SeaWorld San Diego

A 19-year-old female California sea lion (Zalophus californianus) in managed care was euthanized following a 3-week history of hyporexia, diarrhoea, lethargy, abdominal discomfort, dyspnoea and tremors. Ante-mortem ultrasound confirmed splenomegaly with multifocal infiltrates and splenic aspirates revealed malignant cells of undetermined origin. Necropsy confirmed a malignant trabecular to diffuse granulosa cell tumour (GCT) that had metastasized to the liver, spleen, kidneys, adipose tissue, pancreas, adrenal glands, lungs, lymph nodes, brain and bone marrow. The GCT was arising within a corpus luteum and was not causing ovarian enlargement. A reticulin stain was useful to distinguish neoplastic granulosa cells from non-neoplastic cells of the corpus luteum. All neoplastic granulosa cells expressed vimentin and cytokeratin but few expressed inhibin alpha. The GCT had a mitotic count of 17 per 2.37 mm2 and a Ki67 index of 85%. The sea lion delivered a stillborn pup 5 months prior to euthanasia, indicating the interval from tumour onset to severe metastatic disease was less than 5 months. The aggressive behaviour, high proliferation indices, origin of the neoplasm in a corpus luteum and lack of ovarian enlargement are unusual features for a GCT.

The endangered Southern Resident killer whale ( Orcinus orca ) (SRKW) population is burdened by multiple anthropogenic stressors with limited non-invasive approaches for health surveillance. The gut microbiome is interconnected with host physiology and can be characterized using remotely collected fecal samples, creating unique opportunities to integrate environmental and individualized host-associated features of health. In this study, we used fecal samples collected over a 15-year period (2005-2019) from 77% of the living, wild SRKW population (56 individuals, 1-17 time points per individual), as well as fecal samples from the conspecific Northern and Alaska resident killer whale populations, to characterize distal gut microbiota structure and genomic composition. SRKW microbiotas were individualized and distinct from those of the nearby Northern and Alaska Resident populations, both of which exhibit consistently higher fecundity and survivorship. During the study period, SRKW fecal microbiota species richness declined, despite stability over periods of time less than or equal to 1 year. Several potential bacterial pathogens, such as Fusobacterium spp., achieved dominance in the fecal microbiotas of SRKW individuals sampled within 6 months of death. These findings demonstrate the feasibility and value of harnessing non-invasively collected fecal samples and microbiome profiles for longitudinal killer whale health surveillance. ### Competing Interest Statement The authors have declared no competing interest. Fisheries and Oceans Canada, https://ror.org/02qa1x782, MEQ-2023-24-009 National Oceanic and Atmospheric Administration, https://ror.org/02z5nhe81 Exxon Valdez Oil Spill Trustee Council, https://ror.org/02t378715 Marine Mammal Commission, https://ror.org/05sn2fr43

Phenotypic variation among species is a product of evolutionary changes to developmental programs 1,2 . However, how these changes generate novel morphological traits remains largely unclear. Here we studied the genomic and developmental basis of the mammalian gliding membrane, or patagium-an adaptative trait that has repeatedly evolved in different lineages, including in closely related marsupial species. Through comparative genomic analysis of 15 marsupial genomes, both from gliding and non-gliding species, we find that the Emx2 locus experienced lineage-specific patterns of accelerated cis-regulatory evolution in gliding species. By combining epigenomics, transcriptomics and in-pouch marsupial transgenics, we show that Emx2 is a critical upstream regulator of patagium development. Moreover, we identify different cis-regulatory elements that may be responsible for driving increased Emx2 expression levels in gliding species. Lastly, using mouse functional experiments, we find evidence that Emx2 expression patterns in gliders may have been modified from a pre-existing program found in all mammals. Together, our results suggest that patagia repeatedly originated through a process of convergent genomic evolution, whereby regulation of Emx2 was altered by distinct cis-regulatory elements in independently evolved species. Thus, different regulatory elements targeting the same key developmental gene may constitute an effective strategy by which natural selection has harnessed regulatory evolution in marsupial genomes to generate phenotypic novelty.

Continuous active sonar is thought to mitigate severe acoustic impacts due to its lower sound pressure level compared to pulsed active sonar typically used by world navies. However, due to its almost continuous duty cycle, continuous active sonar could have a higher potential for auditory masking. Here, we evaluate the auditory masking potential of several noise types including a recording of continuous active sonar, amplitude modulated noise, and Gaussian noise, on signal detection in two killer whales. Signals were either a 1.5 kHz pure tone or a recording of a broadband burst-pulse killer whale call. For the 1.5 kHz tone, all noise types resulted in statistically significant masking, however, there was a release from masking of approximately 13 dB for the amplitude-modulated noise. When the killer whale call was the signal, the whales employed an off-frequency listening strategy where the whales were able to detect frequency components of the signal that did not directly overlap with the noise. However, this strategy was less useful for the continuous active sonar noise due to its broadband harmonic structure. Continuous active sonar has spectral features that considerably overlap with those of killer whale calls, making this type of noise an effective auditory masker.