Parentage Analysis Research Articles

Genomic Analysis of the Giant Red Shrimp (Aristaeomorpha foliacea) Using Next-Generation Sequencing: Set of Tools for Population Studies

Background/Objectives: The giant red shrimp, Aristaeomorpha foliacea, is a valuable marine fishing resource. The conservation of species, especially exploited ones, depends on a good knowledge of their biology, as well as the development of appropriate management plans based on the identification of genetically differentiated units or genetic stocks. Microsatellites are widely used molecular markers to detect genetic stocks in penaeoid shrimps and prawns. This study aimed to develop and characterize new microsatellites for A. foliacea. Methods: Next-generation sequencing based on 454 pyrosequencing revealed 58 candidate microsatellite loci for A. foliacea. These were tested on a panel of 8 individuals representative of its worldwide geographical distribution, and 19 polymorphic loci were identified and subsequently validated and characterized in 30 individuals from a single population in the Mediterranean Sea. Results: As a result, 10 polymorphic loci were identified, which did not present linkage disequilibrium and showed a range of alleles per locus and an observed and expected heterozygosity of 2–10, 0.0667–0.5567, and 0.0661–0.8511, respectively. Nine out of these loci were under Hardy–Weinberg equilibrium and showed a combined exclusion probability of 0.9202 and 0.9968 in parentage and identity analysis, respectively. Conclusions: This large set of loci will provide a strong set of tools to (i) perform parentage studies and (ii) examine connectivity patterns (horizontal and vertical), including examining the population structure of this species at a variety of geographical scales and, particularly, between exploited populations in shallow waters and deeper unexploited populations.

Genetic diversity and parentage of cacao (Theobroma cacao L.) populations from Ghana using single nucleotide polymorphism (SNP) markers

Abstract Ortet selection remains an integral component of cacao breeding programme to develop improved clones and expand the gene pool of available germplasm. This study assessed the population structure of 168 cacao clones developed recently from selected ortets in on-station and on-farm progeny trials in Ghana using 45 SNP markers. Selection of ortets was primarily based on high bean yield, high yield efficiency, adaptability to marginal growing conditions, and low incidence of black pod and cocoa swollen shoot virus diseases. Additionally, 58 SNPs were employed to verify the parentage of 752 bi-clonal seedlings supplied to farmers for commercial plantations. Pairwise multilocus matching based on 45 SNPs showed that the 168 clones were all distinct. Overall, the clones had moderate genetic diversity (He = 0.349 ± 0.022) and shared ancestry with Marañón, Guiana, Contamana, Iquitos, Amelonado, Trinitario, Nanay and Purús based on Bayesian clustering, principal coordinates, and parentage analyses. Parentage analysis of bi-clonal seedlings assigned parent-offspring trios (>80% confidence level) to 65.2% of the farmers' varieties based on breeder's active clone collection. The results of the parentage analysis suggested the existence of mislabelled clones in the seed gardens, necessitating the need for correct clone identification or rogueing. Taken together, this study presents a new group of cacao genetic resources with potential to broaden the gene pool of cacao in cacao improvement programmes. Further, the study conveys evidence of the need for countries with established seed garden systems to constantly monitor the genetic purity of seedlings produced from the seed gardens.

The genetic basis of resistance to Enterocytozoon hepatopenaei (EHP) and White feces syndrome (WFS) in the whiteleg shrimp (Litopenaeus vannamei)

The microsporidian Enterocytozoon hepatopenaei (EHP) is a yeast-like intracellular fungus, that in the last decade has significantly contributed to major economic losses in the whiteleg shrimp (Litopenaeus vannamei) industry worldwide. In commercial ponds, EHP affected shrimp frequently also shows symptoms of White Feces Syndrome (WFS), characterized by floating white fecal strings, reduced feed consumption, and growth retardation. To elucidate the genetic basis of resistance to EHP + WFS, a challenge test was conducted using a pedigreed shrimp population from the Benchmark Genetics breeding program in Colombia. Out of the total genotyped animals, 1436 individuals from 47 families successfully passed quality control, underwent parentage analysis, had phenotypic records and were available for further analysis. Moderate heritabilities were estimated for binary survival to EHP + WFS using pedigree based (0.31 ± 0.04) and genomic analysis (0.41 ± 0.06). Furthermore, a low genetic correlation between body weight and EHP + WFS challenge test survival traits was observed, implying that genetic improvement of resistance to EHP + WFS can be achieved without compromising growth performance. The genome-wide association analysis showed little evidence for any major QTL, indicating that multiple genes with small effects collectively contribute to EHP + WFS resistance. Furthermore, cross validation analysis showed 0.54 ± 0.01 accuracy of prediction for genomic analysis and 0.49 ± 0.001 for the pedigree analysis, indicating the relevance of a genomic selection strategy for achieving genetic improvement for EHP + WFS resistance in L. vannamei.

A survey in natural olive resources exposed to high inoculum pressure indicates the presence of traits of resistance to Xylella fastidiosa in Leccino offspring.

The epidemic spread of the harmful bacterium Xylella fastidiosa causing the "olive quick decline syndrome", decimating olive trees in southern Italy, in the region of Apulia, prompted investigations to search for olive genotypes harbouring traits of resistance. A prospecting survey was carried out to identify, in the heavily infected area of Apulia, olive genotypes bearing resistance. Given the limited genetic diversity in the commercial olive groves with few cultivars widely cultivated, surveys targeted predominantly spontaneous olive genotypes in natural and uncultivated areas. Trees, selected for the absence of symptoms, were subjected to diagnostic tests and parentage analysis to disclose their genetic background. Transcriptomic analyses were also employed to decipher the molecular pathways in resistant genotypes. Artificial inoculations were carried out to confirm the resistant phenotypes of four open-pollinated seedlings of the cultivar Leccino. Among the 171 olive collected genotypes, 139 had unique simple sequence repeat (SSR) profiles, with the cultivars Leccino, Cellina di Nardò, and Ogliarola salentina being the most frequent candidate parents. Among the Leccino progeny (n. 61), 67% showed a highly resistant (HR), resistant (R), or tolerant (T) phenotype to infection by X. fastidiosa. The occurrence of such phenotypes among those deriving from Cellina di Nardò and Ogliarola salentina was 32% and 49%, respectively. Analyses of the transcriptomic profiles of three Leccino-bearing genotypes, naturally infected and not showing symptoms, unravelled that a total of 17,227, 13,031, and 4,513 genes were found altered in the expression, including genes involved in photosynthesis, cell wall, or primary and secondary metabolism. Indeed, transcriptomic analyses showed that one of these genotypes (S105) was more resilient to changes induced by the natural bacterial infection than the remaining two (S215 and S234). This study consolidates the evidence on the presence and heritage of resistance traits associated with the cv. Leccino. Moreover, valuable insights were gathered when analysing their transcriptomic profiles, i.e., genes involved in mechanisms of response to the bacterium, which can be used in functional genetic approaches to introduce resistance in susceptible cultivars and initiate strategies in olive-breeding programs through marker-assisted selection.

Pomological and Molecular Characterization of Apple Cultivars in the German Fruit Genebank.

Traditional varieties are a valuable tool in modern apple breeding. However, the use of synonyms and missing source documentation hinder an effective identification and conservation of relevant cultivars. During several projects, the authenticity and diversity of the apple cultivar collection of the German Fruit Genebank (GFG) was evaluated extensively. The trueness-to-type of 7890 apple trees was assessed on a pomological and molecular level. Pomological evaluations were performed by at least two experienced experts to identify the original cultivar names. On the molecular level, a set of 17 SSR markers was used to determine a unique genetic profile for each apple cultivar. The pomological and molecular characterization was expressed in terms of a comprehensive trueness-to-type criterion and the results were previously published as a well-curated dataset. In this study, the published dataset was analyzed to evaluate the quality and diversity of the apple collection of the GFG and highlight new findings based on phylogenetic and parentage analysis. The dataset contains 1404 unique genetic profiles corresponding to unambiguous cultivar names. Of these 1404 cultivars, 74% were assessed as true-to-type. The collection of diploid apple cultivars showed a high degree of expected heterozygosity (Hexp = 0.84). Genetic diversity in terms of year and location of origin was investigated with a STRUCTURE analysis. It was hypothesized that genetic diversity might decline overtime due to restrictive breeding programs. The results showed a shift dynamic between older and newer cultivars in one specific cluster, but no significant decrease in genetic diversity was observed in this study. Lastly, a parentage analysis was performed to check parental relationships based on historical research. Out of 128 parent-child trios, 110 trios resulted in significant relationships and reconfirmed the information from the literature. In some cases, the information from the literature was disproven. This analysis also allowed for readjusting the trueness-to-type criteria for previously undetermined cultivars. Overall, the importance of authenticity evaluations for gene bank cultivars was highlighted. Furthermore, the direct use of the dataset was shown by relevant investigations on the genetic diversity and structure of the apple cultivar collections of the GFG.

Moderate evidence for the sex‐dependent effect of poisoning on adult survival in a long‐lived raptor species

AbstractSurvival rate is usually the greatest contributor to population growth in long‐lived species, and its accurate estimation along with the evaluation of the factors influencing it is therefore essential for effective conservation. Here, we studied the survival of breeding eastern imperial eagles Aquila heliaca in Hungary between 2011 and 2022 and investigated the effect of poisoning, the leading known anthropogenic cause of mortality. We used the Cormack‐Jolly‐Seber mark‐recapture model to estimate annual apparent survival and encounter probabilities based on the capture histories of 208 males and 411 females. We obtained encounter data from the DNA profiles of shed feathers collected at the nest sites, which we also supplemented with presences inferred from parentage analysis. The most supported model estimated a constant 91.6% annual survival over the study period, but models including the effect of sex and poisoning rate on survival had similar support. Sex difference in survival was less than 1% on average, but the survival of males decreased more with poisoning rate than the survival of females. However, due to smaller encounter probabilities, the estimates for males were less precise compared to females. Males may be more at risk from poisoning than females not only due to their more active foraging behaviour during incubation and chick‐rearing but also due to their smaller body size. Apart from providing direct practical information for the conservation management of imperial eagles, our results also highlight the importance of long‐term studies for estimating population parameters of birds of prey.

Potential drivers and implications of a balanced breeding sex ratio in a small population of an imperiled species with environmental sex determination.

Small populations of imperiled species are susceptible to the negative consequences of skewed sex-ratios. In imperiled species with environmental sex determination such as sea turtles, examining sex ratios across a range of environments and population abundance levels can provide insight into factors that influence population resilience, which can then be the foci of management plans for these species. Breeding sex ratios (the ratio of actively breeding males to females during a reproductive season; BSRs) extrapolated from genetic parentage analyses are a common approach for enumerating sex ratios in sea turtles. Such analyses also allow for the characterization of multiple paternity within sea turtle clutches, which should reflect BSRs and breeding behaviors. We characterized the first BSR for a breeding assemblage of loggerhead sea turtles (Caretta caretta) belonging to the temperate, low-abundance Northern Gulf of Mexico Recovery Unit using genotypes of 16 microsatellite loci from nesting females and hatchlings. Unlike prior studies at both more-tropical and more-temperate, and higher-abundance, Recovery Units in this region, we found a balanced BSR of 1.3:1 males:female and a low incidence (~17%) of multiple paternity. This suggests that there are relatively few males breeding at this assemblage and within this Recovery Unit. Beaches in this region are expected to produce substantial numbers of male hatchlings based on sand temperature data. The relative dearth of mature males may then be due to hydrologic disturbances that disproportionately affect the fitness and survival of male hatchlings, or due to demographic stochasticity. More work is needed to study the factors that might influence male hatchling production and fitness in this region, particularly as climate change is predicted to lead to feminization in global sea turtle populations. Our work demonstrates the broad utility of characterizing BSRs and other sex ratios across a range of populations in imperiled, environmentally sensitive species.

Masting and Efficient Production of Seedlings: Balancing Costs of Variation Through Synchronised Fruiting.

The efficient conversion of tissues into reproductive success is a crucial aspect affecting the evolution of life histories. Masting, the interannually variable and synchronous seed production in perennial plants, is a strategy that can enhance reproductive efficiency by mitigating seed predation and pollen limitation. However, evaluating benefits is insufficient to establish whether efficiency has improved, as such assessments neglect the associated costs of masting, particularly during the critical seed-to-seedling stage. We conducted a parentage analysis of seedlings and adults in a population of 209 Sorbus aucuparia trees, monitored over 23 years, providing pioneering documentation of the effects of masting on the fitness of individual trees beyond the seed stage. Our results show high costs of interannual variation that can be mitigated by high synchrony and reveal the existence of phenotypes that appear to reap the benefits of masting while avoiding its costs through regular reproduction.

The complete mitochondrial genome and microsatellite discovery of the Chilean kelp crab Taliepus dentatus (Brachuyra, Majoidea)

Abstract The complete sequence of the mitochondrial genome and fifteen microsatellite loci for the Chilean kelp crab Taliepus dentatus are reported for the first time. The DNA assembly obtained from an Illumina sequencing revealed a complete mitochondrial genome of 15 603 bp in length. The gene composition and arrangement were similar to that reported for most decapod crabs, containing 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and a non-coding region. A phylogeny performed with 10 species obtained from GenBank placed T. dentatus close to individuals of the Family Epialtidae. From the 6397 repeated sequences encountered in the data, 15 microsatellite loci primers were designed and five tested for variability in specimens obtained from two sampling sites separated by 300 km of distance. The mean number of alleles per locus was nine (5–15 alleles per locus) and the observed heterozygosities ranged from 0.34 to 0.8. Departure from Hardy–Weinberg equilibrium was observed in two out of the five microsatellites, while none of the loci exhibited significant linkage disequilibrium. This genetic resource will be useful for phylogeny, population genetics and parentage analysis of the commercial species T. dentatus.

Genetic diversity and population structure of an insect-pollinated and bird-dispersed dioecious tree Magnolia kwangsiensis in a fragmented karst forest landscape.

This study combined population genetics and parentage analysis to obtain foundational data for the conservation of Magnolia kwangsiensis. M. kwangsiensis is a Class I tree species that occurs in two disjunct regions in a biodiversity hotspot in southwest China. We assessed the genetic diversity and structure of this species across its distribution range to support its conservation management. Genetic diversity and population structure of 529 individuals sampled from 14 populations were investigated using seven nuclear simple sequence repeat (nSSR) markers and three chloroplast DNA (cpDNA) fragments. Parentage analysis was used to evaluate the pollen and seed dispersal distances. The nSSR marker analysis revealed a high genetic diversity in M. kwangsiensis, with an average observed (Ho) and expected heterozygosities (He) of 0.726 and 0.687, respectively. The mean and maximum pollen and seed dispersal distances were 66.4 and 95.7 m and 535.4 and 553.8 m, respectively. Our data revealed two distinct genetic groups, consistent with the disjunct geographical distribution of the M. kwangsiensis populations. Both pollen and seed dispersal movements help maintain genetic connectivity among M. kwangsiensis populations, contributing to high levels of genetic diversity. Both genetically differentiated groups corresponding to the two disjunct regions should be recognized as separate conservation units.

Inbreeding depression affects the growth of seedlings of an African timber species with a mixed mating reproductive system, Pericopsis elata (Harms) Meeuwen

Selfing or mating between related individuals can lead to inbreeding depression (ID), which can influence the survival, growth and evolution of populations of tree species. As selective logging involves a decrease in the density of congeneric partners, it could lead to increasing biparental inbreeding or self-fertilization, exposing the population to higher ID. We assessed the influence of inbreeding on the growth of a commercial timber species, Pericopsis elata (Fabaceae), which produced about 54% of self-fertilized seedlings in a natural population of the Congo basin. We followed the survival and growth of 540 plants raised in a plantation along a gradient of plant density (0.07–15.9 plants per m2). Parentage analysis allowed us distinguishing selfed and outcrossed seedlings. The annual growth was higher for outcrossed than selfed plants, on average by 10.8% for diameter and 12.9% for height growth. Based on the difference in above ground biomass between selfed and outcrossed seedlings after 41 months, we estimated the level of ID at δ = 0.33, while a lifetime estimate of ID based on the proportions of selfed plants at seedling and adult stages led to δ = 0.7. The level of ID on growth rate did not change significantly with age but tended to vanish under high competition. Pericopsis elata is a particularly interesting model because inbreeding depression is partial, with about 26% of reproducing adults resulting from selfing, contrary to most tropical tree species where selfed individuals usually die before reaching adulthood. Hence, the risks of ID must be considered in the management and conservation of the species.

Odor cues rather than personality affect tadpole deposition in a neotropical poison frog.

Animals constantly need to evaluate available external and internal information to make appropriate decisions. Identifying, assessing, and acting on relevant cues in contexts such as mate choice, intra-sexual competition, and parental care is particularly important for optimizing individual reproductive success. Several factors can influence decision-making, such as external environmental cues and the animal's own internal state, yet, we have limited knowledge on how animals integrate available information. Here, we used an entire island population (57 males, 53 females, and 1,109 tadpoles) of the neotropical brilliant-thighed poison frog Allobates femoralis to investigate how 2 factors (olfactory cues and personality traits) influence the ability of males to find and use new resources for tadpole deposition. We experimentally manipulated the location of tadpole deposition sites and their associated olfactory cues, and repeatedly measured exploration and boldness in adult males. We further reconstructed tadpole deposition choices via inferred parent-offspring relationships of adult frogs and tadpoles deposited in our experimental pools using molecular parentage analysis. We found that the discovery and use of new rearing sites were heavily influenced by olfactory cues; however, we did not find an effect of the measured behavioral traits on resource discovery and use. We conclude that in highly dynamic environments such as tropical rainforests, reliable external cues likely take priority over personality traits, helping individuals to discover and make use of reproductive resources.

Sex-specific overdominance at the maturation vgll3 gene for reproductive fitness in wild Atlantic salmon.

Linking reproductive fitness with adaptive traits at the genomic level can shed light on the mechanisms that produce and maintain sex-specific selection. Here, we construct a multigenerational pedigree to investigate sex-specific selection on a maturation gene, vgll3, in a wild Atlantic salmon population. The vgll3 locus is responsible for ~40% of the variation in maturation (sea age at first reproduction). Genetic parentage analysis was conducted on 18,265 juveniles (parr) and 685 adults collected at the same spawning ground over eight consecutive years. A high proportion of females (26%) were iteroparous and reproduced two to four times in their lifetime. A smaller proportion of males (9%) spawned at least twice in their lifetime. Sex-specific patterns of reproductive fitness were related to vgll3 genotype. Females showed a pattern of overdominance where vgll3*EL genotypes had three-fold more total offspring than homozygous females. In contrast, males demonstrated that late-maturing vgll3*LL individuals had two-fold more offspring than either vgll3*EE or vgll3*EL males. Taken together, these data suggest that balancing selection in females contributes to the maintenance of variation at this locus via increased fitness of iteroparous vgll3*EL females. This study demonstrates the utility of multigenerational pedigrees for uncovering complex patterns of reproduction, sex-specific selection and the maintenance of genetic variation.

Inferring precocial Chinook Salmon production through single‐parentage assignments

AbstractObjectiveParentage analysis is a routine methodology in fisheries research, but study systems exist where it is impractical to sample both parents. The ability to reliably assign offspring to a single parent is beneficial in these situations. We applied single‐parentage assignments to a naturally spawning population of Chinook Salmon Oncorhynchus tshawytscha to quantify production of anadromous returns by unsampled precocial males.MethodsWe used an approach that focused on two important aspects of parentage analyses: (1) addressing the presence of family structure within the set of sampled parents and (2) controlling for false‐positive and false‐negative assignments.ResultResults indicated that 30% of reproductively successful males were precocial males, which produced 20% of the returning anadromous offspring.ConclusionThis study provides a framework for applying single‐parent assignments in a salmonid study system while explicitly addressing sources of assignment errors.

An amplicon panel for high-throughput and low-cost genotyping of Pacific oyster.

Maintaining genetic diversity in cultured shellfish can be challenging due to high variance in individual reproductive success, founder effects, and rapid genetic drift, but is important to retain adaptive potential and avoid inbreeding depression. To support broodstock management and selective breeding in cultured Pacific oysters (Crassostrea (Magallana) gigas), we developed an amplicon panel targeting 592 genomic regions and SNP variants with an average of 50 amplicons per chromosome. Target SNPs were selected based on elevated observed heterozygosity or differentiation in Pacific oyster populations in British Columbia, Canada. The use of the panel for parentage applications was evaluated using multiple generations of oysters from a breeding program on Vancouver Island, Canada (n = 181) and families selected for Ostreid herpesvirus-1 resistance from the Molluscan Broodstock Program in Oregon, USA (n = 136). Population characterization was evaluated using wild, naturalized, farmed, or hatchery oysters sampled throughout the Northern Hemisphere (n = 190). Technical replicates showed high genotype concordance (97.5%; n = 68 replicates). Parentage analysis found suspected pedigree and sample handling errors, demonstrating the panel's value for quality control in breeding programs. Suspected null alleles were identified and found to be largely population dependent, suggesting population-specific variation impacting target amplification. Null alleles were identified using existing data without the need for pedigree information, and once they were removed, assignment rates increased to 93.0% and 86.0% of possible assignments in the two breeding program datasets. A pipeline for analyzing the amplicon sequence data from sequencer output, amplitools, is also provided.

Genetic Characterization of Criolla and European Grapevines Recently Found in Chile: A Key Step for Their Rescue and Conservation

Genetic erosion of grapevine is becoming a serious worldwide problem and preserving its germplasm is an urgent task. Chile is not an exception to this scenario, where diverse factors led by the replacement of traditional varieties by renown cultivars have reduced the vineyard diversity. Therefore, discovering and characterizing minor varieties were the main objectives of this study. In addition to the official catalogue of around 100 grapevine varieties used to produce wine, we present here 89 genotypes not previously described as present in Chile, widely dispersed in the main wine valleys, which were retrieved from vineyards, small collections, and city gardens. Strikingly, we found 49 grapevines with allele patterns not described before. Ten of these may be old European varieties; the other 39 have allele patterns similar to Criolla varieties (e.g., descendants from the crossing of European varieties born in America). A parentage analysis performed with 15 SSR markers in these 39 N.N. samples revealed that most of them are descendants of the so-called foundational varieties Listán Prieto and Muscat of Alexandria, plus others in lower proportion such as Mollar Cano and Muscat à petit grains blancs, as well as known Criollas varieties such as Italiona and Moscatel Rosado. The 89 genotypes not described in Chile structured in three distinguishable groups: Criolla varieties, Central European varieties, and a third group enriched in Iberic varieties. The prevalence of each Criolla accession was quite variable, some corresponding to a single or a few vines found at a single place, while others were spread in several vineyards, even in different valleys, suggesting they were positively selected and propagated at some time. All the new Criolla varieties were different than the recently described Criollas found in Argentina. The discovery, rescue, and documentation of this rich heritage of Vitis vinifera L. genotypes found in Chile is the first step of a long-term work that should be continued with the evaluation of their enological characteristics, yield, and optimal management systems, aiming for the diversification of the local wine industry.

Population dynamics of potentially harmful haplotypes: a pedigree analysis

BackgroundThe identification of low-frequency haplotypes, never observed in homozygous state in a population, is considered informative on the presence of potentially harmful alleles (candidate alleles), putatively involved in inbreeding depression. Although identification of candidate alleles is challenging, studies analyzing the dynamics of potentially harmful alleles are lacking. A pedigree of the highly endangered Gochu Asturcelta pig breed, including 471 individuals belonging to 51 different families with at least 5 offspring each, was genotyped using the Axiom PigHDv1 Array (658,692 SNPs). Analyses were carried out on four different cohorts defined according to pedigree depth and at the whole population (WP) level.ResultsThe 4,470 Linkage Blocks (LB) identified in the Base Population (10 individuals), gathered a total of 16,981 alleles in the WP. Up to 5,466 (32%) haplotypes were statistically considered candidate alleles, 3,995 of them (73%) having one copy only. The number of alleles and candidate alleles varied across cohorts according to sample size. Up to 4,610 of the alleles identified in the WP (27% of the total) were present in one cohort only. Parentage analysis identified a total of 67,742 parent-offspring incompatibilities. The number of mismatches varied according to family size. Parent-offspring inconsistencies were identified in 98.2% of the candidate alleles and 100% of the LB in which they were located. Segregation analyses informed that most potential candidate alleles appeared de novo in the pedigree. Only 17 candidate alleles were identified in the boar, sow, and paternal and maternal grandparents and were considered segregants.ConclusionsOur results suggest that neither mutation nor recombination are the major forces causing the apparition of candidate alleles. Their occurrence is more likely caused by Allele-Drop-In events due to SNP calling errors. New alleles appear when wrongly called SNPs are used to construct haplotypes. The presence of candidate alleles in either parents or grandparents of the carrier individuals does not ensure that they are true alleles. Minimum Allele Frequency thresholds may remove informative alleles. Only fully segregant candidate alleles should be considered potentially harmful alleles. A set of 16 candidate genes, potentially involved in inbreeding depression, is described.

Destocking waterways: Evidence that stocked Murray Cod (Maccullochella peelii) were extracted at pumped irrigation diversions within 24 hours of release

SummaryMillions of native fish are entrained into irrigation pumps in Australian rivers every year. It is often assumed these fish are wild, but stocked fish may also be affected. During fish entrainment surveys at two pump intakes on the Macquarie River, New South Wales, a noticeable increase of entrained juvenile Murray Cod (Maccullochella peelii) was observed. DNA parentage analysis confirmed that a large proportion of these fish were linked to nearby fish restocking events. At both pump intakes, genetic analysis confirmed that at least 70% and 17% of the individuals sampled were stocked fish. This equated to up to 3% of the fish that were stocked – most of which were entrained less than 24 h after their release. Given the large number of unscreened irrigation pumps in this reach of river, and more broadly throughout the Murray–Darling Basin, fish losses at pump intakes have the potential to remove large numbers of stocked fish from the river where they are released to support native fish recovery and boost recreational fishing opportunities. The use of fish‐protection screens at pump intakes may be a suitable solution to reduce the number of fish entrained and thus increase the survival of recently stocked fish in the rivers.

Is promiscuity the key? Multiple paternity in the garden dormouse (Eliomys quercinus)

Many mammals have a promiscuous mating system with multiple sired litters. Promiscuity can increase the genetic variability, reduce the risk of inbreeding, and increase the effective population size, and is therefore crucial for preventing genetic loss and maintaining adaptability. This is particularly true for small and threatened populations. The garden dormouse (Eliomys quercinus) is a threatened species, which exhibited a drastic decline over the last 20–30 years. The aim of this study was therefore to investigate the mating system of the garden dormouse in mountain forest habitat by parentage analyses using 5 polymorphic microsatellite markers combined with morphometric data and information about the nesting behavior. Genetic parentage analyses revealed that 64% (9 of 14) of the litters were sired by at least two males, suggesting that garden dormice have a promiscuous mating system. The genetic findings were further supported by indirect indicators of promiscuity, such as testes, that were nearly four times larger than predicted for a rodent of its body mass and only slight male biased sexual size dimorphism. The finding of a promiscuous mating system in garden dormice should be taken into account in future conservation efforts. Due to its habitat preferences and limited dispersal potential garden dormice are vulnerable to forest fragmentation. The connection of suitable habitats facilitates dispersal and promotes access to potential mating partners, which could be especially important for populations colonizing new habitats. Access to potential mates may also reduce inbreeding, loss of genetic variability which is crucial for populations viability and survival.

Parentage analysis and comparison of cocoa families derived from bi-parental crosses and open-pollination for vigor and precocity in recommended cocoa (Theobroma cacao L.) clones in Ghana

ABSTRACT Bi-parental hybrids (BPHs) are recommended cocoa planting materials in Ghana and other West African countries. However, the inability to produce enough BPHs to meet farmers’ demand makes it almost impossible to avoid open-pollinated families (OPF) in the supply chain. To study the effects of OPF on cocoa production, parentage analysis, vigor, and precocity of seven BPHs generated from a 4 × 2 North Carolina II (NC II) incomplete mating design were compared with eight OPFs. The 15 cocoa progenies together with two checks of Guiana (GU) origin were evaluated in a randomized complete block design with four replications across five contrasting locations for stem diameter increment (SDI) and number of pods per tree (NP). Parentage analyses at 75 single nucleotide polymorphism (SNP) loci of leave samples from the 17 progenies revealed that the BPHs were of the appropriate female and male parents, while the OPF had varying number of male parents. The pollination effect (bi-parental vs open-pollinated progenies) was not significantly different for both traits, but the BPH was relatively better and surpassed on average the OPF by 3.5% for SDI and 7.8% for NP. Crosses involving GU 144/ C, T63/967, and T65/238 as females in both the OPF and BPH showed predominantly higher performance than those with PA 7 and T79/501 for both traits. Among the promising female parents, GU 144/C is the only one that is not in the seed gardens and could be added to parental clones currently used in producing cocoa varieties in the seed garden.