Breeding Events Research Articles

From concept to field: evolution of hybrid pigeonpea technology in India

The role of hybrid vigour in the enhancement of productivity is well recognized. Its application, however, has been restricted to a few crops and legume breeders could never take its advantage due to various seed production issues. Recently, plant breeders have succeeded in creating the world's first commercial hybrid in a food legume, popularly known as red gram or pigeonpea [Cajanus cajan (L.) Millsp.]. This was possible due to success in breeding a stable cytoplasmic nuclear male sterility (CMS) system and exploitation of its partial natural out-crossing. This development has provided golden opportunities to break the decades-old yield plateau in this crop. Among the hybrid combinations evaluated, ICPH 2671 and GTH 1 were found most promising. In the on-farm trials ICPH 2671 recorded 46.5% superiority over the best available cultivar Maruti; while GTH 1 was 33.9% superior to the control, and it was released in Gujarat state in 2004; but for some reasons associated with its stability of fertility restoration it failed to reach the level of commercialization. The outstanding performance of hybrid ICPH 2671 led to its release by both, a private seed company as ‘Pushkal’ and by the state Government of Madhya Pradesh as ‘RV ICPH 2671’ in 2010. The journey of the evolution of hybrid pigeonpea technology was fascinating and challenging. It took a long time of over 39-years from its conceptualization to finally reaching Indian farmers. The impact of this breakthrough was visible when two more hybrids ICPH 2740 and ICPH 3762 were recently released in India. Since it is a path breaking research among food legumes, an attempt has been made here to archive the milestones of this historic plant breeding event.

Mathematical modelling of seasonal migration with applications to climate change

The breeding success of many species depends on the alignment of the period of maximum demand of offspring with a period of food abundance. In this paper, we use piecewise-smooth differential equations to model the variation in the size of a population that has a short interval each year during which successful reproduction is possible. An increase in spring-time temperatures in recent decades has caused these intervals to advance, leading to temporal mismatches between species on different trophic levels. We first consider a one-species model which illustrates the dynamics of a population of specialist feeders over the course of a single breeding season and use it to examine how reproductive success depends on the population's distribution of breeding dates. We then introduce time-dependent switches to extend the model to a broader class of species. Steady-state solutions are used to measure the extent to which a migratory population can sustain itself over long time scales and repeated breeding events. The model's predictions agree with the observed negative effect on population size associated with an advance in the food season if not adequately compensated for by the population. Finally, we discuss how this model can be extended in order to encompass a wider range of ecological systems and to highlight the mechanisms over which climate change may exert an influence.

Indirect detection of genetic dispersal (movement and breeding events) through pedigree analysis of dugong populations in southern Queensland, Australia

Understanding the patterns of movement and breeding within and between wildlife populations is important for the assessment of conservation status of endangered species, the development of conservation management strategies and priorities, and the prediction of population behaviour based on future threats. Methods for determining long term gene flow and dispersal are well researched, but analysis of recent movement is more difficult, typically relying on real-time tracking of individuals using telemetry, or through identification of marked individuals at multiple locations. These methods are limited by the considerable sampling effort required over time periods sufficient to recapture individuals in multiple locations. In contrast, we can infer recent movement from a reconstructed pedigree based on genetic and ancillary biological data, by identifying parent-offspring relationships in which the parent and offspring may be found in different locations. Hence, this method can use a single sampling period to identify movement and possibly associated breeding events over the last one or two generations. This study demonstrates the utility of reconstructed pedigrees in inferring recent movements in a dugongs distributed across a number of spatially distinct foraging locations in southern Queensland, Australia. Dugongs, which are classified as vulnerable to extinction, have long lifespans and protracted breeding cycles and give birth to single offspring at irregular intervals, implying a complex pedigree without distinct generational structure or large sibling groups. A pedigree was constructed for 1002 different dugongs across four locations in southern Queensland: Moreton Bay (n=630), the Great Sandy Straits (n=281), Hervey Bay (n=59) and Shoalwater Bay (n=27) using PR-genie software. PR-genie is a pedigree reconstruction system designed specifically for complex multigenerational wildlife pedigrees based on genetic identity (microsatellite DNA) and including ancillary biological data (sex and body size-class). Movements of genetically tagged individuals between locations were detected as parent-offspring links found across locations. Approximately 30% of assigned parents had at least one offspring found in a different location, implying recent movement of the parent or offspring. Where multiple individuals in a family are present, parsimonious explanations of movement indicate that male dugongs move between populations more frequently than females. Markedly more movement between locations was found than has been previously possible to detect through repeated direct sampling of individuals or through telemetry.

The Osprey reintroduction in Central Italy: dispersal, survival and first breeding data

Capsule Sex-biased dispersal and an age-dependent effect in survival rate accounted for the pattern of first settlement and reproduction in a newly reintroduced Osprey population.Aims We estimate the survival of translocated individuals, describe juvenile movements and evaluate the success of first breeding events to document the re-establishment of an Osprey breeding population.Methods Between 2006 and 2010, 32 fledgling Ospreys were reintroduced via hacking techniques in Maremma Regional Park, Italy. We evaluated the effects of age on survival through multistate capture-mark-recapture analyses. Movements were investigated by radiotracking and using records of resightings.Results Survival was high for juveniles after the release (0.87), markedly decreased during the first winter (0.26), and improved again in subsequent years (annual apparent survival of 0.69 for immatures and 0.93 for adults). Mean distance covered in initial dispersal was greater for females (246.2 km) than for males (38.7 km).Conclusion Our results provided information on dispersal and survival rate of reintroduced Ospreys in a Mediterranean area. Despite low apparent survival in the first year, the high survival rates found in immatures and adults suggested favourable conditions for this new population. The study of demographic parameters is important for calibrating management actions aimed at the establishment of a self-sustaining Osprey population.

Breeding experience and foraging behaviour of Imperial Shags (Leucocarbo atriceps) in Argentina

Breeding success depends on efficient foraging behaviour by breeding individuals. However, foraging skills are acquired over time and foraging behaviour is expected to be optimised over the course of successive breeding events. In 2008, 32 Imperial Shags (Leucocarbo atriceps) breeding at the Punta León colony, Argentina, either with prior breeding experience (4 males and 9 females) or without (10 males, 9 females), were fitted with tracking devices to record one foraging trip during the early chick-rearing period. Birds did not differ in the maximum distance from the colony or duration of foraging trips, but males spent more time flying than females. Inexperienced individuals spent more time diving than experienced individuals, and inexperienced males in particular spent more time flying and performed more dives than other birds. Experienced males and females differed in the areas that they searched most intensively, and inexperienced males used different areas from experienced males. This study shows the importance of considering sex-and age-related differences when studying behavioural aspects, such as foraging patterns in seabirds.

Impact of supplementary feeding on reproductive success of white storks.

European white stork (Ciconia ciconia) populations have been object to several conservation measures such as reintroduction programs, habitat improvement or supplementary feeding in the last decades. Although recent white stork censuses revealed an upward trend of most of the western populations, evaluations of the relative importance of certain conservation measures are still scarce or even lacking. In our study we analyzed the effect of supplementary feeding on the reproductive success of white storks in conjunction with other factors such as weather or nest site characteristics. We present data of 569 breeding events at 80 different nest sites located in variable distances to an artificial feeding site at Affenberg Salem (south-western Germany) collected from 1990–2012. A multilevel Poisson regression revealed that in our study population (1) reproductive success was negatively affected by monthly precipitation in April, May and June, (2) pairs breeding on power poles had a lower reproductive success than pairs breeding on platforms or trees and (3) reproductive success was significantly higher in pairs breeding in close distance to the feeding site. The number of fledglings per nest decreased by 8% per kilometer distance to the feeding site. Our data suggest that supplementary feeding increases fledgling populations which may be a tool to attenuate population losses caused by factors such as habitat deterioration or unfavorable conditions in wintering habitats.

Male-male clasping may be part of an alternative reproductive tactic in Xenopus laevis.

Male Xenopus laevis frogs have been observed to clasp other males in a sustained, amplectant position, the purpose of which is unknown. We examined three possible hypotheses for this counter-intuitive behavior: 1) clasping males fail to discriminate the sex of the frogs they clasp; 2) male-male clasping is an aggressive or dominant behavior; or 3) that males clasp other males to gain proximity to breeding events and possibly engage in sperm competition. Our data, gathered through a series of behavioral experiments in the laboratory, refute the first two hypotheses. We found that males did not clasp indiscriminately, but showed a sex preference, with most males preferentially clasping a female, but a proportion preferentially clasping another male. Males that clasped another male when there was no female present were less likely to “win” reproductive access in a male-male-female triad, indicating that they did not establish dominance through clasping. However, those males did gain proximity to oviposition by continued male-male clasping in the presence of the female. Thus, our findings are consistent with, but cannot confirm, the third hypothesis of male-male clasping as an alternative reproductive tactic.

Age-specific cost of first reproduction in female southern elephant seals.

When to commence breeding is a crucial life-history decision that may be the most important determinant of an individual's lifetime reproductive output and can have major consequences on population dynamics. The age at which individuals first reproduce is an important factor influencing the intensity of potential costs (e.g. reduced survival) involved in the first breeding event. However, quantifying age-related variation in the cost of first reproduction in wild animals remains challenging because of the difficulty in reliably recording the first breeding event. Here, using a multi-event capture-recapture model that accounts for both imperfect detection and uncertainty in the breeding status on an 18-year dataset involving 6637 individuals, we estimated age and state-specific survival of female elephant seals (Mirounga leonina) in the declining Macquarie Island population. We detected a clear cost of first reproduction on survival. This cost was higher for both younger first-time breeders and older first-time breeders compared with females recruiting at age four, the overall mean age at first reproduction. Neither earlier primiparity nor delaying primiparity appear to confer any evolutionary advantage, rather the optimal strategy seems to be to start breeding at a single age, 4 years.

Natural History of an Introduced Population of Squirrel Treefrogs (Hyla squirella) on the Delmarva Peninsula

AbstractHyla squirella was not known to occur on Delmarva until an established population was discovered at the southernmost tip of the peninsula in the Eastern Shore of Virginia Natural Wildlife Refuge in 2005. Male vocalizations were heard periodically throughout the refuge during daytime and evening hours from 27 May to 7 September 2006. Large choruses of males were heard 27 May and 9 and 27 June 2006. A large breeding event was observed on 9 June in a temporary pond. The smallest mature male was 27 mm SVL and weighed 1.1 g and the smallest mature female was 31 mm SVL, 1.7 g, and gravid. Mean adult male SVL was significantly smaller than the mean for adult females. Metamorphs found on 19 October averaged 13.0 ± 0.21 mm SVL and weighed 0.164 ± 0.009 g. Ecological and life history parameters of the introduced population of H. squirella on Delmarva do not appear to differ from those of populations in the natural portion of its range. This established population offers opportunities to elucidate a variety of questions about northward range expansion, genetics, and tolerance limits.

The breeding and foraging ecology and abundance of the Princess Parrot (Polytelis alexandrae) during a population irruption

The Princess Parrot (Polytelis alexandrae) is an Australian endemic that displays irruptive population dynamics. We studied a breeding event in the southern Northern Territory in 2010–11, which followed a peak in primary productivity stimulated by extended above average rainfall. Birds were present from mid-July 2010 to February 2011, with highest numbers in August-November 2010. The maximum count was 172 birds. Multiple nests, all in mature Marble Gum (Eucalyptus gongylocarpa), were detected monthly from August to November 2010 and a single nest in January 2011. Birds fed on flowers, seeds and other material of 11 plant species, both on the ground and within foliage. The decrease in abundance of Parrots over time coincided with a decrease in plant species richness and flower abundance and an increase in availability of seeds and fruit. The area had not been burnt since 2002 indicating that fire-stimulated primary production does not trigger breeding. Despite the time since fire there was evidence of severe effects of past fires. Management of the area now involves efforts to reduce the incidence of high-intensity fires, control of buffel grass (Cenchrus ciliaris) and annual monitoring for the presence of Princess Parrots. Our research highlights the importance of ecological information for making effective conservation management recommendations.

Maximizing colonial waterbirds' breeding events using identified ecological thresholds and environmental flow management

Global wetland biodiversity loss continues unabated, driven by increased demand for freshwater. A key strategy for conservation management of freshwater systems is to maintain the quantity and quality of the natural water regimes, including the frequency and timing of flows. Formalizing an ecological model depicting the key ecological components and the underlying processes of cause and effect is required for successful conservation management. Models linking hydrology with ecological responses can prove to be an invaluable tool for robust decision-making of environmental flows. Here, we explored alternative water management strategies and identified maximal strategies for successful long-term management of colonial waterbirds in the Macquarie Marshes, Australia. We modeled fluctuations in breeding abundances of 10 colonial waterbird species over the past quarter century (1986-2010). Clear relationships existed between flows and breeding, both in frequencies and total abundances, with a strong linear relationship for flows > 200 GL. Thresholds emerged for triggering breeding events in all 10 species, but these varied among species. Three species displayed a sharp threshold response between 100 GL and 250 GL. These had a breeding probability of 0.5 when flows were > 180 GL and a 0.9 probability of breeding with flows > 350 GL. The remaining species had a probability greater than 0.5 of breeding with flows > 400 GL. Using developed models, we examined the effects of five environmental flow management strategies on the variability of flows and subsequent likelihood of breeding. Management to different target volumes of environmental flows affected overall and specific breeding probabilities. The likelihood of breeding for all 10 colonial waterbirds increased from a regulated historical mean (+/-SD) of 0.36 +/- 0.09 to 0.53 +/- 0.14, an improvement of 47.5% +/- 18.7%. Management of complex ecosystems depends on good understanding of the responses of organisms to the main drivers of change. Considerable opportunity exists for implementing similar frameworks for other ecosystem attributes, following understanding of their responses to the flow regime, achieving a more complete model of the entire ecosystem.

From rags to riches and back again: fluctuations in the Green and Golden Bell FrogLitoria aureapopulation at Nowra on the south coast of New South Wales

Systematic (time constrained) and targeted surveys were conducted from 1996-2014 for the green and golden bell frog Litoria aurea on the Crookhaven River floodplain, east of Nowra on the south coast of New South Wales. In April 2008, a large number of metamorphlings were observed at Brundee Swamp Nature Reserve. This was followed by a significant recruitment of frogs so that by February 2010 L. aurea were recorded breeding nearby in Worrigee and Terara Swamps. At the end of April 2010 tens of thousands of metamorphling L. aurea dispersed from these wetlands across the floodplain. So-called explosive breeding events have been reported for this species before but never have they been documented. In December 2010 L. aurea again bred in Worrigee (and presumably Terara Swamp) and in early April 2011 adult and sub-adult animals appeared to have dispersed a distance of approximately 4 km south-west and 11 km to the south-east of Brundee Swamp. This expansion in distribution and abundance resulted in the recoloni...

Fluctuating food resources influence developmental plasticity in wild boar

To maximize long-term average reproductive success, individuals can diversify the phenotypes of offspring produced within a reproductive event by displaying the 'coin-flipping' tactic. Wild boar (Sus scrofa scrofa) females have been reported to adopt this tactic. However, whether the magnitude of developmental plasticity within a litter depends on stochasticity in food resources has not been yet investigated. From long-term monitoring, we found that juvenile females produced similar-sized fetuses within a litter independent of food availability. By contrast, adult females adjusted their relative allocation to littermates to the amount of food resources, by providing a similar allocation to all littermates in years of poor food resources but producing highly diversified offspring phenotypes within a litter in years of abundant food resources. By minimizing sibling rivalry, such a plastic reproductive tactic allows adult wild boar females to maximize the number of littermates for a given breeding event.

Maternal Provisioning Trade-Off Strategies ofAgalychnis callidryas

The trade-offs associated with maternal provisioning strategies in amphibians are well documented. Relevant studies typically demonstrate that female body size is correlated positively with provisioning of resources to offspring; females may augment offspring resources by increasing the size of the clutch or increasing individual egg size. Alternatively, females may practice one or more alternative strategies, including increasing variation of egg size within the clutch or switching from one strategy to another between breeding events. For this study we examined the trade-off provisioning strategy employed by Red-eyed Treefrogs (Agalychnis callidryas), a species with predator-induced flexibility in hatching age. We recorded the mass of 30 females found amplexed with males in the field, as well as clutch size, individual egg diameter, and total yolk volume resulting from the pairings. Our hypothesis that female mass would be correlated positively with total yolk volume was not supported, nor were most other traditionally expected trade-offs. However, we found that there was a significant difference between the largest and smallest eggs within clutches, and that clutches differed in egg size variability, with larger females tending to produce clutches with less variation in egg size. For the largest females, there was a positive trend between female mass and total yolk volume, and a significant and positive relationship between female mass and total number of eggs. These data suggest that a combination of maternal provisioning strategies may be present in this population of A. callidryas, which is likely an adaptive response to an unpredictable environment.

Reproductive pattern in the southernmost populations of South American redbelly toads

Anurans can be classified as explosive or prolonged breeders. In species with short breeding periods, intensive competition for females is expected. We analyse the temporal breeding pattern of Melanophryniscus aff. montevidensis, a bufonid inhabiting grasslands of Argentina, whose breeding is concentrated in events of short duration. Males are active during more than one breeding event per season, whereas most females take part in a single event per season. Active males outnumbered females by up to 14 times at one event, operational sex ratio (OSR) ranged from 0.07 to 0.75 and intensity of sexual selection (I s) from 0.69 to 24. We found a negative association between I s and OSR, but no correlation between number of active males per event and OSR or I s. The OSR is the key that regulates the intensity of sexual selection, nevertheless, and in spite of being explosive breeders, females would potentially have chances to select their mate.

Review of the breeding status of birds in Rio Grande do Sul, Brazil

Information on the breeding biology of birds is essential for improving avian life-history theory and implementing sound management and conservation actions for these organisms. Comprehensive reviews of this kind of information are lacking for most Neotropical regions, including Rio Grande do Sul, the southernmost Brazilian state. Aiming to update the knowledge on the reproductive status of birds in Rio Grande do Sul, we reviewed breeding records of all potential breeding species recorded in the state using a set of predefined, restrictive criteria for accepting breeding evidences as effective. Data satisfying our criteria were available for 165 species in the literature. We also collected novel breeding information obtained in the state for an additional 126 species, including observations for several species whose reproductive biology is poorly known. Among these are birds previously unknown to breed in Brazil. This new data and the critical review of the previous information resulted in a total of 291 species for which breeding evidences are accepted as effective. This corresponds to 54.7% of the 532 species considered either confirmed or potential breeders in the state. In addition to providing information on nesting dates, clutch size, nest architecture and breeding behavior of south Brazilian birds, our review serves as a benchmark for the adequate assessment of avian breeding records elsewhere. We hope to stimulate observers to rigorously document breeding events, especially for taxa for which basic information is lacking.

Population dynamics of two caprellid species (Crustaceae: Amphipoda: Caprellidae) from shallow hard bottom assemblages

The community structure of caprellids associated with shallow hard bottom assemblages was studied in four locations around Pagasitikos Gulf, western coast of the Aegean Sea. Samplings were carried out every 3 months from April 2009 to April 2010. Samples were collected by scraping off the hard substrate, using 400-cm2 handmade quadrate samplers. Water temperature, pH, salinity, dissolved oxygen and sea current velocity were measured in situ. Two caprellid species were found, Caprella acanthifera and Phtisica marina, with a clear dominance of C. acanthifera at all locations. The abundance of both species followed a seasonal pattern with a peak in spring or summer and a decline in winter. Lower abundances were detected at the locations with high current velocity and higher abundances at the locations with low water flow speed. This is an indication that the species might prefer areas with low hydrodynamism. Strong sexual dimorphism in body size was observed for both species, and the sex ratio was 1:1 throughout the samplings. It appears that reproduction for both species is continuous throughout the year, with a possible major breeding event in winter.

The Effect of Nonindependent Mate Pairing on the Effective Population Size

The effective population size (N(e)) quantifies the effectiveness of genetic drift in finite populations. When generations overlap, theoretical expectations for N(e) typically assume that the sampling of offspring genotypes from a given individual is independent among successive breeding events, even though this is not true in many species, including humans. To explore the effects on N(e) of nonindependent mate pairing across breeding events, we simulated the genetic drift of mitochondrial DNA, autosomal DNA, and sex chromosome DNA under three mating systems. Nonindependent mate pairing across breeding seasons has no effect when all adults mate pair for life, a small or moderate effect when females reuse stored sperm, and a large effect when there is intense male-male competition for reproduction in a harem social system. If adult females reproduce at a constant rate irrespective of the type of mate pairing, the general effect of nonindependent mate pairing is to decrease N(e) for paternally inherited components of the genome. These findings have significant implications for the relative N(e) values of different genomic regions, and hence for the expected levels of DNA sequence diversity in these regions.

High prevalence of infection in tadpoles increases vulnerability to fungal pathogen in high-Andean amphibians

The amphibian pathogen Batrachochytrium dendrobatidis (Bd) is causing population declines and species extirpations worldwide. Montane amphibians in tropical and temperate regions are especially vulnerable to chytridiomycosis. High-elevation amphibian assemblages typically include few species, so that epizootics should be limited once high frog mortality hinders transmission of the pathogen. We hypothesized that tadpoles of a high-elevation frog in the Peruvian Andes, Telmatobius jelskii, could function as reservoir for Bd in Andean streams. We postulated that, for tadpoles to function as an efficient reservoir of Bd, they should inhabit streams over extended periods of time, and have high prevalence of Bd. We surveyed streams between 2400 and 4850m in the wet and dry seasons of 2010, where we captured, swabbed and determined the developmental stage of 458 tadpoles. We found that cohorts of tadpoles overlap continuously in these streams, as a consequence of multiple breeding events throughout the year. Prevalence of Bd among tadpoles averaged 53.1% (95% confidence interval: 49.8–56.3%); 8 out of 13 streams inhabited by T. jelskii had a prevalence greater than 50%. Prevalence of Bd was also higher during the dry season and increased with the age of the tadpoles. Our results support the hypothesis that the year-long presence of infected tadpoles in streams makes high-Andean Telmatobius frogs especially vulnerable to chytridiomycosis. The genus is already extirpated in Ecuador, and has been observed to decline rapidly in Peru, Bolivia and Argentina. Conservation strategies to mitigate the impact of Bd on populations of Telmatobius should consider aquatic life-stages.

Whole genome resequencing in tomato reveals variation associated with introgression and breeding events

BackgroundOne of the goals of genomics is to identify the genetic loci responsible for variation in phenotypic traits. The completion of the tomato genome sequence and recent advances in DNA sequencing technology allow for in-depth characterization of genetic variation present in the tomato genome. Like many self-pollinated crops, cultivated tomato accessions show a low molecular but high phenotypic diversity. Here we describe the whole-genome resequencing of eight accessions (four cherry-type and four large fruited lines) chosen to represent a large range of intra-specific variability and the identification and annotation of novel polymorphisms.ResultsThe eight genomes were sequenced using the GAII Illumina platform. Comparison of the sequences with the reference genome yielded more than 4 million single nucleotide polymorphisms (SNPs). This number varied from 80,000 to 1.5 million according to the accessions. Almost 128,000 InDels were detected. The distribution of SNPs and InDels across and within chromosomes was highly heterogeneous revealing introgressions from wild species and the mosaic structure of the genomes of the cherry tomato accessions. In-depth annotation of the polymorphisms identified more than 16,000 unique non-synonymous SNPs. In addition 1,686 putative copy-number variations (CNVs) were identified.ConclusionsThis study represents the first whole genome resequencing experiment in cultivated tomato. Substantial genetic differences exist between the sequenced tomato accessions and the reference sequence. The heterogeneous distribution of the polymorphisms may be related to introgressions that occurred during domestication or breeding. The annotated SNPs, InDels and CNVs identified in this resequencing study will serve as useful genetic tools, and as candidate polymorphisms in the search for phenotype-altering DNA variations.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-14-791) contains supplementary material, which is available to authorized users.