Temperature‐ and predator‐induced phenotypic plasticity in Bosmina cornuta and B. pellucida (Crustacea: Cladocera)

Abstract

SUMMARY 1. Clones of Bosmina cornuta and B. pellucida (B. longirostris species complex) were derived from samples collected from Scheuermühlenteich and Lake Windsborn(westernGermany). Experimental temperature change (to 10 °C and 20 °C) and exposure to Acanthocyclops vernalis copepods (12 L−1) significantly altered external morphology in laboratory cultures of the two species. Morphological traits were derived from eight log10‐transformed and standardised morphometric distances by factorial analysis: factor 1 represented body size, factor 2, size of appendages and factor 3, the head size. 2. Acclimation of clones to cold water (10 °C, >14 days) led to an increase in body, antennule and mucrone size in B. cornuta and B. pellucida. Moreover, at 10 °C, B. cornuta cultures usually collapsed within a few weeks. Compared to the trials at 10 °C, acclimation to 20 °C (the two species) and to 15 °C (B. pellucida only) left the size of body appendages unchanged. Individuals were unequivocally assigned to each species by discriminant functions. Conspecific individuals that were acclimated to different temperatures between 10 and 20 °C also differed in external morphology, but discriminant analysis yielded misclassification rates of 5.3–23.3%. 3. Morphological response to the presence of copepod predators was weaker than that caused by temperature change. Long‐term exposure of clones to copepod predators induced a significant increase in size of appendages in the two species but left body size unaffected. Again, species identification by discriminant functions could be made without any error, whereas conspecific controls and experimentals were misclassified at rates between 19.4 and 29.5%. 4. It is suggested that temperature is the main proximal cue for Bosmina cyclomorphosis. The distinct response to temperature of B. pellucida and B. cornuta may also account for seasonal differences in abundance observed in field.

Proximate factors controlling the morphologic plasticity of Bosmina: linking artificial laboratory treatments and natural conditions

“…Factors related to cyclopoid copepods are known to enhance the development of the protuberant morphology in B. longirostris (Kerfoot, 1987;Kappes & Sinsch, 2002, Sakamoto et al, 2007. Kairomones (chemical signals) are the most prevailing signals used in prey-predator interactions in freshwater plankton (Lass & Spaak, 2003).…”

“…The alarm cue informs the surrounding conspecific animals that they are in a dangerous environment. An abiotic factor, warmer (or colder) water temperature, can induce defensive morphs even in the absence of predators (Havel & Dodson, 1985;Kappes & Sinsch, 2002). To prey cladocerans, disparate water temperature can be a stimulus identical to an abundance of predators in the field: high temperature is a feature of summer, a time when the invertebrate predator, the Chaoborus larva, appears in abundance (Tollrian & Dodson, 1999).…”

“…To prey cladocerans, disparate water temperature can be a stimulus identical to an abundance of predators in the field: high temperature is a feature of summer, a time when the invertebrate predator, the Chaoborus larva, appears in abundance (Tollrian & Dodson, 1999). On the other hand, low temperature (spring and autumn) suggests to the prey that there is a high abundance of cyclopoid copepods (Tollrian & Dodson, 1999;Kappes & Sinsch, 2002).…”

Response of Bosmina size structure to the acidification and recovery of lakes near Sudbury, Canada

“…The influence of invertebrate predation on cladoceran cyclomorphosis has been well-studied, with invertebrate predators inducing an increase in body size and the development of defensive structures such as neck teeth in Daphnia (Hebert and Grewe, 1985;Black, 1993) and elongated mucros and antennules in Bosmina (Kerfoot, 1975;Black, 1980). However, other environmental factors also affect cladoceran size structure, including temperature (Coker, 1939;Brooks, 1946;Hebert, 1978;Kappes and Sinsch, 2002), food availability (Hebert, 1978), and pH (Locke and Sprules, 2000;Korosi et al, 2008). Size structure is an important attribute of zooplankton ecology, influencing algal grazing rates (larger-sized animals tend to be more efficient grazers; DeMott, 1982;Tóth and Kato, 1997), fitness, competitive abilities, and energy transfer up the food web (Lynch, 1977;Hart and Bychek, 2011).…”

Estrutura latitudinal e temporal de assembleias de cnidários bentônicos em placas de recrutamento em dois portos da costa brasileira

“…Rapoport's hypothesis has often been contested, especially when distribution may be related to biogeographic factors (Roy et al, 1994;Macpherson, 2003). Additionally, species have populations that vary by habitat (Koumoundouros et al, 2001;Kappes & Sinsch, 2002), leading to intraspecific variation in eco-physiologies.…”