Egg Clutch Size Research Articles

Hybrids generated by crossing elite laying chickens exhibited heterosis for clutch and egg quality traits

Crossbreeding advantage in hybrids compared with their parents, termed heterosis, has been exhaustively exploited in chicken breeding over the last century. Reports for crossbreeding of elite laying chickens covering rearing and laying period remain infrequent. In this study, resource populations of Rhode Island Red (RIR) and White Leghorn (WL) pure-bred chickens were reciprocally crossed to generate 4 distinct groups that were evaluated for prelaying growth, egg production, and egg quality. Birds monitored for prelaying growth consists of 105 (RIR), 131 (WL), 207 (RIR × WL) and 229 (WL × RIR), and 30 pullets from each group were evaluated. Egg laying records were collected from 102, 89, 147, and 191 hens in the 4 populations, respectively. In addition, expression of 5 candidate genes for egg production in the ovarian follicles was measured by RT-qPCR. Results showed that BW of hatched chicks in the WL line was higher than the other populations. However, the 2 crossbreds grew faster than WL purebred throughout the prelaying period. Low to medium heterosis was observed for BW and body length before the onset of lay. White Leghorn and the hybrids commenced laying earlier than RIR pullets and egg production traits were favorable in the crossbreds compared with purebreds. Heterosis for egg number and clutch size was moderate in WL × RIR but low in RIR × WL hens. Expression of antimullerian hormone gene was high in WL and RIR × WL hybrids, suggesting WL parent-specific enhancing dominant expression. Shell weight was higher in the crossbreds than purebreds at 52 wk of age, but RIR hens laid eggs with higher shell ratio than the other populations (P < 0.05). Conversely, WL and the hybrids had higher eggshell strength than RIR birds (P < 0.05). Eggshell strength was the only egg quality trait that showed heterosis above 10% in WL × RIR hybrids at 32 and 52 wk of age. White Leghorn × RIR hens demonstrated higher percent heterosis for economic traits than birds of the reciprocal hybrid. This means that RIR breed is a better dam than a sire line for growth, egg laying, and egg quality traits.

Gregariousness affects performance and defensive reactions in swallowtail caterpillars

1. Group living in caterpillars may enhance individual performance due to sharing of costs associated with individual tasks when dealing with biotic or abiotic ecological factors.2. In the gregarious caterpillar Battus polydamas archidamas (Papilionidae) egg clusters and caterpillar groups vary in size. We hypothesized that individual survival would be higher in larger groups and that group living would enhance individual performance: shorter development time and/or reduced frequency of (presumably costly) defensive reactions in larvae and larger adult size. We also tested whether the group size conferring the highest survival to laboratory‐reared caterpillars matched the most frequent egg clutch size in the field.3. We collected egg clutches in the field and reared caterpillars in groups of 1, 6, 10, and 14 individuals. We quantified larval survival and stage duration as well as adult mass under laboratory conditions, excluding natural enemies. We also recorded the frequency of larval defensive reactions (thrashing and osmeterium display) against a tactile stimulus of first‐instar larvae.4. Group living enhanced caterpillar survival, particularly during the first instars, when caterpillars are 100% gregarious. Groups of intermediate size reduced larval development time but group living did not affect adult mass. Individual caterpillars in groups showed defensive reactions less frequently than solitary individuals, revealing a cost‐saving feature of gregariousness for this swallowtail species. The most frequent clutch size in the field (9–10 eggs) did not match the larval group with highest survival (14 individuals), but did match the group with shortest development time.

NESTING INFORMATION FOR THE BROWN-WINGED SCHIFFORNIS (SCHIFFORNIS TURDINA)

We present a description of the nest, eggs and limited incubation behavior for the Brown-winged Schiffornis (Schiffornis turdina), a member of the taxonomically challenging Schiffornis taxon, currently included in the family Tityridae. The nest was an open cup, located in a natural crevice between tree roots, and made up largely of dead leaves and dark rootlets. The nest contained two pale cream-colored eggs with black and dark purple blotches. An adult spent 66.45% of the daytime incubating the eggs. The incubation was interrupted by the preda- tion of the incubating adult by a mouse opossum (Marmosa sp.). Overall, the nest and egg characteristics, clutch size and incubation patterns resembled the available nesting information for other Schiffornis species. However, more detailed information about the natural history is needed to understand the nesting biology for the genus Schiffornis and therein lies the importance of long-term studies.

Variation in reproductive output as a function of maternal age and weather conditions in the cultured Asian yellow pond turtle, Mauremys mutica

Abstract Biotic factors (e.g., maternal age) and abiotic factors (e.g., weather) play vital roles in reproduction. However, there is little information about the combined effects of maternal age and weather on the reproductive output of cultured Asian yellow pond turtles, Mauremys mutica. To address this issue, we surveyed and compared the reproductive output of 13-year-old and 25-year-old female turtles on non-rainy and rainy days. The results showed that older females produced larger eggs than younger females regardless of the weather conditions. Females laid larger clutch sizes (number of eggs per nest) under non-rainy conditions compared with those under rainy conditions. However, the variation in clutch frequency (number of clutches per day) was independent of maternal age and weather. There was no effect of an interaction between maternal age and weather on egg mass, clutch size or clutch frequency. Our results suggest that maternal age and weather had significant effects on egg mass and clutch size, respectively. These results imply that maternal age, together with weather conditions (mainly conditions of rain), can affect the reproductive output of M. mutica. Our results provide useful information for the artificial breeding and stock management of M. mutica.

Geographic variation in maternal investment and trade-offs between egg size and clutch size in an endemic toad of the Qinghai-Tibet Plateau

Life history theory predicts that animals often produce fewer offspring of larger size and indicate a stronger trade-off between the number and size of offspring to cope with increasing environmental stress. In order to evaluate this prediction, we tested the life history characteristics of Bufo minshanicus at eight different altitudes on the eastern Tibetan Plateau, China. Our results revealed a positive correlation between female SVL and clutch size or egg size, revealing that larger females produce more and larger eggs. However, high-altitude toads seem to favor more offspring and smaller egg sizes when removing the effect of female SVL, which is counter to theoretical predictions. In addition, there was an overall significantly negative relationship between egg size and clutch size, indicative of a trade-off between egg size and fecundity. Therefore, we suggest that higher fecundity, rather than larger egg size, is a more effective reproductive strategy for this species of anuran living at high-altitude environments.

First evidence for a latitudinal body mass effect in extant Crocodylia and the relationships of their reproductive characters

AbstractRelationships between distribution patterns and body size have been documented in many endothermic taxa. However, the evidence for these trends in ectotherms generally is equivocal, and there have been no studies of effects in crocodylians specifically. Here, we examine the relationship between latitudinal distribution and body mass in 20 extant species of crocodylians, as well as the relationships between seven important reproductive variables. Using phylogenetically independent contrasts to inform generalized linear models, we provide the first evidence of a latitudinal effect on adult female body mass in crocodylians. In addition, we explore the relationships between reproductive variables including egg mass, hatchling mass and clutch size. We report no correlation between egg mass and clutch size, upholding previously reported within-species trends. We also find no evidence of a correlation between measures of latitudinal range and incubation temperature, contrasting with the trends found in turtles.

Comprehensive and Durable Modulation of Growth, Development, Lifespan and Fecundity in Anopheles stephensi Following Larval Treatment With the Stress Signaling Molecule and Novel Antimalarial Abscisic Acid.

The larval environment of holometabolous insects determines many adult life history traits including, but not limited to, rate and success of development and adult lifespan and fecundity. The ancient stress signaling hormone abscisic acid (ABA), released by plants inundated with water and by leaf and root fragments in water, is likely ubiquitous in the mosquito larval environment and is well known for its wide ranging effects on invertebrate biology. Accordingly, ABA is a relevant stimulus and signal for mosquito development. In our studies, the addition of ABA at biologically relevant levels to larval rearing containers accelerated the time to pupation and increased death of A. stephensi pupae. We could not attribute these effects, however, to ABA-dependent changes in JH biosynthesis-associated gene expression, 20E titers or transcript patterns of insulin-like peptide genes. Adult females derived from ABA-treated larvae had reduced total protein content and significantly reduced post blood meal transcript expression of vitellogenin, effects that were consistent with variably reduced egg clutch sizes and oviposition success from the first through the third gonotrophic cycles. Adult female A. stephensi derived from ABA-treated larvae also exhibited reduced lifespans relative to controls. Collectively, these effects of ABA on A. stephensi life history traits are robust, durable and predictive of multiple impacts of an important malaria vector spreading to new malaria endemic regions.

Oviposition preference maximizes larval survival in the grass-feeding butterfly Melanitis leda (Lepidoptera: Nymphalidae)

Phytophagous insects may be expected to prefer host-plant species on which their larvae perform best, but this has rarely been explored in grass-feeding butterflies. We explored links between oviposition preferences, larval food preferences, and performance (larval survival and development time, pupal mass, and adult longevity) on 18 species of grass in the common evening brown, Melanitis leda L. (Nymphalidae: Melanitini), a tropical butterfly that has been recorded from a large number of species of grass. Melanitis leda oviposited on all of the grass species offered in choice experiments, and larvae were able to develop to the adult stage on almost all of them. Oviposition preferences were for species of plants on which larval survival was higher, but were not correlated with larval development. The mother's choice of host plant appeared to affect performance of the resulting adults as large butterflies had longer life spans. Ovipositing females appeared to adjust clutch size and position of their eggs on a plant depending on plant traits. Larval survival was only marginally correlated with larval growth rate on the different species of plants. Larvae showed host-plant preferences that were not correlated with adult oviposition preferences, larval survival, or larval growth. Overall, while M. leda can utilize a large number of species of grass, it shows marked oviposition preferences. Apparent fine-tuning of clutch size and positioning of eggs on plants with different traits might be another adaptation associated with using a large number of species of plants. We conclude that this grass feeding butterfly selects oviposition sites that maximize the chances of their larvae surviving.

Seasonal and annual variations in egg mass and clutch size for Loggerhead Sea Turtles (Caretta caretta): experienced females lay heavier eggs

Organisms modify reproductive traits adaptively or non-adaptively in response to temporal environmental variation. Long-lived iteroparous sea turtles are ideal animals to examine such temporal shifts in resource allocation. We analyzed seasonal shifts in egg mass and clutch size for Loggerhead Sea Turtles (Caretta caretta (Linnaeus, 1758)) nesting at a temperate rookery (Yakushima Island, Japan) over a 2-year period, as well as annual variation in egg mass and clutch size over a 5-year period. Egg mass and clutch size, adjusted for female body size, did not vary seasonally at both the population and individual levels. Adjusted egg mass showed significant annual variation, despite a lack of annual variation in adjusted clutch size. Thus, Loggerhead Sea Turtles are unlikely to exhibit adaptive seasonal variation in reproductive traits, whereas they vary egg size non-adaptively in response to annual environmental conditions. Although experienced Loggerhead Sea Turtles laid heavier eggs, the annual variation in egg mass was not attributable either to breeding experience of the sampled females or to ambient temperature during follicular development, implying that other factors are involved, such as resource availability. Our data show that egg size is a more plastic reproductive trait than clutch size for Loggerhead Sea Turtles inhabiting the North Pacific.

OBSERVATIONS OF SIX REPRODUCTIVE CYCLES AND FOOD HABITS OF BROWN FISH OWL NESTING AT THE HUMAN HABITAT IN BANGLADESH

Background: Research reports on wild nocturnal bird especially Brown fish owl are very limited not only in Bangladesh but also elsewhere. Objectives: This paper describes the diet profile and physiology of reproduction of a pair of wild Brown fish owl. Materials and Methods: A breeding pair of Brown fish owl has been used the abandoned flower planting site on the window sunshade for their reproduction during six breeding cycles from 2013 to 2019. The behavior, food sources, food habits and their physiology of reproduction were observed closely and keenly for six reproductive cycles. Results: The male owl is usually brought prey by hunting at night and supplied to the female owl and their owlet at the nest but the only unconsumed prey lying on the nest were identified visually during the daytime. The most commonly recorded prey consumed by the habitat lost Brown fish owl include fish, frogs, rats, snake, birds and lizards. Investigation of all the six breeding cycles of this species of owl showed that all the six reproductive cycles were completed during the high cold winter months from end of November to early March. The egg clutch size varied from 1-2 with an average of 1.33 and the female owl alone incubated eggs and the incubation period varied from 37 to 38 days with an average of 37.5 days. The brooding and care of owlets were mainly performed by the female owl but the male owl supplied the food usually at night time. All the six reproductive cycles of the owls were successfully completed with fledged the juvenile owls between 53-63 days with an average of 59.25 days parental care with a total of breeding cycle from 91 to 101 with an average of 96.75 days. Conclusions: The objectives of the wild and zoo birds are for the conservation, research, education, recreation, ecology and economic benefits. This article would help to encourage development of bird parks, to create awareness of bird life and generate interest in ornithology and to help promote conservation of endangered species of birds by captive breeding. Keywords: Brown fish owl, Food and food habits, Physiology of reproduction, Egg clutch, Incubation period, Seasonal breeding cycle

Variations in the reproductive strategies of three populations of Phrynocephalus helioscopus in China.

BackgroundEgg size and clutch size are key life history traits. During the breeding period, it is possible for females to increase their reproductive output either by increasing the number of eggs if the optimal egg size (OES) is maintained, or by increasing the allocation of energy to each egg. However, the strategies adopted are often influenced by animals’ morphology and environment.MethodsHere, we examined variation in female morphological and reproductive traits, tested for trade-offs between egg size and clutch size, and evaluated the relationship between egg size and female morphology in three populations of Phrynocephalus helioscopus.ResultsFemale body size, egg size, and clutch size were larger in the Yi Ning (YN) and Fu Yun (FY) populations than in the Bei Tun (BT) population (the FY and YN populations laid more, and rounder eggs). Egg size was independent of female body size in two populations (BT and FY), even though both populations had an egg-size/clutch size trade-off. In the YN population, egg size and clutch size were independent, but egg size was correlated with female body size, consistent with the hypothesis of morphological constraint.ConclusionsOur study found geographical variation in body size and reproductive strategies of P. helioscopus. Egg size was correlated with morphology in the larger-bodied females of the YN population, but not in the smaller-bodied females of the BT population, illustrating that constraints on female body size and egg size are not consistent between populations.

Advanced Breeding Time in Line with Climate Did Not Affect Productivity of Great Reed WarblersAcrocephalus arundinaceusDespite the Shortening of the Nestling Period

Recent climate warming has resulted in advancement in laying dates and changes in various bird breeding parameters. The study of the breeding biology of Great Reed Warblers Acrocephalus arundinaceus was carried out at Milicz fishponds (SW Poland) during 18 discontinuous breeding seasons between 1970 and 2017. Over the study period, Great Reed Warblers started breeding progressively earlier; both the earliest and median first egg laying dates advanced, whereas the latest laying dates remained unchanged. Egg volume and clutch size did not change between 1972 and 2017. Mean clutch size of all nesting attempts was 4.8 (SD = 0.69, n = 1135). Nestling growth rates were similar in 1971 and 2016. Nestling period shortened during the study period. The decrease amounted to 0.7 days between 1970–1984 and 2004–2017. No temporal trends in fledgling production were observed. The proportion of successful broods varied considerably between years (range: 37%−76%) but did not show any consistent trend throughout the study period. More cases of Cuckoo Cuculus canorus parasitism were observed in 1997−2017 than in 1970−1984 (7% of nest losses versus 0 respectively), whereas starvation of nestlings was more frequent in 1970−1984 (10% versus 2% of nest losses). Breeding densities varied between seasons with no significant trend across the study years. This study concludes that the advanced start of breeding has not significantly influenced basic parameters of breeding ecology of the Great Reed Warbler.

The effects of climate on annual variation in reproductive output in Snapping Turtles (Chelydra serpentina)

Reptiles are highly dependent on climatic patterns to regulate their behavior and physiology, and studies of the effects of climate on the biology of organisms are increasingly important given expected climate change. Our study examined the effects of climate variation over 15 of the 26 years between 1990 and 2015 on the reproductive output of the Snapping Turtle (Chelydra serpentina (Linnaeus, 1758)). Egg mass, clutch size, and clutch mass (relative to body size) were significantly higher in years following warmer temperatures in September and October of the year before reproduction, but not related to temperatures in April and May just before reproduction. Of the above life-history traits, egg mass varied the least across years, and after warm autumns small turtles (225–285 mm carapace length) increased clutch mass by increasing clutch size but not egg mass. In contrast, under the same conditions, large turtles increased clutch mass by increasing egg mass but not clutch size. Our data suggest optimal egg mass may vary with female size. Climate change may already have impacted reproductive output in Snapping Turtles at the site because temperatures during September and October have increased about 0.5 °C each decade for the last 45 years.

Effects of food supplementation on the nesting dynamics of wild northern bobwhite

Avian females with food limitation or are unable to meet nutritional requirements could result in negatively influenced egg size, nest initiation date, nesting season duration, and clutch size. Northern bobwhites Colinus virginianus serve as an adequate model species for supplemental feeding studies because of prolific nesting and re‐nesting behavior. We monitored females on treatment and control units to determine if food supplementation influenced: 1) nest initiation, nesting duration, and nesting attempts, 2) nesting success, and 3) egg volume and clutch size. We radio‐marked 196 female bobwhites during the breeding season of 2011 and 2012. Hens with access to supplemental feed produced 0.86 and 1.60 nest per hen while hens on control sites produced 0.15 and 0.81 nest per hen during the 2011 and 2012 nesting season, respectively. Average nest initiation varied slightly between treatment and control; though, average nesting season length was 16 and 31 days longer on treatment units. This benefit indicates females with access to food supplementation were in better physical condition compared to females on control units. However, nest success (β = ‐0.03, SE = 0.40), clutch size (t=‐0.37, p = 0.70), and average intra‐clutch egg volumes (β =‐0.06, SE = 0.20) (t=0.50, p= 0.61) were unaffected by food supplementation. Total net productivity estimates showed more chicks per hen were produced on treatment sites [ = 2.34, SE = 0.04 (2011); = 5.75, SE = 0.12 (2012)] than control units [ = 0.61, SE = 0.001 (2011); = 3.47, SE = 0.13 (2012)]. Our results suggest that bobwhites with access to supplemental feed broadcast into roadside vegetation throughout the breeding season can potentially increase nesting attempts which may result in increased production and offset population fluctuations due to drought conditions.

Evidence of reproductive senescence of released individuals in a reinforced bird population

In free-ranging populations, age-dependent variation in fitness related parameters, in particular the pattern of senescence, has major eco-evolutionary implications and potential influence on population dynamics. Despite the recent surge of studies of senescence in the wild, senescence patterns in species for which population dynamics assessments are crucial, such as translocated populations, remain virtually unexplored. Based on a 15-year nest survey of a North-African Houbara bustard population in Morocco, we investigated age variation in the breeding performance of captive-bred females released in the wild. We identified 781 females, from 1 to 10years of age, on 1094 nests. We examined how age influenced nest initiation date, clutch size, egg volume, daily nest survival and daily brood survival, as well as whether age-dependent patterns varied according to environmental conditions. Most breeding parameters exhibited variation, suggesting an increase in breeding performance with age in young females (those from 1 to 3years old). In older females (>7–8years old), the egg volume and clutch size decreased with age, in concordance with expectations from senescence theories and previous empirical results obtained from captive Houbara bustards. Finally, our analysis uncovered a significant interaction between age and the amount of precipitation prior to the breeding season on clutch size, suggesting differential abilities of females of different ages to increase their breeding investment. Our study suggests that life histories in translocated individuals are not affected by translocation protocols and provides insights for implementing age dependencies in population viability assessments.

Breeding ecology of buff-breasted babbler (Pellorneum tickelli) at Doi Chiang Dao Wildlife Research Station, Chiang Mai province, Thailand

The behavior of the buff-breasted babbler (Pellorneum tickelli) was recorded from April 2010 to May 2012 along creeks in Doi Chiang Dao Wildlife Research Station, Chiang Mai, Thailand. Fifteen nests of the buff-breasted babbler were found on four creeks: Maeka, Maemard, Ong and Sikrobkrua. The general behavior of birds included foraging, excretion, locomotion, preening and vigilance. The complete breeding cycle of the buff-breasted babbler in this study was almost 1 mth. Egg clutch size was in the range 3–4 and the nestlings hatched almost simultaneously. The eggs were incubated by both the males and the females. After hatching, both parents invested in intensive parental care. As well as providing food, they also protected their nestlings. This information can be used to help with conservation planning in the area and elsewhere.

Breeding rate and mortality in Australian parrot (Melopsittacus undulatus) in captivity at Bahawal Pur, Pakistan

The present study was conducted to find out the breeding rate and mortality of Melopsittacus undulatus (budgerigar), a famous species of Australian parrots. A total of 100 birds (50 pairs), kept in a farm house at Bahawal Pur, Pakistan were used in this study. Number of eggs, clutch size, number of hatchings, hatchlings and fledglings were recorded for estimation of breeding rate. Total number of eggs was 537 during whole breeding season. Clutch size varied from 1-9. The hatching and hatchling success was found to be 29.69% and 81.76% respectively. The clutch size and number of eggs laid in breeding season were adequate for rapid increase in population. The hatching rate and fledging rate indicated good reproductive success in captivity. Keywords: Budgerigar; Clutch size; Hatching success; Fledglings http://dx.doi.org/10.19045/bspab.2017.60051

Habitat Geology Influences Intraspecific Variation in the Speckling Patterns of Blue TitCyanistes caeruleusand Great TitParus majorEggs

Abstract. Birds' eggs exhibit a small amount of interspecific diversity in terms of their colors and patterning but considerable variation occurs at the intraspecific level. Here, we examined the contributions of habitat geology, first egg dates, clutch sizes and year in determining intraspecific variation in the intensity of speckling patterns on the eggs of Blue Tits Cyanistes caeruleus and Great Tits Parus major breeding in deciduous woodlands with underlying calcium-rich limestone and calcium-poor gritstone rock types in northwest England. Eggshell speckling patterns varied significantly in relation to habitat geology, with both species laying more heavily speckled eggs in woodlands with gritstone rock types than in woodlands with limestone rock types, even though the weights of laying females and the availability of aerial invertebrates never differed between the two habitat geology types. Meanwhile, there was no variation in eggshell speckling patterns in both species in relation to first egg dates,...

The first stages of coevolution between a brood parasite and its new host: are naïve hosts defenceless?

ABSTRACTLittle is known about the early stages of the coevolutionary interactions between brood parasites and their hosts or how rapidly hosts evolve defences. We investigated the success of breeding attempts by the brood-parasitic Pacific Koel (Eudynamys orientalis) and its newest host, the Red Wattlebird (Anthochaera carunculata), at two sites where wattlebirds have been exposed to different durations of parasitism: Sydney (38–86 years) and Canberra (8–33 years). Parasitism was more frequent in Sydney and nest predation increased in Sydney after the arrival of migratory koels, yet the nest success rate of wattlebirds was not significantly lower than in Canberra. Wattlebirds rarely reject foreign eggs, but their low clutch size, earlier breeding and abandonment of koel eggs laid before the host’s laying period might explain the low impact of koels. Parasitised nests fledged wattlebird and koel young at equal rates, but fledged fewer wattlebird young than unparasitised nests. The koel’s later breeding and poor timing of egg laying may have contributed to the low success of koel eggs. These results suggest that host switching may have a negative impact on the reproductive success of both the parasite and the new host, and naïve hosts may avoid parasitism using generalised defences that require no egg or parasite recognition.

The cestode parasite Schistocephalus pungitii: castrator or nutrient thief of ninespine stickleback fish?

In this investigation, the host-parasite relationship of ninespine stickleback fish Pungitius pungitius and the cestode parasite Schistocephalus pungitii was studied using samples from Dog Bone Lake, Kenai Peninsula, Alaska, to test the hypothesis that S. pungitii is a castrator of ninespine stickleback. Infected, adult females of all sizes (ages) were capable of producing clutches of eggs. S. pungitii had a negative effect on the ability of host females to produce a clutch, which was related to increasing parasite:host mass ratio (parasite index, PI). Among infected females with egg clutches, both clutch size and egg size were reduced; and the reduction increased with greater PI. The results of this study are consistent with the hypothesis that S. pungitii causes host sterility as a result of simple nutrient theft and is not a true castrator as hypothesized in earlier reports. The degree of parasite-induced sterility appears to vary among populations of the ninespine stickleback, perhaps reflecting differences in resource availability. Populations of ninespine stickleback appear to show a greater reduction in host reproductive capacity with PI than populations of the threespine stickleback infected by Schistocephalus solidus, possibly owing, in part, to the length-adjusted somatic mass of the threespine stickleback being greater.