The Mueller lab is currently interested in three interrelated areas of developmental physiology research:
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Chorus frog metamorphs feeding
Immediate & Long-term Effects of Developmental Temperature on PhysiologyTemperature has a pervasive effect on all animals, particularly ectotherms. We are interested in responses to temperature in embryos and larval stages, which can often be particularly thermally sensitive. Temperature can have lasting impacts on the later life phenotypes of organisms, which is likely to effect juvenile and adult performance and fitness. Thus, this research is vital for understanding the impacts of predicted increases in temperature with climate change on not just developmental stages, but throughout the entire life history of the organism. We are examining the effects of temperature on developmental traits across all of our model species. In particular, we are examining how temperature during development may influence function in embryos, tadpoles and froglets of the Baja California chorus frog. This allows us to explore if phenotypic traits are maintained across metamorphosis.
Respirometry system used to measure metabolism under controlled temperature
Rainbow trout embryo incubation
Baja California chorus frog tadpoles
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Critical window construct
Rainbow trout embryos
Developmental Critical Windows of PlasticityInteractions between the developmental trajectory of an animal and the environment are key in shaping an animal’s phenotype. Periods of development during which an animal may show greater likelihood of phenotypic changes are termed developmental ‘critical windows’. Our goal is to understand the timing and mechanisms of plasticity during critical windows. Dr. Mueller, working with her postdoc supervisor Warren Burggren, devised a novel 3-D critical window approach that she has used to examine the effect of salinity on brine shrimp development and the effect of temperature on lake whitefish hatchling phenotypes. We have observed that the patterns that emerge are often dependent on the phenotypic trait being measured. We have also applied the 3-D construct to understand the effect of temperature on rainbow trout (Oncorhynchus mykiss).
3-D critical windows for lake whitefish hatchling traits in response to temperature
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Intertidal copepod
Metabolic Compensation in Aquatic InvertebratesAquatic invertebrates used as models in the lab, such as brine shrimp (Artemia franciscana) and intertidal copepods (Tigriopus californicus), live in variable environments. This variability is likely to influence the manner in which their physiology responds to the environment. For example, variable temperatures experienced in the intertidal zone may result in a high degree of metabolic compensation, resulting in temperature-independent function following chronic temperature acclimation. We have observed this effect in brine shrimp and copepod studies in response to temperature. When we explore the time course of this compensation we see that metabolic compensation is rapid, and occurs within a few hours in copepods. We are further exploring the time course, limits and mechanisms of this rapid metabolic compensation. We are also examining whether there are physiological differences between different populations of copepods from the Pacific coast of the US to understand how local adaptation may influence functional responses to temperature.
This research is partly supported by funding from CSU Council on Ocean Affairs, Science & Technology (COAST) 
Oxygen consumption rate before, immediately after, and in the hours following a temperature change from 20 to 25°C measured in copepods from different populations.
Brine shrimp
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Collaborators
Our exploration of copepod physiology is in collaboration with Dr. Felipe Barreto at Oregon State University. Felipe is an evolutionary and ecological geneticist who examines the genetic divergence of copepod populations and the generation of novel phenotypes produced from interpolation crosses. Our physiological research on copepods provides a whole animal functional aspect to complement Felipe's genomic, genetic and molecular approaches.
We are working with Dr. John Eme, a fellow CSUSM Biological Sciences faculty, Russell Barabe, an Environmental Scientist with California Department of Fish and Wildlife, and Sandra Jacobson, the Steelhead Coalition Coordinator at CalTrout on the rainbow trout research. You can read the story of steelhead recovery in southern California here.
We continue to discuss the complexities of critical windows, and developmental physiology in general, with Dr. Warren Burggren at the University of North Texas.
Our exploration of copepod physiology is in collaboration with Dr. Felipe Barreto at Oregon State University. Felipe is an evolutionary and ecological geneticist who examines the genetic divergence of copepod populations and the generation of novel phenotypes produced from interpolation crosses. Our physiological research on copepods provides a whole animal functional aspect to complement Felipe's genomic, genetic and molecular approaches.
We are working with Dr. John Eme, a fellow CSUSM Biological Sciences faculty, Russell Barabe, an Environmental Scientist with California Department of Fish and Wildlife, and Sandra Jacobson, the Steelhead Coalition Coordinator at CalTrout on the rainbow trout research. You can read the story of steelhead recovery in southern California here.
We continue to discuss the complexities of critical windows, and developmental physiology in general, with Dr. Warren Burggren at the University of North Texas.
