Progeny Quality Research Articles

The role of progeny quality and male size in the nesting success of smallmouth bass: integrating field and laboratory studies

Smallmouth bass display size-specific variation in reproductive success with larger brood-guarding males in a population more likely to rear offspring to independence than smaller individuals. The exact mechanisms responsible for this size-specific increase in reproductive output have yet to be identified. To assist in this process, we investigated the relationship between the size of brood-guarding male smallmouth bass and offspring quality (in this case, egg physiology, egg morphology, egg size, hatching success and lab survival). Further, we examined how factors such as egg physiology, egg morphology and egg size influenced reproductive success in the wild and hatching success in a controlled laboratory environment. Nesting male smallmouth bass that successfully reared their offspring to independence spawned earliest in the nesting period were the largest individuals, and guarded eggs with greater concentrations of cortisol compared to males that abandoned their offspring prematurely. Offspring survival in the laboratory was not correlated with offspring survival in the wild, indicating that caution should be used interpreting studies that attempt to relate laboratory-derived survival metrics to the wild. Together, results demonstrate size-specific differences in offspring quality for nesting smallmouth bass, which are correlated with higher concentrations of cortisol in eggs. However, hatching success under laboratory conditions was dissimilar to nesting success in the field relative to cortisol concentrations.

Phase-specific responses to different qualities of food in the desert locust, Schistocerca gregaria: Developmental, morphological and reproductive characteristics

Solitarious female adults are known to produce smaller hatchlings than those produced by gregarious adults of the desert locust, Schistocerca gregaria. This study investigated developmental, morphological and reproductive responses to different qualities of food in hatchlings of different phases. Mortality was higher, the duration of nymphal development longer and adult body weight lighter with a low-quality food than a high-quality food. Gregarious hatchlings showed better survivorship, grew faster and became larger adults than did solitarious ones. The incidence of locusts exhibiting extra molting, which was typically observed in the solitarious phase, was dramatically increased when a low-quality food was given to the solitarious hatchlings. Low-quality food caused locusts to shift morphometric ratios toward the values typical of gregarious forms; smaller F/C (hind femur length/maximum head width) and larger E/F (elytra length/hind femur length). Solitarious hatchlings grown at either high- or low-quality foods and then given high-quality food after adult emergence revealed that food qualities during the nymphal stage influence their progeny quality and quantity via adult body size that influenced reproductive performance. Female adults showed an overshooting response to a shift from low- to high-quality food by increasing egg production that was specific to body size. This study may suggest that gregarious hatchlings are better adapted to adverse food conditions than solitarious counterparts and extra molting is induced even among gregarious hatchlings under poor food conditions.

An Examination of the P Requirements of Broiler Breeders for Performance, Progeny Quality and P Balance 1. Non-phytate Phosphorus

A 40-wk study was performed to assess the effects of reduced dietary Non-Phytate Phosphorus (NPP) on broiler breeder performance, progeny quality and P balance. Seven hundred Cobb 500 chicks were reared according to Cobb guidelines (Cobb-Vantress, 2005) and transferred to a production house at 21 wk. At 24 wk, 285 birds were switched over to one of five experimental diets (5 groups of 57) that differed only in NPP. Phosphorus levels ranged from 0.2% to 0.4% NPP in 0.05% increments; and corresponded to a daily intake of 288, 360, 432, 504 and 576 mg at peak. Production performance, egg quality, breeder and progeny skeletal quality, hatchability, progeny weight and P retention were monitored throughout the experimental period. Results show that total egg production, egg number, age at sexual maturity and egg weight were not negatively effected by lowering NPP levels to 0.20% (288 mg/day). Shell quality, though statistically impacted by NPP level, remained at high levels for all treatments (above 1.081). Reproductively, reduced dietary NPP did not negatively impact hatchability or subsequent progeny performance. Day old progeny wt and progeny bone quality were not significantly different from the breeders fed different NPP intake. Breeder tibia ash and relative strength was impaired at 0.20% NPP. The % total P (TP) retention showed a negative linear response with increasing dietary NPP, although absolute P retained increased with increasing dietary NPP. The amount of P deposited into the egg was not different among the treatment groups. Results appear to indicate that 360 mg NPP/day at peak (0.25% NPP) is sufficient for breeder hen performance, progeny 1 d wt and progeny skeletal quality. Breeder hens are able to maintain their performance by mobilizing bone reserves to meet the demands of egg formation and utilize dietary sources to replenish these reserves.

The parameters of reproduction, sizes, and activities of hydrolases in Daphnia magna straus of successive generations affected by Roundup herbicide

The influence of sublethal concentrations of Roundup (25 and 50 mg/l of the active compound glyphosate) was studied in the Daphnia magna Straus of successive generations. The toxic effects were assessed by the parameters of fecundity, quality of progeny, and linear sizes of daphnia, as well as by the activities of carbohydrases and proteases. The effect of the toxicant may be traced both in the parent specimens and in the specimens of successive generations. No adaptation to Roundup’s toxic impact was revealed for four generations of Daphnia magna. However, a considerable decrease in resistance to the herbicide was noted in the fourth generation when compared to the maternal line.

Evaluation of <i>Ephestia kuehniella</i> and <i>Corcyra cephalonica</i> as hosts for mass rearing trichogramma species nr. Mwanzai and trichogrammatoidea species nr. <i>Lutea</i>

Production of vegetables free of chemical pesticides requires, among other things, use of biocontrol agents that can be effectively and efficiently produced in large quantities. Two factitious hosts were evaluated for their suitability in mass rearing of two native Trichogrammatids. Egg cards bearing host eggs were separately offered to female parasitoids in glass vials and allowed to parasitise for 24 hours. New egg cards were offered daily till death of the female parasitoid. The number of eggs parasitised, emerged adult progeny and female progeny differed significantly between the two parasitoids, with Trichogramma sp. nr. Mwanzai appearing to be superior to Trichogrammatoidea sp. nr. lutea.There were no differences in the mass production efficiency and quality of progeny between the Ephestia kuehniella and Corcyra cephalonica. The two hosts can be effectively used for mass production of either of the parasitoids. Keywords: Egg-parasitoids, biocontrol, Helicoverpa armigera, tomato pests Journal of Agriculture, Science & Technology Vol. 9 (1) 2007: pp. 44-54

Carcass characteristics and meat quality of progeny of five Merino dam lines, crossed with Dormer and Suffolk sires

This study details the slaughter traits of lambs born from a terminal crossbreeding experiment that involved five Merino type dam lines crossed with Dormer and Suffolk sires. Dam lines included dual purpose types; South African Mutton Merino (SAMM), Dohne Merino, SAMM rams crossed to commercial Merino ewes (SAMM cross) and specialist Merino lines selected either for clean fleece weight (FW+) or for an increased fertility (Rep+). Data include between 228 and 483 individual records, depending on the trait. The unadjusted fat depth 25 mm from the midline at the 13 th rib of lambs from dual-purpose ewes was between 22 and 32% greater than that of lambs from FW+ Merino ewes. Progeny from Rep+ Merino ewes showed a closer resemblance to the progeny of dual-purpose breeds than to those of FW+ Merino ewes in this instance. Adjustment for slaughter weight eliminated these differences. The initial pH of meat from progeny of FW+ Merino ewes was lower than that from progeny of dual-purpose ewes, and Rep+ Merino ewes. No differences in Warner-Bratzler shear values of the meat were found between the different crosses. Crossbred progeny of the Merino lines performed satisfactorily for all the traits considered, and will not be discriminated against in the market. No conclusive differences in favour of either sire breed were found.

Trade-offs between size and energy reserves reflect alternative strategies for optimizing larval survival potential in rockfish

Reproductive strategies balancing offspring size and offspring number have been well documented in empirical tests of life-history theory. Here we found an additional trade-off between offspring size and offspring condition. Among 5 species of live-bearing rockfishes (Sebastes spp.) from central Californian populations, we observed a negative relationship between larval length at parturition and the size of their oil globule (a triacylglycerol-rich energy reserve). When compared with a variety of performance variables (resistance to starvation, growth, startle-escape performance and routine activity levels), it appears that this trade-off leads to a conflict when trying to optimize survival potential, with differing benefits to each trait. A large oil globule greatly increases resistance to starvation, whereas larger body size is associated with numerous performance benefits likely to synergistically decrease predation-based mortality and increase success at capturing prey (increased startle speeds and distances, as well as more rapid onset of growth and larger size at age). The tradeoff between energy reserves and body size is further reflected in the seasonal patterns of parturition of the 5 species, with larvae having large oil globules and small body size being released in winter, when productivity in the California Current is low but transport is generally onshore, and those with small oil globule reserves and large body size released in late spring, when productivity is high but transport is generally offshore. These 2 apparent reproductive strategies also reflect subgeneric phylogenetic relationships, suggesting a potential lineage-specific basis for the contrast in larval traits. The results highlight the importance of measuring both physical and performance traits of larvae, as well as considering multiple attributes of both, when evaluating progeny quality.

Pollen limitation affects progeny vigour and subsequent recruitment in the insect‐pollinated herb Ranunculus acris

Pollen limitation on seed production appears to be widespread among the angiosperms. However, few studies have examined if pollen limitation affects population growth. We supplementally hand‐pollinated all flowers of 20 individuals of Ranunculus acris in the temperate meadow Rudsviki, Kaupanger, west Norway in 2003. The seed production did not respond to pollen addition, but the achene weight increased by 18% after supplemental pollination. To test whether this progeny quality response to the pollen‐supplementation experiment could contribute to population growth, we sowed achenes from hand‐pollinated plants and control plants into natural conditions in ten blocks at three densities. During the subsequent season (2004), the number of seedlings and juveniles (pooled) from hand‐pollinated plants were substantially (64%) higher than from controls. There was also a clear positive effect of seed sowing‐density on recruitment, suggesting that recruitment is seed‐limited in this system. However, the density of vegetative individuals in 2005 was generally low and did not differ significantly between plots that received achenes from control or supplementary pollinated plants. Our results show that pollen limitation may affect germination through seed quality, and thereby impact plant population dynamics. However, in our system it appears that other factors, such as intra‐ and interspecific competition, may have outweighed the potential contribution from pollen limitation on population demography.

Progeny Quality of <I>Gonatocerus ashmeadi</I> (Hymenoptera: Mymaridae) Reared on Stored Eggs of <I>Homalodisca coagulata</I> (Hemiptera: Cicadellidae)

This study assessed the effects of refrigerated storage on the suitability of eggs of the glassy-winged sharpshooter, Homalodisca coagulata (Say) (Hemiptera: Cicadellidae), as hosts for propagation of the parasitoid Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae). Development of the host eggs was terminated by chilling at 2 degrees C for 5 d before storage was initiated at 10 degresC for up to 70 d. Parasitism, adult emergence rate, developmental time, and sex ratio were used to gauge the suitability of the eggs as hosts after storage. In addition to these measures, demographic growth parameters also were used to assess the quality of the wasp progeny through the F2 generation. Host eggs stored 20 d remained fully acceptable to the wasps for attack. Although the parasitism rate decreased with storage time, > 80% adult parasitoid emergence was realized from eggs stored 30 d. After 70 d storage, adult emergence rate was decreased by 48%, fecundity decreased by 53%, female production by 19%, developmental time was extended 3 d, and female longevity was shortened 5 d. The emergence pattern of F1 but not F2 adults varied with storage time of the parental and grandparental hosts, respectively. For the F1 generation, emergence rate, development, and sex ratio did not vary with storage time when the F1 parents parasitized fresh host eggs. Demographic parameters for the F, population showed that net reproductive rate was > 20 although it decreased significantly after their parental host eggs were stored for > 30 d. The intrinsic and finite rates of increase, population doubling time, and mean generation time decreased only after storage for 60 d. Our results show that short-term cold storage could be used for maintaining wasp populations in a mass-rearing program and that the detrimental effects of chilling host eggs in storage for over 30 d do not extend to F2 generation.

Characteristics of the hatchery-reared Black Sea salmon Salmo trutta labrax

For conserving the unique representative of salmonids—the Black Sea salmon Salmo trutta labrax—its hatchery rearing was initiated in 1998 at the Adler trout hatchery farm (Northern Caucasia). Fish were kept in concrete tanks. The comparative assessment of hatchery-reared fish and salmon from natural populations revealed their similarity by dates of the onset of smoltification, ratio of spawners maturing at different ages, and the weight, sizes, and fecundity of females. The quality of sexual products and progeny obtained from spawners of the initial brood stock was high. The data obtained indicate that the method of hatchery rearing the Black Sea salmon is promising.

Cytogenetic Effect of Radiation in Seed of Oak (Quercus robur L.) Trees Growing on Sites Contaminated by Chernobyl Fallout

Abstract The Chernobyl accident was one of the largest man made environmental disasters and had significant consequences for people, animal and plants, particularly on land contaminated by radionuclides. Common oak (Quercus robur L.) is the main forest species on land contaminated by Chernobyl fallout areas in the Voronezh region. Therefore it is very important to know how irradiation of oak trees will affect the quality of oak progeny in future consequently. Cytogenetic characteristics such as mitotic activity, level and spectrum of mitotic disturbances, frequency of the cells with persistent nucleoli in the stages of metaphase, anaphase, telophase and multinuclei in interphase cells were investigated in progeny of common oak (Quercus robur L.) trees subjected to different degrees of radioactive contamination. In progeny growing under the influence of this radioactive contamination we observed variability of such cytogenetic characteristics as mitotic activity. However, the variability of this trait was also connected to fluctuations in the weather. The duration of mitotic stages (which may be connected with disturbance of spindle division formation and absence of cytotomy) also varied. An increase in chromosomal bridges among other types of mitotic abnormalities may be considered a result of increases in the meristematic cells repair activities. Activity of some dormant nucleolus organizer regions was also observed. The level of pathological mitoses increased in particular years and was decreased in others. Thus irradiation induces instability of cytogenetic characteristics in oak progeny that produces a type of “wave kinetics” in the mutation rate. This makes them more sensitive to environmental conditions. Therefore we do not recommend to use the oak seeds collected from irradiated areas for reforestation because undesirable genetic changes may have occurred in them.

Effects of Dietary Lipid and Fatty Acids on White Bass Reproductive Performance, Egg Hatchability, and Overall Quality of Progeny

AbstractWe evaluated the dietary effects of graded levels of highly unsaturated fatty acids (HUFAs) fed to broodstock female white bass Morone chrysops on reproductive performance, egg hatchability, and larval survival of sunshine bass (female white bass × male striped bass M. saxatilis) through the endogenous feeding stage. Dietary treatments consisted of four isocaloric, isonitrogenous diets formulated to contain 45% crude protein and 15% lipid with graded levels of menhaden oil (0, 25, 75, and 100%) or corn oil as the dietary lipid variable. Significant differences existed among the dietary groups in egg fatty acids, which reflected levels in the maternal diet, especially for the neutral lipid component. Similar trends were also found in fatty acids of the polar lipid component and conservation of HUFAs; significantly higher quantities of linoleic acid (18:2[n‐6]) were associated with increasing dietary inclusion of corn oil. Eggs with higher hatchability were associated with higher levels of n‐3 HUFAs, including eicosapentaenoic acid (20:5[n‐3]), docosapentaenoic acid (22:5[n‐3]), and docosahexaenoic acid (22:6[n‐3]). Our results suggest that white bass broodstock females possess low and moderate regulatory control of fatty acid deposition to the egg within the neutral and polar components, respectively. These results indicate that little to no elongation or desaturation of dietary fatty acids occurs during egg development. Accordingly, the inclusion of elevated levels of dietary HUFAs for white bass broodstock appears to be warranted.

Female compensation through the quantity and quality of progeny in a gynodioecious plant, Geranium maculatum (Geraniaceae)

One of the major evolutionary trends in flowering plants is the evolution of unisexual flowers (male or female) from perfect flowers. This transition has occurred repeatedly in many taxa and has generated a wonderful array of variation in sexual expression among species. Theoretical studies have proposed a number of mechanisms to explain how this level of variation could be maintained in natural systems. One possible mechanism is the female compensation hypothesis, which predicts that female mutants require an increase in their seed fitness in order to invade a hermaphroditic system. Using Geranium maculatum, I tested this hypothesis and showed that female mothers produced more and larger seeds than hermaphroditic mothers even though they were indistinguishable in their vegetative traits and the flower production. Seeds from females were also more likely to germinate and produced seedlings with larger above- and belowground biomass. These seedlings were more likely to flower than those from hermaphrodites in at least one of the two populations studied. Combined, these results indicated that females in G. maculatum did compensate for their loss of male function by producing more and better seeds than hermaphrodites. This provides a mechanism for the maintenance of female plants in this species.

Effect of host egg viability on reproduction and development of Trichogramma cacoeciae and T. principium (Hymenoptera: Trichogrammatidae)

A combination of a sterile insect technique, resulting in infertile eggs, and of an egg parasitoid, should provide better control of codling moth than either alone. Non-choice laboratory experiments were conducted with infertile and fertile codling moth eggs to evaluate the potential parasitism and reproduction of Trichogramma cacoeciae Marchal and T. principium Sug. et Sor. The tendency of T. cacoeciae females to attack infertile eggs was similar to that for fertile eggs, whereas T. principium showed a greater preference for infertile eggs than fertile eggs. The fertility status of the host did not affect the number of eggs that were parasitized but fewer F1 progeny emerged from infertile eggs when parasitized than from fertile eggs. When T. cacoeciae and T. principium parasitized infertile host eggs their mean developmental time was prolonged but the viability and quality of parasitoid progeny was not influenced by the fertility status of the host eggs. The study demonstrates the compatibility of use of T. cacoeciae and T. principium in an integrated program employing the sterile insect technique for codling moth management.

Preferences of Pollinators and Herbivores in Gynodioecious Geranium sylvaticum

For the maintenance of gynodioecy (i.e. the coexistence of female and hermaphroditic plants), females need to compensate for the lack of pollen production through higher seed production or better progeny quality compared to hermaphrodites. In Geranium sylvaticum, females produce more seeds per flower than hermaphrodites. This difference in seed production might be modified by biological interactions with pollinators and herbivores that may favour one sex and thus affect the maintenance of gynodioecy. Sexual dimorphism in flower size and flowering phenology, and in attractiveness to pollinators, pre-dispersal seed predators and floral herbivores were examined in natural populations of G. sylvaticum. Pollinators preferred hermaphrodites 25 % more often than females in two of the three study populations, and floral herbivores attacked hermaphrodites 15 % more often than females in two of the six study populations. These preferences might be explained by the larger flower size of hermaphrodites. In contrast, seed predators did not prefer either sex. The data suggest that pollinator preference does not benefit females, whereas the higher floral herbivory of hermaphrodites might enhance the maintenance of females in G. sylvaticum. Thus, although the data support the view that ecological factors may contribute to the maintenance of gynodioecy, they also suggest that these contributions may vary across populations and that they may function in opposite directions.

Paternal effects on functional gender account for cryptic dioecy in a perennial plant.

Natural selection operates on the mating strategies of hermaphrodites through their functional gender, i.e. their relative success as male versus female parents. Because functional gender will tend to be strongly influenced by sex allocation, it is often estimated in plants by counting seeds and pollen grains. However, a plant's functional gender must also depend on the fate of the seeds and pollen grains it produces. We provide clear evidence of a paternal effect on the functional gender of a plant that is independent of the resources invested in pollen. In the Mediterranean tree Fraxinus ornus, males coexist with hermaphrodites that disperse viable pollen and that sire seeds; the population would thus appear to be functionally androdioecious. However, we found that seedlings sired by hermaphrodites grew significantly less well than those sired by males, suggesting that hermaphrodites may be functionally less male than they seem. The observed 1 : 1 sex ratios in F. ornus, which have hitherto been difficult to explain in the light of the seed-siring ability of hermaphrodites, support our interpretation that this species is cryptically dioecious. Our results underscore the importance of considering progeny quality when estimating gender, and caution against inferring androdioecy on the basis of a siring ability of hermaphrodites alone.

Effect of host availability and egg load in Trichogramma platneri Nagarkatti (Hymenoptera: Trichogrammatidae) and its consequences on progeny quality

Experiments were conducted to determine whether Trichogramma platneri Nagarkatti manifested a somatic-gametic trade-off and whether it was affected by host availability and host size. Large wasps produced on Trichoplusia ni Hübner and limited to five or 15 T. ni eggs daily, produced a similar number of progeny as wasps offered hosts from emergence. Similar results were obtained when they were deprived of T. ni eggs for one, three, five, or ten days and then provided with unlimited hosts daily until death. In contrast, small wasps produced from Sitotroga cerealella (Olivier) and deprived of T. ni eggs for one to three days suffered a significant reduction in progeny production. Regardless of size, the egg load of non-ovipositing wasps increased significantly with time and a positive relationship existed between the life span of a female and the length of time she was deprived of hosts.

Assessing frequency-dependent seed size selection: a field experiment

Seed size is a life history attribute that affects the probability of seed predation, and therefore affects plant fitness. Compared with smaller seeds, those with large size should be more attractive to predators, as they constitute a more profitable food item because of higher energetic and/or nutrient content. However, predator preferences may be frequency-dependent in the sense that they may be modulated by the relative abundance of alternative seeds of different sizes. We set up a field experiment to evaluate frequency-dependent seed predation using seeds of Cryptocarya alba (Lauraceae), at La Campana National Park in central Chile. Predators (rodents and birds) preferentially consumed large seeds in an antiapostatic manner. These selective responses were maintained throughout the experiment and seed selection by predators was not affected by previous seed consumption. Our results suggest that (a) large seeds are very profitable food items actively sought by seed predators even at low relative abundance, (b) seed selection is expressed in a short time scale and (c) seed predators, by consuming large seeds consistently, have the potential to modify significantly the quality of plant progeny. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 307–312.

Lifetime Wool. 8. Progeny wool production and quality

The perceived costs of maintaining ewe liveweights during the autumn/winter feed-gap means that ewes often lose 0.5 to 1.5 of a condition score by mid-pregnancy or lambing. Poor ewe nutrition during pregnancy and lactation can influence wool follicle initiation and maturation processes in the developing Merino lamb (Short 1955). These effects on the follicle population are permanent and have a direct impact on both the amount and fibre diameter of wool produced for the duration of the lamb’s life (Kelly et al. 1996), but their importance in the context of developing practical ewe feeding systems has received little attention. The ‘Lifetime Wool’ project (Thompson and Oldham 2004; these proceedings) aims to determine ewe nutrition targets that optimise ewe and progeny production and systems profitability. This paper provides preliminary data on the characteristics of hogget wool from progeny that experienced different maternal environments.

MULTIPLE INCENTIVES FOR PARENTAL OPTIMISM AND BROOD REDUCTION IN BLACKBIRDS

Why do parent birds hatch their young asynchronously? This phenotypic handicap exacts a cost of reduced growth and elevated mortality from the last-hatched or “marginal” offspring, while conferring advantages to the more senior “core” brood. David Lack long ago proposed that marginal offspring allow parents to track resources that are uncertain at the time of clutch initiation. If food is insufficient for the entire brood, hatching asynchrony allows surplus marginal offspring to be culled from the brood efficiently. This in effect represents a secondary adjustment of clutch size. Today Lack's hypothesis remains a central, although controversial, component, of discussions of hatching asynchrony and avian brood reduction. Most field workers report results inconsistent with Lack's hypothesis (e.g., a failure of asynchronously hatching broods to produce more fledglings than do experimentally synchronized broods) and have offered a variety of alternative explanations. Previous workers have focused, with limited success, on single explanations for the complex phenomena of hatching asynchrony. Here we use parental optimism theory to study the secondary adjustment of clutch size in an integrated framework emphasizing ecological (tracking uncertain resources) and developmental (unpredictable survival, quality and/or sex of progeny) uncertainty. We present the results of a 6-yr study of Yellow-headed Blackbirds (Xanthocephalus xanthocephalus), a marsh-nesting icterid. Marginal offspring that are the products of hatching asynchrony serve multiple functions simultaneously: in tracking resources that vary temporally; as a hedge against hatching failure; and in progeny choice via sex-biased brood reduction. The effect of the phenotypic handicap was diminished both by improving ecological conditions and by hatching failure/experimental clutch reduction. Marginal offspring represent high variance progeny, and synchrony represents a high variance strategy. Brood reduction occurred at low cost and was rendered more efficient by hatching asynchrony, particularly under conditions of stringency.