Factors Limiting Reproductive Performance and Nestling Sex Ratio in the Lesser Spotted EagleAquila pomarinaat the Northern Limit of Its Range: the Impact of Weather and Prey Abundance

2012 ◽  
Vol 47 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Ülo Väli
Keyword(s):  
Sex Ratio ◽  
Reproductive Performance ◽  
Prey Abundance ◽  
Northern Limit ◽  
The Impact

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

scholarly journals The impact of sex ratio and economic status on local birth rates

2013 ◽  
Vol 9 (2) ◽  
pp. 20130027 ◽  
Author(s):  
A. Chipman ◽  
E. Morrison
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Economic Status ◽  
Life History Strategy ◽  
Reproductive Behaviour ◽  
Female Competition ◽  
Birth Rates ◽  
Economically Deprived ◽  
Human Mating ◽  
The Impact

Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female–female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

Akodon molinae (Rodentia Cricetidae), a new laboratory animal: breeding, management and reproductive performance

1980 ◽  
Vol 14 (2) ◽  
pp. 129-131 ◽  
Author(s):  
Maria Susana Merani ◽  
Marta Susana Lizarralde
Keyword(s):  
Sex Ratio ◽  
Reproductive Performance ◽  
Sexual Maturity ◽  
Laboratory Animal ◽  
Post Partum ◽  
Animal Breeding ◽  
Haemorrhagic Fever ◽  
Sex Ratio At Birth ◽  
Breeding Management ◽  
Laboratory Colony

Akodon molinae, a vole mouse widely distributed in central Argentina, shows remarkable chromosome polymorphisms. It is one of the natural reservoirs of the actiologic agent of haemorrhagic fever, and a laboratory colony could be of great help in investigating this disease. Pregnancy lasted 23 (range 21-25) days. Litters of 4-5 young were born to monogamous breeding pairs about every 30 days, with weaning at 26 days post partum. The sex ratio at birth was 505 males to 500 females: at weaning it was 460 to 440. Sexual maturity was attained at about 16 weeks of age in males and 12-20 weeks in females. Akodon molinae is easy to handle, but fighting and killing or neglect of young are problems.

128 Differences in PRRSV Resilience for Reproductive Performance Between Landrace and Duroc Sows

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 18-19
Author(s):  
Felipe Hickmann ◽  
José Braccini Neto ◽  
Luke M Kramer ◽  
Kent A Gray ◽  
Yijian Huang ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Mixed Model ◽  
Performance Data ◽  
The Other ◽  
Wild Type ◽  
Prrs Virus ◽  
The Difference ◽  
The Impact

Abstract Studies on differences in resilience to porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) between breeds are scarce in the literature. Thus, the objective of this work was to assess PRRSV resilience in PRRSV wild-type infected sows from two breeds. Farrowing data included 2546 and 2522 litters from 894 Duroc and 813 Landrace sows, respectively, which were housed together and experienced the same PRRSV outbreak. Traits used for this study were number of piglets born alive (NBA), number born dead (NBD), total number born (TNB), and number weaned (NW). The impact of PRRSV infection was evaluated by comparing the reproductive performance of breeds between PRRS phases (pre-PRRS, PRRS, and post-PRRS). PRRS phases were defined based on the reproductive performance data. NBA, NBD, and NW were analyzed as a proportion of TNB using a Poisson mixed model. Pre-defined contrasts were used to evaluate the effect of breed on PRRSV resilience and on return to PRRSV-free performance, representing the differences between breeds for the difference between pre-PRRS and PRRS phases, and pre-PRRS and post-PRRS phases, respectively. There was a significant (P ≤ 0.003) interaction between PRRS phase and breed for all traits, as shown in Table 1. In general, reproductive performance reduced from pre-PRRS to PRRS, and then increased from PRRS to post-PRRS, as expected. The resilience contrast was significant for all traits (P ≤ 0.003). In all cases, the drop in percent reproductive performance from pre-PRRS to PRRS was lower for Duroc than for Landrace, indicating that Duroc sows have greater PRRSV resilience than Landrace sows. The return to PRRSV-free performance contrast had a trending effect for NBD (P = 0.055), and it was not significant for the other traits (P ≥ 0.515). These results indicate that Duroc sows have overall greater phenotypic PRRSV resilience for reproductive performance than Landrace sows.

The impact of dietary protein:carbohydrate balance on lifespan and reproduction in Protaetia brevitarsis (Coleoptera: Scarabaeidae: Cetoniinae)

2021 ◽  
pp. 1-8
Author(s):  
S.-H. Kim ◽  
H. Park ◽  
W. Kim ◽  
J.-H. Song ◽  
S.J. Roh ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Egg Production ◽  
Detailed Knowledge ◽  
Reproductive Senescence ◽  
Egg Hatchability ◽  
Edible Insect ◽  
Age Related ◽  
Medicinal Value ◽  
Egg Production Rate ◽  
The Impact

The establishment of efficient and sustainable production of industrially important insects necessitates the detailed knowledge of the optimal mixture of macronutrients required for maximising their performance and fitness. The white spotted flower chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae: Cetoniinae), is one of the most important edible insects in East Asia with high nutritional and medicinal value. Here, we report how the ratio of protein to digestible carbohydrate (P:C) in the diet influenced lifespan and reproductive performance in the adults of P. brevitarsis. Throughout their lifespan, beetles were fed ad libitum one of five diets with differing P:C ratio (0:1, 3:7, 1:1, 7:3, 1:0). Both lifespan and the number of eggs produced over the lifetime were maximised at the P:C ratio of 3:7 and declined as the ratio deviated away from this optimal P:C composition. Beetles fed a diet containing only protein (P:C 1:0) not only had the shortest lifespan but also exhibited substantially reduced lifetime egg production compared to those fed the other diets. However, the effects of dietary P:C ratio on daily egg production rate and egg hatchability were marginal. The number of eggs produced at each age stage peaked at the age of week 2 and then gradually declined with increasing age, showing the sign of reproductive senescence. Age-specific egg production was higher in beetles confined to three intermediate P:C ratios (3:7, 1:1, 7:3) than those confined to two extreme P:C ratios (0:1, 1:0) throughout their lifespan. The speed of age-related decrease in reproductive performance was the slowest at P:C 3:7. Our data have implications for optimising the production of this edible insect with emerging economic importance.

scholarly journals The density of females of Palmistichus elaeisis Delvare and LaSalle (Hymenoptera: Eulophidae) affects their reproductive performance on pupae of Bombyx mori L. (Lepidoptera: Bombycidae)

2010 ◽  
Vol 82 (2) ◽  
pp. 323-331 ◽  
Author(s):  
Fabricio F. Pereira ◽  
José C. Zanuncio ◽  
José E. Serrão ◽  
Teresinha V. Zanuncio ◽  
Dirceu Pratissoli ◽  
...  
Keyword(s):  
Life Cycle ◽  
Relative Humidity ◽  
Sex Ratio ◽  
Bombyx Mori ◽  
Reproductive Performance ◽  
Climatic Chamber ◽  
Glass Tubes ◽  
Bombyx Mori L

Palmistichus elaeisis Delvare and LaSalle (Hymenoptera: Eulophidae) is a gregarious and polyphagous parasitoid mainly of Lepidoptera pupae. The objective of this paper as to study the developent of parasitoid on Bombyx mori L. (Lepidoptera: Bombycidae) pupae exposed to one, nine, 18, 27, 36, 45 or 54 female P. elaeisis, respectively. The females of the parasitoid remained in contact with pupae for 24 hours in glass tubes (14.0 x 2.2 cm), packed in a climatic chamber regulated at 25 ± 2°C, 70 ± 10% relative humidity and photo phase of 12 hours. With the exception of density 1:1 (72.72%), in other densities parasitism was 100%. Adults of P. elaeisis did not emerge from pupae at densities of 1:1 and 9:1, but 100.0% of parasitoid emergence was observed at the density of 45:1 and 54.54% at 54:1. The duration of the life cycle of this parasitoid ranged from 20 to 28 days. P. elaeisis produced 49 to 589 descendants per pupa of B. mori. The sex ratio of P. elaeisis ranged from 0.93 ± 0.01 to 0.97 ± 0.01 without differences with 18, 27, 36, 45 and 54 females/host. This parasitoid should be reared with the density of 45 females per pupa of B. mori.

Cumulative reproductive performance effect on overall lifetime productivity in Merino sheep

2018 ◽  
Vol 58 (8) ◽  
pp. 1470
Author(s):  
J. S. Richards ◽  
M. A. Sladek ◽  
G. J. Lee
Keyword(s):  
Reproductive Performance ◽  
New South ◽  
Dental Health ◽  
Age Groups ◽  
The South ◽  
Performance Effect ◽  
South West ◽  
South Wales ◽  
The Impact ◽  
Effect Of Age

Reproduction is an important driver of profitability in commercial sheep flocks. Historically, Merino flocks have been run with a fixed age structure, ignoring individual merit and casting for age at a specific age. More recently, research has focussed on utilising the variation within age groups by keeping productive older ewes longer and culling less productive ewes earlier. Previous studies have also examined the effect of age on reproduction and the impact of reproduction status on productivity, but little research has been conducted on cumulative effects of reproductive performance on later productivity, reproduction and health. The present study examined the impact of higher lifetime reproduction on other key production and fitness traits in older ewes run under commercial conditions. Data were collected from two commercial wool-producing properties in the South West Slopes and the Central West Plains of New South Wales during 2009–2011. Reproduction, fleece measurements, bodyweight and condition and dental health were recorded during the study. The results showed that age had a bigger effect on productivity and dental health than did cumulative lifetime reproduction. Environment and genetics determined the level of impact, with minimal loss in productivity from increased age of animals occurring in the South West Slopes flock, whereas the Central West Plains flock would appear to require closer monitoring of productivity as ewes aged. The data collected did not allow separation of the genetic and environmental influences within the study. Retaining animals with a higher reproductive performance past normal culling age does not necessarily result in reduction of productivity or ewe health, but this must be monitored.

scholarly journals Sexual dimorphism in a top predator ( Notophthalmus viridescens ) drives aquatic prey community assembly

2018 ◽  
Vol 285 (1890) ◽  
pp. 20181717 ◽  
Author(s):  
Denon Start ◽  
Stephen De Lisle
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Intraspecific Variation ◽  
Structure And Function ◽  
Sexually Dimorphic ◽  
Ecological Communities ◽  
Top Predator ◽  
Aquatic Mesocosms ◽  
And Function ◽  
The Impact

Intraspecific variation can have important consequences for the structure and function of ecological communities, and serves to link community ecology to evolutionary processes. Differences between the sexes are an overwhelmingly common form of intraspecific variation, but its community-level consequences have never been experimentally investigated. Here, we manipulate the sex ratio of a sexually dimorphic predacious newt in aquatic mesocosms, then track their impact on prey communities. Female and male newts preferentially forage in the benthic and pelagic zones, respectively, causing corresponding reductions in prey abundances in those habitats. Sex ratio differences also explained a large proportion (33%) of differences in the composition of entire pond communities. Ultimately, we demonstrate the impact of known patterns of sexual dimorphism in a predator on its prey, uncovering overlooked links between evolutionary adaptation and the structure of contemporary communities. Given the extreme prevalence of sexual dimorphism, we argue that the independent evolution of the sexes will often have important consequences for ecological communities.

Long-term reproductive patterns and sighting bias in Weddell seals (Leptonychotes weddelli)

1987 ◽  
Vol 65 (5) ◽  
pp. 1091-1099 ◽  
Author(s):  
J. Ward Testa
Keyword(s):  
Reproductive Performance ◽  
Age At First Reproduction ◽  
Reproductive Patterns ◽  
Weddell Seals ◽  
Signy Island ◽  
First Reproduction ◽  
Reproductive Rates ◽  
The Cost ◽  
The Impact

The reproductive performance of tagged Weddell seals (Leptonychotes weddelli) was monitored at McMurdo Sound, Antarctica, from 1970 to 1984. An age-specific reproductive schedule revealed the major onset of pupping at age 6 years, and a mean age of first birth of 7.1 years. The average asymptotic pupping rate of 0.61 is reached by age 10. The cost of pupping in a given year is reflected in a 0.05 drop in the probability of pupping the following year. This cost is not evident in females over 7 years old, suggesting that postweaning condition affects newly mature females more than those that are fully mature. Annual adult reproductive rates ranged from 0.46 to 0.79, with a possible periodicity of 5 to 6 years. Simulations were conducted to determine the impact on reproductive estimates of sighting biases associated with seals having had at least one pup (Parous) or having pupped that season (With-Pup). Age at first reproduction as deduced from an age-specific pupping schedule is strongly affected by both forms of sighting bias, but bias in sighting Parous females was the more important. Estimates of adult reproduction were affected minimally. Comparisons of reproductive estimates with those of Weddell seals at Signy Island are discussed with regard to the effects of sighting biases.

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