Number Of Sires Research Articles

91 Assessing Variability of Herd Sire Economic Value for Commercial Operations

Abstract Number of calves (n = 596) and weaning calf value (n = 574) from natural service, multi-sire breeding groups were evaluated in a crossbred research herd. Sires and dams that were F1 crosses of Angus (A) and Nellore (N) were mated annually during 60 to 90-day breeding seasons to produce spring-born calves in 2009–2015. Numbers of sires used annually varied from 5 to 9; numbers of females exposed per bull ranged from 14 to 22 across years. Bulls were pastured together throughout the year as well as breeding seasons. Sires were identified based on calf DNA genotyping. Calf number, birth date, birth weight, weaning weight, and economic value were determined per bull annually. Calf value was based on weaning weight and reported prices for respective weaning dates. Calf prices were calculated separately for steers and heifers relative to 22.7 kg (50 lb) increments for corresponding weight class and year. Mixed model analyses were conducted that included fixed categorical effects of calf birth year, type of F1 sire (A-sired vs. N-sired), sire nested within type, calf sex, and the interaction of F1 sire type with calf sex. Covariates of Julian birth date and calf weaning age were included for birth weight and weaning weight, respectively. Large differences in calf numbers and performance (P < 0.05) were observed. Weaned calves produced annually per sire ranged from 0 to 48. Average annual calf performance per sire ranged from 28.4 to 50.8 kg for birth weight and 146.5 to 249.0 kg for weaning weight. Annual economic value per sire ranged from $0 to $30,870 when considering half of each calf’s value as attributed to the sire. Commercial producers should consider potential sire variability for calf numbers, birth date distribution, and ratio of female-to-male calves in combination with calf performance for economic assessments.

Assessing age, breeding stage, and mating activity as drivers of variation in the reproductive microbiome of female tree swallows.

Sexually transmitted microbes are hypothesized to influence the evolution of reproductive strategies. Though frequently discussed in this context, our understanding of the reproductive microbiome is quite nascent. Indeed, testing this hypothesis first requires establishing a baseline understanding of the temporal dynamics of the reproductive microbiome and of how individual variation in reproductive behavior and age influence the assembly and maintenance of the reproductive microbiome as a whole. Here, we ask how mating activity, breeding stage, and age influence the reproductive microbiome. We use observational and experimental approaches to explain variation in the cloacal microbiome of free‐living, female tree swallows (Tachycineta bicolor). Using microsatellite‐based parentage analyses, we determined the number of sires per brood (a proxy for female mating activity). We experimentally increased female sexual activity by administering exogenous 17ß‐estradiol. Lastly, we used bacterial 16S rRNA amplicon sequencing to characterize the cloacal microbiome. Neither the number of sires per brood nor the increased sexual activity of females significantly influenced female cloacal microbiome richness or community structure. Female age, however, was positively correlated with cloacal microbiome richness and influenced overall community structure. A hypothesis to explain these patterns is that the effect of sexual activity and the number of mates on variation in the cloacal microbiome manifests over an individual's lifetime. Additionally, we found that cloacal microbiome alpha diversity (Shannon Index, Faith's phylogenetic distance) decreased and community structure shifted between breeding stages. This is one of few studies to document within‐individual changes and age‐related differences in the cloacal microbiome across successive breeding stages. More broadly, our results contribute to our understanding of the role that host life history and behavior play in shaping the cloacal microbiomes of wild birds.

Pedigree Analysis of Warmblood Horses Participating in Competitions for Young Horses.

The aim of the study was to characterize the population structure and assess the genetic diversity of warmblood horses used in the show jumping discipline. Pedigree data of 1,048 horses participating in the Polish Championships for Young Horses were analyzed. The pedigree of these animals included 12 863 individuals. The study consisted in analysis of the pedigree structure of the horses and characterization of the homozygosity and genetic diversity in the population. It was found that pedigree completeness and depth were sufficient for reliable assessment of the genetic diversity in the analyzed population. Although the average inbreeding coefficient exhibited at an acceptable level (approx. 1.01%), the increasing percentage of inbred animals seems disturbing. The results have shown that modern sport horses are derived from a small number of high-quality sires whose offspring were intensively used for breeding—bottleneck effect. In consequence, a greater part of the genetic variation reduction was observed in the non-founder generations. Given the changes in the studied population, the level of inbreeding in modern sport horses should be monitored, and pedigree data should be effectively used in selection for mating.

Multiple paternity and the number of offspring: A model reveals two major groups of species.

Parentage analyses via microsatellite markers have revealed multiple paternity within the broods of polytocous species of mammals, reptiles, amphibians, fishes and invertebrates. The widespread phenomenon of multiple paternity may have attending relationships with such evolutionary processes as sexual selection and kin selection. However, just how much multiple paternity should a species exhibit? We developed Bayesian null models of how multiple paternity relates to brood sizes. For each of 114 species with published data on brood sizes and numbers of sires, we compared our null model estimates to published frequencies of multiple paternity. The majority of species fell close to our null model, especially among fish and invertebrate species. Some species, however, had low probabilities of multiple paternity, far from the predictions of the null model, likely due to sexual selection and environmental constraints. We suggest a major division among species' mating systems between those with close to random mating and high levels of multiple paternity, and those with constraints that produce low levels of multiple paternity.

Genetic Diversity and the Impact of the Breed Proportions of US Brown Swiss in German Brown Cattle.

Simple SummaryThe main aim of modern breeding programs in dairy cows is to improve productivity, functional and health traits. The use of only a few top sires leads to more efficient milk production, but also it could lead to a decline in the gene pool, smaller effective population size and an increase of inbreeding. Deleterious effects of inbreeding in dairy cattle may reduce the benefits of the genetic gains. Due to this fact, it is important to monitor the genetic diversity in dairy cattle breeds. In this study, pedigree data were used to show the losses of genetic variability and its association with the heavy use of imported US Brown Swiss bulls and semen in the German Brown population. Strategies to decrease rate of inbreeding through sires with less relationships to the most important ancestors should be considered in future breeding strategies.Increase of inbreeding and loss of genetic diversity have large impact on farm animal genetic resources. Therefore, the aims of the present study were to analyse measures of genetic diversity as well as recent and ancestral inbreeding using pedigree data of the German Brown population, and to identify causes for loss of genetic diversity. The reference population included 922,333 German Brown animals born from 1990 to 2014. Pedigree depth and completeness reached an average number of complete equivalent generations of 6.24. Estimated effective population size for the German Brown reference population was about 112 with a declining trend from 141 to 95 for the birth years. Individual inbreeding coefficients increased from 0.013 to 0.036. Effective number of founders, ancestors and founder genomes of 63.6, 36.23 and 20.34 indicated unequal contributions to the reference population. Thirteen ancestors explained 50% of the genetic diversity. Higher breed proportions of US Brown Swiss were associated with higher levels of individual inbreeding. Ancestral inbreeding coefficients, which are indicative for exposure of ancestors to identical-by-descent alleles, increased with birth years but recent individual inbreeding was higher than ancestral inbreeding. Given the increase of inbreeding and decline of effective population size, measures to decrease rate of inbreeding and increase effective population size through employment of a larger number of sires are advisable.

7 A record of 485 viable cumulus–oocyte complexes recovered and 165 viable embryos produced in a single ovum pickup session from a Senepol breed donor

The recovery of an exceptionally high number of cumulus–oocyte complexes (COC) in a single ovum pickup (OPU) session is rare, and thus seldom reported in the literature. In the present report, we describe one of these cases. The present data refers to an OPU session performed by author A. O. Resende in a commercial beef farm, located in the rural area of the city of Barretos, Brazil, on October 15, 2019. Breed heifers (N=12) underwent OPU at a random stage of oestrous cycle without any hormonal treatment. Follicle aspirations were performed following the standard operation procedures (SOP) established by ABS Pecplan OPU team, using a portable ultrasound (DP2200, Mindray do Brasil) equipped with a 7.5-MHz microconvex probe, a vacuum pump (WTA), and 18 gauge disposable Jelco catheter (Smith Medical). Invitro embryo production (IVP) was performed at Invitro Technologies laboratory, ABS Pecplan Uberaba, located 140km from the farm. On this day, 1312 oocytes were recovered from the 12 donors. However, a single heifer produced 485 viable COC, from over 500 total COC recovered. The COC from this donor were distributed in four groups, which underwent IVF with Y-sorted semen from four Senepol sires. The invitro embryo production was performed following the SOP established by invitro Technologies, ABS Pecplan. Embryo production was compared among sires by the chi-squared test. Of the 4 sires used during IVF, sire number 4 resulted in a higher blastocyst rate compared with the others (sire 1=25.4%, sire 2=30.6%, sire 3=33.9%, and sire 4=46.3%; P<0.01).The blastocyst rate differed (P<0.01) among sires: 25.4%a (31/122), 30.6%a (37/121), 33.9%a (41/121), and 46.3%b (56/121) for bulls A, B, C, and D, respectively. From the total of 165 viable embryos produced (34.0%), 120 were transferred fresh and the remaining 45 were vitrified using the SOP established by IVB Technologies, ABS. These results highlight the huge potential variation in antral follicle population and number of COC recovered from donors within the same population, breed, and reproductive status. It also shows the potential of IVP in the generation of offspring from high genetic indices.

"A child with sickle cell disease can't live with just anyone." A mixed methods study of socio-behavioral influences and severity of sickle cell disease in northern Nigeria.

BackgroundThe modulatory effects of psychosocial and biophysical environments on sickle cell disease (SCD) severity during childhood has not been well characterized in high burden settings, such as Nigeria.ObjectivesWe identified socio‐demographic correlates and explored caregivers' perceptions on socio‐behavioral and environmental influences on hospitalization for pain and blood transfusion of children with SCD in Kano, Nigeria.MethodsUsing mixed methods, structured questionnaires were administered to a clinic‐based sample of caregivers of children with SCD (n = 372), complemented with eight focus group discussions. Binary logistic regression models and the framework approach were used to analyze the data.ResultsThe majority (73.1%, n = 272) of the children had at least one vaso‐occlusive crisis (VOC), and 41.1% (n = 153) required hospitalization in the preceding year. A total of 170 children (45.7%) received blood transfusion. Hospitalization was predicted by the child's age (Adjusted Odds Ratio, AOR = 1.89; 95% Confidence Interval, CI: 1.18‐4.07, ≥10 vs <5 years), relationship with caregiver (AOR = 5.41; 95%CI: 1.17‐25.05, mother vs “others”), father's number of children (AOR = 2.21; 95%CI: 1.19‐5.31, ≥10 vs ≤4), and siblings with SCD (AOR = 2.36; 95%CI: 1.16‐8.80, 2 vs 0). Caregivers perceived maternal care, stable home environment, medication adherence, anti‐mosquito measures, and adequate nutrition as protective factors, whereas poverty, extreme emotions, physical exertion, and extreme temperatures were identified as detrimental to the health of the child.ConclusionsHospitalizations for VOC and transfusion rates among children with SCD were high. Understanding the modulatory effects of socio‐behavioral factors on SCD severity could inform preventive measures and enhance the quality of life of affected children.

Accessing Multiple Paternity in the Shortfin Mako Shark (Isurus oxyrinchus).

Multiple paternity has been demonstrated in a variety of sharks with different reproductive modes (i.e., viviparous, ovoviviparous, adelphophagy, oviparous), although the number of sires per litter varies considerably among species. To date, such analyses have focused mainly on coastal and nearshore shark species due to the difficulty in sampling oceanic sharks. In the present study, we observed multiple paternity in the oceanic shark Isurus oxyrinchus from seven polymorphic microsatellite loci and three litters collected from Nanfangao Fishing Port. Paternity tests showed that an average of 4.6 sires were assigned to each litter of I. oxyrinchus using COLONY software, and that the average number of sires dropped to 2.5 when using GERUD. These findings suggest that multiple paternity could be a common reproductive strategy used by the shortfin mako shark, and that this mating system should be integrated into a demographic model to make more accurate population projections and risk analyses in the future.

Sire evaluation based on first lactation milk yield traits in HF X Gir halfbred

The data on first lactation milk production performance of 422, HF X Gir halfbred cows maintained at Research Cum Development Project on Cattle, MPKV, Rahuri were utilized for estimation of least squares means, correlation among the traits and heritability of traits. Breeding values of sires were estimated by REML computer programme. The overall least squares means (kg) of first lactation monthly test day milk yield (from 1 st to 6 th month) (FLMTDMY), first lactation peak milk yield (FLPMY) and first lactation 300 days milk yield (FL300 DMY) were 10.54 ± 0.14, 10.57 ± 0.13, 10.10 ± 0.12, 9.48 ± 0.12, 8.93 ± 0.11, 8.23 ± 0.11, 14.22 ± 0.14 and 2438.98 ± 38.49 respectively. Phenotypic and genotypic correlations among the traits were positive and significant (P&lt;0.01). Heritability of traits was low to moderate and ranged from 0.06 to 0.25. Sire number HG-412 and HG-129 had highest breeding values for FLMTDMY and H-28I and HG-15 had highest breeding value for FLPMY and FL300DMY and ranked first.

High Degree of Multiple Paternity and Reproductive Skew in the Highly Fecund Live-Bearing Fish Poecilia gillii (Family Poeciliidae)

Multiple paternity is a common phenomenon within the live-bearing fish family Poeciliidae. There is a great variety in brood sizes of at least two orders-of-magnitude across the family. However, little is known about the ramifications of this remarkable variation for the incidence and degree of multiple paternity and reproductive skew. Mollies (subgenus Mollienesia, genus Poecilia) produce some of the largest broods in the family Poeciliidae, making them an excellent model to study the effects of intra-specific variation in brood size on patterns of multiple paternity. We collected samples of the live-bearing fish Poecilia gillii from 9 locations in Costa Rica. We measured body size of 159 adult females, of which 72 were pregnant. These samples had a mean brood size of 47.2 ± 3.0 embryos, ranging from 4 to 130 embryos. We genotyped 196 field-collected specimens with 5 microsatellite markers to obtain location-specific allele frequencies. In addition, we randomly selected 31 pregnant females, genotyped all their embryos (N = 1346) and calculated two different parameters of multiple paternity: i.e., the minimum number of sires per litter using an exclusion-based method (GERUD) and the estimated number of sires per litter using a maximum likelihood approach (COLONY). Based on these two approaches, multiple paternity was detected in 22 and 27 (out of the 31) females, respectively, with the minimum number of sires ranging from 1 to 4 (mean ± SE: 2.1 ± 0.16 sires per female) and the estimated number of fathers ranging from 1 to 9 (mean ± SE: 4.2 ± 0.35 sires per female). The number of fathers per brood was positively correlated with brood size, but not with female size. Next, we calculated the reproductive skew per brood using the estimated number of sires, and found that in 21 out of the 27 multiply sired broods sires did not contribute equally to the offspring. Skew was not correlated with either female size, brood size or the number of sires per brood. Finally, we discuss several biological mechanisms that may influence multiple paternity and reproductive skew in P. gillii as well as in the Poeciliidae in general.

Evaluating Reproductive Strategies and Female Bateman Gradients in Ditrema temminckii: Is the Number of Fathers a Good Approximation for the Number of Mates?

Surfperches (Embiotocidae) are a unique family of viviparous fishes that have internal fertilization, gestation to the sub-adult stage, and live-birth; therefore, maternal investment is extremely high. This invokes the expectation that brood size is limited and females should be choosy and select few mates. Yet multiple paternity occurs in all eight species examined to date, with high prevalence ranging from 92–100%. Most surfperches are found along the Eastern Pacific coast, but Ditrema temminckii is distributed in the Western Pacific and we found differences in their mating strategy compared to other surfperches. In D. temminckii, prevalence of multiple paternity was only 60%. Further, the average number of sires was only 1.86 per brood even though brood sizes ranged from 12–45, and paternity was skewed, with the majority of paternity allocated to a single male. We propose that these differences may be associated with strong female selection on males in this species. Finally, we evaluated whether the number of fathers is an accurate estimate for the number of mates by comparing the number of alleles detected from fathers within the brood to the number of alleles from mates via genotyping alleles from spermatozoa within the uterine sac and found no significant difference, suggesting that the number of sires is a reasonable estimate for the number of mates in D. temminckii.

The evolution of pueriparity maintains multiple paternity in a polymorphic viviparous salamander

The reduction in fecundity associated with the evolution of viviparity may have far-reaching implications for the ecology, demography, and evolution of populations. The evolution of a polygamous behaviour (e.g. polyandry) may counteract some of the effects underlying a lower fecundity, such as the reduction in genetic diversity. Comparing patterns of multiple paternity between reproductive modes allows us to understand how viviparity accounts for the trade-off between offspring quality and quantity. We analysed genetic patterns of paternity and offspring genetic diversity across 42 families from two modes of viviparity in a reproductive polymorphic species, Salamandra salamandra. This species shows an ancestral (larviparity: large clutches of free aquatic larvae), and a derived reproductive mode (pueriparity: smaller clutches of larger terrestrial juveniles). Our results confirm the existence of multiple paternity in pueriparous salamanders. Furthermore, we show the evolution of pueriparity maintains, and even increases, the occurrence of multiple paternity and the number of sires compared to larviparity, though we did not find a clear effect on genetic diversity. High incidence of multiple paternity in pueriparous populations might arise as a mechanism to avoid fertilization failures and to ensure reproductive success, and thus has important implications in highly isolated populations with small broods.

Edge effects and mating patterns in a bumblebee-pollinated plant.

Researchers have long assumed that plant spatial location influences plant reproductive success and pollinator foraging behaviour. For example, many flowering plant populations have small, linear or irregular shapes that increase the proportion of plants on the edge, which may reduce mating opportunities through both male and female function. Additionally, plants that rely on pollinators may be particularly vulnerable to edge effects if those pollinators exhibit restricted foraging and pollen carryover is limited. To explore the effects of spatial location (edge vs. interior) on siring success, seed production, pollinator foraging patterns and pollen-mediated gene dispersal, we established a square experimental array of 49 Mimulus ringens (monkeyflower) plants. We observed foraging patterns of pollinating bumblebees and used paternity analysis to quantify male and female reproductive success and mate diversity for plants on the edge versus interior. We found no significant differences between edge and interior plants in the number of seeds sired, mothered or the number of sires per fruit. However, we found strong differences in pollinator behaviour based on plant location, including 15 % lower per flower visitation rates and substantially longer interplant moves for edge plants. This translated into 40 % greater pollen-mediated gene dispersal for edge than for interior plants. Overall, our results suggest that edge effects are not as strong as is commonly assumed, and that different plant reproduction parameters respond to spatial location independently.

Pooled parameter estimates for traits of economic importance in indigenous chicken in the tropics

Genetic and phenotypic parameter estimates obtained in different studies, may be heterogeneous. This is because they are obtained in different locations, using different sample sizes and estimation methods. The choice of which parameter estimates to use, is in most cases subjective and this may lead to underestimation or overestimation of potential genetic gain. The objective of the current study was to use meta-analysis to estimate genetic and phenotypic parameters of traits of economic importance in indigenous chicken (IC) breeding program. Estimates from literature were included where it was clearly indicated that the study was conducted on indigenous chicken and in the tropics. Information captured included country of study, method of evaluation, sample size, mean and standard deviation or standard error of the estimate, and for genetic correlations, number of sires. Seventy three (73) heritabilities and 38 genetic and phenotypic correlations traits were used. A random effect model was used so as to include the variances within and between studies. Weighted heritabilities for body weight at hatch (Bw0) and twelve weeks (Bw12), egg number at twelve weeks (EN12) and antibody response (Ab) were 0.46, 0.24, 0.12, and 0.27 respectively. Pooled and non-pooled heritability values were varied for body weight among other traits for instance the pooled genetic value for body weight at hatch was 0.46 as compared to 0.56 in one of the studies. The weighted genetic and phenotypic correlations were also varied from the ones from single studies. Heritability estimates differed due to method of estimation, location and time at which the data was collected.

Runaway fathers? Limited pollen dispersal and mating system in Rhizophora racemosa populations of a disturbed mangrove estuary

The contribution of pollen mediated gene flow in demographic stability is largely dependent on how far pollen can be dispersed, as well as how this dispersal affects the mating in breeding individuals. In this study patterns of pollen dispersal and mating systems in Rhizophora racemosa populations of the Cameroon Estuary complex (CEC) were assessed from 29 adult trees with their progeny seedlings (i.e., 483 propagules), sampled from three plots. Using progeny arrays constructed from eight microsatellite markers, we employed two-generational analyses to assess pollen pool structure, pollen dispersal distances, and mating systems. We found mean number of sires contributing to the pollen pool of a mother tree was low (2–3) and pollen dispersal distances were short (<12 m). Male gametic divergence among siblings was moderate (0.158 ≤ Φft ≤ 0.277). Low biparental inbreeding rates and moderate multi-locus outcrossing rates (0.559–0.650), suggest a mixed mating system comprising of spontaneous selfing (geitonogamy) and outcrossing. Our results show that pollen dispersal does not contribute to among patch genetic connectivity since the spatial scales of the patches far exceeds estimated pollen dispersal distances; indicating high gene flow previously reported within the CEC is predominantly mediated by propagule dispersal.

Assessment of sire contribution and breed-of-origin of alleles in a three-way crossbred broiler dataset

ABSTRACTBroiler breeding programs rely on crossbreeding. With genomic selection, widespread use of crossbred performance in breeding programs comes within reach. Commercial crossbreds, however, may have unknown pedigrees and their genomes may include DNA from 2 to 4 different breeds. Our aim was, for a broiler dataset with a limited number of sires having both purebred and crossbred offspring generated using natural mating, to rapidly derive parentage, assess the distribution of the sire contribution to the offspring generation, and to assess breed-of-origin of alleles in crossbreds. The dataset contained genotypes for 56,075 SNPs for 5,882 purebred and 10,943 3-way crossbred offspring generated by natural mating of 164 purebred sires to 1,016 purebred and 1,386 F1 crossbred hens. Using our algorithm FindParents, joint parentage derivation for the offspring and parent generations required only 1 m 29 s to retrieve parentage for 20,253 animals considering 4,504 possible parents. FindParents was similarly accurate as a maximum likelihood based method, apart from situations where settings of FindParents did not match the genotyping error rate in the data. Numbers of offspring per sire had a very skewed distribution, ranging from 1 to 270 crossbreds and 1 to 154 purebreds. Derivation of breed-of-origin of alleles relied on phasing all genotypes, including 8,205, 372, and 720 animals from the 3 pure lines involved, and allocating haplotypes in the crossbreds to purebred lines based on observed frequencies in the purebred lines. Breed-of-origin could be derived for 96.94% of the alleles of the 1,386 F1 crossbred hens and for 91.88% of the alleles of the 10,943 3-way crossbred offspring, of which 49.49% to the sire line. The achieved percentage of assignment to the sire line was sufficient to proceed with subsequent analyses requiring only the breed-of-origin of the paternal alleles to be known. Although required number of animals may be population dependent, to increase the total percentage of assigned alleles, it seems advisable to use at least approx. 1,000 genotyped purebred animals for each of the lines involved.

Does experimentally altered plumage brightness influence extra-pair mating success in female Tree Swallows (Tachycineta bicolor)?

Recent empirical evidence suggests that ornamental traits displayed by female birds may reflect aspects of their quality, and function during competitive interactions and (or) social mate attraction; however, less is known about how such traits influence extra-pair paternity. In Tree Swallows (Tachycineta bicolor (Vieillot, 1808)), plumage brightness of females signals their quality and may be related to extra-pair paternity if it enables them to invade the territories of other females to seek extra-pair copulations and (or) if potential extra-pair mates perceive their plumage brightness as attractive. Therefore, to examine whether the plumage brightness displayed by females influence rates of extra-pair paternity and the number of sires per brood, we experimentally enhanced and reduced the plumage brightness of females relative to controls. Our results showed that plumage brightness treatment of the female did not influence the number of extra-pair offspring in nests or the likelihood of a brood containing extra-pair offspring. Additionally, the number of extra-pair males siring offspring within the broods of females did not differ by plumage brightness treatment. Although extra-pair paternity has been shown to be beneficial for female Tree Swallows, our results suggest that plumage brightness of females does not influence their ability to engage in extra-pair mating.

Estimating a Key Parameter of Mammalian Mating Systems: The Chance of Siring Success for a Mated Male.

Studies of multiple paternity in mammals and other animal species generally report proportion of multiple paternity among litters, mean litter sizes, and mean number of sires per litter. It is shown how these variables can be used to produce an estimate of the probability of reproductive success for a male that has mated with a female. This estimate of male success is more informative about the mating system that alternative measures, like the proportion of litters with multiple paternity or the mean number of sires per litter. The probability of success for a mated male can be measured both theoretically and empirically, and gives an estimate of the intensity of sperm competition and of a male's "confidence of paternity" upon mating. The probability of success for mated males for ten "exemplar" species of mammals is estimated and they are compared for insights into the functioning of their mating systems.

Primary pollinator exclusion has divergent consequences for pollen dispersal and mating in different populations of a bird-pollinated tree.

Pollination by nectarivorous birds is predicted to result in different patterns of pollen dispersal and plant mating compared to pollination by insects. We tested the prediction that paternal genetic diversity, outcrossing rate and realized pollen dispersal will be reduced when the primary pollinator group is excluded from bird-pollinated plants. Pollinator exclusion experiments in conjunction with paternity analysis of progeny were applied to Eucalyptus caesia Benth. (Myrtaceae), a predominantly honeyeater-pollinated tree that is visited by native insects and the introduced Apis mellifera (Apidae). Microsatellite genotyping at 14 loci of all adult E.caesia at two populations (n=580 and 315), followed by paternity analysis of 705 progeny, revealed contrasting results between populations. Honeyeater exclusion did not significantly impact pollen dispersal or plant mating at Mount Caroline. In contrast, at the Chiddarcooping site, the exclusion of honeyeaters led to lower outcrossing rates, a threefold reduction in the average number of sires per fruit, a decrease in intermediate-distance mating and an increase in near-neighbour mating. The results from Chiddarcooping suggest that bird pollination may increase paternal genetic diversity, potentially leading to higher fitness of progeny and favouring the evolution of this strategy. However, further experimentation involving additional trees and study sites is required to test this hypothesis. Alternatively, insects may be effective pollinators in some populations of bird-adapted plants, but ineffective in others.

Female guppies increase their propensity for polyandry as an inbreeding avoidance strategy

Mating with close relatives often causes a decline in offspring fitness, termed inbreeding depression. Consequently, pre- and postcopulatory inbreeding avoidance mechanisms are likely to evolve, especially in females due to their relatively high levels of reproductive investment. If precopulatory inbreeding avoidance mechanisms are absent or unreliable, females may exploit postcopulatory sexually selected inbreeding avoidance mechanisms by mating with multiple males (polyandry). Despite this expectation, few studies have tested whether females alter their propensity to mate multiply in an inbreeding avoidance context. Here, we tested whether the perceived risk of inbreeding promotes polyandrous behaviour in guppies, Poecilia reticulata, a species susceptible to inbreeding depression. Virgin females were assigned to either a sibling or nonsibling mating and subsequently presented with three unrelated males simultaneously. Consistent with previous studies, we found that females did not discriminate between initially encountered males based on relatedness. However, females increased their propensity to mate multiply after mating with a brother. Subsequent paternity tests were performed to determine whether polyandry minimizes inbreeding through a dilution effect (i.e. greater number of sires in the related treatment) or through postcopulatory biasing mechanisms (i.e. greater paternity skew towards unrelated males). Surprisingly, our results supported neither scenario; we detected no significant difference in paternity skew or the number of sires between treatments. Overall, our study provides a rare example of females responding to an increased risk of inbreeding by increasing their propensity to remate, but the postcopulatory processes arising from this behaviour, along with the mechanisms underlying kin recognition, await further investigation.