Intra-population variation in reproductive timing covaries with thermal plasticity of offspring performance in perch Perca fluviatilis.

Life history theory posits that organisms should time their reproduction to coincide with environmental conditions that maximize their fitness. Population-level comparisons have contributed important insights on the adaptive value of reproductive timing and its association to environmental variation. Yet, despite its central role to ecology and evolution, the causes and consequences of variation in reproductive timing among individuals within populations are poorly understood in vertebrates other than birds. Using a combination of observational field studies and a split-brood experiment, we investigated whether differences in breeding time were associated with changes in hatching success, reproductive allocation and reaction norms linking offspring performance to temperature within an anadromous Baltic Sea population of perch Perca fluviatilis. Field observations revealed substantial variation in reproductive timing, with the breeding period lasting almost 2 months and occurring in temperatures ranging from 10 to 21℃. The hatching success of perch decreased as the reproductive season progressed. At the same time, the reproductive allocation strategy changed over the season, late breeders (the offspring of which were introduced into a high resource environment and increased predation pressure) produced more and smaller eggs that resulted in smaller larvae, compared with early breeders. The split-brood experiment in which eggs were incubated in different temperatures (10, 12, 15, 18°C) showed that differences in reproductive timing were associated with a change in the shape of the reaction norm linking offspring performance to water temperature indicative of adaptive phenotypic plasticity, with the offspring of early breeders performing best in low temperatures and the offspring of late breeders performing best in high temperatures. The seasonal changes in reproductive traits and the shape of the thermal performance suggest time-dependent adaptive differences among individuals within the population. Management actions aimed at preserving and restoring variation in the timing of reproductive events will thus likely also influence variation in associated life history traits and thermal performance curves, which could safeguard populations against environmental challenges and changes associated with exploitation and global warming.

Phenotypic flexibility in background-mediated color change in sticklebacks.

Phenotypic flexibility may incur a selective advantage in changing and heterogeneous environments, and is increasingly recognized as an integral aspect of organismal adaptation. Despite the widespread occurrence and potential importance of rapid and reversible background-mediated color change for predator avoidance, knowledge gaps remain regarding its adaptive value, repeatability within individuals, phenotypic correlates, and whether its expression is context dependent. We used manipulative experiments to investigate these issues in two fish species, the three-spined stickleback (Gasterosteus aculeatus) and nine-spined stickleback (Pungitius pungitius). We sequentially exposed individuals to dark and light visual background treatments, quantified color change from video recordings, and examined associations of color change with phenotypic dimensions that can influence the outcome of predator-prey interactions. G. aculeatus expressed a greater degree of color change compared to P. pungitius. In G. aculeatus, the color change response was repeatable within individuals. Moreover, the color change response was independent of body size but affected by sex and boldness, with males and bolder individuals changing less. Infection by the parasite Schistocephalus solidus did not affect the degree of color change, but it did modulate its association with sex and boldness. G. aculeatus adjusted the expression of color change in response to predation risk, with enhanced color change expression in individuals exposed to either simulated attacks, or olfactory cues from a natural predator. These results provide novel evidence on repeatability, correlated traits, and context dependence in the color change response and highlight how a suite of factors can contribute to individual variation in phenotypic flexibility.

Functional Outcomes Post Lisfranc Injury-Transarticular Screws, Dorsal Bridge Plating or Combination Treatment?

OBJECTIVE: To identify whether transarticular screws, dorsal bridging plates or a combination of the 2 result in the best functional outcome after Lisfranc injury. DESIGN: Case series. SETTING: Level one trauma center. PATIENTS: Fifty patients who underwent surgical fixation of Lisfranc injuries over a 6-year period were retrospectively reviewed. INTERVENTION: One of 3 treatment arms: transarticular screw fixation alone, dorsal bridge plating alone or a combination of dorsal bridge and transarticular screw fixation. MAIN OUTCOME MEASURES: The primary outcome measures were 1 of 2 midfoot scores-the American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Score and the Foot Function Index (FFI) Score. Secondary results included postoperative complications. RESULTS: Quality anatomical reduction is the best predictor of functional outcomes (FFI-P = 0.008, AOFAS-P = 0.02). Functional outcomes with both FFI and AOFAS scores were not significantly associated with any of the fixation groups (FFI-P = 0.495, AOFAS-P = 0.654) on univariate analysis. Injury type by Myerson classification systems or open versus closed status was also not significantly associated with any fixation group. Open exposures were more likely to result in soft-tissue complications, but there was no significant difference in metalware failure or need for removal. CONCLUSION: Functional outcomes after Lisfranc fractures are most dependant on the quality of anatomical reduction and not the choice of fixation implant used. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.