Contrasting levels of extra-pair paternity in mainland and island populations of the house sparrow (Passer domesticus): is there an 'island effect'?

Despite the many studies that have investigated the genetic mating system of socially monogamous birds, very little is known about the underlying causes of extra-pair paternity and few studies have attempted to test those hypotheses which have been suggested. This study describes die analysis of die genetic mating system of two populations of the house sparrow [Passer domesticus) , and uses the results from four other populations to test existing hypodieses using an intra-specific comparative approach. The parentage analysis was conducted using a combination of published and newly presented microsatellite loci isolated from the house sparrow. One population in Kentucky, U.S.A. was found to contain what may be considered to be a typical level of extra-pair paternity for mis species (10.5%, 19/185 offspring). The second, a population on the island of Lundy, UK, exhibited a very low level (1.3%, 4/305 offspring), significandy lower dian that in all the other populations studied so far. The finding of such diverse rates of extra-pair paternity, along with the existing estimates from ofher populations, has allowed us to test the effects of breeding density and genetic variation on die level of extra-pair paternity. We found no effect of either factor on the frequency of extra-pair paternity in the house sparrow, leaving the cause of this variation open to fresh ideas.     

Industry calling! Is there a doctor in the house?

Medical service is needed in industry by both management and labor as never before. Industry is just beginning to awaken to this need. The medical profession is largely unaware of it. Unless physicians are prepared to heed this call, there is danger that management and labor will come to a bipartisan agreement over the bargaining table which will specify the amount, quality, and price of medical service irrespective of the effects of such an agreement on the practice of medicine. Such agreements should invariably be tripartite-between management, labor and medicine-if we are to continue to strive for medicine's traditional ideals: The best of medical care for all alike. This situation imposes at least two important obligations on organized medicine at the national level and especially at state and local levels where there is industrial concentration:1. Provision of a strong and competent committee or council whose members are especially interested in occupational medicine and who will make their presence known to management and labor alike, offering to advise with them on all medical problems, to mediate their disagreements or medical questions, and to help them attain a common goal.2. Assisting the members of organized medicine who are interested, to learn more about the medical problems peculiar to occupational health.     

Multiple paternity and postcopulatory sexual selection in a hermaphrodite: what influences sperm precedence in the garden snail Helix aspersa?

Sperm competition has been studied in many gonochoric animals but little is known about its occurrence in simultaneous hermaphrodites, especially in land snails. The reproductive behaviour of the land snail Helix aspersa involves several features, like multiple mating, long-term sperm storage and dart-shooting behaviour, which may promote sperm competition. Cryptic female choice may also occur through a spermatheca subdivided into tubules, which potentially allows compartmentalized sperm storage of successive mates. In order to determine the outcome of postcopulatory sexual selection in this species, we designed a cross-breeding experiment where a recipient ('female') mated with two sperm donors ('males'). Mates came from either the same population as the recipient or from a distinct one. To test for the influence a recipient can have on the paternity of its offspring, we excluded the effects of dart shooting by using only virgin snails as sperm donors because they do not shoot any dart before their first copulation. We measured the effects of size of mates as well as time to first and second mating on second mate sperm precedence (P2; established using microsatellite markers). Multiple paternity was detected in 62.5% of clutches and overall there was first-mate sperm precedence with a mean P2 of 0.24. Generalized linear modelling revealed that the best predictors of paternity were the time between matings and the time before first mating. Overall, both first and second mates that copulated quickly got greater parentage, which may suggest that postcopulatory events influence patterns of sperm precedence in the garden snail.     

Extrapair paternity and egg hatchability in tree swallows: evidence for the genetic compatibility hypothesis?

Tree swallows (Tachycineta bicolor) show one of the highestlevels of extrapair paternity in birds, and there is evidencethat females have control over who fathers their offspring.However, it is unclear which benefits female tree swallows obtainfrom mating with multiple males. Using microsatellite DNA fingerprinting,we studied extrapair paternity in relation to nesting successand male, female, and offspring characteristics. More than 70%of all nests contained extrapair young, and more than half ofall offspring were extrapair. Within broods, the extrapair youngwere often fathered by several males. Despite screening allresident and some floater males, we could identify the biologicalfather of only 21% of all extrapair offspring. All identifiedextrapair males were close neighbors. Extrapair males did notdiffer from within-pair males in any of the measured characteristics,except that the former had larger cloacal protuberances than thelatter. Extrapair males were equally successful in gaining paternityin their own broods as males that did not father extra young.In nests with mixed paternity, extrapair young did not differfrom within-pair young in body size or mass. However, nestswith extrapair young had higher hatching success than nestswithout extrapair young. All examined unhatched eggs were fertilizedand thus hatch failure resulted from embryo mortality. The availabledata are in accordance with the genetic diversity and the geneticcompatibility hypothesis, but not with the good genes hypothesis.     

Genetic paternity analyses in Little Owls (Athene noctua): does the high rate of paternal care select against extra-pair young?

Summary Previous studies have shown that extra-pair fertilizations are much less frequent in Non-Passeriformes, especially in raptors, than in Passeriformes. Low breeding densities, high breeding synchrony and high rates of paternal effort have been discussed as possible causes of these low extra-pair fertilization rates. Using DNA fingerprinting, we studied the mating system of Little Owls (Athene noctua) in a population of relatively high breeding density and comparatively low breeding synchrony. We found no cases of extra-pair fertilization among 53 nestlings of 16 breeding pairs. We conclude that paternal effort is probably the most important factor in preventing extra-pair fertilizations in Little Owls.

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Genetische Vaterschaftsanalysen bei Steinkäuzen (Athene noctua): Beeinflußt der hohe elterliche Aufwand der Männchen das Auftreten von Vaterschaften außerhalb des Paarbundes?

Zusammenfassung Zahlreiche Untersuchungen haben gezeigt, dass Befruchtungen außerhalb des Paarbundes bei Nicht-Singvogelarten wesentlich seltener vorkommen als bei Singvögeln. Dies gilt insbesondere auch für Greifvögel. Als Ursache für das seltene Auftreten von Befruchtungen außerhalb des Paarbundes in dieser Gruppe werden niedrige Brutpaardichten, eine hohe Brutsynchronisation und ein hoher elterlicher Aufwand auf Seiten der Männchen diskutiert. In der vorliegenden Studie haben wir das Paarungssystem des Steinkauzes (Athene noctua) in einer Population im Kreis Viersen (Niederrhein) mit Hilfe des DNA-Fingerprinting untersucht. Diese Population wies eine relativ hohe Brutpaardichte und eine vergleichsweise niedrige Brutsynchronisation auf. Bei der Analyse von 16 Bruten, die insgesamt 53 Nestlinge enthielten, konnte kein einziger Fall einer Befruchtung außerhalb des Paarbundes nachgewiesen werden. Dies führt uns zu dem Schluss, dass der wichtigste Faktor für die genetische Monogamie — zumindest beim Steinkauz — das hohe Maß des väterlichen Aufwandes bei der Brutversorgung ist.

     

Male infanticide and paternity analyses in a socially natural herd of Przewalski's horses: Sexual selection?

The sexual selection hypothesis explains infanticide by males in many mammals. In our 11-year study, we investigated this hypothesis in a herd of Przewalski's horses where we had witnessed infanticidal attacks. Infanticide was highly conditional and not simply linked to takeovers. Attacks occurred in only five of 39 cases following a takeover, and DNA paternity revealed that, although infanticidal stallions were not the genetic fathers in four cases out of five, stallions present at birth did not significantly attempt to kill unrelated foals. Infanticide did not reduce birth intervals; only in one case out of five was the infanticidal stallion, the father of the next foal; mothers whose foals were attacked subsequently avoided associating with infanticidal stallions. Therefore, evidence for the sexual selection hypothesis was weak. The “human disturbance” hypothesis received some support, as only zoo bred stallions which grew up in unnatural social groups attacked foals of mares which were pregnant during takeovers.     

Lipooxygenase inhibition in osteoarthritis: a potential symptomatic and disease modifying effect?

5-Loxin is a compound extracted from an ancient herb that might be considered as a potent lipooxygenase inhibitor. The results observed in a preliminary trial suggest a highly intriguing clinically relevant symptomatic effect contrasting with a poor bioavailability of this compound. Moreover, in this trial, a statistically significant decrease in matrix metalloproteinase enzyme serum level suggests that, in addition to the observed symptomatic effect, such a compound might have a disease modifying effect in osteoarthritis. Further studies are required both to confirm the symptomatic efficacy and acceptable safety profile and to evaluate the potential chondromodulating effect of this compound.     

High levels of multiple paternity in Littorina saxatilis: hedging the bets?

The mating system of a species can have great effects on its genetic structure and evolution. We studied the extent of multiple paternity in a gastropod with internal fertilization, the intertidal snail Littorina saxatilis. Paternal genotype reconstruction based on microsatellite markers was performed on the offspring of wild, naturally fertilized females from 2 populations. The numbers of males contributing to the offspring per female were among the highest detected in invertebrates so far, with the exception of social insects. No reproductive skew in favor of males that were genetically more distant from the females was detected, and the pattern of fertilization appeared random. The result fits a hypothesis of indiscriminate mating, with genetic bet hedging as the most likely explanation. Bet hedging may have evolved as a form of inbreeding avoidance, if the snails are not able to recognize relatives. However, nutritional benefits from sperm or sexual conflict with males are additional possibilities that remain to be assessed in this species. Whatever the causes, such high levels of multiple paternity are remarkable and are likely to have a large impact on population structure and dynamics in a species in which migration between populations is spurious.     

Coexistence and coevolution in fluctuating environments: can the storage effect evolve?

Both theoretical and empirical work have shown that the temporal storage effect can promote coexistence. However, the storage effect depends on temporally fluctuating demographic rates, such as interannually variable germination rates. Because variable demographic rates often reduce fitness, we asked how a storage effect might evolve. Using a model of competing annual plants, we find that variable germination (and hence a storage effect) can evolve only if germination is positively correlated with high-fecundity years (predictive germination) or if one species has limited ability to evolve. Outside of these conditions, the storage effect is evolutionarily unstable: if two species were thrown together with traits that would permit a storage effect, they would coevolve constant germination rates and the storage effect would vanish. Our results suggest that for the temporal storage effect to be widespread, either germination must commonly be positively correlated with later growth or fecundity or community assembly must reflect biogeographic processes more than they do coevolution.     

Genetic variation and structure of house sparrow populations: is there an island effect?

Population genetic structure and intrapopulation levels of genetic variation have important implications for population dynamics and evolutionary processes. Habitat fragmentation is one of the major threats to biodiversity. It leads to smaller population sizes and reduced gene flow between populations and will thus also affect genetic structure. We use a natural system of island and mainland populations of house sparrows along the coast of Norway to characterize the different population genetic properties of fragmented populations. We genotyped 636 individuals distributed across 14 populations at 15 microsatellite loci. The level of genetic differentiation was estimated using F‐statistics and specially designed Mantel tests were conducted to study the influence of population type (i.e. mainland or island) and geographic distance on the genetic population structure. Furthermore, the effects of population type, population size and latitude on the level of genetic variation within populations were examined. Our results suggest that genetic processes on islands and mainland differed in two important ways. First, the intrapopulation level of genetic variation tended to be lower and the occurrence of population bottlenecks more frequent on islands than the mainland. Second, although the general level of genetic differentiation was low to moderate, it was higher between island populations than between mainland populations. However, differentiation increased in mainland populations somewhat faster with geographical distance. These results suggest that population bottleneck events and genetic drift have been more important in shaping the genetic composition of island populations compared with populations on the mainland. Such knowledge is relevant for a better understanding of evolutionary processes and conservation of threatened populations.     

Is there a link between paternity concern and female genital cutting in West Africa?

Here we explore the relationship between female genital cutting (FGC), sexual behaviour, and marriage opportunities in five West African countries. Using large demographic datasets (n 72,438 women, 12,704 men, 10,695 couples) we explore key (but untested) assumptions of an evolutionary proposal that FGC persists because it provides evolutionary fitness benefits for men by reducing non-paternity rates. We identify and test three assumptions implicit in this proposal. We test whether cut women have reduced extra-pair sex before or within marriage; whether FGC is associated with a younger age at marriage as an indication of partner preference; and whether individual and group-level indicators of paternity concern are associated with a stronger preference for marriage to women with FGC.Our results show that FGC status does not affect the odds of women engaging in several indicators of premarital sex, however women with FGC have significantly lower odds of having more than one lifetime sexual partner. We also show that women with FGC get married at a younger age which supports the argument that FGC status influences women's marriage opportunities, even when it does not restrict sexual activity. Finally, we find that in population groups where reported sexual activity and perceived risk of women's extra-pair sex is high, men have higher odds of marrying a first wife with FGC. Together, these results indicate that paternity certainty may be one of several factors contributing to the persistence of FGC in this sample, and that group-level sexual norms are key to maintaining the practice of FGC through the marriage market.     

Indirect selection on female extra-pair reproduction? Comparing the additive genetic value of maternal half-sib extra-pair and within-pair offspring

One specific hypothesis explaining the evolution of extra-pair reproduction (EPR) by socially monogamous females is that EPR is under indirect selection because extra-pair offspring (EPO) sired by extra-pair males have higher additive genetic value for fitness than the within-pair offspring (WPO) a female would have produced had she solely mated with her socially paired male. This hypothesis has not been explicitly tested by comparing additive genetic value between EPO and the WPO they replaced. We show that the difference in additive genetic breeding value (BV) between EPO and the WPO they replaced is proportional to the genetic covariance between offspring fitness and male net paternity gain through EPR, and estimate this covariance with respect to offspring recruitment in free-living song sparrows (Melospiza melodia). Recruitment and net paternity gain showed non-zero additive genetic variance and heritability, and negative genetic covariance. Opposite to prediction, EPO therefore had lower BV for recruitment than the WPO they replaced. We thereby demonstrate an explicit quantitative genetic approach to testing the hypothesis that EPR allows polyandrous females to increase offspring additive genetic value, and suggest that there may be weak indirect selection against female EPR through reduced additive genetic value for recruitment of EPO versus WPO in song sparrows.     

Do male paternity guards ensure female fidelity in a duetting fairy-wren?

Most socially monogamous bird species engage in extra-pair mating,and consequently males may adopt various behavioral strategiesto guard paternity. However, the relationship between mate guardingand extra-pair paternity is unclear: low levels of extra-pairpaternity can be associated either with no mate guarding orwith intense mate guarding. We investigate paternity guardsin the purple-crowned fairy-wren (Malurus coronatus), a duettingspecies where extra-pair paternity is rare. This species isunusual in a genus known for extremely high levels of extra-pairmating. We examine the behavioral interactions between the sexesunderlying these low rates of extra-pair paternity and showthat male purple-crowned fairy-wrens do not use frequent copulationor courtship feeding to assure paternity or guard females acousticallyby duetting. Males maintain close proximity to females bothwhen they are fertile and when they are not breeding and donot invest in courtship displays to extra-pair females. Consistentwith predictions of theoretical models, low extra-pair paternityin this species may be related to female fidelity rather thanmale paternity assurance strategies, but short-term removalof males would be necessary to test this experimentally.     

Do changes in gene expression contribute to sexual isolation and reinforcement in the house mouse?

Expression divergence, rather than sequence divergence, has been shown to be important in speciation, particularly in the early stages of divergence of traits involved in reproductive isolation. In the two European subspecies of house mice, Mus musculus musculus and Mus musculus domesticus, earlier studies have demonstrated olfactory‐based assortative mate preference in populations close to their hybrid zone. It has been suggested that this behaviour evolved following the recent secondary contact between the two taxa (~3,000 years ago) in response to selection against hybridization. To test for a role of changes in gene expression in the observed behavioural shift, we conducted a RNA sequencing experiment on mouse vomeronasal organs. Key candidate genes for pheromone‐based subspecies recognition, the vomeronasal receptors, are expressed in these organs. Overall patterns of gene expression varied significantly between samples from the two subspecies, with a large number of differentially expressed genes between the two taxa. In contrast, only ~200 genes were found repeatedly differentially expressed between populations within M. m. musculus that did or did not display assortative mate preferences (close to or more distant from the hybrid zone, respectively), with an overrepresentation of genes belonging to vomeronasal receptor family 2. These receptors are known to play a key role in recognition of chemical cues that handle information about genetic identity. Interestingly, four of five of these differentially expressed receptors belong to the same phylogenetic cluster, suggesting specialization of a group of closely related receptors in the recognition of odorant signals that may allow subspecies recognition and assortative mating.     

Whom do the sparrows follow? The effect of kinship on social preference in house sparrow flocks

Non-aggressive social interactions between group-mates, e.g. maintenance of spatial proximity or activity synchrony are basic elements of a species’ social structure, and were found to be associated with important fitness consequences in group-living animals. In the establishment of such affiliative relationships, kinship has often been identified as one of the key predictors, but this has rarely been studied in simple social groups such as flocks of gregarious birds. In this study we investigated whether kinship affects social preference, as measured by the tendency to associate with others during various social activities, in captive house sparrow (Passer domesticus) flocks where birds could interact with differently related flock-mates. We found that preference between flock-mates was correlated with familiarity from early nestling period: same-brood siblings followed their sib initiating new activities more often than non-sib birds. The strength of association between birds also tended to correlate with genetic relatedness, but this was mainly due to the effect of siblings’ affiliation. Thus we concluded that house sparrows prefer the company of their siblings during social activities even well after fledging, which may facilitate kin-biased behaviours.     

Does the house mouse self-regulate its density in maturing sorghum and wheat crops?

1. One of the central questions in population ecology and management is: what regulates population growth? House mouse Mus domesticus L. populations erupt occasionally in grain-growing regions in Australia. This study aimed to determine whether mouse populations are self-regulated in maturing sorghum and wheat crops. This was assessed by examining food supply to mice (i.e. yield) and the relationship between initial mouse density (D(I)) and density at harvest (D(H)). Eight levels of D(I) ranging from 89 to 5555 mice ha(-1) were introduced to sorghum at the hard dough stage and to wheat crops at the milky stage in mouse-proofed pens. D(H) was measured by trapping out mice 49 days after the introduction. 2. There were at least 3.11 tonnes ha(-1) of wheat and 1.85 tonnes ha(-1) of sorghum grain available for mice at harvest. The estimated relationship between D(I) and D(H) was asymptotic exponential, with D(H) initially increasing almost linearly with D(I). When D(I) was above c. 500 mice ha(-1), D(H) increased asymptotically with D(I) and then saturated at c. 3100 mice ha(-1). The asymptotic increases in and saturation of D(H) was due partly to more young mice being born and recruited in pens treated with lower levels of D(I). 3. Our findings indicated that mouse densities in maturing cereal crops were driven by a numerical response of mice to the abundant supply of grain, modified by some unknown self-regulation mechanism that reduced this numerical response of mice at higher mouse densities. The mechanism was possibly spacing behaviours. Although the nature of this self-regulation mechanism is not known our model is, nevertheless, useful for predicting increases and eruptions in mouse population density in sorghum and wheat crops. Understanding the nature of this mechanism may provide insights into population processes that can be exploited in controlling mice in cereal crops.     

Male competition and paternity in wild chimpanzees of the Taï forest

In social animals, competition among males for mates affects individual reproductive success. The priority‐of‐access model attempts to account for the influence of demographic conditions within groups upon male reproductive success, but empirical data for testing this model are scarce. Our long‐term study of chimpanzees in the Taï National Park, Côte d'Ivoire, encompasses a period of steady decrease in community size and fluctuating numbers of competing males and sexually receptive females. These demographic changes, in combination with genetic assessment of paternity for 48 offspring from three communities, allowed us to quantify the effects of varying levels of competition upon male reproductive success. On average, the highest‐ranking male sired 50% of all analyzed offspring during a 14‐year period from 1987–2000. Competition among males strongly decreased the relative reproductive success of the alpha male, such that the alpha male's rate of success decreased from 67% with few competitors to only 38% with four or more competitors. The increasing number of synchronously receptive females in large groups also reduced the proportion of paternities by the alpha male. Thus, patterns of paternity in Taï chimpanzees fit well the predictions of the priority‐of‐access model. We also found that despite the inability of dominants to monopolize reproduction, they achieved a higher reproductive rate in large multimale groups, because these have more females and a higher infant survival rate. Varied levels of male competition within communities seem to explain differences in the reproductive success of alpha males observed in different chimpanzee populations, and in other primate species. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.