The maintenance of phenotypic plasticity within a species ensures survival through environmental flux. Plastic strategies are increasingly important given the number and magnitude of modern anthropogenic threats to the environment. We tested for phenotypic plasticity in the odonate Argia vivida in response to resource limitation. By limiting food availability, effectively inducing hunger, we were able to quantify shifts in agonistic behavior during intraspecific interactions. Scoring behavior in one-on-one combat trials after 1 and 4 days without food revealed phenotypic plasticity. Three classes of genotypes were identified, genotypes exhibiting either increased aggression, decreased aggression, or no phenotypic plasticity, in response to resource limitation. The variable plastic strategies in this population of odonates likely aids in maintaining fitness in fluctuating environments.

Ocean acidification is the decline in seawater pH that results from the absorption of atmospheric carbon dioxide (CO 2 ). Decreased pH has negative effects on survivability, growth, and development in many marine calcifiers, potentially resulting in reduced coral species richness. This reduction in richness could open new niche space, allowing the spread of invasive species, such as the upside-down jellyfish (Cassiopea spp.). Like corals, this jellyfish forms symbiotic relationships with zooxanthellae, photosynthetic dinoflagellates. This study focused on the effect of seawater acidification in Cassiopea spp. We monitored zooxanthellae density and two measures of health (bell diameter and volume) in individuals of Cassiopea sp. at three pH levels chosen to mimic different open-ocean average conditions: 8.2, representing pre-industrial revolution conditions; and 7.9 and 7.6, representing predicted declines in pH in the next century. Zooxanthellae density and health of the jellyfish were measured twice-prior to experimental manipulations and after four weeks of exposure to experimental pHs-in three consecutive trials. The effects of pH and Trial on proportional change in jellyfish attributes were analyzed using generalized linear mixedmodels. We found no significant effects of either factor. These results indicate that decreasing seawater pH has no apparent negative effect on zooxanthellae density or health in Cassiopea, which suggests that these jellyfish may be relatively insensitive to the impacts of ocean acidification, heightening its potential as an invasive species. K E Y W O R D Sendosymbiotic, mutualistic, ocean acidification, photosynthetic, Symbiodiniaceae

The β‐ketoacyl [acyl carrier protein] reductase (β‐k‐ACPR) enzymes, a 690‐member subset of the SCOR short‐chain oxidoreductase family, are essential to fatty acid synthesis in bacteria and plants. There is one member of the family in every bacterial and archeal genome sequenced to date. We have discovered that (1) the most primitive member of the family was an NADP reductase, (2) that NADP binding was originally contingent upon a Ser or Thr residue in a specific turn, (3) that a specific dimer assembly is stabilized by the stacking of aromatic groups and (4) that a previously undetected GGMXM sequence at the C‐terminus, conserved in all species of proteobacteria, stabilizes the functionally required tetramer by multiple hydrogen bonding and aromatic ring stacking crosslinking the four monomers together. Our analysis indicates that the primordial members of the β‐k‐ACPR family probably arose in the GC‐rich α‐proteobacteria and that they are distinguished by the presence of multiple open reading frames (MORFs), an extreme codon bias in their DNA and an amino acid bias in their protein composition. This research was supported by NIH grant No. DK26546.