How to measure reproductive success?

To date there have been few empirical comparisons between alternative methods for measuring reproductive success (RS). We consider the pros and cons of alternative measures of RS to provide guidance for the design of field studies in human behavioral ecology. We compare cross-sectional measures that count offspring alive at the time of the interview and retrospective measures that require data on offspring age at death or censoring. We consider analyses that include adult women (yielding age-specific estimates of RS) as well as analyses restricted to postreproductive women (yielding data on lifetime RS). These methods are applied to reproductive data for the Dogon of Mali, West Africa. Am. J. Hum. Biol. 15:361–369, 2003. © 2003 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35101/1/10154_ftp.pd

Effects of cattle grazing and haying on wildlife conservation at National Wildlife Refuges in the United States

The National Wildlife Refuge System is perhaps the most important system of federal lands for protecting wildlife in the United States. Only at refuges has wildlife conservation been legislated to have higher priority than either recreational or commercial activities. Presently, private ranchers and farmers graze cattle on 981,954 ha and harvest hay on 12,021 ha at 123 National Wildlife Refuges. US Fish and Wildlife Service policy is to permit these uses primarily when needed to benefit refuge wildlife. To evaluate the success of this policy, I surveyed grassland management practices at the 123 refuges. The survey results indicate that in fiscal year 1980 there were 374,849 animal unit months (AUMs) of cattle grazing, or 41% more than was reported by the Fish and Wildlife Service. According to managers' opinions, 86 species of wildlife are positively affected and 82 are negatively affected by refuge cattle grazing or haying. However, quantitative field studies of the effect of cattle grazing and haying on wildlife coupled with the survey data on how refuge programs are implemented suggest that these activities are impeding the goal of wildlife conservation. Particular management problems uncovered by the survey include overgrazing of riparian habitats, wildlife mortality due to collisions with cattle fences, and mowing of migratory bird habitat during the breeding season. Managers reported that they spend $919,740 administering cattle grazing and haying; thus refuge grazing and haying programs are also expensive. At any single refuge these uses occupy up to 50% of refuge funds and 55% of staff time. In light of these results, prescribed burning may be a better wildlife management option than is either cattle grazing or haying.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48162/1/267_2005_Article_BF01867177.pd

The reproductive ecology of the Dogon of Mali.

Little is known about menstrual cycling in the noncontracepting populations characteristic of human evolutionary history. I report the results of a longitudinal investigation of menstrual cycling among the Dogon, a noncontracepting population of Mali. During menses Dogon women sleep at a menstrual hut. This custom permitted me to continuously monitor virtually all menstruations occurring in a village of 460 people over two years. I use data on menstrual cycling to address three questions about Dogon reproductive ecology: (1) Do women synchronize their menstrual cycles?, (2) What is the function of menstrual segregation?, and (3) What are the causes of variation in the waiting time to conception?. Tests for menstrual synchrony provide no evidence for this phenomenon among Dogon women. Neither the mean difference in menstrual onset dates for co-wife pairs, related pairs, or friend pairs differs significantly from that of age-matched random pairs. Moreover, the number of menstrual onsets per day is consistent with a Poisson distribution so the null hypothesis that women's menses occur at independent times cannot be rejected. These results caution against the assumption that menstrual synchrony is adaptive. Previous hypotheses on menstrual segregation appear to overlook the reproductive significance of menstrual huts. Among the Dogon, menstrual huts may promote confidence of paternity by enabling men to selectively marry women who have recently menstruated. This custom reduces their risk of marrying pregnant women. Given the prevalence of serial remarriage, this risk would otherwise be substantial. If the confidence of paternity hypothesis is correct, it supports the broader argument that the consideration of individual reproductive interests is helpful for understanding culture. From data on menstrual hut visitation, I calculated the waiting times to conception among Dogon women. Using hazard analysis, I then determined which variables are significantly associated with the elapsed time before a woman conceives. Conception waits are significantly associated with age, nursing status, marital duration, and gravidity. I found no evidence for a significant association between conception waits and the following: nutrition, economic status, polygyny, and the length or variability of menstrual cycles.Ph.D.Biological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105290/1/9116303.pdfDescription of 9116303.pdf : Restricted to UM users only

Some observations on the response of breeding birds to human disturbance.

http://deepblue.lib.umich.edu/bitstream/2027.42/53049/1/1482.pdfDescription of 1482.pdf : Access restricted to on-site users at the U-M Biological Station

Life-history theory, fertility and reproductive success in humans.

According to life-history theory, any organism that maximizes fitness will face a trade-off between female fertility and offspring survivorship. This trade-off has been demonstrated in a variety of species, but explicit tests in humans have found a positive linear relationship between fitness and fertility. The failure to demonstrate a maximum beyond which additional births cease to enhance fitness is potentially at odds with the view that human fertility behaviour is currently adaptive. Here we report, to our knowledge, the first clear evidence for the predicted nonlinear relationship between female fertility and reproductive success in a human population, the Dogon of Mali, West Africa. The predicted maximum reproductive success of 4.1+/-0.3 surviving offspring was attained at a fertility of 10.5 births. Eighty-three per cent of the women achieved a lifetime fertility level (7-13 births) for which the predicted mean reproductive success was within the confidence limits (3.4 to 4.8) for reproductive success at the optimal fertility level. Child mortality, rather than fertility, was the primary determinant of fitness. Since the Dogon people are farmers, our results do not support the assumptions that: (i) contemporary foragers behave more adaptively than agriculturalists, and (ii) that adaptive fertility behaviour ceased with the Neolithic revolution some 9000 years ago. We also present a new method that avoids common biases in measures of reproductive success

Risk factors for placental malaria, sulfadoxine-pyrimethamine doses, and birth outcomes in a rural to urban prospective cohort study on the Bandiagara Escarpment and Bamako, Mali

Abstract Background Malaria in Mali remains a primary cause of morbidity and mortality, with women at high risk during pregnancy for placental malaria (PM). Risk for PM and its association with birth outcomes was evaluated in a rural to urban longitudinal cohort on the Bandiagara Escarpment and the District of Bamako. Methods Placental samples (N = 317) were collected from 249 mothers who were participants in a prospective cohort study directed by BIS in the years 2011 to 2019. A placental pathologist and research assistant evaluated the samples by histology in blinded fashion to assess PM infection stage and parasite density. Generalized estimating equations (GEE) were used to model the odds of PM infection. Results In a multivariable model, pregnancies in Bamako, beyond secondary education, births in the rainy season (instead of the hot dry season), and births to women who had ≥ 3 doses of sulfadoxine-pyrimethamine (SP) instead of no doses were associated with reduced odds of experiencing PM (active and past infections combined). Births in later years of the study were strongly associated with reduced odds of PM. Maternal age, which was positively associated with offspring year of birth, was significant as a predictor of PM only if offspring year of birth was omitted from the model. Gravidity was positively associated with both maternal age and offspring year of birth such that if either variable was included in the model, then gravidity was no longer significant. However, if maternal age or year of offspring birth were not adjusted for, then the odds of PM were nearly two-fold higher in primigravida compared to multigravida. Birth outcomes improved (+ 285 g birth weight, + 2 cm birth length, + 75 g placental weight) for women who had ≥ 3 doses of SP compared to no doses, but no difference was detected in birth weight or length for women who had 2 instead of ≥ 3 SP doses. However, at 2 instead of ≥ 3 doses placentas were 36 g lighter and the odds of low birth weight ( 10% erythrocytes infected) were significantly associated with decreases in birth weight, birth length, and placental weight, as were chronic PM infections. The women who received no SP during pregnancy (7% of the study total) were younger and lacked primary school education. The women who received ≥ 3 doses of SP came from more affluent families. Conclusions Women who received no doses of SP during pregnancy experienced the most disadvantageous birth outcomes in both Bamako and on the Bandiagara Escarpment. Such women tended to be younger and to have had no primary school education. Targeting such women for antenatal care, which is the setting in which SP is most commonly administered in Mali, will have a more positive impact on public health than focusing on the increment from two to three doses of SP, although that increment is also desirable.http://deepblue.lib.umich.edu/bitstream/2027.42/173706/1/12936_2022_Article_4125.pd