Summary Reproduction and immune function are critical processes, but organisms can rarely optimize both traits. Resultant reproduction–immunity trade‐offs may be ‘facultative’, occurring only when resources scarce, or they ‘obligate’, regardless of resource availability. Previous research has tested for the ‘facultative’ ‘obligate’ nature by measuring allocation (e.g. follicle size). However, alone insufficient gauging fitness consequences because number quality eggs offspring trade off with...

Parents can maximize their reproductive success by balancing the trade-off between investment per offspring and fecundity. According to theory, environmental quality influences relationship fitness, such that well-provisioned fare better when is lower. A major prediction of classic then, optimal will increase as decreases. To test this prediction, we release over 30,000 juvenile Atlantic salmon (Salmo salar) into eight wild stream environments, monitor subsequent growth survival juveniles....

Directional selection on size is common but often fails to result in microevolution the wild. Similarly, macroevolutionary rates are low relative observed strength of nature. We show that many estimates have been measured juveniles, not adults. Further, parents influence juvenile by adjusting investment per offspring. In light these observations, we help resolve this paradox suggesting upward balanced against offspring, resulting little or no net gradient size. find trade-offs between...

Abstract Phenotype-environment associations in neonatal animals may arise wild environments by virtue of ecological dynamics within the nest. Such be special importance to evolution temperature-dependent sex determination (TSD), an enigmatic trait which can adaptive when incubation temperatures that affect sexual differentiation also have differential effects on fitness sexes. To infer causal nest environment fitness-relevant phenotypes, we apply structural equation modeling (SEM) a 14-year...

How parents divide the energy available for reproduction between size and number of offspring has a profound effect on parental reproductive success. Theory indicates that relationship fitness is fundamental importance to evolution strategies: this predicts optimal division resources offspring, it describes consequences deviate from optimality, its shape can predict most viable type investment strategy in given environment (e.g., conservative vs. diversified bet‐hedging). Many previous...

Abstract Captive‐breeding programs can be implemented to preserve the genetic diversity of endangered populations such that controlled release captive‐bred individuals into wild may promote recovery. A common difficulty, however, is are founded with limited broodstock, and inbreeding become increasingly difficult avoid successive generations in captivity. Program managers must choose between maintaining purity populations, at risk depression, or interbreeding outbreeding depression. We...

Bergmann's rule is the propensity for species‐mean body size to decrease with increasing temperature. Temperature‐dependent oxygen limitation has been hypothesized help drive temperature–size relationships among ectotherms, including rule, where organisms reduce under warm oxygen‐limited conditions, thereby maintaining aerobic scope. should be most pronounced aquatic ectotherms that cannot breathe aerially, as solubility in water decreases We use phylogenetically explicit analyses show adult...

Abstract The consequences of individual variation in life‐history traits have been well studied due to their importance evolutionary ecology. However, a trait that has received little empirical attention is the rate indeterminate growth. In long‐lived ectotherms, subtle growth after maturity could major effects over animals’ lifetimes. These are difficult measure challenges involved reliably estimating face environmental stochasticity, and need account for trade‐offs among growth,...

Life histories evolve in response to constraints on the time available for growth and development. Nesting date its plasticity spring temperature may therefore be important components of fitness oviparous ectotherms near their northern range limit, as reproducing early provides more embryos complete development before winter. We used data collected over several decades compare air nest populations painted turtles snapping from a relatively warm environment (southeastern Michigan) southern...

In reptiles, thermoregulation is important because it alters the rate of many physiological processes. Thermoregulation may be especially to reproductive females that inhabit regions where growing season short, amount thermal energy experienced during limit devoted egg production. We studied basking behavior Painted Turtles (Chrysemys picta) in Algonquin Park, Ontario, period follicular recrudescence, a time year when allocate developing follicles. Based on notion bask (in part) increase...

Classic egg size theory predicts that, in a given environment, there is level of maternal investment per offspring that will maximize fitness. However, positive correlations among and female body are observed within populations diverse animal taxa. A popular explanation for this phenomenon some populations, morphological constraints on size, such as ovipositor (insects) or pelvic aperture width (lizards turtles), limit size. Egg may therefore increase with due to size‐specific offspring,...

For many oviparous animals, incubation temperature influences sex through temperature-dependent determination (TSD). Although climate change may skew ratios in species with TSD, few available methods predict under natural conditions, fewer still are based on mechanistic hypotheses of development, and field tests existing rare. We propose a new approach that calculates the probability masculinization (PM) nests. This subsumes describing outcome by integrating embryonic development...

For long-lived, iteroparous organisms whose annual reproductive success is low and unpredictable, the “bet-hedging” life-history paradigm predicts that an increase in resource acquisition should result stored lipids not output. We tested whether patterns a population of midland painted turtles ( Chrysemys picta marginata Agassiz, 1857) are consistent with this prediction. Assuming temperature variation proxy for acquisition, we hypothesized if harvested resources generally sequestered future...

Temperate ectotherms have responded to recent environmental change, likely due the direct and indirect effects of temperature on key life cycle events. Yet, a substantial number are fossorial, spending vast majority their lives in subterranean microhabitats that assumed be buffered against change. Here, we examine whether seasonal climatic conditions influence body condition (a measure general health vigor), reproductive output, breeding phenology northern population fossorial salamander...

We compared shell temperatures of Painted Turtles (Chrysemys picta) overwintering in two different ponds Algonquin Park, Canada, over one winter. Movements under the ice occurred from late November into December or early January, and based on thermal data, turtles were likely not buried substrate. Over course winter, pond became severely hypoxic, whereas other remained more highly oxygenated. hypoxic exhibited significantly lower than did normoxic environment, despite cooler average water...

Oxygen limitation and surface area to volume relationships of the egg were long thought constrain size in aquatic environments, but more recent evidence indicates that per se does not influence oxygen availability embryos. Here, we suggest investment offspring is nevertheless constrained anamniotes by virtue transport free-living larvae. Drawing on well-supported assumption relatively pronounced versus terrestrial environments particularly severe warm employ comparative methods Amphibia...

Predators use visual and olfactory cues to locate turtle nests. Since 1999, we marked Painted Turtle (Chrysemys picta) nests at a long-term study site by inserting Popsicle™ sticks part way into the nest cavity. Because nest-marking provides cue potential predators, tested whether increases depredation rates. During nesting season, 15 artificial pairs (N = 30 in total) were created digging refilling holes (presumably emulating excavation turtles) site. Nests each pair 45 cm apart, but only...