Environmental sensitivity differs between rabbit lines selected for reproductive intensity and longevity

To better understand the mechanisms that allow some animals to sustain their productive effort in harsh environmental conditions, rabbit does from two selection lines (LP and V) were housed in normal (NC), nutritional (NF) or heat (HC) challenging environmental conditions from first to third partum. The LP line (n=85) was founded on reproductive longevity criteria by selecting does from commercial farms that had a minimum of 25 partum with more than 7.5 kits born alive per parity. Line V (n=79) was constituted from four specialised maternal lines into a composite synthetic line and then selected by litter size at weaning for 36 generations. Female rabbits in NC and NF environments were housed at normal room temperature (18°C to 24°C) and fed with control [11.6 MJ digestible energy (DE)/kg dry matter (DM)] or low-energy diets (9.1 MJ DE/kg DM). HC does were housed at high room temperatures (25°C to 35°C) and fed the control diet. Female rabbits in the HC and NF environments ingested 11.5% and 6% less DE than NC does, respectively (P<0.05). These differences between environments occurred in both lines, with the differences being higher for LP than for V does (+6%; P<0.05). Milk yield responses followed those of energy intake also being higher for LP does (+21.3 g/day; P<0.05). The environmental conditions did not affect the perirenal fat thickness (PFT), but a genotype by environment interaction was observed. In NC and HC, the PFT was higher for line V (+0.23 and +0.35 mm, respectively; P<0.05) than for LP does, but this was not the case at NF (−0.01 mm). Moreover, the PFT evolution was different between them. In the NC environment, LP does used the accreted PFT in late lactation (−0.29 mm), whereas V does did not (−0.08 mm). Conversely, in the HC environment, LP does showed a flat PFT evolution in late lactation, whereas V does accumulated PFT. In the NF environment, LP and V does had a similar PFT evolution. There was also a litter size reduction for V does of −2.59 kits total born in HC and −1.78 kits total born in NF environments, whereas this was not observed for LP does. The results for LP does indicate a direct use of DE ingested for reproduction with little PFT change, whereas V does actively use the PFT reserves for reproduction.     

Differences in productive robustness in rabbits selected for reproductive longevity or litter size

The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; +128 g; P < 0.05), PFT (+0.47 mm; P < 0.05) and estimated body energy (EBE; +0.29 MJ/kg; P < 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW0.75 day for LP and V does, respectively; P < 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P < 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (+210 g; P < 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (+6 g DM/kg LW0.75 day; P < 0.05) and milk yield (+27 g/day; P < 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (+206 g for LP does; P < 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.     

Suppression of reproductive development and longevity in the redshouldered leaf beetle,Monolepta australis (Col.: Chrysomelidae) by the tachinid,Monoleptophaga caldwelli (Dipt.)

This paper examines the level and seasonal incidence of parasitism of the redshouldered leaf beetle,Monolepta australis (Jacoby), by the tachinid,Monoleptophaga caldwelli Baranov, and assesses the impact of this fly on the beetle's reproductive development and longevity. Highest average numbers ofM. australis were trapped at light in north Queensland in January and February while parasitism peaked at 6.6 and 6.8% in June and July respectively, averaging 4.8% over the entire sampling period and reaching 28% for a single occasion. Overall, only 2.4% of parasitized beetles were represented in the final two stages of ovarian development compared to 29.1% of non-parasitized ones. There was a highly significant (P<0.001) difference in the distribution frequencies of parasitized and non-parasitized females in the various stages of ovarian development, and most parasitized males possessed atrophied testes. For field-collected beetles maintained in the laboratory, average longevity for those parasitized was 15.6 days compared to 72.2 days for those not parasitized.     

Early deviations in performance,metabolic and immunological indicators affect stayability in rabbit females

The main purpose of this study was to find several early factors affecting stayability in rabbit females. To reach this goal, 203 females were used from their first artificial insemination to their sixth parturition. Throughout that period, 48 traits were recorded, considered to be performance, metabolic and immunological indicators. These traits were initially recorded in females’ first reproductive cycle. Later, removed females due to death or culling and those that were non-removed were identified. A first analysis was used to explore whether it was possible to classify females between those reaching and those not reaching up to the mean lifespan of a rabbit female (the fifth reproductive) cycle using information from the first reproductive cycle. The analysis results showed that 97% of the non-removed females were classified correctly, whereas only 60% of the removed females were classified as animals to be removed. The reason for this difference lies in the model’s characteristics, which was designed using early traits and was able to classify only the cases in which females would be removed due to performance, metabolic or immunologic imbalances in their early lives. Our results suggest that the model defines the necessary conditions, but not the sufficient ones, for females to remain alive in the herd. The aim of a second analysis was to find out the main early differences between the non-removed and removed females. The live weights records taken in the first cycle indicated that the females removed in their first cycle were lighter, while those removed in their second cycle were heavier with longer stayability (−203 and +202 g on average, respectively; P < 0.05). Non-removed females showed higher glucose and lower beta-hydroxybutyrate concentrations in the first cycle than the removed females (+4.8 and −10.7%, respectively; P < 0.05). The average lymphocytes B counts in the first cycle were 22.7% higher in the non-removed females group (P < 0.05). The females removed in the first reproductive cycle presented a higher granulocytes/lymphocytes ratio in this cycle than those that at least reached the second cycle (4.81 v. 1.66; P < 0.001). Consequently, non-removed females at sixth parturition offered adequate body development and energy levels, less immunological stress and a more mature immune function in the first reproductive cycle. The females that deviated from this pattern were at higher risk of being removed from the herd.     

Nestling telomere length does not predict longevity,but covaries with adult body size in wild barn swallows

Telomere length and dynamics are increasingly scrutinized as ultimate determinants of performance, including age-dependent mortality and fecundity. Few studies have investigated longevity in relation to telomere length (TL) in the wild and none has analysed longevity in relation to TL soon after hatching, despite the fact that telomere shortening may mostly occur early in life. We show that TL in nestling barn swallows (Hirundo rustica) in the wild does not predict longevity. However, TL positively covaries with body size, suggesting that individuals with large TL can afford to grow larger without paying the cost of reduced TL, and/or that benign rearing conditions ensure both large body size and low rates of telomere shortening. Overall, our study hints at a role of TL in developmental processes, but also indicates a need for further analyses to assess the expectation that TL in young individuals predicts longevity in the wild.     

Initial reproductive investment and parental body size in Cryptocercus punctulatus (Dictyoptera: Cryptocercidae)

Abstract. Females of the subsocial woodroach Cryptocercus punctulatus Scudder generally have a single oviposition period during which they produce one to four oöthecae. Monogamous pairs and their recently deposited oöthecae were collected in the field, and measured, weighed and analysed for nitrogen in the laboratory. Females put 9.8 ± 2.4% (mean ± SD) of their dry weight and 11.6 ±0.5% of their body nitrogen into oöthecae. The total nitrogen and dry weight of the brood were positively related to the post-oviposition total nitrogen and dry weight of the mother. A female's investment, on a per nymph basis, averaged 0.06% of her post-oviposition dry weight. Females may be able to recover up to 58.7% of the nitrogen invested into a brood by consuming the egg cases after hatch. Overall, there was little variation in the width of head capsules of adults in this species, and this parameter was not significantly different between the sexes. Females were heavier than males (dry weight) (P = 0.06). Within pairs, the weights and nitrogen contents of males and females were positively correlated, probably because they feed together in the same log for nearly a year prior to reproduction.     

Multitrait evolution in lines of Drosophila melanogaster selected for increased starvation resistance: the role of metabolic rate and implications for the evolution of longevity

Starvation resistance is a trait often associated with longevity. Animals with increased longevity frequently show elevated starvation resistance and vice versa. Consequently, both life-history traits are thought to share genetic and physiological mechanisms, such as increased fat content and lowered metabolic rate. Here, we present results from 20 generations of selection on Drosophila melanogaster for increased starvation resistance at the time of adult eclosion. We observe that starvation resistance can be the result of more than one mechanism, all associated with an increase in fat resources. In general, metabolic rate is lowered under starved conditions relative to fed conditions. Metabolic rate in the starvation resistant lines is generally higher than in control lines under starved conditions. Starvation resistant flies are able to sustain a higher metabolic rate for a longer period of time when food is unavailable. This implies depletion of the increased fat reserves. However, longevity was not consistently affected by selection for increased starvation resistance. Similarly, paraquat resistance differed between selection lines and did not associate with starvation resistance, but rather with longevity. The results are discussed in relation to previous reported results on starvation resistance and its relation with mechanisms of aging and longevity.     

Effects of parental body condition and size on reproductive success in a tenebrionid beetle with biparental care

Abstract. 1. The beetle Parastizopus armaticeps (Coleoptera: Tenebrionidae) inhabits the Kalahari desert of southern Africa, constructs breeding burrows after rainfall, and shows extensive biparental care. Previous work has shown that it is predominantly male size, not female size, that determines breeding success; however, in the field these beetles show size assortative mating. This might obscure or override effects of female size on reproduction. Moreover, the inaccessibility of the breeding burrows makes it impossible to test effects of female and male size on offspring development and survival before adulthood. 2. To disentangle the effects of male and female length, body mass, and body condition on reproductive success, males and females were paired randomly in small breeding cages in the laboratory (n = 887 breeding pairs). The construction of the breeding cages allowed a clear view of the brood chamber contents at each stage in offspring development. Larva, pupa, and imago numbers and development were monitored daily, and imago mass at hatching from the pupa (hatchlings), offspring mass, and offspring body length at complete exoskeleton melanisation (juveniles) were determined. 3. There was a weak positive correlation between body condition and body length for females only. Breeding chronology was related to male body condition: males in better condition were fast to start and finish a breeding bout. Males in better condition produced heavier hatchlings and juveniles, and larger‐sized males produced larger‐sized juveniles. In contrast, numbers of larvae and juveniles produced were determined mainly by female length and body condition: larger females in better condition hatched more larvae and produced more offspring. 4. The results suggest that male size and condition will be the most important determinant of reproductive success under relatively dry conditions, when burrow length is critical for reproductive success. Female size might be more important for the pair's reproductive success under wet breeding conditions, when burrow length is less critical for successful reproduction.     

Mapping QTL for growth and shank traits in chickens divergently selected for high or low body weight

An F₂ population (695 individuals) was established from broiler chickens divergently selected for either high (HG) or low (LG) growth, and used to localize QTL for developmental changes in body weight (BW), shank length (SL9) and shank diameter (SD9) at 9 weeks. QTL mapping revealed three genome‐wide QTL on chromosomes (GGA) 2, 4 and 26 and three suggestive QTL on GGA 1, 3 and 5. Most of the BW QTL individually explained 2–5% of the phenotypic variance. The BW QTL on GGA2 explained about 7% of BW from 3 to 7 weeks of age, while that on GGA4 explained 15% of BW from 5 to 9 weeks. The BW QTL on GGA2 and GGA4 could be associated with early and late growth respectively. The GGA4 QTL also had the largest effect on SL9 and SD9 and explained 7% and 10% of their phenotypic variances respectively. However, when SL9 and SD9 were corrected with BW9, a shank length percent QTL was identified on GGA2. We identified novel QTL and also confirmed previously identified loci in other chicken populations. As the foundation population was established from commercial broiler strains, it is possible that QTL identified in this study could still be segregating in commercial strains.     

Aromatase gene and its effects on growth, reproductive and maternal ability traits in a multibreed sheep population from Brazil

We determined the polymorphism C242T of the aromatase gene (Cyp19) and its allelic frequency, as well as the effect of the variants on productive and reproductive traits in 71 purebred Santa Inês sheep, 13 purebred Brazilian Somali sheep, nine purebred Poll Dorset sheep, and 18 crossbred 1/2 Dorper sheep. The animals were genotyped using the PCR-RFLP technique. The influence of the animal's genotype on its performance or on the performance of its lambs was analyzed by the least square method. Another factor assessed was the importance of the animal's genotype in analysis models for quantitative breeding value estimates, and whether there were differences among the averages of breeding values of animals with different genotypes for this gene. In the sample studied, no AA individuals were observed; the AB and BB frequencies were 0.64 and 0.36, respectively. All Brazilian Somali sheep were of genotype BB. All 1/2 Dorper BB animals presented a lower age at first lambing, and the Santa Inês BB ewes presented a lower lambing interval. In these same genetic groups, AB ewes presented higher litter weight at weaning. This is evidence that BB ewes have a better reproductive performance phenotype, whereas AB ewes present a better maternal ability phenotype. However, in general, animals with genotype AB presented better average breeding values than those with genotype BB.     

Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population

The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.     

Correlated response in body condition and energy mobilisation in rabbits selected for litter size variability

A divergent selection experiment on litter size variability (high and low lines) was performed in rabbits over seven generations. The aim of this study was to evaluate the correlated responses to selection in body condition and fat reserves mobilisation. Litter size variability was estimated as phenotypic variance of litter size within female after correcting for the year-season and the parity-lactation status effects. A total of 226 females were used in this study, of which 158 females were used to measure body condition and energy mobilisation. Body condition was measured as BW and perirenal fat thickness. Females were stimulated with the adrenergic isoproterenol. Mobilisation capacity of fat reserves was measured by the lipolytic potential, defined as the increment in non-esterified fatty acids (NEFA) levels from basal concentration until adrenergic stimulation at mating, delivery and 10 days after delivery of the second reproductive cycle. Females were classified as survivor or non-survivor when they were culled for sanitary reasons or died before the third kindling. Data were analysed using Bayesian methodology. Survivor females presented higher BW than the non-survivor females at delivery (238 g, P=1.00) and 10 days after delivery (276 g, P=1.00). They also showed higher perirenal fat thickness at 10 days after delivery (0.62 mm, P=1.00). At delivery, basal NEFA levels was lower in survivor than non-survivor females (−0.18 mmol/l, P=1.00), but their lipolytic potential (∆NEFA) was higher (0.08 mmol/l, P=0.94). Body weight was similar between lines in survivor females. Perirenal fat thickness was lower in the high line than in the low line at delivery (−0.23 mm, P=0.90) and 10 days after delivery (−0.28 mm, P=0.92). The high line exhibited higher NEFA (0.10 mmol/l, P=0.93) and lower ∆NEFA (−0.08 mmol/l, P=0.92) than the low line at delivery. The low line showed a favourable correlated response to selection on body condition and fat reserves mobilisation. In conclusion, the low line selected for litter size variability seems to adapt better to adverse conditions, as it has a greater capacity to mobilise energy reserves at delivery than the high line. Females that adequately manage their body reserves and perform energy mobilisation correctly have a lower risk of dying or being culled.     

Life history tactics of darters (Percidae: Etheostomatiini) and their relationship with body size, reproductive behaviour, latitude and rarity

Patterns of covariation of life history traits of darters in the genus Etheostoma are reviewed. The primary pattern is associated with body size. Large darters grow faster, mature at a larger size, produce bigger clutches, and have longer reproductive and life spans, and shorter spawning seasons, than do small darters. When the effects of size are removed statistically, the dominant secondary pattern matched the r-K continuum from fast-growing, short-lived, primarily semelparous species with many small ova and a high reproductive effort (r-species) to slow-growing, long-lived, iteroparous species with few large ova and a low reproductive effort (K-species). Variation in life history traits is also influenced by reproductive behaviour, latitude, and rarity (as measured by geographic range). There are significant differences in the primary and secondary life history patterns among reproductive guilds. Latitude and rarity are not correlated with these primary and secondary patterns. Instead, they account for variation of tertiary patterns. Rare species may not match the reproductive performance of more common and widely distributed species. Future studies of life history traits in darters should focus on species whose reproductive behaviour differs from that of the species reviewed in this study, and on the demographic characteristics of rare or declining populations.     

The detoxication of nitrate by two antioxidants or a probiotic,and the effects on blood and seminal plasma profiles and reproductive function of New Zealand White rabbit bucks

Forty-two New Zealand White male rabbits were housed individually in wire cages and randomly distributed among six experimental groups of seven rabbits each, during 16 to 61 weeks of age. There were three main nitrate groups: 0 (tap water), 350 and 700 ppm. Within the 700 ppm of nitrate, there were four subgroups, in which one group was used as control group and the other three groups were supplemented with either 200 ppm of ascorbic acid (vitamin (Vit) C), 200 ppm of Vit E with 0.2 ppm of selenium (Se) and 1000 ppm of probiotic. The nitrate was supplemented as a sodium nitrate. The aim is to test the ability of Vit C and Vit E, Se and probiotic on the deleterious effects (blood and seminal plasma biochemical constituents, semen quality and productive performance) of nitrate in drinking water. Rabbits given nitrate at 700 ppm had significantly lower plasma globulin, red blood cells (RBCs), hemoglobin (Hgb), packed cell volume % (PCV%) and total antioxidant capacity (TAC) than those given the other concentrations of nitrate. Vit C, Vit E with Se and probiotic resulted in significantly (P < 0.05) greater Hgb, RBCs, PCV% and TAC than those of bucks given water supplemented with only 700 ppm nitrate, but the aspartate aminotransferase and alanine aminotransferase concentrations in seminal plasma were lower. Testosterone in the blood plasma and the seminal plasma was significantly (P < 0.05) lower in rabbits given 700 ppm nitrate than in those given other concentrations of nitrate. Vit C, Vit E with Se and the probiotic significantly increased testosterone, fertility, number of offspring and total offspring weight of rabbits sired by bucks supplemented with 700 ppm of nitrate.     

Polyphagy,flightlessness, and reproductive output of females: a case study with bagworms (Lepidoptera: Psychidae)

Abstract 1. We evaluated the relation between plant‐mediated larval traits and the fitness of female bagworms, Thyridopteryx ephemeraeformis Haworth (Lepidoptera: Psychidae) by sampling 29 populations of bagworms on five plant genera (Thuja, Pinus, Picea, Juniperus, and Gleditsia). 2. Compared with those on other genera of plants, female larvae on Thuja attained a larger size at pupation and developed faster. The superior quality of Thuja as a larval food plant resulted in a higher potential fitness of females, as indicated by a low level of pupal mortality and high fecundity. 3. The fecundity of females increased with pupal size on different plant genera, and the effect of host plant genus was negligible compared with pupal size. 4. The mating success of females varied among different populations (0–37% unmated females), but neither host plant, emergence time, nor the size of females had a significant influence on the proportion of mated females. 5. The conversion of adult biomass into reproductive tissue, measured as the ratio between the biomass of eggs divided by the biomass of calling females, increased with the pupal size of females and approached 90% for large females. The high rate of egg conversion in bagworms may be related to the neoteny of short‐lived females that invest little in somatic tissue.     

Relationships of reproductive traits and body size with attainment of sexual maturity and age in Blanding's turtles (Emydoidea blandingi)

To place associations among body size, age at maturity, age, and reproductive traits of a long-lived organism in the context of current life history models based on the concept of norms of reaction, we examined data from a mark-recapture study of Blanding's turtles (Emydoidea blandingi) in southeastern Michigan during 24 of the years between 1953 and 1988. Females matured between 14 and 20 years of age. Both the smallest and largest adult females in the population were reproducing for the first time in their lives. This result suggests that a combination of differences in juvenile growth rates and ages at maturity, and not indeterminate growth, are the primary cause of variation in body size among adults. Body size variation among individuals was not related to age at sexual maturity. Females that had slower growth rates as juveniles matured later at similar mean body size compared to those with more rapid growth that matured at an earlier age. As a result, a linear model of age at sexual maturity with growth rates of primiparous females between hatching and maturity was significant and negative (R² = 0.76). Frequency of reproduction of the largest and smallest females was not significantly different. Clutch size did not vary significantly with age among either primiparous or multiparous females. Clutch sizes of primiparous females and multiparous females were not significantly different. However, older females (>55 years minimum age) reproduced more frequently than did younger females (minimum age <36 y).     

Effect of oral theaflavin administration on body weight,fat, and muscle in healthy subjects: a randomized pilot study

Theaflavins are reddish-colored polyphenols in black tea. To test the efficacy of theaflavin administration on body fat and muscle, we performed a randomized, double-blind, placebo-controlled study and investigated the effect of theaflavins administration on the body composition using of healthy subjects. In this study, 30 male and female Japanese were enrolled and participants were randomly allocated to receive placebo, theaflavin (50 or 100 mg/day), or catechin (400 mg/ml) for 10 weeks. The effects were evaluated using body weight, body fat percentage, subcutaneous fat percentage, and skeletal muscle percentage. Theaflavin administration significantly improved body fat percentage, subcutaneous fat percentage, and skeletal muscle percentage when compared to with the placebo. In contrast, there was no significant difference in all measured outcomes between the catechin and the placebo groups. The results indicate that oral administration of theaflavin had a beneficial effect on body fat and muscle in healthy individuals.     

Dietary effects on body composition, glucose metabolism, and longevity are modulated by skeletal muscle mitochondrial uncoupling in mice

Little is known about how diet and energy metabolism interact in determination of lifespan under ad libitum feeding. From 12 weeks of age until death, male and female wild-type (WT) and transgenic (TG) mice with increased skeletal muscle mitochondrial uncoupling (HSA-mUCP1 mice) were fed one of three different semisynthetic diets differing in macronutrient ratio: control (high-carbohydrate/low-fat-HCLF) and two high-fat diets: high-carbohydrate/high-fat (HCHF), and low-carbohydrate/high-fat (LCHF). Compared to control and LCHF, HCHF feeding rapidly and significantly increased body fat content in WT. Median lifespan of WT was decreased by 33% (HCHF) and 7% (LCHF) compared to HCLF. HCHF significantly increased insulin resistance (HOMA) of WT from 24 weeks on compared to control. TG mice had lower lean body mass and increased energy expenditure, insulin sensitivity, and maximum lifespan (+10%) compared to WT. They showed a delayed development of obesity on HCHF but reached similar maximum adiposity as WT. TG median lifespan was only slightly reduced by HCHF (-7%) and unaffected by LCHF compared to control. Correlation analyses showed that decreased longevity was more strongly linked to a high rate of fat gain than to adiposity itself. Furthermore, insulin resistance was negatively and weight-specific energy expenditure was positively correlated with longevity. We conclude that (i) dietary macronutrient ratios strongly affected obesity development, glucose homeostasis, and longevity, (ii) that skeletal muscle mitochondrial uncoupling alleviated the detrimental effects of high-fat diets, and (iii) that early imbalances in energy homeostasis leading to increased insulin resistance are predictive for a decreased lifespan.     

Seasonal variation in ornament expression,body size,energetic reserves,immune response,and survival in males of a territorial insect

Abstract 1. Seasonal variation in immune response has rarely been investigated in invertebrates and, therefore, we have studied this using territorial adult males of the damselfly, Hetaerina americana (Fabricius), in several generations, for a year and a half. 2. We investigated and related seasonal variation in red pigmented wing spot size (an ornamental trait) and body size to fat reserves using four immunity components – melanisation ability, phenoloxidase (PO) and nitric oxide (NO) activity, and haemolymph protein concentration – and survival ability after a bacterial immune challenge. 3. There was seasonal variation in spot expression, being more intense in the non‐winter months and less intense in winter months, and, to some extent, a similar pattern was found for NO. Although there was also variation in melanisation, PO activity, protein concentration and fat reserves, this was not consistently related to variation in spot size. Survival was lower in the winter than in non‐winter months. 4. Animals with larger spot and body size had greater values of melanisation, PO and NO activity, and protein concentration. The relation of spot and body size with fat reserves is still not clear. 5. Unlike other studies, ornament was not similarly correlated with all typical immune components (at best, mainly NO). 6. Similar to what occurs in vertebrates, survival is lower during the winter months. In the case of vertebrate studies, however, the same individual suffers these changes. In the American rubyspot, distinct cohorts demonstrated seasonal differences.