Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely distributed of marine mammals, the killer whale (Orcinus orca), using a global data set of over 450 samples. This marine top predator inhabits coastal and pelagic ecosystems ranging from...

Forecasting species' responses to climate change requires understanding the underlying mechanisms governing environmental stress tolerance, including acclimation capacity and acute stress responses. Current knowledge of these physiological processes in aquatic ectotherms is largely drawn from eurythermal or extreme stenothermal species. Yet many species of conservation concern exhibit tolerance windows and acclimation capacities in between these extremes. We linked transcriptome profiles to organismal tolerance in a mesothermal endangered fish, the delta smelt (Hypomesus transpacificus), to quantify...

Endothermy (the metabolic production and retention of heat to warm body temperature above ambient) enhances physiological function, and whole-body endothermy generally sets mammals and birds apart from other animals. Here, we describe a whole-body form of endothermy in a fish, the opah (Lampris guttatus), that produces heat through the constant “flapping” of wing-like pectoral fins and minimizes heat loss through a series of counter-current heat exchangers within its gills. Unlike other fish, opah distribute warmed...

Bycatch of mid-trophic level anadromous fishes that connect marine and freshwater ecosystems is a growing conservation concern. Anadromous alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis) are important components of coastal freshwater and marine food webs, but have experienced dramatic declines in the abundances of spawning adults. Freshwater-focused restoration efforts have yielded few consistent signs of recovery; raising concerns that bycatch in Northwest Atlantic commercial fisheries may be negating these conservation actions. Using data from...

We show that the algorithm in the program FLOCK (Duchesne & Turgeon 2009) can be interpreted as an estimation procedure based on a model essentially identical to the STRUCTURE (Pritchard et al. 2000) model with no admixture and non-correlated allele frequency priors. Rather than using MCMC, the FLOCK algorithm searches for the maximum-a-posteriori estimate of this STRUCTURE model via a simulated annealing algorithm with a rapid cooling schedule (namely, the exponent on the objective function...

Salmonid fishes are cold water piscivores with a native distribution spanning nearly the entire temperate and subarctic northern hemisphere. Trout in the genus Oncorhynchus are the most widespread salmonid fishes and are among the most important fish species in the world, due to their extensive use in aquaculture and valuable fisheries. Trout that inhabit northwestern Mexico are the southernmost native salmonid populations in the world, and the least studied in North America. They are unfortunately...

Mating with multiple partners is common across species, and understanding how individual males secure fertilization in the face of competition remains a fundamental goal of evolutionary biology. Game theory stipulates that males have a fixed budget for reproduction that can lead to a trade-off between investment in precopulatory traits like body size, armaments, and ornaments, and postcopulatory traits such as testis size and spermatogenic efficiency. Recent theoretical and empirical studies have shown that if males...

The loss of genetic and life history diversity has been documented across many taxonomic groups, and is considered a leading cause of increased extinction risk. Juvenile salmon leave their natal rivers at different sizes, ages and times of the year, and it is thought that this life history variation contributes to their population sustainability, and is thus central to many recovery efforts. However, in order to preserve and restore diversity in life history traits, it...

Aim: The frequency and severity of habitat alterations and disturbance are predicted to increase in upcoming decades, and understanding how disturbance affects population integrity is paramount for adaptive management. Although rarely is population genetic sampling conducted at multiple time points, pre- and post-disturbance comparisons may provide one of the clearest methods to measure these impacts. We examined how genetic properties of the federally threatened Coachella Valley fringe-toed lizard (Uma inornata) responded to severe drought and...

1. Trace element concentrations in fish earstones (“otoliths”) are widely used to discriminate spatially discrete populations or individuals of marine fish, based on a commonly held assumption that physiological influences on otolith composition are minor, and thus variations in otolith elemental chemistry primarily reflect changes in ambient water chemistry. 2. We carried out a long-term (1-yr) experiment, serially sampling seawater, blood plasma and otoliths of mature and immature European plaice (Pleuronectes platessa L.) to test...