Armaments and ornaments: an evolutionary explanation of traits of dual Utility

Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual function, we propose that they commonly arise through intersexual selection processes and serve as honest signals to other males regarding fighting ability or dominance. Faking these traits, here called armaments, (i.e. weapons and status badges) is difficult, as they are constantly put to trial in male-male contests. Females that subsequently utilize them as indicators of male phenotypic quality when selecting a partner will benefit by acquiring males of higher quality to father their offspring. Thus, evolution of armaments through male-male competition is seen as a usually initiating process, whereas female choice later may assume a role as an additional selective factor. The reverse, that males use information from traits evolved through female choice, is, however, also possible. The traditional view of independently evolved and temporarily unordered intra- and intersexual selection processes fails to explain dual trait functions. Moreover, our model may more satisfyingly than traditional ones explain how trait honesty and trait genetic variance are maintained: theoretical and empirical evidence suggests that such honesty and variation are more easily maintained under male-male competition than under female choice.     

Genetic variation in North Africa and Eurasia: Neolithic demic diffusion vs. paleolithic colonisation

The hypothesis that both genetic and linguistic similarities among Eurasian and North African populations are due to demic diffusion of neolithic farmers is tested against a wide database of allele frequencies. Demic diffusion of farming and languages from the Near East should have determined clines in areas defined by linguistic criteria; the alternative hypothesis of cultural transmission does not predict clines. Spatial autocorrelation analysis shows significant gradients in three of the four linguistic families supposedly affected by neolithic demic diffusion; the Afroasiatic family is the exception. Many such gradients are not observed when populations are jointly analyzed, regardless of linguistic classification. This is incompatible with the hypothesis that major cultural transformations in Eurasia (diffusion of related languages and spread of agriculture) took place without major demographic changes. The model of demic diffusion seems therefore to provide a mechanism explaining coevolution of linguistic and biological traits in much of the Old World. Archaeological, linguistic, and genetic evidence agree in suggesting a multidirectional process of gene flow from the Near East in the neolithic. However, the possibility should be envisaged that some allele frequency patterns can predate the neolithic and depend on the initial spread of Homo sapiens sapiens from Africa into Eurasia. © 1994 Wiley-Liss, Inc.     

Factor affecting body mass of young fat dormics (Glis glis) at weaning and by hibernation

This paper describes the factors affecting body mass at weaning and by hibernation of young fat dormice (Glis glis) We studied a free-living population in 1991 and 1992 in a mixed forest where 100 nest-boxes were placed. In the two years, 128 females used the nest-boxes to give birth and rear their litters and more than 900 dormice have been individually marked. Body mass of young at weaning was positively correlated to body mass of the mother in both years and to birth date in 1991, while litter size was negatively correlated to body mass of the young in 1992 only, when birth took place about two weeks later than in 1991. On the contrary, by the time of hibernation, young born later weighed significantly less than those born earlier in the season, and heavier young at weaning remained heavier by hibernation, while maternal body mass and litter size did not significantly affect body mass of young at this stage. Body mass of the mother was negatively related to the date of parturition and early breeding females lost weight during lactation, while females that bred later did not. It seems, therefore, that early breeding carries a cost that only females in good condition can afford. It appears that females may follow two strategies: those in poor body condition will delay pregnancy so that lactation occurs when environmental feeding conditions are at their best; those in good condition will breed earlier, since they can afford to lose weight during lactation. Their young will have more time to grow before hibernation and the mothers themselves will have a longer period of time for restoring their fat reserves.     

Genetic similarity in long-eared owl communal winter roosts: a DNA fingerprinting study

The long-eared owl is a nocturnal predator which winters communally and breeds in the same areas in loose colonies during the spring. We tested the hypothesis that roosts, particularly stable roosts, are formed by close relatives, a condition under which group-related behaviours such as information sharing or helping at nest are more likely to be developed. DNA fingerprinting analysis was used to examine genetic similarity within and between two long-eared owl populations, one wintering in a traditional roost and the other in an unstable roost, and both breeding around their roosting sites. Although genetic similarity within roosts was higher than that between roosts, the difference was not significant. Observed genetic similarity within roosts was smaller than that reported in the bird species whose roosts work as information centres. On the other hand, the presence of some closely related individuals in the roost and behavioural observations suggest that co-operation between kin might have occurred, at least in one of the two study sites.     

Maternal predator‐exposure affects offspring size at birth but not telomere length in a live‐bearing fish

The perception of predation risk could affect prey phenotype both within and between generations (via parental effects). The response to predation risk could involve modifications in physiology, morphology, and behavior and can ultimately affect long‐term fitness. Among the possible modifications mediated by the exposure to predation risk, telomere length could be a proxy for investigating the response to predation risk both within and between generations, as telomeres can be significantly affected by environmental stress. Maternal exposure to the perception of predation risk can affect a variety of offspring traits but the effect on offspring telomere length has never been experimentally tested. Using a live‐bearing fish, the guppy (Poecilia reticulata), we tested if the perceived risk of predation could affect the telomere length of adult females directly and that of their offspring with a balanced experimental setup that allowed us to control for both maternal and paternal contribution. We exposed female guppies to the perception of predation risk during gestation using a combination of both visual and chemical cues and we then measured female telomere length after the exposure period. Maternal effects mediated by the exposure to predation risk were measured on offspring telomere length and body size at birth. Contrary to our predictions, we did not find a significant effect of predation‐exposure neither on female nor on offspring telomere length, but females exposed to predation risk produced smaller offspring at birth. We discuss the possible explanations for our findings and advocate for further research on telomere dynamics in ectotherms.     

Exercise training in childhood-onset systemic lupus erythematosus: a controlled randomized trial

Introduction

Exercise training has emerged as a promising therapeutic strategy to counteract physical dysfunction in adult systemic lupus erythematosus. However, no longitudinal studies have evaluated the effects of an exercise training program in childhood-onset systemic lupus erythematosus (C-SLE) patients. The objective was to evaluate the safety and the efficacy of a supervised aerobic training program in improving the cardiorespiratory capacity in C-SLE patients.

Methods

Nineteen physically inactive C-SLE patients were randomly assigned into two groups: trained (TR, n = 10, supervised moderate-intensity aerobic exercise program) and non-trained (NT, n = 9). Gender-, body mass index (BMI)- and age-matched healthy children were recruited as controls (C, n = 10) for baseline (PRE) measurements only. C-SLE patients were assessed at PRE and after 12 weeks of training (POST). Main measurements included exercise tolerance and cardiorespiratory measurements in response to a maximal exercise (that is, peak VO₂, chronotropic reserve (CR), and the heart rate recovery (ΔHRR) (that is, the difference between HR at peak exercise and at both the first (ΔHRR1) and second (ΔHRR2) minutes of recovery after exercise).

Results

The C-SLE NT patients did not present changes in any of the cardiorespiratory parameters at POST (P > 0.05). In contrast, the exercise training program was effective in promoting significant increases in time-to-exhaustion (P = 0.01; ES = 1.07), peak speed (P = 0.01; ES = 1.08), peak VO₂ (P = 0.04; ES = 0.86), CR (P = 0.06; ES = 0.83), and in ΔHRR1 and ΔHRR2 (P = 0.003; ES = 1.29 and P = 0.0008; ES = 1.36, respectively) in the C-SLE TR when compared with the NT group. Moreover, cardiorespiratory parameters were comparable between C-SLE TR patients and C subjects after the exercise training intervention, as evidenced by the ANOVA analysis (P > 0.05, TR vs. C). SLEDAI-2K scores remained stable throughout the study.

Conclusion

A 3-month aerobic exercise training was safe and capable of ameliorating the cardiorespiratory capacity and the autonomic function in C-SLE patients.

Trial registration

NCT01515163.     

Pattern of inbreeding depression,condition dependence,and additive genetic variance in Trinidadian guppy ejaculate traits

In polyandrous species, a male's reproductive success depends on his fertilization capability and traits enhancing competitive fertilization success will be under strong, directional selection. This leads to the prediction that these traits should show stronger condition dependence and larger genetic variance than other traits subject to weaker or stabilizing selection. While empirical evidence of condition dependence in postcopulatory traits is increasing, the comparison between sexually selected and ‘control’ traits is often based on untested assumption concerning the different strength of selection acting on these traits. Furthermore, information on selection in the past is essential, as both condition dependence and genetic variance of a trait are likely to be influenced by the pattern of selection acting historically on it. Using the guppy (Poecilia reticulata), a livebearing fish with high levels of multiple paternity, we performed three independent experiments on three ejaculate quality traits, sperm number, velocity, and size, which have been previously shown to be subject to strong, intermediate, and weak directional postcopulatory selection, respectively. First, we conducted an inbreeding experiment to determine the pattern of selection in the past. Second, we used a diet restriction experiment to estimate their level of condition dependence. Third, we used a half‐sib/full‐sib mating design to estimate the coefficients of additive genetic variance (CV_A) underlying these traits. Additionally, using a simulated predator evasion test, we showed that both inbreeding and diet restriction significantly reduced condition. According to predictions, sperm number showed higher inbreeding depression, stronger condition dependence, and larger CV_A than sperm velocity and sperm size. The lack of significant genetic correlation between sperm number and velocity suggests that the former may respond to selection independently one from other ejaculate quality traits. Finally, the association between sperm number and condition suggests that this trait may mediate the genetic benefits of polyandry which have been shown in this species.     

Automated Entire Thrombus Density Measurements for Robust and Comprehensive Thrombus Characterization in Patients with Acute Ischemic Stroke

Background and Purpose

In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim was first to introduce an automated method to assess the entire thrombus density and then to compare the measured entire thrombus density with respect to current standard manual measurements.

Materials and Method

In 135 AIS patients, the density distribution of the entire thrombus was determined. Density distributions were described using medians, interquartile ranges (IQR), kurtosis, and skewedness. Differences between the median of entire thrombus measurements and commonly applied manual measurements using 3 regions of interest were determined using linear regression.

Results

Density distributions varied considerably with medians ranging from 20.0 to 62.8 HU and IQRs ranging from 9.3 to 55.8 HU. The average median of the thrombus density distributions (43.5 ± 10.2 HU) was lower than the manual assessment (49.6 ± 8.0 HU) (p<0.05). The difference between manual measurements and median density of entire thrombus decreased with increasing density (r = 0.64; p<0.05), revealing relatively higher manual measurements for low density thrombi such that manual density measurement tend overestimates the real thrombus density.

Conclusions

Automatic measurements of the full thrombus expose a wide variety of thrombi density distribution, which is not grasped with currently used manual measurement. Furthermore, discrimination of low and high density thrombi is improved with the automated method.