scholarly journals Does differential mortality after parental investment affect sex ratio evolution? No

Evolution ◽  
2021 ◽  
Author(s):  
Alistair Pirrie ◽  
Ben Ashby
Keyword(s):  
Sex Ratio ◽  
Parental Investment ◽  
Differential Mortality

Sex ratios of Sitodiplosis mosellana (Diptera: Cecidomyiidae): implications for pest management in wheat (Poaceae)

2004 ◽  
Vol 94 (6) ◽  
pp. 569-575 ◽  
Author(s):  
M.A.H. Smith ◽  
I.L. Wise ◽  
R.J. Lamb
Keyword(s):  
Life Cycle ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Adult Emergence ◽  
Differential Mortality ◽  
Sitodiplosis Mosellana ◽  
Single Sex ◽  
Crop Resistance ◽  
Wheat Midge ◽  
Population Average

AbstractSex ratios of populations of the wheat midge Sitodiplosis mosellana Géhin, developing on wheat Triticum aestivum L., were determined at reproduction, adult emergence, and dispersal. The patterns of sex ratio through the life cycle of S. mosellana result from: (i) a genetic mechanism that causes all or nearly all of the progeny of individual females to be a single sex, with an overall sex ratio that is slightly biased at 54–57% females; (ii) a differential mortality during diapause that increases the sex ratio to 60–65% females; (iii) mating which occurs near the emergence site followed by female dispersal which causes the post-dispersal sex ratio to rise to nearly 100% females; and (iv) oviposition which spreads eggs among different plants and assures that the next generation has a local sex ratio close to the population average. These changes in sex ratio through the life cycle have implications for using crop resistance or pheromones to manage S. mosellana, because mating takes place quickly near emergence sites, and because mated females but not males disperse from emergence sites to oviposition sites. Crop refuges used to protect resistance genes against the evolution of virulence by S. mosellana must be interspersed to prevent assortative mating that would occur in separate blocks of resistant and susceptible plants. Monitoring or mating disruption using a pheromone would be ineffective when wheat is grown in rotation with a non-host crop.

scholarly journals Population traits of the burrowing toad Rhinella fernandezae (Gallardo, 1957) (Anura, Bufonidae)

2008 ◽  
Vol 68 (1) ◽  
pp. 137-140 ◽  
Author(s):  
LC. Sanchez ◽  
M. Busch
Keyword(s):  
Sex Ratio ◽  
Size Distribution ◽  
Total Population ◽  
Buenos Aires ◽  
The Other ◽  
Differential Mortality ◽  
Buenos Aires Province ◽  
Country House

Size distribution, sex ratio and use of burrows of the burrowing toad Rhinella fernandezae were studied in Buenos Aires province, Argentina. Two sites separated by approximately 300 m were studied: one was a road next to a swamp, and the other a garden of a country house located further from the swamp. We identified toad burrows, and individuals were sexed, measured and given an individual mark. Burrows were examined in subsequent months after the first sampling to assess the presence of toads. We found significant differences in the size distribution between areas, being the proportion of juveniles greater at the site next to the swamp where the reproduction of the species was observed. This result may suggest that the site located near to the swamp functions as a source habitat of individuals that migrate to the other site, where recruitment would be very scarce. Sex proportion of adults did not differ from 1:1 in neither the total population nor in each site, suggesting that there was not differential mortality by sex. Some toads changed burrows throughout the study period, but there were not differences in the frequency of change between adults and juveniles.

EARLY DIFFERENTIAL MORTALITY IN NEODIPRION SERTIFER (HYMENOPTERA: DIPRIONIDAE)

1974 ◽  
Vol 106 (1) ◽  
pp. 1-10 ◽  
Author(s):  
L. A. Lyons ◽  
C. R. Sullivan
Keyword(s):  
Sex Ratio ◽  
Larval Period ◽  
Differential Mortality ◽  
Neodiprion Sertifer ◽  
Primary Sex Ratio ◽  
Secondary Sex Ratio ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship ◽  
Early Larvae

AbstractIn Neodiprion sertifer (Geoff.), mortality is greater in males than in females in the egg stage and probably also among early larvae, but in the late larval period females are more susceptible. The evidence consists of the difference in mortality between all-male and mixed (male + female) colonies, as well as the relationship of secondary sex ratio to preceding mortality and the number of survivors per colony. The effect of differential mortality on estimation of the primary sex ratio is discussed.

Fetal sex ratio in relation to maternal mass and age in reindeer

1997 ◽  
Vol 75 (4) ◽  
pp. 648-650 ◽  
Author(s):  
Eigil Reimers ◽  
Dag Lenvik
Keyword(s):  
Natural Selection ◽  
Sex Ratio ◽  
Parental Investment ◽  
Similar Condition ◽  
Rangifer Tarandus ◽  
Good Condition ◽  
Maternal Condition ◽  
Fetal Sex ◽  
Poor Condition ◽  
Parental Ability

Theory suggests that a male in good condition at the end of the period of parental investment will outproduce a sister in similar condition, while she will outproduce him if both are in poor condition. Accordingly, natural selection should favor parental ability to adjust the sex ratio of offspring produced according to parental ability to invest. As maternal condition declines from good to poor, the fetal sex ratio should decline from a high proportion of males to a high proportion of females. Data from 1525 domestic reindeer (Rangifer tarandus) in six different herds slaughtered during December and January in 1976 through 1979 do not support a relationship between the sex of the fetus and either the condition of the mother or her age.

scholarly journals SEX RATIO AND PARENTAL INVESTMENT IN AN ANT POPULATION

Evolution ◽  
1981 ◽  
Vol 35 (6) ◽  
pp. 1252-1253 ◽  
Author(s):  
Adrian Forsyth
Keyword(s):  
Sex Ratio ◽  
Parental Investment

Sex Ratio and Differential Mortality between the Sexes

1970 ◽  
Vol 104 (936) ◽  
pp. 205-210 ◽  
Author(s):  
Egbert G. Leigh,
Keyword(s):  
Sex Ratio ◽  
Differential Mortality

scholarly journals Sex Ratio of Small Hive Beetles: The Role of Pupation and Adult Longevity

Insects ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 133 ◽  
Author(s):  
Anna Papach ◽  
Jérémy Gonthier ◽  
Geoffrey R. Williams ◽  
Peter Neumann
Keyword(s):  
Sex Ratio ◽  
Field Studies ◽  
Differential Mortality ◽  
Adult Longevity ◽  
Published Data ◽  
Larval Feeding ◽  
Intraspecific Interactions ◽  
Adult Sex Ratio ◽  
Biased Sex Ratio ◽  
Small Hive Beetles

The sex ratio of sexually reproducing animal species tends to be 1:1, which is known as Fisher’s principle. However, differential mortality and intraspecific competition during pupation can result in a biased adult sex ratio in insects. The female-biased sex ratio of small hive beetles (SHBs) is known from both laboratory and field studies, but the underlying reasons are not well understood. Here, we used laboratory mass and individual pupation to test if differential mortality between sexes and/or intraspecific interactions can explain this sex ratio. The data show a significant female-biased adult sex ratio in both mass and individual rearing, even when assuming that all dead individuals were males. Our results therefore suggest that neither differential mortality during pupation nor intraspecific interactions are likely to explain the female-biased sex ratio of freshly emerged adult SHBs. We regard it as more likely that either competition during the larval feeding stage or genetic mechanisms are involved. In addition, we compared our data with previously published data on the sex ratio of both freshly emerged and field-collected SHBs to investigate possible gender differences in adult longevity. The data show a significantly greater female bias in the sex ratio upon emergence, compared to field-collected SHBs, suggesting that adult females have a shorter longevity.

PARENTAL INVESTMENT THEORY AND BIRTH SEX RATIOS IN NEPAL

1997 ◽  
Vol 29 (3) ◽  
pp. 283-295 ◽  
Author(s):  
S. S. STRICKLAND ◽  
V. R. TUFFREY
Keyword(s):  
Sex Ratio ◽  
Social Status ◽  
Parental Investment ◽  
Economic Status ◽  
Farm Size ◽  
Live Births ◽  
Investment Theory ◽  
Proximate Factors ◽  
Parental Investment Theory ◽  
Biased Sex Ratio

Parental investment theory postulates that where physical condition varies significantly then birth sex ratio will be correlated with social status. Application of this theory to man remains contentious. This study examines physique, wealth, and social status in relation to the sex of live births. It reports a female-biased sex ratio in high social and economic status Nepalese. Close consanguineous marriage, intended to conserve landed wealth within related lineages, and increased female work burdens accompanying larger farm size, are proximate factors which may underlie this finding. A differential payback hypothesis is one way of explaining this pattern.

Unexpected offspring sex ratios in response to habitat quality in a size-dimorphic bark beetle

1999 ◽  
Vol 77 (4) ◽  
pp. 524-529 ◽  
Author(s):  
Risa D Sargent ◽  
Mary L Reid
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Habitat Quality ◽  
Bark Beetle ◽  
Sex Ratios ◽  
Diploid Species ◽  
Differential Mortality ◽  
Male Reproductive Success ◽  
Offspring Sex

Facultative sex ratio manipulation has been examined in a limited number of diploid species, mainly vertebrates. We tested the prediction that mothers would preferentially place males in conditions conducive to large size in the diploid pine engraver bark beetle, Ips pini. In this species, males are the larger sex and therefore male reproductive success was expected to be more dependent on body size than female reproductive success. Because body size is largely environmentally determined in bark beetles, mothers were expected to alter sex ratios in response to habitat quality. Contrary to predictions, offspring sex ratios tended to be more female biased in situations conducive to large offspring size than in situations producing offspring of small size. We were able to rule out nonadaptive explanations such as differential mortality or development times of males and females, suggesting that the observed pattern is adaptive. This study provides a rare example of sex ratio manipulation in diploid insects. However, the unexpected direction of sex ratio biases suggests that daughters gain a yet unknown benefit from being reared in high-quality conditions that surpasses the fitness that would be gained from producing relatively larger sons.

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