Factors affecting the reproductive success of dominant male meerkats

Identifying traits that affect the reproductive success of individuals is fundamental for our understanding of evolutionary processes. In cooperative breeders, a dominant male typically restricts mating access to the dominant female for extended periods, resulting in pronounced variation in reproductive success among males. This may result in strong selection for traits that increase the likelihood of dominance acquisition, dominance retention and reproductive rates while dominant. However, despite considerable research on reproductive skew, few studies have explored the factors that influence these three processes among males in cooperative species. Here we use genetic, behavioural and demographic data to investigate the factors affecting reproductive success in dominant male meerkats (Suricata suricatta). Our data show that dominant males sire the majority of all offspring surviving to 1 year. A male's likelihood of becoming dominant is strongly influenced by age, but not by weight. Tenure length and reproductive rate, both important components of dominant male reproductive success, are largely affected by group size and composition, rather than individual traits. Dominant males in large groups have longer tenures, but after this effect is controlled, male tenure length also correlates negatively to the number of adult females in the group. Male reproductive rate also declines as the number of intra- and extra-group competitors increases. As the time spent in the dominant position and reproductive rate while dominant explain > 80% of the total variance in reproductive success, group composition thus has major implications for male reproductive success.     

Factors affecting breeding success of the Flea Bay white-flippered penguin (

The little blue penguin (Eudyptula minor) is in decline throughout much of its range in New?Zealand and Australia, largely due to introduced predators, human disturbance and roadkill mortalities. The white-flippered penguin is a unique morphological variant of the blue penguin, which is traditionally given subspecific status (Eudyptula minor albosignata), and is found only on Banks Peninsula and Motunau Island in Canterbury, New?Zealand. We monitored a varying number of nest boxes from 1996 to 2009. Overall breeding success was 64% over 13 years of monitoring, with a hatching success rate of 75% and a fledging success rate of 85%. We used a set of generalised linear mixed models and model selection to examine the relative influence of various explanatory variables on hatching, fledging and overall breeding success. Breeding success in nest boxes significantly increased with shorter average pair bond length, longer guard period and later relative lay date. Guard period length was the best predictor of breeding success, followed by relative lay date and average pair bond length. Hatching success also increased with later relative lay date but fledging success was not influenced by any of the explanatory variables measured.     

Factors affecting the success of surgical and nonsurgical equine embryo transfer

Nonsurgical embryo recovery was attempted from light-horse and draft mares. Embryo recovery rates were not affected (P>.05) by technician or stallion but were lower (P<.05) from draft mares (44%) than light-horse mares (67%). Sham transfer of embryos on day 8 post-ovulation did not (P>.05) increase the number of mares returning to estrus by 22 days post-ovulation. Method of embryo transfer greatly affected pregnancy rates. Embryos transferred surgically during March–June resulted in 0 of 12 pregnancies versus 13 of 25 pregnancies obtained during July–September, This strongly suggests a seasonal influence on pregnancy rates. Technician influenced (P<.05) the success of nonsurgical transfer (46.2% vs. 7.7%). In addition, protection of the insemination rod with a sheath (guarded method) appeared to provide some advantage over an unguarded method of nonsurgical transfer (54% vs. 23%). Lastly, a preliminary experiment was conducted to evaluate transfer of embryos via flank incision. Four of 5 embryos transferred by this method resulted in a pregnancy at 50 days post estrus.     

神农架川金丝猴冬春季节取食影响因素

以样方调查法和粪便显微组织学分析法确定了冬春季神农架地区川金丝猴的食物组成,分析了主要食源植物的营养成分,探讨了影响川金丝猴冬春季节取食的主要因素.结果表明:在冬季,川金丝猴食物组成与食源植物的粗灰分含量( r=0.709,P=0.015)呈正相关,而与食源植物的相对丰富度(r=0.543,P=0.084)、粗蛋白含量(r=0.036,P=0.916)、粗纤维含量(r=0.458,P=0.156)、粗脂肪含量(r=0.445,P=0.170)、含水量(r=-0.099,P=0.771)和无氮浸出物含量(r=-0.522,P=0.100)均不相关;在春季,与食源植物的相对丰富度(r=0.721,P=0.000)呈正相关,与含水量(r=0.114,P=0.507)、粗脂肪含量(r=0.151,P=0.380)、无氮浸出物含量(r=0.084,P=0.625)、粗蛋白含量(r=-0.275,P=0.105)、粗纤维含量(r=-0.010,P=0.956)和粗灰分含量(r=-0.178,P=0.299)不相关.主成分分析表明,食源植物的粗纤维(0.992)、粗脂肪(0.944)、粗蛋白(0.905)和食物丰富度(0.885)为川金丝猴冬季取食的主要影响因子,粗蛋白(0.946)、无氮浸出物(0.939)、含水量(0.920)和食物丰富度(0.898)为川金丝猴春季取食的主要影响因子.     

Shoal composition determines foraging success in the guppy

The composition of an animal group can impact greatly on thesurvival and success of its individual members. Much recentwork has concentrated on behavioral variation within animalpopulations along the bold/shy continuum. Here, we screenedindividual guppies, Poecilia reticulata, for boldness usingan overhead fright stimulus. We created groups consisting of4 bold individuals (bold shoals), 4 shy individuals (shy shoals),or 2 bold and 2 shy individuals (mixed shoals). The performanceof these different shoal types was then tested in a novel foragingscenario. We found that both bold and mixed shoals approacheda novel feeder in less time than shy shoals. Interestingly,we found that more fish from mixed shoals fed than in eitherbold or shy shoals. We suggest that this can be explained bythe fact that nearly all the cases where one fish was followedinto the feeder by another occurred within mixed shoals andthat it was almost always a shy fish following a bold one. Theseresults suggest clear foraging benefits to shy individuals throughassociating with bold ones. Surprisingly, our results also suggestpotential foraging benefits to bold individuals through associatingwith shy individuals. This study highlights a possible mechanismby which interindividual variation in behavioral types is maintainedin a population.     

Factors affecting differential mating success in male crested newts, Triturus cristatus

This study investigates differences in mating success in male crested newts, Triturus cristatus. In experiments, mating success varies considerably between individual males. Male size affects mating success, but the maximal height of the male's crest is more important. Male size and crest height are correlated, but in partial correlation analysis only crest height is significantly correlated with mating success. Motivation is also an important factor in determining male mating success as males that had been isolated for a week were more successful than freshly caught males. Newts might be limited in their ability to produce spermatophores, and isolation gives the male time to produce more spermatophores. It is likely that motivational state is less important in a natural population than size and crest height, because wild males are often interrupted during courtship before spermatophore deposition and hence are highly motivated to mate.     

Factors affecting success of embryo collection and transfer in large dairy herds

Our objective was to evaluate factors that affected the success of embryo transfer programs in large dairy herds. Non-lactating donor cows produced a larger number of ova/embryos (P<0.01) and viable embryos (P<0.01) than lactating cows. The interaction between season and donor class was correlated with the proportion of ova/embryos classified as fertilized (P=0.03), because lactating donors had fewer fertilized ova in the summer. There was no correlation between 305-day mature equivalent milk yield and response to superstimulation. Although the interval between superstimulation protocols was correlated with the number of ova/embryos (P=0.03), there was no correlation with the number of viable embryos. Pregnancy per embryo transfer (P/ET) in heifer recipients was correlated with embryo quality grade (P<0.01), season (P=0.04), and whether embryos were fresh or frozen/thawed (P<0.01). Lactating recipient cows tended to have a lower rate of P/ET during the summer (P=0.12 to P=0.08). Synchronization protocols tended to be (P=0.06; Herd 1) or were (P=0.02; Herd 2) correlated with P/ET. Lactating cows receiving vitrified IVF embryos had a lower (P=0.01) P/ET than those receiving fresh IVF embryos, especially in the summer (P=0.09). Milk yield was not correlated with P/ET. The use of heat abatement systems is critical to improve embryo production and P/ET. Synchronization protocols that optimized synchrony of ovulation may increase fertility of recipient cows and eliminate the need for estrous detection.     

Factors affecting breeding success of Peregrine and Lanner Falcons in South Africa

Jenkins, A.R. 2000. Factors affecting breeding success of Peregrine and Lonner Falcons in South Africa. Ostrich 71 (384): 385-392. Breeding success was recorded for three Peregrine Falcon, Falco peregrinus, populations in South Africa over nine years, and for Peregrine and Lanner Falcon, Ebiarmicus, populations in an area of sympatry over three years. The objectives of the study were to measure geographic and interspecific variation in reproductive performance, and determine environmental correlates of productivity. Territory occupancy, the frequency of breeding per occupied territory and clutch size did not vary significantly between the three Peregrine populations. However, Peregrine breeding success was generally lower on the Cape Peninsula (1. 11 young fledged per territorial poir), higher in the Soutpansberg (1.36) and highest on the Orange River (1.70). Overall, fledging rates of Soutpansberg Peregrines and Lanners were not significantly different, although annual productivity of the Lonner population was consistently higher. Neither species' breeding success was significantly depressed by the presence of close neighbouring pairs of the other, suggesting that they were not active competitors. Breeding performance of Peregrines on the Cape Peninsula correlated strongly with spring weather conditions: egg and hatchling survival was lower in wet years, and fledging rates were higher in warm years. Annual productivity of Orange River Peregrines correlated positively with the height of the river at the onset of breeding, and productivity of Soutpansberg Peregrines was higher in seasons following years of high rainfall. Elements of the physical structure of the nesting habitat (exposure of the nest ledge, height of the nest cliff) correlated positively with Peregrine breeding performance. Breeding success of Soutpansberg Lanners was largely unaffected by any of the environmental variables considered. Overall, it is proposed that Peregrine productivity reflected variation in the physical environment and its affect on prey availability.     

Factors affecting the success of oocyte transfer in a clinical program for subfertile mares

Oocyte transfer is a potential method to produce offspring from valuable mares that cannot carry a pregnancy or produce embryos. From 2000 through 2004, 86 mares, 19.2 +/- 0.4 yr of age (mean +/- S.E.M.), were used as oocyte donors in a clinical program at Colorado State University. Oocytes were collected from 77% (548/710) of preovulatory follicles and during 96% (548/570) of cycles. Oocytes were collected 21.0+/-0.1h after administration of hCG to estrous donors and cultured 16.4 +/- 0.2 h prior to transfer into recipients' oviducts. At 16 and 50 d after transfer, pregnancies were detected in 201 of 504 (40%) and 159 of 504 (32%) of recipients, respectively, with an embryo-loss rate of 21% (42/201). Pregnancy rates were similar (P > 0.05) for cyclic and noncyclic recipients and for recipients inseminated with cooled, fresh or frozen semen. One or more recipients were detected pregnant at 16 and 50 d, respectively, for 80% (69/86) and 71% (61/86) of donors. More donors <20 than > or = 20 yr (mean ages +/- S.E.M. of 15.5 +/- 0.4 and 23.0 +/- 0.3 yr, respectively) tended (P = 0.1) to have one or more pregnant recipients at 50 d (36/45, 80%; 28/45, 62%, respectively). Results of the program confirm that pregnancies can consistently be obtained from older, subfertile mares using oocyte transfer.     

Factors affecting nest site selection and nesting success in the Common Eider Somateria mollissima

Nesting site selection and nesting success in Common Eiders Somateria mollissima were studied over a 3-year period (1991–1993) in the Mast River delta (58^o24'N, 94^o24'W), 40 km east of Churchill, Manitoba, Canada. Eiders preferentially nested on islands that had incubating Lesser Snow Geese Anser caerulescens caerulescens on them; this effect was also seen between years on the same islands. Eiders which nested on islands with geese had a reduced chance of having eggs taken by predators during egg-laying and had a greater chance of hatching once incubation had begun, independent of the number of other eiders nesting on the island. The distance to a goose nest was less in nests which did not lose eggs prior to incubation than in those which did, but there was no difference in the distance to a goose nest in eider clutches which did or did not hatch. Artificial eider eggs placed closer to goose nests had a lower probability of being predated than those placed farther away. Nests on islands farther up the river and farther from the mainland had higher nesting success, presumably because these nesting islands were inaccessible to Arctic Foxes Alopex lagopus.     

Factors affecting social behavior and reproductive success of male rhesus monkeys

This paper reviews aspects of life history that influence the reproductive success of male rhesus monkeys. Recent theories propose that there is some optimum level of inbreeding for each population and that behaviors related to group transfer by males are the result of selection pressure toward such an optimum. Group changing by males is clearly linked to the effects of testosterone at sexual maturation. A male’s maternal genealogical rank is not consistently related to the age at which it leaves the natal group, but social interactions within the natal group may influence the age of departure. Choice of the new group is influenced by the operational sex ratio and the presence of maternal relatives. Rank in the new group is positively correlated with seniority. Seniority, in turn, is influenced by the rank of the male’s natal group, his mother’s genealogical rank, and the presence of male siblings in the new group. Much of this effect is due to the high mortality of males born to females and/or groups of low rank. Most studies show a positive association between male reproductive success and rank. Males from high-ranking groups and/or maternal genealogies that join groups containing brothers tend to remain in those groups longer, attain a higher rank, and probably achieve higher levels of reproduction than other males.     

Factors affecting success of embryo collection and transfer in a transgenic goat program

During a goat transgenic program that took place in Israel from July 1995 to February 1996, Saanen (n = 343) and Nubian x Damascus (n = 378) crossbred goats of mixed ages were used as donors (n = 433) and recipients (n = 288). The effects of season, age, number of surgical procedures, previous hormonal treatments and ovulation rate on the number of microinjectable embryos collected were studied. Likewise, the effects of these parameters on the pregnancy rate as well as the number of embryos transplanted, endogenous progesterone concentrations and exogenous progesterone supplementation were studied in recipient does. Following superovulation with ovine follicle stimulating hormone, 85% of the does responded with 13.6 +/- 5.7 (mean +/- S D) ovulations/doe. Age, month and number of previous hormonal treatments significantly affected the ovulation rate. The average recovery rate was 70%, and it was affected only by the ovulation rate. Pronuclei were visualized in about 30% of the flushed embryos (including unfertilized ova), and those were microinjected with human serum albumin gene construct. About 68% of the injected embryos underwent at least one division during an overnight incubation, and those embryos were transferred, giving about 2.0 transferred embryos per ovulated donor. Of the recipients, 86% responded following synchronization with 3.1 +/- 1.6 (mean +/- S D) ovulations per doe. Breed and month had a significant effect on the ovulation rate. Two or three microinjected embryos were transferred to each recipient, resulting in more than a 40% pregnancy rate during September to November. Lower pregnancy rates were obtained before and after that period. By monitoring plasma progesterone concentrations in the recipients it was found that progesterone concentration was correlated with the ovulation rate. However, the pregnancy rate was not affected by progesterone concentration. During January and February, 30 to 50% of the recipients failed to develop functional corpora lutea (CL) following embryo transfer, which explained the lower pregnancy rate in those months. Of the 86 kids born 4 were transgenic.     

Starling foraging success in relation to agricultural land-use

Changes in agricultural land-use have been suggested to contribute to the decline of several bird species through negative effects on their food supply during breeding. One important change in land-use has been loss of pastures, especially permanent pastures. In this study we investigated how different forms of agricultural land-use affected foraging success of a declining bird species, the European starling Sturnus vulgaris . We let caged starlings forage in different forms of agricultural fields and determined time spent foraging and foraging success. The starlings' activity level (time spent actively foraging) as well as the number of prey caught per time unit was strongly related to the abundance of prey in soil samples. Also the body mass change during the experiment was positively related to activity level and prey capture rate. We found consistent differences in foraging variables between habitats. In spring sown grain starlings were least active and found fewer prey items at a lower rate than in any other habitat. The other three habitats differed less, but in general mowed hay fields appeared slightly more valuable than the cultivated and natural pastures. We did not find any differences between natural and cultivated pastures in foraging variables. Thus, starling foraging success is higher in grass-covered fields than in cultivated fields, but the management of the grass-covered fields mattered less. The results are consistent with starlings having higher population densities and breeding success in areas with higher availability of pasture. We suggest that the physical structure of the habitat (sward height) and moisture may be additional variables that need to be taken into account to explain starling breeding density and success in the agricultural landscape.     

Factors affecting nesting success of a bird assembly in the central Monte Desert, Argentina

We estimated nesting success of a breeding bird assemblage in the central Monte Desert in four breeding seasons (1995–1999). We analyzed the effect of year, period within the breeding season, nest type, and nest location on daily survival rates (DSR). Averaged nesting success of passeriforms in natural habitats was very low (<20% on average, n=12 species). DSR tended to be lower during the egg-laying stage in Furnariidae, Rhinocryptidae, Mimidae, and Emberizidae. Tyrannidae had the highest DSR for all nesting stages and Emberizidae the lowest. Predation was the main cause of nest failure (>90% on average, n=12 species). DSR differed among years, being higher in the driest year (1995) and lower in the most humid year (1997). Nests initiated in the first half of the breeding season had higher DSR than those initiated in the second half. Closed nests had similar survival rates to open nests. DSR differed according to species of plant that supported the nest. Nest predation in the central Monte Desert may be an important selective pressure in birds' life history, which is in accordance with other results for South American temperate birds.     

Factors affecting piping plover hatching success on Long Island,New York

Low hatching success may limit progress towards reaching productivity goals for Atlantic Coast piping plover (Charadrius melodus) recovery, despite management strategies to protect eggs from predators and decrease human disturbance of birds on nests. We measured piping plover hatching success on Eastern Long Island beaches and identified the major causes of egg failure to better understand why eggs that were otherwise intact (not depredated or destroyed by tidal flooding) failed to hatch. We documented egg and nest fates, dissected contents of unhatched eggs to determine viability, and recorded human and predator activity near a subset of plover nests on Suffolk County Parks properties. The low hatching success we recorded (0.60) in 2006 and 2007 would require higher chick survival rates than are typically observed for piping plovers to meet recovery targets for productivity. Few eggs showed signs of poor viability and overall egg hatchability was comparable to other ground nesting birds. Most egg failure was due to either depredation at unexclosed nests or nest abandonment by adults. The best predictor of nest abandonment was the maximum number of red fox tracks (Vulpes vulpes) counted on nearby transects (β = −1.16, 95% CI: −2.0 to −0.3) and we found evidence that plovers abandoned eggs in response to predation risk (e.g., a fox circling a nest exclosure). Adults from abandoned nests may have deserted eggs or been depredated. In either case, intact and viable eggs were abandoned. Nest abandonment was not related to human activity near nests, which were buffered from human disturbance by symbolic string fencing. Our results suggest that depredation and nest abandonment (e.g., desertion or death of adults) due to predator disturbance, not human disturbance or poor egg viability, contributed to the low hatching success we recorded. Active predator removal in addition to modification of predator exclosure use and design may be necessary to prevent direct (egg depredation) and indirect (nest abandonment) negative effects of predators on hatching success. © 2010 The Wildlife Society.     

Factors affecting survivorship of defouled communities and the effect of fragmentation on establishment success

The environmental risks associated with the defouling of artificial structures (e.g., vessels, oil rigs, marina pontoons, aquaculture structures) in the marine environment are gaining international attention. This paper presents a series of laboratory- and field-based experiments that collectively aimed to elucidate biotic and abiotic factors that influence re-establishment success of biofouling organisms and fragmented colonial organisms defouled to the seabed. Reattachment success of colonial organisms experimentally fragmented was found to be species specific and dependent on fragment size. In both laboratory and field trials, some colonial ascidians had consistently greater reattachment success for larger size classes of fragments, while other encrusting and erect taxa showed poor reattachment capabilities. This study also revealed that sedimentation and turbidity are likely to have a strong influence on the survivorship of defouled material. Furthermore, for both high and low sedimentary environments, survivorship was found to be greater where predators were excluded. Despite risks posed by non-indigenous species (NIS), it is proposed that in-water defouling may be an appropriate management response in situations where a “do nothing” approach is potentially more detrimental. Moreover, results from this study suggest that environmental risks associated with defouling may be mitigated through appropriate defouling strategies (e.g., defouling location, frequency and method). In order to increase our predictive abilities for NIS establishment success resulting from in-water defouling, future studies should aim to further elucidate the relative importance of factors affecting survivorship of defouled material at locations where defouling is routinely undertaken.