To ensure results were not an artifact of curtailing men’s later potential reproductive lifespan, all tests were rerun, dropping men who had not yet reached their fifty-fifth birthday . The majority of the sample are ethnic Pimbwe, but a small percentage are Fipa, Rungwe, Konongo, or other related ethnicities represented in the Rukwa Valley; the few Sukuma families with houses in the village were dropped because of their very different family system . Variables used in the analysis were sex, number of spouses over the lifetime, age , number of live births, and the number of offspring surviving to five years of age, beyond which mortality is low. Speed of remarriage was estimated in two ways: the mean interval between marriages and the interval of time since last divorce or widowing to the latest census or death , coded according to whether or not a remarriage had occurred . To examine spousal age differences the dataset was restructured as independent marriages ; a much smaller sample of these marriages also had data on the age of the replaced spouse at death or divorce.The predictions generated by the view of serial monogamy as polygyny found little consistent support in this study . First, there is no evidence that men are less likely to have ever married than women. Second,pot legs variance in reproductive success is not statistically significantly higher for men than women. Looking only at married individuals, men do indeed marry more spouses over their lifetimes than do women.

Results for the speed of remarriage after a widowing or divorce are inconsistent; the average waiting period between a divorce is no shorter for men than women, but in the most recent intermarriage interval men replace their spouses more rapidly than do women, with women delaying longer as they age. Furthermore, while men marry wives who are younger than themselves , the more precise prediction that they replace those wives with relatively younger women is not supported . Since the sex ratio is very close to unity, these results suggest more than simple demographic constraint. Finally, there is no evidence that men benefit from multiple marriages more than do women; in fact, the beneficiaries of third and higher-order marriages are women. Severe limitations to the current analyses must be acknowledged. It would be analytically much cleaner to look at the probability of bearing a child, or the probability of raising a child to age five, as a function of the marital status of the parents. Currently, overall reproductive performance is analyzed simply in relation to the number of spouses married over the lifetime. Furthermore, the findings do not take into account the marital status of the spouse. It is tempting to think that women who have married many husbands are married to men who have had many wives, but this is not necessarily the case given the structure of the sample. Finally empirical analyses of economic performance will be far preferable to reported work ethic, although for the families I know well these rankings were very accurate. The findings, while illuminating, are therefore not conclusive. New work with a larger dataset that includes currently reproductive women and analyzes production of children per year suggests a similar pattern . Regarding fitness variances, it is clear that sex differences are not pronounced. Men show greater variance in fertility than women, at least in the sample of individuals who had reached their forty-fifth birthday. After excluding men who had not yet passed their fifty-fifth birthday the statistical significance disappears, suggesting a cohort effect, namely that it is younger men who are showing higher sex-specific variance in fertility.

Furthermore in both samples the number of children surviving to age five is not significantly different between the two sexes, suggesting that men with very high fertility successfully raise few of these “extra” children. Recent theoretical work demonstrates that secure conclusions about the operation of sexual selection cannot be drawn from observations about sex differences in variance. This is because variation can arise from random, non-heritable factors . Much more important for our understanding of reproductive strategy is the relationship between breeding success and physiological or behavioral phenotypes , and therefore we turn to partner number. A key finding here is that while men do not benefit from multiple marriages, women do . Although the data are very variable , women appear to gain more from multiple mating than do men. Furthermore, results from the ranking exercise indicate that the men who engage in many marriages tend to be “lazy” workers and “heavy” drinkers, whereas the women who marry multiple times tend to be “hard” workers. These findings raise two questions. First, what parallel evidence do we have for other populations, human or nonhuman, and second, what are the possible explanations? Regarding parallel evidence, I know of no cases in which males fail to benefit from multiple serial mates; the Pimbwe case is therefore unique . For females the number of reproductive partners is associated with fitness in sex-role-reversed and other species, as discussed in the section on behavioral ecology above, reflecting either direct contributions to the protection and nutrition of offspring or possibly indirect benefits arising from female choice for high-quality males. In humans there are indications from South American “partible paternity” cultures that children born with “secondary” fathers have higher survival rates than children born without “secondary” fathers—for example, among the Bari and the Ache , an effect attributed to the gifts and protection the co-fathers provide. Overall effects of multiple paternity on a woman’s fitness are not known, although modeling suggests such systems might thrive at in populations with female-biased sex ratios , not apparently characteristic of the Pimbwe population.

In terms of more typical marriage systems, women’s second marriages are much less productive than their first marriages , such that there is no net benefit of multiple marriages to women. Forsberg and Tullberg’s study of modern Sweden shows a fitness benefit to men of serial marriages but also concludes that there are no reproductive benefits of remarriage to women. Rather amazingly, I could find no evidence in the demographic, sociological, or economic literature on how divorce affects women’s overall fitness in other Western populations; it is simply assumed that the reduced period at risk dominates any selection effects such as non-marital fertility . Recent data from the Indian Khasi suggest that women in second marriages have shorter inter birth intervals than women in first marriages, although it is unclear how much of this effect is attributable to the fact that most women in second marriages are not living with their mothers ; furthermore, the implications for the overall fitness of women in multiple versus single marriages are not examined. In short, the reproductive benefit of multiple marriages to women requires much further empirical scrutiny. The remaining question then is why do Pimbwe men and women mate multiply? One possibility is that multiple marriages result from male coercion.Insofar as high-order marriages are common among the heavy drinking and slack working men in Mpimbwe,plastic plant pots these men’s multiple marriages might reflect an associated lax socio sexual lifestyle. Nevertheless, men in multiple marriages do not father more children, so unless all such pregnancies end up in miscarriage, this is unlikely to be the sole route to multiple marriage. Ethnographic observations drawn from household surveys suggest that lazy and heavy-drinking men are often divorced and end up marrying post reproductive women, often for economic support in raising their dependent children. Their multiple marriages may therefore, rather counterintuitively, reflect a parental rather than a mating strategy, although who exactly marries these men remains a puzzle. Why might women marry multiply in Mpimbwe? The host of hypotheses in the literature can be separated into direct and indirect benefits. With respect to direct benefits, women may mate with and marry multiple men to obtain the resources needed to support reproduction. This explanation seems quite plausible in that women can benefit from the farming activities of men, as well as from the products of their hunting, fishing, honey production, and other enterprises. Men’s provisioning activities are highly unpredictable, in part because of poor farming conditions and in part because of the current illegality of utilizing many natural resources . Given the potentially high inter- and intra-individual variability in men’s provisioning abilities it is quite possible that women switch mates to maximize economic income, the “musical chairs” hypothesis reviewed by Choudhury . These findings for the Pimbwe suggest parallels with Schuster’s “new women of Lusaka,” who marry and remarry in search of supportive husbands, as well as Malawian women who use sexual relations to negotiate dependencies somewhat akin to patron-client relationships . Similar arguments have been made for the instability of marriages among the poor in the contemporary USA . There are also some similarities with baboons, among which serial if nonexclusive pair bonds produce temporary male protectors for mothers .

The idea here then is that hardworking women have higher mate-choice standards and do not put up with lower-quality mates. However, without further analysis of the economic data, and of the initiation of divorce, it is not yet possible to determine the validity of this explanation. Furthermore, it is somewhat odd that the women who marry more than two times are for the most part very hardworking and presumably relatively economically independent; for them the marginal benefits of men’s contributions would be lowest, suggesting the need to consider indirect benefits. As regards indirect benefits, numerous mechanisms have been proposed . The most plausible in this context is the idea that a woman can afford to forgo the benefits of paternal care for mates with high genetic potential. This argument has been made most forcefully for humans by Gangestad and Simpson , and it is particularly plausible in environments with high disease loads where demonstration of heritable fitness is so important . In support of this explanation is the fact that the division of Mpimbwe is beset by all of the health problems typical of rural tropical Africa and minimal health care infrastructure. In addition, it is the economically autonomous women who appear to be most concerned with potential genetic quality. On the other hand, female choice for indirect benefits is usually associated with polygyny insofar as males with heritable resistance to disease are differentially attractive to females. If choice for good genes were the explanation in this population we would expect a correlation between a man’s number of partners and fitness, which we do not find. Indeed, indirect benefits could only be driving polyandry if pathogen evolution is rapid, such that there is no single “best” male, or if mate choice is self-referential, such that there are many “best” males .Strawberry is an important soft fruit crop that is grown worldwide on more than 370 000 hectares and, for the United States alone, the total value of the annual strawberry production exceeds US$2.3 billion . Strawberries are beneficial to the human diet as a source of macro- and micro-nutrients, vitamins and health promoting antioxidants . Strawberry is a perennial herbaceous plant with short stems and densely spaced leaves. Strawberry produces complex accessory and aggregate fruit composed of achenes and a receptacle . Achenes are small single-seeded fruit, whereas the receptacle is considered to be anatomically equivalent to floral meristem tissue . F. × ananassa is an allo-octoploid that originated as a synthetic hybrid between the octoploid species Fragaria chiloensis and Fragaria virginiana . Strawberry is affected by several pathogens including fungi, bacteria, viruses and nematodes. The most economically impactful pathogens of strawberry are fungi, which can infect all parts of the plant and cause severe damage or death . Amongst the fungal pathogens, the ascomycete Botrytis cinerea is considered the primary pathogen of harvested strawberries in the world leading to impactful economical losses to the strawberry industry. B. cinerea causes grey mould in fruit and senescing organs but can also affect vegetative tissues . Under wet conditions, more than 80% of strawberry flowers and fruits can be lost if plants are not sprayed with fungicides .B. cinerea has no apparent host specificity and can infect more than 1000 plant species . The pathogen is found worldwide and causes disease in many fruit, flower and leafy vegetable crops . B. cinerea is classified as a necrotroph, meaning that it prefers to infect and grow on damaged or senescing tissues, eventually causing tissue death.