drive patterns in algal host specificity, with important implications for the evolution of niche width.

Evolution of Decoration Behavior in the Majoidea
  As part of an on-going project, I am working on a phylogeny of the Majoidea superfamily to examine 1) large-scale patterns of decoration behavior in the Majoidea, and 2) among-species correlations between color change and decoration camouflage in the Epialtidae using independent contrasts.

Loxorhynchus crispatus is found in subtidal regions from Washington south to Baja California. Bodega Bay populations of L. crispatus preferentially decorate with the bryozoan Bugula neritina.

Decoration Specialization in Loxorhynchus crispatus
  In several locations along the California coast, the decorator crab Loxorhynchus crispatus specializes on using Bugula neritina as a decoration material. I am investigating the adaptive significance of this specialization, and what factors (chemistry, morphology, handling time) may affect this pattern.

Hultgren, K.M., P.D. Thanh, and M. Sato. In Press. Geographic Variation in Decoration selectivity of Micippa platipes and Tiarinia cornigera in Japan. Marine Ecology Progress Series.

Byrnes, J.E., J.J. Stachowicz, K.M. Hultgren, A.R. Hughes, S.V. Olyarnik, and C.S. Thornber. In press. Predator diversity increases trophic cascades in kelp forests by modifying herbivore behavior. Ecology Letters. 9:61-71. [-link-]

Harley, C.D.G., A.R. Hughes,A.R., K.M. Hultgren, B.G. Miner, L. Rodriguez, C.J.B. Sorte, C. Thornber, L. Tomanek, and S.L. Williams. In press. The impacts of climate change in coastal marine systems. Ecology Letters. 9:228-241. [-link-]