scholarly journals Prolonged diapause has sex-specific fertility and fitness costs

2019 ◽  
Vol 34 (1) ◽  
pp. 41-57 ◽  
Author(s):  
Aigi Margus ◽  
Leena Lindström
Keyword(s):  
Stress Tolerance ◽  
Adult Survival ◽  
Fitness Costs ◽  
Older Parents ◽  
Development Times ◽  
Risk Spreading ◽  
The Difference ◽  
Prolonged Diapause ◽  
Breeding Seasons ◽  
Diapause Duration

AbstractDiapause in seasonal environments allows insects to survive adverse seasons. However, individuals can sometimes enter a prolonged diapause for more than a year, and also skip favourable seasons, which can bring additional costs through e.g. loss of metabolic resources. At the same time, prolonged diapause can be beneficial if it allows individuals to have a risk-spreading strategy to skip potentially suboptimal breeding seasons. We studied if prolonged diapause (2-year diapause) negatively affects the fertility and fitness of female and male Colorado potato beetles (Leptinotarsa decemlineata) compared to control (1-year diapause) beetles. We also tested the parental effects on the subsequent chemical stress tolerance of their offspring. We found that prolonged diapause carried fertility costs only for females who were less fertile than the control females. However, no differences in fertility were observed in males. Furthermore, prolonged diapause in females resulted in offspring with lower larvae-to-adult survival even though these offspring had accelerated development times. In contrast, paternal diapause duration had no effects on their offspring larvae-to adult survival, but prolonged diapause males sired offspring with slower development times than control males. Perhaps to compensate the costs related to prolonged diapause both older parents produced or sired offspring with higher body mass than control parents. Despite the differences in emergence mass, parental diapause duration did not affect offspring insecticide stress tolerance. The difference between females and males most likely results from the observed differences in prolonged diapause females’ capacity to fight against cellular oxidative damage which was poorer compared to the control females. Even though prolonged diapause allows individuals to have a risk-spreading strategy it carries sex-specific fertility and fitness costs indicating that selection could favour this in males but not in females.

scholarly journals OPPOSITION TO INBREEDING AMONG CLOSE KIN

2018 ◽  
Author(s):  
Jan Antfolk ◽  
Debra Lieberman ◽  
Christopher Harju ◽  
Anna Albrecht ◽  
Andreas Mokros ◽  
...  
Keyword(s):  
Inclusive Fitness ◽  
Large Population ◽  
Self Regulation ◽  
Family Members ◽  
Indirect Costs ◽  
Population Based ◽  
Fitness Costs ◽  
Inclusive Fitness Theory ◽  
The Difference ◽  
Close Relatives

Due to the intense selection pressure against inbreeding, humans are expected to possess psychological adaptations that regulate mate choice and avoid inbreeding. From a gene’s-eye perspective, there is little difference in the evolutionary costs between situations where an individual him/herself is participating in inbreeding and inbreeding among other close relatives. The difference is merely quantitative, as fitness can be compromised via both routes. The question is whether humans are sensitive to the direct as well as indirect costs of inbreeding. Using responses from a large population-based sample (27,364 responses from 2,353 participants), we found that human motivations to avoid inbreeding closely track the theoretical costs of inbreeding as predicted by inclusive-fitness theory. Participants were asked to select in a forced choice paradigm, which of two acts of inbreeding with actual family members they would want to avoid most. We found that the estimated fitness costs explained 83.6% of participant choices. Importantly, fitness costs explained choices also when the self was not involved. We conclude that humans intuit the indirect fitness costs of mating decisions made by close family members and that psychological inbreeding avoidance mechanisms extend beyond self-regulation.

scholarly journals Associations of parental age with offspring all-cause and cause-specific adult mortality

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
David Carslake ◽  
Per Tynelius ◽  
Gerard J. van den Berg ◽  
George Davey Smith
Keyword(s):  
Adult Mortality ◽  
Paternal Age ◽  
Adult Survival ◽  
Parental Age ◽  
Offspring Survival ◽  
Older Parents ◽  
Childhood Environment ◽  
Sibling Comparison ◽  
Common Causes

AbstractPeople are having children later in life. The consequences for offspring adult survival have been little studied due to the need for long follow-up linked to parental data and most research has considered offspring survival only in early life. We used Swedish registry data to examine all-cause and cause-specific adult mortality (293,470 deaths among 5,204,433 people, followed up to a maximum of 80 years old) in relation to parental age. For most common causes of death adult survival was improved in the offspring of older parents (HR for all-cause survival was 0.96 (95% CI: 0.96, 0.97) and 0.98 (0.97, 0.98) per five years of maternal and paternal age, respectively). The childhood environment provided by older parents may more than compensate for any physiological disadvantages. Within-family analyses suggested stronger benefits of advanced parental age. This emphasises the importance of secular trends; a parent’s later children were born into a wealthier, healthier world. Sibling-comparison analyses can best assess individual family planning choices, but our results suggested a vulnerability to selection bias when there is extensive censoring. We consider the numerous causal and non-causal mechanisms which can link parental age and offspring survival, and the difficulty of separating them with currently available data.

The role of blood intake in density regulation of populations of Triatoma infestans (Klug) (Hemiptera: Reduviidae)

1982 ◽  
Vol 72 (4) ◽  
pp. 617-629 ◽  
Author(s):  
C. J. Schofield
Keyword(s):  
Population Density ◽  
Triatoma Infestans ◽  
Female Fecundity ◽  
Density Regulation ◽  
Dependent Relationship ◽  
Development Times ◽  
Different Temperatures ◽  
Development Processes ◽  
The Difference

AbstractThe growth of populations of Triatoma infestans (Klug) depends on temperature and blood-intake. Experiments are described which demonstrated the density-dependent relationship between population size, blood intake and population growth at different temperatures. The number of bugs feeding and their mean blood intake was lower at high bug densities than at low ones, both with restrained chickens and with unrestrained mice as hosts. When blood intake was restricted, the development times of all nymphal stages were increased, and female fecundity was decreased. Previous work showed also that reduced blood intake led to an increased tendency for adult flight. It is thought that at high bug density the three factors, increased development times, decreased fecundity and increased flight, operate to restore the population to a stable density without promoting an increase in mortality. The mechanism linking population density to nutritional status seemed to depend on host irritability, which interrupted the bugs' feeding. Bugs which passed a certain threshold meal size would not resume feeding if interrupted, even though their blood intake was well below normal. The difference between the minimal threshold meal and a normal meal is thought to provide the nutritional elasticity within which the development processes are regulated. It is suggested that this mechanism is characteristic of K-strategists, whereas r–strategists such as mosquitoes tend to continue attacking, even if interrupted, until they achieve a normal meal.

scholarly journals Winter temperature predicts prolonged diapause in pine processionary moth species across their geographic range

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6530 ◽  
Author(s):  
Md H.R. Salman ◽  
Carmelo P. Bonsignore ◽  
Ahmed El Alaoui El Fels ◽  
Folco Giomi ◽  
José A. Hodar ◽  
...  
Keyword(s):  
Geographic Range ◽  
Winter Temperature ◽  
Thaumetopoea Pityocampa ◽  
Mortality Factors ◽  
Pine Processionary Moth ◽  
Adverse Conditions ◽  
Thermal Range ◽  
Risk Spreading ◽  
Prolonged Diapause ◽  
Diapause Incidence

Prolonged diapause occurs in a number of insects and is interpreted as a way to evade adverse conditions. The winter pine processionary moths (Thaumetopoea pityocampa and Th. wilkinsoni) are important pests of pines and cedars in the Mediterranean region. They are typically univoltine, with larvae feeding across the winter, pupating in spring in the soil and emerging as adults in summer. Pupae may, however, enter a prolonged diapause with adults emerging one or more years later. We tested the effect of variation in winter temperature on the incidence of prolonged diapause, using a total of 64 individual datasets related to insect cohorts over the period 1964–2015 for 36 sites in seven countries, covering most of the geographic range of both species. We found high variation in prolonged diapause incidence over their ranges. At both lower and upper ends of the thermal range in winter, prolonged diapause tended to be higher than at intermediate temperatures. Prolonged diapause may represent a risk-spreading strategy to mitigate climate uncertainty, although it may increase individual mortality because of a longer exposure to mortality factors such as predation, parasitism, diseases or energy depletion. Climate change, and in particular the increase of winter temperature, may reduce the incidence of prolonged diapause in colder regions whereas it may increase it in warmer ones, with consequences for population dynamics.

scholarly journals Breeding-Season Decisions, Renesting, and Annual Fecundity of Female Eastern Meadowlarks (Sturnella Magna) in Southeastern Illinois

The Auk ◽  
2004 ◽  
Vol 121 (3) ◽  
pp. 796-805 ◽  
Author(s):  
Eric L. Kershner ◽  
Jeffery W. Walk ◽  
Richard E. Warner
Keyword(s):  
Site Selection ◽  
Population Biology ◽  
Nest Site ◽  
Adult Survival ◽  
Demographic Parameter ◽  
Site Characteristics ◽  
Sturnella Magna ◽  
Double Brooding ◽  
Selection For ◽  
Breeding Seasons

Abstract Annual fecundity is a demographic parameter that is elemental to population biology, but accurate measures of fecundity are rarely obtained. We used radiotelemetry to follow female Eastern Meadowlarks (Sturnella magna) throughout the 1999-2000 breeding seasons in southeastern Illinois to estimate their annual fecundity and assess if the outcome of initial nesting attempts affected site selection for subsequent nests. Thirty-four females built 52 nests (1.53 ± 0.12 nests female−1), but only 21 females (62%) fledged young. Only 44% of females renested at the study site, and more females (53%) emigrated after successfully fledging young from an initial nest than after failing in their first attempt (21%). Nest-site characteristics were similar between successful and failed nests for both initial and subsequent attempts. Females that failed during first attempts did not change nest characteristics for renests. Given that few females were double-brooded and that unsuccessful females did not persistently renest, annual fecundity for females nesting at the study site was between 1.27 ± 0.38 and 1.36 ± 0.37 female young year−1. On the basis of our fecundity measure, we estimated that annual adult survival of 59–61% was necessary for maintenance of a stable population (λ = 1.0). Failure of most females to attempt to raise two broods suggests that double brooding carries substantial costs for meadowlarks.

scholarly journals Pleiotropy of adaptive changes in populations: comparisons among insecticide resistance genes in Culex pipiens

1997 ◽  
Vol 70 (3) ◽  
pp. 195-204 ◽  
Author(s):  
CHRISTINE CHEVILLON ◽  
DENIS BOURGUET ◽  
FRANÇOIS ROUSSET ◽  
NICOLE PASTEUR ◽  
MICHEL RAYMOND
Keyword(s):  
Resistance Genes ◽  
Culex Pipiens ◽  
Pleiotropic Effect ◽  
Adult Survival ◽  
Fitness Costs ◽  
Adaptive Changes ◽  
Repeated Sampling ◽  
The Impact ◽  
Insecticide Control ◽  
Convenient Model

Resistance to toxicants is a convenient model for investigating whether adaptive changes are associated with pleiotropic fitness costs. Despite the voluminous literature devoted to this subject, intraspecific comparisons among toxicant resistance genes are rare. We report here results on the pleiotropic effect on adult survival of Culex pipiens mutants involved in the same adaptation: the resistance to organophosphorus insecticides. This field study was performed in southern France where four resistance genes sequentially appeared and increased in frequency in response to intense insecticide control. By repeated sampling of overwintering females through winter, we analysed the impact of each of three resistance genes on adult survival. We showed that (i) the most recent gene seems to be of no disadvantage during winter, (ii) the oldest affects survival in some environmental conditions, and (iii) the third induces a constant, severe and dominant survival cost. Such variability is discussed in relation to the physiological changes involved in resistance.

scholarly journals Proposed power transmission lines in Cambodia constitute a significant new threat to the largest population of the Critically Endangered Bengal floricanHoubaropsis bengalensis

Oryx ◽  
2016 ◽  
Vol 52 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Simon P. Mahood ◽  
João P. Silva ◽  
Paul M. Dolman ◽  
Robert J. Burnside
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Survival Rates ◽  
Critically Endangered ◽  
Adult Survival ◽  
Power Transmission Lines ◽  
Migration Routes ◽  
Tonle Sap ◽  
Using Data ◽  
Breeding Seasons

AbstractThe remaining Indochina population of the Critically Endangered Bengal floricanHoubaropsis bengalensisbreeds in the floodplain of Cambodia's Tonle Sap Lake. The population has declined substantially but survival rates have not been published previously. Survival could potentially be reduced by the planned construction of high-tension power transmission lines that may begin in 2016. Using data from 17 individuals monitored by satellite transmitters over 4 years we estimated the annual adult survival rate to be 89.9% (95% CI 82.2–97.6%), which is comparable to that of other bustards. Interrogation of movement paths revealed that for the 13 individuals for which we had sufficient data for non-breeding seasons, all annual migration routes between breeding and non-breeding areas crossed the proposed route of the transmission line. The route also impinged on the margins of one important and one minor breeding concentration. A review of bustard collision rates confirmed the vulnerability of bustards to power lines, and the proposed development therefore presents an additional threat to the future of this species in Indochina.

scholarly journals Demography of Brown-Headed Cowbirds at Delta Marsh, Manitoba

The Auk ◽  
2001 ◽  
Vol 118 (1) ◽  
pp. 156-166 ◽  
Author(s):  
Bonnie E. Woolfenden ◽  
H. Lisle Gibbs ◽  
Spencer G. Sealy
Keyword(s):  
Sex Ratio ◽  
Site Fidelity ◽  
Breeding Site ◽  
Adult Survival ◽  
Parameter Estimates ◽  
Delta Marsh ◽  
The Social ◽  
Biased Sex Ratio ◽  
Breeding Seasons

Abstract Available estimates of demographic parameters for Brown-headed Cowbirds (Molothrus ater) vary geographically. However, few estimates are based on long-term studies of marked individuals. We conducted a mark–recapture study on the population of cowbirds at Delta Marsh, Manitoba during the 1993–1998 breeding seasons. We estimated annual survival, breeding site fidelity, and sex ratio, and compared those parameter estimates to other populations of Brown-headed Cowbirds. The Delta Marsh population had higher adult survival (male 90.1%; female 69.6%) and breeding site fidelity (males 66.9%, female 59.5%) than reported for other populations, and the sex ratio was significantly different from unity (1.9 males:1 female). We suggest that differences in survival and breeding-site fidelity between the Delta Marsh population and others may be due to differences in methods used to calculate parameter estimates. In contrast, variation in sex ratios is likely real and due to differences in the local ecological conditions. In our population, high survivorship and breeding-site fidelity may lead to low recruitment of new birds into the resident population and intense competition for limited breeding opportunities. The highly male biased sex ratio may result in strong sexual-selection pressure on males competing for the limited breeding opportunities. Those circumstances have implications for the social behavior and mating system of cowbirds.

Stomatal conductance as a screen for osmotic stress tolerance in durum wheat growing in saline soil

2010 ◽  
Vol 37 (3) ◽  
pp. 255 ◽  
Author(s):  
Afrasyab Rahnama ◽  
Richard A. James ◽  
Kazem Poustini ◽  
Rana Munns
Keyword(s):  
Stomatal Conductance ◽  
Osmotic Stress ◽  
Durum Wheat ◽  
Stress Tolerance ◽  
Triticum Turgidum ◽  
Genotypic Variation ◽  
Relative Size ◽  
Shoot Biomass ◽  
Osmotic Stress Tolerance ◽  
The Difference

The change in stomatal conductance measured soon after durum wheat (Triticum turgidum ssp. durum Desf.) was exposed to salinity was verified as an indicator of osmotic stress tolerance. It was a reliable and useful screening technique for identifying genotypic variation. The minimum NaCl treatment needed to obtain a significant stomatal response was 50 mM, but 150 mM was needed to obtain significant differences between genotypes. The response to the NaCl was osmotic rather than Na+-specific. Stomatal conductance responded similarly to iso-osmotic concentrations of KCl and NaCl, both in the speed and extent of closure, and in the difference between genotypes. The new reduced rate of stomatal conductance in response to addition of 50 mM NaCl or KCl occurred within 45 min, and was independent of the concentration of Na+ in leaves. The difference between genotypes was long-lasting, translating into differences in shoot biomass and tiller number after a month. These results indicate that the relative size of the change in stomatal conductance when the salinity is introduced could be a means of screening for osmotic stress tolerance in wheat and other cereals.

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