Can sexual selection drive female life histories? A comparative study on Galliform birds

Sexual selection is an important driver of many of the most spectacular morphological traits that we find in the animal kingdom (for example see Andersson, 1994). As such, sexual selection is most often emphasized as

Differential sex-related winter energetics in free-ranging snowshoe hares.

Animals spend considerable time and energy acquiring food to meet their metabolic requirements, but if energetic or fitness costs are substantive, such as during winter, some individuals may limit daily energy expenditure by reducing foraging duration. To date the prevalence and magnitude of such compensatory foraging responses are poorly known. We examined energy balance compensation in free-ranging snowshoe hares (Lepus americanus (Erxleben 1777)) via a food supplementation experiment to determine whether individuals reduced their daily energy expenditure (DEE) and activity periods in response to increased food availability. Overall, food supplementation had no effect on diel activity patterns, although males had higher DEE compared to females. During early- and mid-winter, hares did not alter their activity periods in response to food supplementation, but during late-winter, when natural food availability declined, food-supplemented females (but not males) were ~11% less active compared to controls. Natural food likely was sufficient and could have been acquired at relatively low energetic cost, but because males likely have higher DEE due to mating behavior, whereas females may limit their activity (and thus DEE) to reduce predation risk, we conclude that gender-specific life history demands can over-ride predicted responses to supplemental food when baseline food abundance is adequate.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Fibroblast growth factor-18 stimulates chondrogenesis and cartilage repair in a rat model of injury-induced osteoarthritis

SummaryObjectiveOsteoarthritis (OA) is the most common form of arthritis and a primary cause of disability, however, there are no treatments that can slow disease progression or repair damaged joint cartilage. Fibroblast growth factor-18 (FGF18) has been reported to have significant anabolic effects on cartilage. We therefore examined its effects on repair of cartilage damage in a rat meniscal tear model of OA.DesignSurgical damage to the meniscus in rats leads to joint instability and significant damage to the articular cartilage at 3 weeks post-surgery. At this time, animals received bi-weekly intra-articular injections of FGF18 for 3 weeks, and the knee joints were then harvested for histologic examination.ResultsFGF18-induced dose-dependent increases in cartilage thickness of the tibial plateau, due to new cartilage formation at the articular surface and the joint periphery. The generation of new cartilage resulted in significant reductions in cartilage degeneration scores. The highest dose of FGF18 also induced an increase in chondrophyte size and increased remodeling of the subchondral bone.ConclusionsThe results of this study demonstrate that FGF18 can stimulate repair of damaged cartilage in a setting of rapidly progressive OA in rats