Breeding Stage Research Articles

Adult piping plover habitat selection varies by behavior

AbstractPiping plovers (Charadrius melodus, “plover”) are beach‐nesting shorebirds that occupy their breeding range from about April to August. When plovers arrive on the breeding grounds, they select and defend territories, lay and incubate eggs, and tend to precocial broods; additionally, adults can return to a non‐breeding stage after final nest failure or after chicks have fledged or died. We hypothesized that habitat selection would differ among these phases of the breeding cycle because the needs of the birds differ among them. We monitored plovers on Fire Island and Westhampton Island, New York, during 2016–2018, recording individual locations of adult birds. We used resource selection functions to determine whether breeding stage (pre‐breeding, nesting, brooding, post‐breeding), breeding status (breeding, non‐breeding), or instantaneous behavior class (parental [incubating, brooding, and accompanying chicks], non‐parental [all other behaviors]) best explained relationships with landscape characteristics known to be important to breeding plovers. Differences in habitat selection between adults exhibiting parental behaviors and non‐parental behaviors had the greatest support in our model set. Compared with non‐parental plovers, plovers displaying parental behavior selected areas closer to bay intertidal habitats and with proportionally more dry sand in the surrounding landscape than other habitat types. Non‐parental plovers avoided areas with more dry sand and did not select for or against bay intertidal habitats. Additionally, non‐parental plovers avoided development and higher elevation areas more than parental plovers, although both exhibited avoidance of these features. The total amount of suitable habitat ranged from 100.14 ha to 151.07 ha. In each year, there was more suitable habitat for parental plovers (129.57–151.07 ha) than non‐parental plovers (100.14–108.83 ha). Due to these differences, when improving, creating, and protecting plover habitat, managers should consider habitat needs of both behavioral classes. Habitat management for nesting and brooding plovers should focus on maintaining vegetation‐free sand and access to foraging habitat, and habitat management for non‐parental plovers should focus on flat, low‐elevation foraging habitats, particularly areas further from development.

Novel Tools for Adjusting Spatial Variability in the Early Sugarcane Breeding Stage.

The detection of spatial variability in field trials has great potential for accelerating plant breeding progress due to the possibility of better controlling non-genetic variation. Therefore, we aimed to evaluate a digital soil mapping approach and a high-density soil sampling procedure for identifying and adjusting spatial dependence in the early sugarcane breeding stage. Two experiments were conducted in regions with different soil classifications. High-density sampling of soil physical and chemical properties was performed in a regular grid to investigate the structure of spatial variability. Soil apparent electrical conductivity (ECa) was measured in both experimental areas with an EM38-MK2® sensor. In addition, principal component analysis (PCA) was employed to reduce the dimensionality of the physical and chemical soil data sets. After conducting the PCA and obtaining different thematic maps, we determined each experimental plot’s exact position within the field. Tons of cane per hectare (TCH) data for each experiment were obtained and analyzed using mixed linear models. When environmental covariates were considered, a previous forward model selection step was applied to incorporate the variables. The PCA based on high-density soil sampling data captured part of the total variability in the data for Experimental Area 1 and was suggested to be an efficient index to be incorporated as a covariate in the statistical model, reducing the experimental error (residual variation coefficient, CVe). When incorporated into the different statistical models, the ECa information increased the selection accuracy of the experimental genotypes. Therefore, we demonstrate that the genetic parameter increased when both approaches (spatial analysis and environmental covariates) were employed.

Combination Breeding and Marker-Assisted Selection to Develop Late Blight Resistant Potato Cultivars

(1) Background: Although resistance to pathogens and pests has been researched in many potato cultivars and breeding lines with DNA markers, there is scarce evidence as to the efficiency of the marker-assisted selection (MAS) for these traits when applied at the early stages of breeding. A goal of this study was to estimate the potential of affordable DNA markers to track resistance genes that are effective against the pathogen Phytophthora infestans (Rpi genes), as a practical breeding tool on a progeny of 68 clones derived from a cross between the cultivar Sudarynya and the hybrid 13/11-09. (2) Methods: this population was studied for four years to elucidate the distribution of late blight (LB) resistance and other agronomical desirable or simple to phenotype traits such as tuber and flower pigmentation, yield capacity and structure. LB resistance was phenotypically evaluated following natural and artificial infection and the presence/absence of nine Rpi genes was assessed with 11 sequence-characterized amplified region (SCAR) markers. To validate this analysis, the profile of Rpi genes in the 13/11-09 parent was established using diagnostic resistance gene enrichment sequencing (dRenSeq) as a gold standard. (3) Results: at the early stages of a breeding program, when screening the segregation of F1 offspring, MAS can halve the workload and selected SCAR markers for Rpi genes provide useful tools.

Estimation features of winter bread wheat quality by the method of sedimentation analysis

It is known that the breeding process is in a great need for fast methods, working on minimal weights of experimental material and revealing the qualitative potential of the varieties. For this purpose, in order to get rid of unpromising numbers, the laboratory assessments widely use a sedimentation analysis, this type of analysis being the main one at the primary stages of breeding and when estimating winter wheat in the pre-harvesting period. The purpose of the current study was to identify the most valuable genotypes in seed plots by sedimentation analysis to optimize the breeding process of winter bread wheat for grain quality. The sedimentation index was estimated by the method using a 2% surfactant (SAS) solution of the sodium dodecyl sulfate (SDS) and 9.4% lactic acid. Gluten content and its quality, volumetric bread yield and falling number were assessed according to generally accepted methods. For the most accurate interpretation of the study results there has been used a one-way analysis of variance. The range of variation of the sedimentation index in the seed plot of CVT was 35–57 ml (2017); 50–83 ml (2018); 56–84 ml (2019); in KP-1 it was 44–95 ml (there were analyzed 945 samples); in KP-2 it was 50–94 ml (there were analyzed 100 samples). Inthe studied seed plot of CVT, which was laid fallow, 25 of 36 variety samples were very strong in quality; 7 ones were strong; 4 ones were medium; there were not identified any satisfactory and weak samples. As for the seed plot KP-2, 88 of 100 were very strong, 11 ones were strong and only one sample was average in quality. In the seed plot KP-1 480 of 945 were very strong (51%); 440 samples were strong (46%), and only 3% (25 pieces) were average in quality; there were not identified any satisfactory and weak samples.

Foraging strategies and physiological status of a marine top predator differ during breeding stages

Habitat characteristics determine the presence and distribution of trophic resources shaping seabirds' behavioural responses which may result in physiological consequences. Such physiological consequences in relation to foraging strategies of different life-history stages have been little studied in the wild. Thus, we aim to assess differences in oxidative status, condition (fat stores, i.e. triglyceride levels, TRI), stress (Heterophil/Lymphocyte (H/L) ratio), and leukocyte profiles between incubation and chick rearing highlighting the role of foraging strategies in a seabird (Calonectris diomedea). Chick rearing was more energetically demanding and stressful than incubation as demonstrated by high stress levels (H/L ratio and leukocytes) and lower body stores (assessed by TRI and the increment of weight) due to the high energy requirements of rearing chicks. Also, our results make reconsider the simplistic trade-off model where reproduction increases metabolism and consequently the rate of oxidative stress. In fact, high energy expenditure (VeDBA) during chick rearing was correlated with low levels of oxidative damage likely due to mechanisms at the level of mitochondrial inner membranes (uncoupling proteins or low levels of oxygen partial pressure). Further (more distant) and longer (more days) foraging trips were performed during incubation, when antioxidants showed low levels compared to chick rearing due to incubation fasting, a change in diet, or a combination of these factors; but unlikely because of oxidative shielding since no relation was found between oxidative damage and antioxidant capacity. Males showed higher numbers of monocytes which were positively correlated with antioxidant capacity compared to females, suggesting sexual differences in immune profiles. Species-specific costs and energetic demands of different breeding phases trigger behavioural and physiological adjustments.

Immune function differs among tropical environments but is not downregulated during reproduction in three\xa0year-round breeding equatorial lark populations

Seasonal variation in immune function can be attributed to life history trade-offs, and to variation in environmental conditions. However, because phenological stages and environmental conditions co-vary in temperate and arctic zones, their separate contributions have not been determined. We compared immune function and body mass of incubating (female only), chick-feeding (female and male), and non-breeding (female and male) red-capped larks Calandrella cinerea breeding year-round in three tropical equatorial (Kenya) environments with distinct climates. We measured four immune indices: haptoglobin, nitric oxide, agglutination, and lysis. To confirm that variation in immune function between breeding (i.e., incubating or chick-feeding) and non-breeding was not confounded by environmental conditions, we tested if rainfall, average minimum temperature (Tmin), and average maximum temperature (Tmax) differed during sampling times among the three breeding statuses per location. Tmin and Tmax differed between chick-feeding and non-breeding, suggesting that birds utilized environmental conditions differently in different locations for reproduction. Immune indices did not differ between incubating, chick-feeding and non-breeding birds in all three locations. There were two exceptions: nitric oxide was higher during incubation in cool and wet South Kinangop, and it was higher during chick-feeding in the cool and dry North Kinangop compared to non-breeding birds in these locations. For nitric oxide, agglutination, and lysis, we found among-location differences within breeding stage. In equatorial tropical birds, variation in immune function seems to be better explained by among-location climate-induced environmental conditions than by breeding status. Our findings raise questions about how within-location environmental variation relates to and affects immune function.

Phytosanitary monitoring of the narrow-leaved lupine collection of VIR in the northwest of Russia

Background. Narrow-leaved lupine (Lupinus angustifolius L.) is an important high-protein forage and green manure crop, also promising for food use. This is a plastic species produced under various ecogeographic conditions and the only cultivated species of lupine adapted to high northern latitudes – up to 60° NL. Gradual expansion of lupine production areas led to the accumulation of pathogens, damage to lupine crops by harmful organisms, and significant harvest losses. Breeding and cultivating resistant varieties is the most profitable and environmentally sound way to control diseases and pests. Studying the species composition of pathogens and searching for source material are the necessary stages of plant breeding for immunity.Materials and methods. A set of 101 accessions of L. angustifolius from the VIR collection were studied in the northwest of the Russian Federation (Pushkin, St. Petersburg) in 2019, and 62 accessions from the same set in 2020. Mycological examination of the affected leaves was carried out on potato sucrose agar medium under laboratory conditions. The degree of damage to plants by diseases and infestation by pests was assessed during the period of flowering, fruit formation and ripening using point scales.Results and conclusions. A wide range of harmful organisms were identified for their negative impact on the growth and development of narrow-leaved lupine plants. The dominant pest was the lupine aphid (Macrosiphum albifrons Essig), discovered in Russia for the first time. A whole set of fungal pathogens was identified, among which the most common and harmful were the causative agents of Fusarium, brown leaf spot, powdery mildew, gray mold, and Sclerotinia stem rot. Narrow-leaved lupine accessions with weak degrees of pathogenic damage were selected.

Eavesdropping on Referential Yellow Warbler Alarm Calls by Red-Winged Blackbirds Is Mediated by Brood Parasitism Risk

Referential alarm calls that denote specific types of dangers are common across diverse vertebrate lineages. Different alarm calls can indicate a variety of threats, which often require specific actions to evade. Thus, to benefit from the call, listeners of referential alarm calls must be able to decode the signaled threat and respond to it in an appropriate manner. Yellow warblers (Setophaga petechia) produce referential “seet” calls that signal to conspecifics the presence of nearby obligate brood parasitic brown-headed cowbirds (Molothrus ater), which lay their eggs in the nests of other species, including yellow warblers. Our previous playback experiments have found that red-winged blackbirds (Agelaius phoeniceus), a species also parasitized by brown-headed cowbirds, eavesdrop upon and respond strongly to yellow warbler seet calls during the incubation stage of breeding with aggression similar to responses to both cowbird chatters and predator calls. To assess whether red-winged blackbird responses to seet calls vary with their own risk of brood parasitism, we presented the same playbacks during the nestling stage of breeding (when the risk of brood parasitism is lower than during incubation). As predicted, we found that blackbirds mediated their aggression toward both cowbird chatter calls and the warblers’ anti-parasitic referential alarm calls in parallel with the low current risk of brood parasitism during the nestling stage. These results further support that red-winged blackbirds flexibly respond to yellow warbler antiparasitic referential calls as a frontline defense against brood parasitism at their own nests.

Estimation of oil flax intra-species hybrids by breeding-genetic parameters for the creation of material with altered habitus

The creation of a selection material for oil flax with a large number of stems, side shoots and an optimal height for cultivation is an urgent task, since the formation of additional bolls on the side shoots will increase the yield of seeds, and an increase in the vegetative mass of plants will increase its competitiveness against weeds and reduce moisture evaporation. from the soil surface. The use of genetic and statistical parameters allows to efficiently plan and carry out breeding work for oil flax, purposefully select parental pairs in crosses, select valuable genotypes, and reject low-value material at the first stages of breeding. The purpose of this study is to identify promising interspecific hybrid combinations based on breeding and genetic parameters for creating a new breeding material for multi-stem and multi-shoot forms. The studies were carried out at the Institute of Oilseeds NAАS of Ukraine in 2018-2020. The material of the research was F1 and F2 hybrids obtained in a system of dialle crosses with the participation of two wild species (L. angustifolium and L. hispanicum) and three samples of cultivated flax – L 6 (India), M 32/2 (Ukraine), L 5 (Czech Republic). The degree of dominance of traits in hybrids of the first generation was determined by the formula (Beil, Atkins 1965). The degree of heterosis is according to the formula (Rasul et al 2002). The coefficient of heritability in hybrids of the second generation – according to the formula (Ayala 1984). As a result of the research, interspecific hybrid combinations have been identified that are promising for obtaining breeding material with a modified habit: – with the effect of heterosis: by plant height – seven combinations of F1 (Ht = 3,58-13,76%); the number of stems per plant – one (Ht = 35,77%); the number of side shoots is six (Ht = 5,68-43,79%). The most valuable are combinations in which the effect of heterosis manifested itself simultaneously on two grounds – the height of the plants and the number of lateral shoots on the plant – L. angustifolium / L 6, L 5 / L. angustifolium, L. hispanicum / L 6, L 6 / L. hispanicum; plant height and number of stems per plant – M 32/2 / L. hispanicum; – with high coefficients of heritability: by plant height – four combinations of F2 (H = 0,67-0,87); the number of stems per plant – six (H = 0,66-0,81); the number of side shoots is four (H = 0,66-0,72). Interspecific combinations of L. hispanicum / M 32/2 and M 32/2 / L. hispanicum were distinguished by high rates of heritability by two characteristics – the number of stems and the number of lateral shoots on the plant. The potential of the selected combinations will be used in the further breeding process for increased branching.

Duration of the period for creating apple cultivars and tasks on reducing it

The greatest period of time was spent on creating a cultivar at the first stage of breeding in our institution, when we did not have proper experience in apple breeding. For example, in the sixties of the last century, cultivars Pepin Orlovsky, Orlovskaya Zarya, Nizkorosloye and Sinap Orlovsky were created, in which the period from hybridization to inclusion in the State Register of Breeding Achievements allowed for use was 48, 45, 43 and 34 years respectively. With the acquisition of breeding experience in selecting the initial parent cultivars and improving the methods of growing seedlings in the breeding orchard (growing hybrid seedlings in the crown of a semi-dwarf or dwarf rootstock or on insert rootstocks) the period was significantly reduced — to 20 years for such cultivars as Yablochny Spas, Aleksander Boyko, Maslovskoye and a number of others. The first immune domestic cultivar Imrus (immune russian) was created and included in the State Register of Breeding Achievements allowed for use in just 15 years. It took 16 years to create the Rozhdestvenskoye cultivar. Naturally, on average, much less time was spent on the creation of columnar cultivars due to the earlier entry into flowering and fruiting. Due to the fact that high agricultural technology improves the growth processes of hybrid seedlings in the breeding nursery and in the breeding orchard and reduces their juvenile period, it must necessarily be carried out. This report gives a brief production and biological characteristics of the best apple cultivars of the Institute’s breeding. One of the best cultivars immune to scab is the winter cultivar Imrus (immune russian). The cultivar has a rapid fruitfulness and high yield. Its fruit can be stored in the cold storage until mid-March. Veniaminovskoye and Kandil Orlovsky are also valuable immune cultivars. The fruits of Veniaminovskoye are stored in the refrigerator until the end of February; the cultivar is characterized by the dessert quality of the fruit. The advantages of Kandil Orlovsky are also high rapid fruitfulness and productivity. Triploid Aleksander Boyko is immune to scab and has large size of fruit (220 g) and regular fruiting. Columnar cultivars Priokskoye and Poezia are of great interest. Priokskoye is characterized by scab immunity and high productivity. The fruits are characterized by marketability and high consumer qualities. In the refrigerator, the fruits can be stored until February. It took only 18 years to create this cultivar. The columnar scab-immune cultivar Poezia is characterized by high rapid fruitfulness. Its fruits are stored in the refrigerator until February.

Neither sex appears to benefit from divorce within migratory Northern Flickers consistent with accidental loss and bet-hedging

AbstractDivorce is widespread among species of birds and may either be an adaptive strategy to secure a better mate or territory or be a nonadaptive result of a failure to maintain the pairbond. I examined the causes and consequences for divorce in the Northern Flicker (Colaptes auratus), a migratory woodpecker with a high annual mortality rate. In a long-term population study of 1,793 breeding pairs over 17 years, the within-season divorce rate was 4.6% and the between-season divorce rate was 15.5%. Retained pairs within a season initiated their renest 5 days faster than divorced birds that had no greater fledgling production, suggesting that within-season divorce was making the best of a bad job with severe time constraints. Poor performance in the year prior to divorce was not strongly associated with divorce, and analysis of multiple breeding stages revealed that divorcing individuals in the subsequent year had later laying dates, smaller clutches, and fewer fledglings than retained pairs but no better performance than widowed individuals. Analyzing the data separately by sex showed that neither males nor females benefitted from divorce. Thus, there is a reproductive cost linked to finding a new partner per se, but no reproductive advantage associated with divorce. New mates after divorce were usually not older (not higher quality) than previous mates, so intrasexual competition was probably not driving partnership splits. The most plausible explanation seems to be a “bet-hedging” hypothesis in which birds re-pair rapidly in spring if their previous mate does not quickly arrive during spring migration. Divorce in Northern Flickers does not appear to be adaptive and future studies on arrival and interactions of individuals in spring will elucidate proximate constraints on relocating the previous partner.

Genetic Analysis of Yield and Quality Characteristics in Provitamin A Hybrid Cassava Families in Ghana

Cassava is the most widely cultivated and consumed crop in Ghana. Malnutrition is endemic in cassava-producing regions of Africa, partly due to the low micronutrient content of this crop. The aim of this study was to generate genetic information on characteristics such as total carotenoid content, dry matter content, root weight and number, and cassava mosaic disease (CMD), and their possible combination in cassava clones, using a North Carolina II breeding scheme. Five genetically diverse yellow-fleshed clones at advanced selection stages, with CMD resistance, were used as females and two high dry matter content white-fleshed clones, selected from farmers’ fields in Ghana, were used as males. Ten F1 families were generated, and evaluated at two locations in Ghana. General combining ability (GCA) mean squares were larger than specific combining ability (SCA) mean squares for harvest index, CMD, and carotenoid content, indicating additive genetic effects. The positive significant correlations that were observed between pulp color and carotenoid content; carotenoid content and CMD; pulp color and CMD; and pulp color and cortex color, make the screening of large numbers of progenies possible in the cassava breeding program. This could allow breeders to combine carotenoid content and CMD at the early breeding stages through visual assessment of pulp color and CMD symptoms. Large numbers of genotypes can be evaluated and a few can be selected to be quantified for carotenoid content at later stages of the breeding program, to save costs. One of the parents (P6), showed positive GCA effects for carotenoid content, dry matter content, CMD and storage root weight, hence could be used as a parent to generate clones that combine carotenoid content and dry matter content.

Antibiotic resistance genes in layer farms and their correlation with environmental samples

Livestock farms are generally considered to be the important source of antibiotic resistance genes (ARGs). It is important to explore the spread of ARGs to reduce their harm. This study analyzed 13 resistance genes belonging to 7 types in 68 samples of layer manure including different stages of layer breeding, layer manure fertilizer, and soil from 9 laying hen farms in Guangdong Province. The detection rate of antibiotic resistance genes was extremely high at the layer farm in manure (100%), layer manure fertilizer (100%), and soil (> 95%). The log counts of antibiotic resistance genes in layer manure (3.34–11.83 log copies/g) were significantly higher than those in layer manure fertilizer (3.45–9.80 log copies/g) and soil (0–7.69 log copies/g). In layer manure, ermB was the most abundant antibiotic resistance gene, with a concentration of 3.19 × 109– 6.82 × 1011 copies/g. The average abundances of 5 antibiotic resistance genes were above 1010 copies/g in the descending order ermB, sul2, tetA, sul1, and strB. The relative abundances of ARGs in layer manure samples from different breeding stages ranked as follows: brooding period (BP), late laying period (LL), growing period (GP), early laying period (EL), and peak laying period (PL). There was no significant correlation between the farm scale and the abundance of antibiotic resistance genes. Moreover, the farther away from the layer farm, the lower the abundance of antibiotic resistance genes in the soil. We also found that compost increases the correlation between antibiotic resistance genes, and the antibiotic resistance genes in soil may be directly derived from layer manure fertilizer instead of manure. Therefore, when applying layer manure fertilizer to cultivated land, the risk of antibiotic resistance genes pollution should be acknowledged, and in-depth research should be conducted on how to remove antibiotic resistance genes from layer manure fertilizer to control the spread of antibiotic resistance genes.

Prevalence and multilocus sequence typing of Clostridium perfringens isolated from different stages of a duck production chain

Clostridium perfringens (C. perfringens) is a zoonotic microorganism and rarely reported in duck production chain. This study aimed to investigate prevalence, serotype distribution, antibiotic resistance and genetic diversity of C. perfringens at different stages of a duck production chain. In total, 319 samples were collected from a large-scale rearing and slaughter one-stop enterprise in Weifang, China, of which 42.95% of samples were positive for C. perfringens. All isolates were genotype A. Cpe and cpb2 genes were found in 2.54% and 24.87% of the isolates, respectively. Antimicrobial susceptibility testing revealed that 55.47% of the isolates resistant to at least 5 classes of commonly used antibiotics. Multilocus sequence typing (MLST) results showed that 65 representative isolates were divided into 47 sequences types (STs), 33.85% of them were included into four clonal complexes (CC). Some of isolates from breeding and slaughtering stages were distributed in the same CC or ST, indicating duck products may be contaminated by C. perfringens originated from the breeding stage. Part of duck isolates were distributed in the same CC as human isolates and systemically close with human isolates. The high contamination rates of duck products, the isolates with multi-drug antibiotic resistance or the cpe gene, and the close relationship between strains from human and ducks, indicated potential public health risks, not only control measures at slaughtering stage but also at rearing stage should be considered to reduce this risks.

The significance of biomass allocation to population growth of the invasive species Ambrosia artemisiifolia and Ambrosia trifida with different densities

BackgroundAmbrosia artemisiifolia and Ambrosia trifida are globally distributed harmful and invasive weeds. High density clusters play an important role in their invasion. For these two species, the early settled populations are distributed at low densities, but they can rapidly achieve high population densities in a short period of time. However, their response to intraspecific competition to improve the fitness for rapid growth and maintenance of high population densities remains unclear. Therefore, to determine how these species form and maintain high population densities, individual biomass allocations patterns between different population densities (low and high), and plasticity during seedling, vegetative, breeding and mature stages were compared. In 2019, we harvested seeds at different population densities and compared them, and in 2020, we compared the number of regenerated plants across the two population densities.ResultsMost biomass was invested in the stems of both species. Ambrosia trifida had the highest stem biomass distribution, of up to 78%, and the phenotypic plasticity of the stem was the highest. Path analysis demonstrated that at low-density, total biomass was the biggest contributor to seed production, but stem and leaf biomass was the biggest contributors to high-density populations. The number of seeds produced per plant was high in low-density populations, while the seed number per unit area was huge in high-density populations. In the second year, the number of low-density populations increased significantly. A. artemisiifolia and A. trifida accounted for 75.6% and 68.4% of the mature populations, respectively.ConclusionsHigh input to the stem is an important means to regulate the growth of the two species to cope with different densities. These two species can ensure reproductive success and produce appropriate seed numbers. Therefore, they can maintain a stable population over time and quickly form cluster advantages. In the management, early detection of both species and prevention of successful reproduction by chemical and mechanical means are necessary to stop cluster formation and spread.

Outbreaks of SARS-CoV-2 in naturally infected mink farms: Impact, transmission dynamics, genetic patterns, and environmental contamination.

SARS-CoV-2 infection outbreaks in minks have serious implications associated with animal health and welfare, and public health. In two naturally infected mink farms (A and B) located in Greece, we investigated the outbreaks and assessed parameters associated with virus transmission, immunity, pathology, and environmental contamination. Symptoms ranged from anorexia and mild depression to respiratory signs of varying intensity. Although the farms were at different breeding stages, mortality was similarly high (8.4% and 10.0%). The viral strains belonged to lineages B.1.1.218 and B.1.1.305, possessing the mink-specific S-Y453F substitution. Lung histopathology identified necrosis of smooth muscle and connective tissue elements of vascular walls, and vasculitis as the main early key events of the acute SARS-CoV-2-induced broncho-interstitial pneumonia. Molecular investigation in two dead minks indicated a consistently higher (0.3–1.3 log10 RNA copies/g) viral load in organs of the male mink compared to the female. In farm A, the infected farmers were responsible for the significant initial infection of 229 out of 1,000 handled minks, suggesting a very efficient human-to-mink transmission. Subsequent infections across the sheds wherein animals were being housed occurred due to airborne transmission. Based on a R0 of 2.90 and a growth rate equal to 0.293, the generation time was estimated to be 3.6 days, indicative of the massive SARS-CoV-2 dispersal among minks. After the end of the outbreaks, a similar percentage of animals were immune in the two farms (93.0% and 93.3%), preventing further virus transmission whereas, viral RNA was detected in samples collected from shed surfaces and air. Consequently, strict biosecurity is imperative during the occurrence of clinical signs. Environmental viral load monitoring, in conjunction with NGS should be adopted in mink farm surveillance. The minimum proportion of minks that need to be immunized to avoid outbreaks in farms was calculated at 65.5%, which is important for future vaccination campaigns.

Spatial modeling increases accuracy of selection for Phytophthora infestans‐resistant tomato genotypes

AbstractAt initial breeding stages, using a replicated check design is a viable alternative to reduce experimental field area as well as financial and operational costs. In this situation, spatial modeling could act to increase prediction accuracy of plant genotypic values. The objectives of this study were to demonstrate how spatially adjusted models can be used to reduce experimental error and how to compare statistical models in order to identify the best model for accurate genotype selection. For this purpose, we assessed 200 F3:4 tomato families for their resistance to Phytophthora infestans isolates. NC1CELBR, NC25P, and the cultivar Santa Clara were used as checks. Under field conditions, plants were inoculated with P. infestans isolates and scored according to their level of disease severity. Nine statistical models were adjusted to estimate family genotypic values. The selection of the fittest model was based on residual variance values, accuracy, Akaike and Bayesian information criteria, and the maximum likelihood ratio test. We observed spatial patterns within the experimental field area. Spatial modeling decreased error, which is indicated by the better experimental variation distribution. Residual variance decreased, while genotypic variance increased ∼10% when spatial analysis was used. Spatial analysis improved selection accuracy by 19% compared with the traditional analysis. Therefore, we recommend incorporating spatial modeling into data analysis in breeding trials for disease resistance because it can provide higher gains from selection compared with traditional modeling approaches, depending on the experimental condition.

Defense of Eggs and Chicks in the Polyandrous Pheasant-Tailed Jacana (Hydrophasianus chirurgus) in Sri Lanka: Sex-Roles, Stage of Breeding, and Intruder Type

Pheasant-tailed Jacana (Hydrophasianus chirurgus) have a polyandrous mating system, with females defending larger territories within which males compete for and defend smaller territories. The role of the sexes in territorial defense is therefore potentially complex yet remains poorly known. The sex-roles of defensive responses to intruders were monitored at Anawilundawa Ramsar site, North-Western Province, Sri Lanka, where birds encountered conspecifics and other potential predators: Purple Coots (Porphyrio porphyrio), aerial predators, and other waterbirds. Females contributed to defense, though males performed most defense. Females increased their propensity to defend as breeding progressed; by the chick-rearing phase defense was shared more or less equitably between the sexes. Females were more likely to defend against aerial predators than males, and males were more likely to defend against conspecifics than they were to other intruders. When defending against conspecifics, most male defense was directed at intruding males, and most female defense at intruding females. Defense in this polyandrous species relied on cooperation between the sexes but also on some defense specialization whereby females focussed on defending against aerial predators and conspecific females, perhaps because of their larger body size. Both female and male Pheasant-tailed Jacanas therefore contribute to parental care via their defensive activities.

The diet of greater crested terns off southeast Australia varies with breeding stage and sea surface temperature

Monitoring seabird diet can provide insights into marine ecosystems that are logistically difficult or costly to observe with traditional fisheries survey methods. Using digital photography, we described the diet of greater crested terns (Thalasseus bergii) breeding on Montague Island (36°15′ S, 150°13′ E), a colony located in an oceanographically dynamic region of southeast Australia. We investigated how the type and size of prey brought back to the colony changed in relation to both breeding stage and variation in local environmental conditions. 2469 prey items were identified to species or family level over 35 consecutive days of photo-sampling in 2018. Australian anchovy (Engraulis australis), a surface-schooling clupeid fish, was the most abundant prey returned to the colony during all breeding stages (84.5%). The proportion of anchovy increased from 77.0% when birds were provisioning their adult partners during incubation, to 92.4% when they were provisioning chicks, suggesting selective foraging behaviour on this energy-rich species to facilitate rapid chick growth. Anchovy size was significantly larger during incubation (91.1 ± 14.9 mm), smaller during early chick provisioning (71.8 ± 11.0 mm), and increased slightly during mid provisioning (79.6 ± 11.9 mm), indicating adaptive prey selection that is matched to the physical requirements of different breeding stages. The proportion of anchovy prey was also influenced by sea surface temperature (SST), with anchovy becoming more dominant with increasing local SSTs, up to ~ 17.5 °C. This study gives new insight into the types of prey that are seasonally available to predators in this region. The strong specialisation by greater crested terns for one energy-rich species of schooling fish (anchovy) suggests that variation in the size and composition of their prey may serve as an indicator of change in the pelagic ecosystem off southeast Australia.

Trialling camera traps to determine occupancy and breeding in burrowing seabirds

AbstractBurrowing seabirds are important in ecological and conservation terms. Many populations are in flux due to both negative and positive anthropogenic impacts, but their ecology makes measuring changes difficult. Reliably recording key metrics, the proportion of burrows with breeding pairs and the success of breeding attempts requires burrow‐level information on occupancy. We investigated the use of camera traps positioned at burrow entrances for determining the number of breeding pairs in a sample to inform population estimates, and for recording breeding success. The performance of two cameras makes we tested differed markedly, with Spypoint Force 10 trail cameras prone to malfunction while Reconyx HC600 Hyperfire cameras performed well. Nevertheless, both makes yielded season‐long activity patterns for individual burrows, eliminating uncertainty around successful fledging attempts. Dimensionality reduction of activity metrics derived from camera time series suggests breeding and non‐breeding burrows may be identifiable using linear discriminant analyses but sample sizes from our trial were low and group means were only significantly different during certain breeding stages (permutational multivariate analysis of variance: early chick‐rearing f = 3.64, P = 0.06; late chick‐rearing f = 8.28, P = 0.009). Compared with traditional techniques for determining burrow occupancy (e.g. manual burrow inspection and playback of conspecific calls at burrow entrances), camera traps can reduce uncertainty in estimated breeding success and potentially breeding status of burrows. Significant up‐front investment is required in terms of equipment and human resources but for long‐term studies, camera traps may deliver advantages, particularly when unanticipated novel observations and the potential for calibrating traditional methods with cameras are factored in.