The protracted spawning period of broadcast-spawning marine fishes has potential to generate considerable variability in metrics of individual reproductive output. We undertook a temporally detailed genetic study of larvae produced by Atlantic cod (Gadus morhua) from two spatially proximate populations spawning under controlled semi-natural conditions over 94 days. Based on daily samples of larvae (n = 4489 in total), we document fine-scaled temporal changes in, and correlates of, offspring phenotype and reproductive output (egg batches produced or fertilized). Larval length and standardized yolk-sac volume declined 11 and 49% over the spawning period, respectively. The adaptive significance of these trends is unclear. Longer, heavier females produced longer, better-provisioned larvae. Body size affected the number of egg batches to which an individual contributed genetically but not spawning duration. Males contributed gametes to a greater number of egg batches (19.5 vs. 9.2), and spawned over a longer period of time (48.9 vs. 30.8 days), than females. After accounting for body size and condition, egg batch number and spawning duration differed between adjacent populations separated by < 10 km. Our work highlights the need to understand the environmental and adaptive causes of temporal variability in offspring quality and its consequences to individual fitness and per capita population growth in batch-spawning fishes.

The abundance-occupancy relationship is one of the most well-examined relationships in ecology. At the species level, a positive association has been widely documented. However, until recently, research on the nature of this relationship at broad taxonomic and spatial scales has been limited. Here, we perform a comparative analysis of 12 taxonomic groups across a large spatial scale (Canada), using data on Canadian species at risk: amphibians, arthropods, birds, freshwater fishes, lichens, marine fishes, marine mammals, molluscs, mosses, reptiles, terrestrial mammals, and vascular plants. We find a significantly positive relationship in all taxonomic groups with the exception of freshwater fishes (negative association) and lichens (no association). In general, our work underscores the strength and breadth of this apparently fundamental relationship and provides insight into novel applications for large-scale population dynamics. Further development of species-independent abundance-occupancy relationships, or those of a similar nature, might well prove instrumental in serving as starting points for developing speciesindependent reference points and recovery strategies.Résumé : La relation abondance-occupation est une des relations les plus intensément examinées en écologie. À l'échelle de l'espèce, une association positive est abondamment documentée. Jusqu'à tout récemment, cependant, la recherche sur la nature de cette relation à de larges échelles taxonomiques et spatiales était limitée. Nous réalisons une analyse comparative de 12 groupes taxonomiques sur une grande échelle spatiale (le Canada) en utilisant des données sur les espèces en péril canadiennes, comprenant des amphibiens, arthropodes, oiseaux, poissons d'eau douce, lichens, poissons de mer, mammifères marins, mollusques, mousses, reptiles, mammifères terrestres et plantes vasculaires. Nous constatons une relation positive significative dans tous les groupes taxonomiques, à l'exception des poissons d'eau douce (association négative) et des lichens (pas d'association). En général, nos travaux font ressortir la force et l'étendue de cette relation apparemment fondamentale et mettent en lumière de nouvelles applications pour l'étude de la dynamique des populations à grande échelle. D'autres avancées sur les relations abondance-occupation indépendantes des espèces ou de relations de nature similaire pourraient bien s'avérer utiles comme points de départ pour l'établissement de points de référence et de stratégies de rétablissement indépendants des espèces. [Traduit par la Rédaction]

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Successful resource‐management and conservation outcomes ideally depend on matching the spatial scales of population demography, local adaptation, and threat mitigation. For marine fish with high dispersal capabilities, this remains a fundamental challenge. Based on daily parentage assignments of more than 4,000 offspring, we document fine‐scaled temporal differences in individual reproductive success for two spatially adjacent (<10 km) populations of a broadcast‐spawning marine fish. Distinguished by differences in genetics and life history, Atlantic cod (Gadus morhua) from inner‐ and outer‐fjord populations were allowed to compete for mating and reproductive opportunities. After accounting for phenotypic variability in several traits, reproductive success of outer‐fjord cod was significantly lower than that of inner‐fjord cod. This finding, given that genomically different cod ecotypes inhabit inner‐ and outer‐fjord waters, raises the intriguing hypothesis that the populations might be diverging because of ecological speciation. Individual reproductive success, skewed within both sexes (more so among males), was positively affected by body size, which also influenced the timing of reproduction, larger individuals spawning later among females but earlier among males. Our work suggests that spatial mismatches between management and biological units exist in marine fishes and that studies of reproductive interactions between putative populations or ecotypes can provide an informative basis on which determination of the scale of local adaptation can be ascertained.