Family first! Influence of parental investment in Guinea pigs (Cavia porcellus) prosocial choices.

Literature often assumed that prosocial behaviours (behaviours that benefit others with or without a cost for the actor) would have evolved many species to improve the effectiveness of parental care (Decety and Cowell 2014). While this hypothesis is rarely questioned at a phylogenetic scale, it was never tested at an individual scale to the best of our knowledge. Therefore, we chose to study the impact of effective parental care on prosociality by comparing the prosocial tendencies of Guinea pigs before mating, during mating and after parturition. We conducted Prosocial Choice Tests on three groups of Guinea pigs (males, multiparous females, and nulliparous females). Subjects had to choose between three options: a prosocial option (subject and recipient being rewarded), a selfish option (only subject was rewarded), and a null option (no reward). Our results showed high prosociality towards their mating partner and their young both in male and in female subjects. Males became selfish towards other males after parturition. Among other interesting results, we found a direct reciprocity phenomenon. We also highlighted an ability in our subjects to consider both the identity and relationship shared with the recipient, such as tolerance (enhancing prosociality), dominance rank (being tested with a dominant recipient increasing selfish responses), and its behaviour (begging calls eliciting prosociality, while threatening ones decreasing it), to choose an option. These findings suggested that prosociality could be modulated by many factors and that the constraints and stakes induced by breeding would highly influence prosocial strategies.

Post-copulatory sexual selection allows females to alleviate the fitness costs incurred when mating with senescing males.

Male senescence has detrimental effects on reproductive success and offspring fitness. When females mate with multiple males during the same reproductive bout, post-copulatory sexual selection that operates either through sperm competition or cryptic female choice might allow females to skew fertilization success towards young males and as such limit the fitness costs incurred when eggs are fertilized by senescing males. Here, we experimentally tested this hypothesis. We artificially inseminated female North African houbara bustards with sperm from dyads of males of different (young and old) or similar ages (either young or old). Then, we assessed whether siring success was biased towards young males and we measured several life-history traits of the progeny to evaluate the fitness costs due to advanced paternal age. In agreement with the prediction, we found that siring success was biased towards young males, and offspring sired by old males had impaired hatching success, growth and post-release survival (in females). Overall, our results support the hypothesis that post-copulatory sexual selection might represent an effective mechanism allowing females to avoid the fitness costs of fertilization by senescing partners.

Sperm competition accentuates selection on ejaculate attributes.

Ejaculate attributes are important factors driving the probability of fertilizing eggs. When females mate with several males, competition between sperm to fertilize eggs should accentuate selection on ejaculate attributes. We tested this hypothesis in the North African houbara bustard ( Chlamydotis undulata undulata) by comparing the strength of selection acting on two ejaculate attributes when sperm from single males or sperm from different males were used for insemination. In agreement with the prediction, we found that selection on ejaculate attributes was stronger when sperm of different males competed for egg fertilization. These findings provide the first direct comparison of the strength of selection acting on ejaculate attributes under competitive and non-competitive fertilizations, confirming that sperm competition is a major selective force driving the evolution of ejaculate characteristics.

Sexually extravagant males age more rapidly.

Evolutionary theories of ageing posit that increased reproductive investment occurs at the expense of physiological declines in later life. Males typically invest heavily in costly sexual ornaments and behaviour, but evidence that the expression of these traits can cause senescence is lacking. Long-lived houbara bustards (Chlamydotis undulata) engage in extravagant sexual displays to attract mates and here we show that males investing most in these displays experience a rapid senescent deterioration of spermatogenic function at a younger age. This effect is sufficiently large that the expected links between male 'showiness' and fertility reverse in later life, despite 'showy' males continuing to display at near maximal levels. We show that our results cannot be explained by the selective disappearance of competitive phenotypes and that they are instead consistent with an early vs. late life trade-off in male reproductive competence, highlighting the potential significance of sexual selection in explaining rates of ageing.

Influence of molt on plasma protein electrophoretic patterns in bar-headed geese (Anser indicus).

Plasma protein electrophoresis is recognized as a reliable diagnostic tool in avian medicine; however, the influence of circannual phenomena such as molt on protein electrophoregrams is poorly documented. The molt is a period of heavy hormonal and metabolic change in birds. The purpose of this study was to investigate the effects of molt on total protein concentration and electrophoresis patterns in birds. Blood samples were taken from 19 Bar-headed Geese (Anser indicus) from mid-May to mid-August, at 15-day intervals. At the same time, molting stage of each bird was recorded. Total protein concentrations were measured and plasma agarose gel electrophoresis was performed on these samples. The Bar-headed Goose was chosen as a model, because they molt over a very short period. The total protein concentration and albumin, alpha-2, beta, and gamma fractions were at their minimum values during molt, whereas the prealbumin and alpha-1 fractions rose to their maximum levels. This study provides baseline information relevant to changes occurring in avian proteinograms throughout the molt. The increase in prealbumin and alpha-1 fractions may be related to an increase in plasma thyroid hormones during molt. The decrease observed in albumin, alpha-2, beta, and gamma fractions may be related to protein and energy shifts toward feather growth, as well as to an expansion of the circulatory system located around the feather follicles with secondary dilutional effects on protein fractions. From a clinical point of view, the observed changes associated with molting were less significant than initially expected, and would not likely results in incorrect diagnoses based on interpretation of the protein electrophoretic patterns.

Identification of apolipoprotein A-I in the alpha-globulin fraction of avian plasma.

BACKGROUND: Plasma protein electrophoresis is frequently used in birds as a tool for the diagnosis and monitoring of disease. Identification of proteins in individual peaks can help improve our understanding of changes in protein concentration in physiologic and pathologic conditions. OBJECTIVE: The aim of this study was to verify the presence and identity the protein(s) in the prominent alpha-globulin peak of orange-winged parrots (Amazona amazonica), black kites (Milvus migrans), and rock pigeons (Columba livia). METHODS: Heparinized plasma samples were obtained from 12 birds of each species. Agarose gel electrophoresis and total protein concentration were determined using standard techniques. One plasma sample from each species was then electrophoresed using high-resolution agarose gels to isolate the alpha-globulin band. Gel strips were digested in trypsin and peptides were extracted and analyzed using liquid chromatography with tandem mass spectrometry. De novo sequencing was used to identify the protein based on homology scoring against a protein database. RESULTS: Electrophoresis verified the presence of a single prominent alpha-globulin peak, usually in the alpha(1)-region, that had a median concentration of 9.4 g/L (range, 2.1-11.7 g/L, 21.6% of total protein) in parrots, 12.2 g/L (10.4-13.2 g/L, 35.9%) in kites, and 10.7 g/L (9.0-11.5 g/L, 40.0%) in pigeons. Mass spectrometry and sequencing analysis unequivocally identified the protein as a mature circulating form of apolipoprotein A-I (apo A-I) in all 3 species. CONCLUSIONS: Apo A-I accounts for the prominent alpha-globulin peak and comprises a major proportion of total protein concentration in diverse avian species. As a high-density lipoprotein and negative acute phase protein with a pivotal role in cholesterol homeostasis, further study is warranted to determine the significance of changes in apo A-I concentration in avian electrophoretograms.

Effect of hemolysis on plasma protein levels and plasma electrophoresis in birds.

Protein electrophoresis is recognized as a reliable diagnostic tool for birds even though results are seldom pathognomonic. Unfortunately, this technique is underused in avian medicine because many factors interfere with electrophoresis patterns; hemolysis is one of these factors and is often associated with improper specimen handling. In human laboratory medicine, hemolysis is a known interference factor that can lead to erroneous results. Published data on the influence of hemolysis on protein electrophoresis in birds is currently restricted to a single study in Psittacidae. The aim of this study was to further investigate this effect and to analyze potential interspecific differences. Blood samples were drawn from 28 Black Kites (Milvus migrans) and 19 Bar-headed Geese (Anser indicus) and separated into two aliquots. One aliquot was dipped into liquid nitrogen for 5 sec in order to cause freeze-thawing hemolysis before centrifugation. Total plasma protein concentration, plasma hemoglobin concentration, and plasma protein electrophoresis patterns were determined for both hemolyzed and nonhemolyzed samples. In both species, hemolysis resulted in falsely elevated total plasma protein concentration. In Bar-headed Geese, hemolysis caused a rise in the gamma fraction. In Black Kites, this rise involved not only the gamma fraction but also the beta fraction, stressing the potential for species-related differences. In both species, the effects of hemolysis mimicked a chronic inflammatory condition with resulting antigenic stimulation.

Non-defendable resources affect peafowl lek organization: a male removal experiment.

A lekking mating system is typically thought to be non-resource based with male providing nothing to females but genes. However, males are thought to clump their display sites on areas where they are more likely to encounter females, which may depend on non-defendable resource location. We tested this hypothesis on a feral population of peacocks. In agreement, we found that, within the lek, display site proximity to food resources had an effect on female visitation rate and male mating success. The attractiveness of display sites to male intruders was explained by the distance to the feeding place and by the female visitation rate. We randomly removed 29 territorial males from their display sites. Display sites that were more attractive to male intruders before removal remained highly attractive after removal and display sites closer to the feeding area attracted the attention of intruders significantly more after removal. Similarly, display sites that were more visited by females before removal remained more visited after removal, suggesting again that the likelihood of encountering females is determined by the display site location. Overall, these results are in agreement with non-defendable resources affecting lek spatial organization in the peafowl.