The impact of self-reported oligo-amenorrhea and hirsutism on fertility and lifetime reproductive success: results from the Northern Finland Birth Cohort 1966

SUMMARYThe impact of haematozoan infection on host fitness has received substantial attention since Hamilton and Zuk posited that parasites are important drivers of sexual selection. However, short-term studies testing the assumption that these parasites consistently reduce host fitness in the wild have produced contradictory results. To address this complex issue, we conducted a long-term study examining the relationship between naturally occurring infection withHaemoproteusandPlasmodium, and lifetime reproductive success and survival of Mountain White-crowned Sparrows. Specifically, we tested the hypothesis that birds infected with haematozoan parasites have reduced survival (as determined by overwinter return rates) and reproductive success. Contrary to expectation, there was no relationship betweenHaemoproteusandPlasmodiuminfection and reproduction or survival in males, nor was there a relationship betweenPlasmodiuminfection and reproduction in females. Interestingly,Haemoproteus-infected females had significantly higher overwinter return rates and these females fledged more than twice as many chicks during their lifetimes as did uninfected females. We discuss the impact of parasitic infections on host fitness in light of these findings and suggest that, in the case of less virulent pathogens, investment in excessive immune defence may decrease lifetime reproduction.

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The impact of parental investment on lifetime reproductive success in Iceland

PeerJ ◽

10.7717/peerj.2904 ◽

2017 ◽

Vol 5 ◽

pp. e2904 ◽

Cited By ~ 2

Author(s):

Robert F. Lynch ◽

Emily C. Lynch

Keyword(s):

Reproductive Success ◽

Parental Investment ◽

Genetic Data ◽

Lifetime Reproductive Success ◽

Narrow Sense ◽

Narrow Sense Heritability ◽

Full Sibling ◽

Close Relatives ◽

The Impact ◽

The Relationship

BackgroundDemonstrating the impact that parents have on the fitness of their children is a crucial step towards understanding how parental investment has affected human evolution. Parents not only transfer genes to their children, they also influence their environments. By analyzing reproductive patterns within and between different categories of close relatives, this study provides insight into the genetic and environmental effects that parents have on the fitness of their offspring.MethodsWe use data spanning over two centuries from an exceptionally accurate Icelandic genealogy, Íslendingabók, to analyze the relationship between the fertility rates of close relatives. Also, using genetic data, we determine narrow sense heritability estimates (h2) to further explore the genetic impact on lifetime reproductive success. Finally, we construct four simulations to model the expected contribution of genes and resources on reproductive success.ResultsThe relationship between the reproduction of all full sibling pairs was significant and positive across all birth decades (r = 0.19) while the reproductive relationship between parents and offspring was often negative across many decades and undetectable overall (r = 0.00) (Fig. 1 and Table 1). Meanwhile, genetic data among 8,456 pairs of full siblings revealed a narrow sense heritability estimate (h2) of 0.00 for lifetime reproductive success. A resources model (following the rule that resources are transmitted from parents to children, distributed equally among siblings, and are the only factor affecting reproductive success) revealed a similar trend: a negative relationship between parent and offspring reproduction (r = − 0.35) but a positive relationship among full siblings (r = 0.28). The relationship between parent and offspring lifetime reproductive success (LRS) and full sibling LRS was strongly and positively correlated across time (r = 0.799,p < 0.001). Similarly, the LRS among full siblings was positively correlated with both the LRS among half siblings (r = 0.532,p = 0.011) and the relationship between the LRS of aunts and uncles with their nieces and nephews (r = 0.438,p = 0.042).DiscussionWe show that an individual’s lifetime reproductive success is best predicted by the reproduction of their full and half siblings, but not their parents, grandparents or aunts and uncles. Because all siblings share at least one parent, we believe parental investment has had an important impact on fitness. Overall, these results indicate that direct parental investment, but not genes, is likely to have had an important and persistent impact on lifetime reproductive success across more than two centuries of Icelandic history.

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Peer Review #1 of "The impact of parental investment on lifetime reproductive success in Iceland (v0.2)"

10.7287/peerj.2904v0.2/reviews/1 ◽

2017 ◽

Keyword(s):

Reproductive Success ◽

Peer Review ◽

Parental Investment ◽

Lifetime Reproductive Success ◽

The Impact

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Forest management effects on survival of a long-lived bird

10.32942/osf.io/fnbj7 ◽

2019 ◽

Author(s):

Paul James Haverkamp ◽

Julian Klein ◽

Michael Griesser

Keyword(s):

Life History ◽

Forest Management ◽

Reproductive Success ◽

Boreal Forests ◽

Late Onset ◽

Life History Evolution ◽

Lifetime Reproductive Success ◽

High Exposure ◽

Natural Landscapes ◽

The Impact

1.A high number of reproductive events is a critical fitness correlate for long-lived species. Thus, individuals of these species should be sensitive to factors that increase their mortality. Living in habitats with high exposure to predators can decrease lifespan, but the ecological drivers of longevity within populations remain poorly studied. Forest management in boreal forests can increase the predation risk by creating edges and open forests, which facilitate prey detection for visual hunters.2.We assessed the impact of forest structure on breeding lifespan and lifetime reproductive success on a population of Siberian jays (Perisoreus infaustus) in northern Sweden located in managed and natural landscapes. 3.We used survival analyses to assess the influence of life history and ecological correlates on lifespan after attaining breeder status. The analyses included N=133 individuals within 38 territories in the managed landscape, and N=74 individuals within 25 territories in the natural landscape. The same correlates were used to investigate influences on the number of surviving offspring, as a measure of lifetime reproductive success.4.Breeder lifespan was longest when individuals attained breeder status at an older age, in territories with dense understory, and few linear edges and natural openings, which reduce the risk of detection by primary predators (accipiter hawks). Moreover, a late onset of reproduction was associated with a higher lifetime reproductive success. Remarkably, these effects were only found in the managed landscape. 5.These results suggest that forestry shapes risk gradients in landscapes that particularly affect individuals that begin to breed at an earlier age. Thus, experience may be more critical to survive in managed than natural landscapes, making populations less resilient to disturbance and affecting life history evolution.

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