Annual Reproductive Rate Research Articles

Reconstructing mountain goat history in the Olympic Mountains, USA

AbstractBetween 1925 and 1930, 11 or 12 non‐native mountain goats (Oreamnos americanus) were translocated from Alaska and British Columbia to the foothills of the Olympic Range. By 1970, descendants of these goats had colonized the entire range and concerns about the management of this introduced species developed as damage to alpine soil and vegetation occurred. A series of removals reduced the population from 1175 in 1983 to 389 by 1990, eventually growing to 584 in 2016. We used demographic and genetic data to parameterize a population genetics individual‐based simulation model of the Olympic Range mountain goats. We calibrated the model to replicate the population trajectory for Olympic mountain goats from establishment in the 1920s through the 1983 first census. As expected, modeled population dynamics from 1928 to 1983 mimicked parameter initialization from expanding populations. However, simulated heterozygosity did not align with observations, suggesting a process not accounted for within the simulation model, such as a bottleneck or founder effect. Sensitivity analyses showed changes in annual reproductive rate, juvenile mortality, and adult female mortality influencing population trajectories, but variation in male mortality revealed no changes. Evaluating the population dynamics of the model after removals showed that approximately 80% of the total animals removed during the 1980s needed to be female in order for the observed population estimates to occur. This model has the potential to be used more widely with established or introduced mountain goat populations, as well as to provide an approach for studying other introduced species and their population dynamics.

Genetic evaluation of growth and reproductive traits for Dawuro sheep in Ethiopia

This study aimed to estimate genetic parameters and genetic trends for growth, reproductive traits, and inbreeding levels in Dawuro sheep. Data on the studied traits were collected between 2017 and 2022.The genetic parameters were estimated by fitting different univariate models, considering/ignoring maternal effects, using WOMBAT software. The estimated direct heritability obtained from the best-fit models were 0.07±0.03, 0.16 ± 0.04, 0.45 ± 0.27, 0.21 ± 0.07, and 0.48 ± 0.04 for birth weight (BWT), weaning weight (3WT), 6-month weight (6WT), average daily gain from birth to weaning (ADG1), and average daily gain from weaning to 6 months of age (ADG2), respectively. The estimated direct heritability for litter size (LS), lambing interval (LI), and annual reproductive rate (ARR) were 0.10 ± 0.10, 0.001 ± 0.10, and 0.09 ± 0.49, respectively. The trait selected for improvement was 6WT, which exhibited a positive genetic trend and moderate heritability estimates. Positive genetic trend suggests the potential for further enhancement of post-weaning lamb growth traits.

Reproductive performance and productivity of local and Dorper x local crossbred ewes under community-based management system, Ethiopia

This study evaluated the reproductive and productivity of local and Dorper crossbred ewes in a community-based management system. We analyzed data collected from 2013 to 2021, taking into account different factors such as dam-breed, location, type of birth, season, and year of lambing. Lambing was observed all year-round, but the majority (35%) occurred in September, October, and December. This suggests that pasture availability, which is influenced by climatic-factors, may play a role in the seasonality of lambing. Litter-size at birth and weaning did not show any significant difference. Age at first lambing varied between breeds (P < 0.001), while lambing-interval and annual reproductive rates were unaffected by dam-breed (P > 0.05). The annual number of lambing per year significantly varied based on location and lambing seasons (P < 0.001), with a higher frequency during the major rainy-season compared to the dry-season (1.58vs1.42), highlighting the influence of feed availability. Productivity indices of ewes were calculated. Location and season of lambing had a significant impact on annual ewe productivity, while the ewe genotype showed no significant influence on productivity indices, except for the weight of lambs produced per kilogram of metabolic weight (0.84vs0.72 lambs per kg ewe and year; P < 0.01: 2.02vs1.77 kg lamb per kg0.75 ewe and year), where local ewes outperformed Dorper crossbred ewes. The difference in annual-productivity indices between local and Dorper crossbred ewes was more evident when considering the postpartum weight, as the ewes exhibited higher postpartum weights. However, both ewe genotypes produced comparable lamb weights per year (20.91vs20.16 kg lamb weaned per ewe and year for local and Dorper crossbred ewes, respectively). In summary, under low-input conditions, Dorper crossbred ewes demonstrated comparable reproductive performances and productivity traits to local ewes. Nevertheless, breed and environmental factors identified in this study should be taken into account to enhance sheep productivity in both local and Dorper crossbred ewes.

Productive and reproductive performance of Dawuro highland sheep managed under community-based breeding program in Ethiopia.

The objective of this study was to evaluate growth and reproductive performance of highland Dawuro sheep population managed under a community-based breeding program in Ethiopia. Records used in the study were collected over 6 years (2017-2022). In the current study, 3554 records were considered. Studied traits were birth weight (BWT), 3-month weight (WWT), 6-month weight (SMWT), daily gain from birth to weaning (ADG0-3), daily gains from weaning to 6-month age(ADG3-6), litter size(LS), lambing interval (LI), and annual reproductive rates(ARR). The data were analyzed using general linear models of SAS software. The overall least squares mean (LSM± SE) for BWT, WWT, SMWT, ADG0-3, and ADG3-6 were 2.69±0.02; 14.6±0.49, 22.8±0.22 kg, 128.05±2.27 gram (g), and 71.5±0.23 gram respectively. Site difference exerted significantly on BWT, WWT, and SMWT. The result of WWT and SMWT results of Dawuro sheep were comparable with previously reported known Ethiopian sheep breeds. The overall least squares mean ± standard error of LS, LI and, ARR were 1.67±0.04 lambs, 239±31.91 days, and 2.19±0.06 lambs, respectively. WWT and SMWT traits showed good responses to selection. The general implication of the result to future improvement program was continue selection, strengthening the existing breeder cooperatives, integration of full animal health, feed packages, conservation of prolific flocks, improving the management of animals, expanding the current CBBP to adjacent potential kebele, create market linkage and scaling out the existing best practice to a new sites.

Effects of the breeding season, birth type and sex on growth and reproductive performances of sheep breeds.

The study aimed at determining the effects of breed type, breeding season, sex and type of birth on the growth and reproductive traits of lambs. Two ewe breed types (Gellaper and Swakara) and four ram breed types (Damara, Dorper, GeDo and Swakara) were used. Two lambing seasons, spring (March-May) and autumn (September-November), were considered. Gellaper-based lambs born in autumn had higher (P < 0.05) mean birth weight (4.58 kg) compared to spring-born lambs (3.43 kg). Ram lambs were heavier (P < 0.05) than ewe lambs at weaning and post-weaning age. Singletons were heavier than twins (P < 0.05) at birth, weaning and breeding. Single and autumn-born lambs had a higher average daily gain (ADG) than spring-born lambs (P < 0.05). Ram lambs had a higher pre-weaning and overall ADG (P < 0.05) compared with ewe lambs. Swakara-based lambs gained more from weaning to mating compared to Gellaper-based lambs (P < 0.05). The conception, lambing and annual reproductive rate were all influenced by breed type and season (P < 0.05). Swakara-based lambs had higher reproductive capabilities, while Gellaper-based lambs grew faster but take longer to breed type; autumn lambing gave rise to low birth weights but heavier lambs at weaning and post-weaning, hence suitable for mutton production.

Persistent differences in recruitment variability among co-occurring North Atlantic groundfish species

Abstract Knowledge of recruitment and its variability in marine fish populations contributes to sustainable fisheries but a full understanding remains elusive. An earlier study showed that haddock (Melanogrammus aeglefinus) stocks exhibited consistently higher variability and lower reproductive rates compared to cod (Gadus morhua) stocks in the geographic regions where they co-occurred. Thus, cod may have a higher resilience to overexploitation, whereas haddock stocks may be more likely to be rescued by chance strong recruitments events. Since that initial study, the ecosystems and stocks have experienced large structural and functional changes, as well as changes in management practice and ocean warming. Here, we updated the previous earlier analysis with new data and found that despite large changes in the ecosystems explored, the patterns of recruitment variability have persisted. Recruitment variability remains higher in haddock than in cod, and the maximum annual reproduction rate at low spawning stock biomass (SSB) remains higher in cod than in haddock, although the latter difference is now less pronounced. Despite the economic and ecological importance of cod and haddock, and their long history of scientific scrutiny, the persistent difference in their reproductive biology remains unexplained.

Analysis of genetic parameters and genetic trends for early growth and reproductive traits of Doyogena sheep managed under community-based breeding program

This study aims to estimate genetic parameters and genetic trends for early growth and reproductive traits of Doyogena sheep. Data used in the study were collected over 6 years (2013–2018). Studied traits were birth weight (BWT), weaning weight (WWT), 6-month weight (SMWT), average daily gains from birth to weaning (ADG0-3), average daily gains from weaning to 6-month age (ADG3-6), average daily gain from birth to 6-month age (ADG0-6), litter size (LS), lambing interval (LI), age at first lambing (AFL), and annual reproductive rate (ARR). (Co) variance components and genetic parameters were estimated using restricted maximum likelihood (REML). The analyses were carried out using WOMBAT program. Univariate analysis was applied to estimate genetic parameters. Six different animal models were fitted by including or excluding maternal effects. The direct heritability estimates for BWT, WWT, SMWT, ADG0-3, ADG3-6 and ADG0-6 were 0.33 ± 0.06, 0.31 ± 0.06, 0.14 ± 0.06, 0.13 ± 0.04, 0.11 ± 0.07, and 0.02 ± 0.05 respectively. Direct heritability for LS, LI, and AFL were 0.28 ± 0.12, 0.20 ± 0.5, and 0.001 ± 0.3, respectively. The maternal heritability estimates for BWT, WWT, and LS were 0.24 ± 0.12, 0.60 ± 0.07, and 0.24 ± 0.08, respectively. The genetic correlation between BWT with WWT and BWT with SMWT were 0.21 ± 0.07 and 0.21 ± 0.09, respectively. Genetic progress for most of the studied traits has shown promising improvements. Thus, continuation of selection, therefore, suggested for more improvements in the performance of Doyogena sheep. Direct heritability estimates decrease as lamb age increases and selection based on earlier body weight will be more efficient.

Implications of non-ideal occupancy for the measurement of territory quality

Territory quality shapes population dynamics and has conservation implications for territorial species. Yet, quantifying territory quality using different measures can yield conflicting results, particularly if territory selection is non-ideal, thus challenging the understanding of territory quality. We used a 25-year population study of spotted owls ( Strix occidentalis ) occupying 72 territories to evaluate five commonly used demographic- and occupancy-based measures of territory quality: occupancy rate, annual apparent survival rate, territory fitness, mean annual reproductive rate, and total reproductive output. To do so, we evaluated pairwise relationships between measures of territory quality and assessed the extent to which spotted owls selected territories based on their potential to promote fitness. Measures of territory quality were generally positively correlated. Notably, however, territory occupancy explained less than half of the variation (R 2 = 0.37) in territory fitness (the expected fitness of territory holders). Non-ideal patterns in territory occupancy were the result of weak linkages between the likelihood of vacant territories becoming colonized and their fitness potential, particularly their capacity to promote reproduction. Imperfect territory colonization was likely the product of the spotted owl’s strong site fidelity to even low-fitness territories and constraints on the ability of dispersing individuals to locate high quality territories. Mismatches emerging from non-ideal colonization have important conservation implications because populations may benefit more from habitat restoration at low fitness-high occupancy territories and more from conspecific attraction measures at high fitness-low occupancy territories. Our findings for spotted owls were reasonably consistent with broad patterns observed for other species in previous studies, but the strength of associations between pairs of territory quality measures often varied considerably, suggesting that species-specific assessments of patterns in territory quality are important. Finally, when practical, examination of the ecological processes shaping multiple measures of territory quality will benefit the study and conservation of territorial species.

A 24-year investigation of the reproductive ecology of the Edible Dormouse (Glis glis)

The Edible Dormouse is a non-native rodent introduced to the Chilterns, UK, in 1902. It shows extreme annual variation in breeding; either having one litter per year or, in some years, failing to breed at all. Despite this slow reproductive rate compared to other rodents, its population is increasing, and has spread beyond the anticipated landscape barriers. Communal nesting is sometimes observed. This study aims to characterise the reproduction parameters over time, including from communal breeding. Based on a population of &amp;gt;11,000 PIT-tagged individuals, 600 litters and 4000 nestlings at our Chilterns study site over 24 years, we show the best fit of the number of new-borns is an increasing exponential. Monthly weight of nestlings also increased over the 24 years, while annual reproduction rate, litter size and nestling growth rates remained unchanged. Litter size decreased from 6.6 new-borns in August to 4.3 in October, indicating an average death rate of 37% in the first two months of life. Preliminary analysis suggests a small decrease in death rate over the years. Average growth rate of nestlings was c.100% of birth weight per week in their first month, but then slowed. We also examined evidence of kinship between nest sharers and investigated whether this, or communal breeding in general, promotes offspring survival. Our results will provide a deeper insight into the factors that drive the reproductive success of this invasive species and enable investigation of the effect of climatic variables on the number, survival and growth rate of nestlings.

High vulnerability of juvenile Nathusius' pipistrelle bats (Pipistrellus nathusii) at wind turbines.

Large numbers of bats are killed by wind turbines globally, yet the specific demographic consequences of wind turbine mortality are still unclear. In this study, we compared characteristics of Nathusius' pipistrelles (Pipistrellus nathusii) killed at wind turbines (N=119) to those observed within the live population (N=524) during the summer migration period in Germany. We used generalized linear mixed-effects modeling to identify demographic groups most vulnerable to wind turbine mortality, including sex (female or male), age (adult or juvenile), and geographic origin (regional or long-distance migrant; depicted by fur stable hydrogen isotope ratios). Juveniles contributed with a higher proportion of carcasses at wind turbines than expected given their frequency in the live population suggesting that juvenile bats may be particularly vulnerable to wind turbine mortality. This effect varied with wind turbine density. Specifically, at low wind turbine densities, representing mostly inland areas with water bodies and forests where Nathusius' pipistrelles breed, juveniles were found more often dead beneath turbines than expected based on their abundance in the live population. At high wind turbine densities, representing mostly coastal areas where Nathusius' pipistrelles migrate, adults and juveniles were equally vulnerable. We found no evidence of increased vulnerability to wind turbines in either sex, yet we observed a higher proportion of females than males among both carcasses and the live population, which may reflect a female bias in the live population most likely caused by females migrating from their northeastern breeding areas migrating into Germany. A high mortality of females is conservation concern for this migratory bat species because it affects the annual reproduction rate of populations. A distant origin did not influence the likelihood of getting killed at wind turbines. A disproportionately high vulnerability of juveniles to wind turbine mortality may reduce juvenile recruitment, which may limit the resilience of Nathusius' pipistrelles to environmental stressors such as climate change or habitat loss. Schemes to mitigate wind turbine mortality, such as elevated cut-in speeds, should be implemented throughout Europe to prevent population declines of Nathusius' pipistrelles and other migratory bats.

Cause for the Occurrence of Freemartin and Its Influence on Livestock Reproductive Performance

Livestock reproductive performance is a prerequisite for any successful livestock production program and it is depends up on the factors viz. parturition interval, ovarian activity, days open, fertility and age at first parturition, litter size and annual reproductive rate. However, the above mentioned factors are influenced directly or indirectly by the occurrence of freemartin animal within the flock or farm. The objective of this review was to organize the condensed information about the causes for the occurrence of freemartin, development and way of examining a freemartin animal and its influence on livestock reproductive performance. A freemartin is genetically female, but has many characteristics of a male. The ovaries of the freemartin do not develop correctly, and they remain very small, also the ovaries do not produce the hormones necessary to induce the behavioral signs of heat. The external vulvar region can range from a very normal looking female to a female that appears to be male. Usually, the vulva is normal except that in some animals an enlarged clitoris and large tufts of vulvar hair exist. It can be diagnosed in a number of ways ranging from simple examination of the placental membranes to chromosomal analysis. Understanding about the freemartin syndrome is important to take measure by the livestock keepers, farm managers or veterinarian to cull the heifer at her early age or keep it as a teaser bull and/or as draft animal. Keywords: Freemartin; Livestock; M asculinization; Reproductive Performance DOI: 10.7176/JNSR/12-21-03 Publication date: November 30 th 2021

On-farm evaluation of growth and reproductive performances of Washera and Gumuz sheep in northwestern Ethiopia: Basics for setting up breeding objectives/goals.

Growth and reproductive performance traits are traits of economic importance for sheep selection and productivity improvement interventions. This study aimed at comparative evaluation of growth and reproductive performance traits of sheep in the highland and lowland agro-ecologies of northwestern Ethiopia. Data on growth performance traits were collected from 144 Washera (78 males and 66 females) lambs and 72 Gumuz (37 males and 35 females) lambs. Data on reproductive performance traits were collected from 260 Washera (130 rams and 130 ewes) sheep and 150 Gumuz (75 rams and 75 ewes) sheep. General linear model univariate procedure was employed to analyze the collected data. Breed, the interaction effect between breed and season of birth as well as the interaction effect between breed and type of birth all exerted very high significant effect (P<0.001) on live weight at all age groups. Breed type affected pre-weaning average daily weight gain significantly (P<0.01). Pre-weaning average daily weight gain of Washera (70 g/day) was found much better performance than 60 g/day of Gumuz. Breed type exerts significant (P<0.05) effect on age at first lambing, lambing interval, annual reproductive rate and number of lambs born per ewe life time. Average age at first lambing and lambing interval of Washera sheep were 11.69 months and 9.27 months, respectively. The corresponding values for Gumuz sheep were 12.51 months and 10.43 months, respectively. Production and reproduction performance values of traits varied across the two breeds and sexes as well. These values can be used to set up breeding objectives or goals for selective breeding of sheep giving special emphasis to growth traits believed to have medium heritability values.

The El Niño – Southern Oscillation dramatically influences the probability of reproduction and reproductive rate of a tropical forest bird

Although climate change has been implicated in population declines of tropical forest birds, there is a critical lack of data on the mechanisms underlying these declines. Attempts to link climatic factors to variation in adult survival, fecundity or nest success have been largely inconclusive. Recent community‐scale analyses have suggested that tropical birds may be less likely to breed under adverse conditions, but long‐term data on individual reproduction are needed to test this hypothesis. Here we leverage 12 years of data on a lowland forest bird, the greater ani Crotophaga major, to investigate how demographic parameters vary with phase of the El Niño – Southern Oscillation (ENSO), a major driver of climatic conditions in tropical wet forest. The likelihood of breeding and annual reproductive rate both decreased dramatically in El Niño‐like years, with only 37.5% of adults attempting breeding in 2015 (a strong El Niño year). For birds that did breed, however, clutch size and daily nest predation rate were unaffected by climate. Of the local climate variables investigated, dry season length and the frequency of high temperatures were most closely associated with reproductive failure. These results indicate that El Niño conditions alter the demography of greater anis by reducing the likelihood of reproduction, a response that may be more widespread than currently recognized. We suggest that reduced reproduction under adverse conditions represents an important and understudied aspect of the life histories of tropical forest birds.

Dissolved Oxygen-And Temperature-Dependent Simulation of the Population Dynamics of Moon Jellyfish (Aurelia coerulea) Polyps

As the extent of hypoxia in coastal waters increases, the survivorship of jellyfish polyps relative to that of competing sessile organisms often increases, enabling them to reproduce more prolifically, leading to a medusa bloom in the following year. Quantifying the population of polyps can be used to predict when these blooms will occur. We used a time-delayed logistic equation to quantify the response to variable dissolved oxygen (DO) concentrations and temperatures in a population of moon jellyfish (Aurelia coerulea) polyps on substrates that carried competing sessile organisms. The availability of substrate depends on the DO threshold for each competitor, and substrates only become available to the polyps during hypoxic periods. We used the median sublethal concentration (SLC50) thresholds of hypoxia for different groups of benthic organisms to calculate the DO-dependent survivorship of A. coerulea polyps competing on the substrate. Since the median lethal time (LT50) for cnidarians is close to 240 h, we chose a 10-day delay in the time-delayed logistic equation. The carrying capacity is determined every 10 days depending on DO concentrations and temperature. The polyps reproduce by budding at a temperature-dependent rate after settling on the substrate during the hypoxic period, and thus, the annual polyp reproduction rate is determined by multiplying the temperature-dependent budding rate by the DO-dependent survivorship. The duration of hypoxia is a key factor determining the polyp population, which can increase more as the duration of hypoxia increases. Modeling simulations were compared to observed data. In this model, the DO and temperature distribution data make it possible to quantify variations in the population of the A. coerulea polyps, which can be used to predict the abundance and appearance of medusa the following year.

On-Farm Comparative Evaluation of Growth and Reproductive Performance Traits of Washera and Gumuz Sheep Populations in Northwestern Ethiopia

Growth and reproductive performance traits are traits of economic importance for sheep selection and productivity improvement. This study aimed at comparative evaluation of growth and reproductive performance traits of Washera and Gumuz indigenous sheep in the highland and lowland agro-ecologies of northwestern Ethiopia. Data on growth performance traits were collected from 412 Washera (162 male and 250 female) lambs and 208 Gumuz (72 male and 136 female) lambs. Concurrently, data on reproductive performance traits were collected from 406 Washera (130 rams and 276 ewes) sheep and 213 Gumuz (75 rams and 138 ewes) sheep. General linear model (GLM) univariate procedure was employed to analyze the collected data. Mean±SD values of adjusted yearling weight of Washera and Gumuz sheep was 21.80±1.91 and 20.37±1.85 kg, respectively. Breed type affect live weight significantly (P<0.001). Mean±SD values of age at first lambing, lambing interval and annual reproductive rate of Washera sheep were 11.69±1.96 months, 9.27±3.53 months and 2.12 lambs, respectively. The corresponding values for Gumuz sheep were 12.51±1.95 months, 10.43±1.25 months and 1.71 lambs, respectively. Production and reproduction performance values for traits of Washera and Gumuz sheep were comparable to other Ethiopian and African breeds. These values can be used to set up breeding objectives for optimizing breeding schemes of sheep breeding program. In addition, the varied minimum and maximum values of growth and reproductive performance traits indicates that there is within breed variability. This variation could be used as a basis for within breed selection among indigenous sheep by giving special consideration to growth rate traits, believed to have medium heritability values. Keywords: breeding practice, ewe, growth and reproductive performance, lamb, productivity DOI: 10.7176/JBAH/11-8-01 Publication date: April 30 th 2021

Estimation of co-variance components, genetic parameters, and genetic trends of reproductive traits in community-based breeding program of Bonga sheep in Ethiopia.

ObjectiveThe objectives of the study were to evaluate reproductive performance and selection response through genetic trend of community-based breeding programs (CBBPs) of Bonga sheep.MethodsReproduction traits data were collected between 2012 and 2018 from Bonga sheep CBBPs. Phenotypic performance was analyzed using the general linear model procedures of Statistical Analysis System. Genetic parameters were estimated by univariate animal model for age at first lambing (AFL) and repeatability models for lambing interval (LI), litter size (LS), and annual reproductive rate (ARR) traits using restricted maximum likelihood method of WOMBAT. For correlations bivariate animal model was used. Best model was chosen based on likelihood ratio test. The genetic trends were estimated by the weighted regression of the average breeding value of the animals on the year of birth/lambing.ResultsThe overall least squares mean±standard error of AFL, LI, LS, and ARR were 375± 12.5, 284±9.9, 1.45±0.010, and 2.31±0.050, respectively. Direct heritability estimates for AFL, LI, LS, and ARR were 0.07±0.190, 0.06±0.120, 0.18±0.070, and 0.25±0.203, respectively. The low heritability for both AFL and LI showed that these traits respond little to selection programs but rather highly depend on animal management options. The annual genetic gains were −0.0281 days, −0.016 days, −0.0002 lambs and 0.0003 lambs for AFL, LI, LS, and ARR, respectively.ConclusionImplications of the result to future improvement programs were improving management of animals, conservation of prolific flocks and out scaling the CBBP to get better results.

Reproductive parameters of the North Atlantic right whale

North Atlantic right whale reproduction was assessed for the period 1980 through 1998. At the end of this period, we estimated there werebetween 299 and 437 right whales alive, including 70 mature females. Using maximum and minimum population estimates for the entireperiod, mean values for gross annual reproductive rate were 0.36 and 0.49 respectively, and the mean value for calves per mature femaleper year was 0.25. There is a significant decreasing trend in calves per mature female per year over the entire study period. The mean ageat first calving is 9.53 years. The mean number of cows recruited annually since 1985 is 3.8. Mean annual calving intervals have increasedsignificantly during the study period from 3.67 years (1980-1992) to over 5 years (1993-1998). Although the North Atlantic population isaffected by significant anthropogenic mortality, diminishing reproductive rates are probably also responsible for the plight of thisspecies.

Seasonal variation of health in Asian elephants

Long-lived species are often predicted to be buffered against seasonal variation: longevity means low annual mortality and reproductive rates and annual variability in climate may therefore have a smaller impact on population growth rates of long-lived species in comparison to short-lived ones. However, little is known of the physiological mechanisms underlying such patterns in long-lived species. In this study, we investigated seasonal variation in the health of Asian elephants living in a seasonal monsoon climate. We used two complementary methods: (i) global and (ii) trait-by-trait analyses of seasonal effects on 23 health parameters of 225 individually marked elephants with known age and reproductive and health history, with repeated measures per individual over a 26-month period. The global analysis highlighted the biggest differences in health between the hot and monsoon seasons. Our trait-specific analyses identified the physiological functions underlying such health variation in different ecological settings, including haematological, immunological, muscular, kidney and liver functions, as well as protein balance and electrolytes. Overall, the results suggest that even long-lived, large mammals may experience physiological changes in response to seasonal variation that in extreme circumstances can pose a significant health risk.

Parasite resistance predicts fitness better than fecundity in a natural population of the freshwater snail Potamopyrgus antipodarum.

The cost of males should give asexual females an advantage when in competition with sexual females. In addition, high-fecundity asexual genotypes should have an advantage over low-fecundity clones, leading to reduction in clonal diversity over time. To evaluate fitness components in a natural population, we measured the annual reproductive rate of individual sexual and asexual female Potamopyrgus antipodarum, a New Zealand freshwater snail, in field enclosures that excluded competitors and predators. We used allozyme genotyping to assign the asexual females to particular clonal genotypes. We found that the most fecund asexual clones had similar or higher fecundity as the top 10% of sexual families, suggesting that fecundity selection, even without the cost of males, would lead to replacement of the sexual population by clones. Consequently, we expected that the clones with the highest fecundity would dominate the natural population. Counter to this prediction, we found that high annual reproductive rates did not correlate with the frequency of clones in the natural population. When we exposed the same clones to parasites in the laboratory, we found that resistance to infection was positively correlated with the frequency of clones in the population. The correlation between fecundity and parasite resistance was negative, suggesting a trade-off between these two traits. Our results thus suggest that parasite resistance is an important short-term predictor of the success of asexual P. antipodarum in this population.

Statistical modeling of patterns in annual reproductive rates.

Reproduction by individuals is typically recorded as count data (e.g., number of fledglings from a nest or inflorescences on a plant) and commonly modeled using Poisson or negative binomial distributions, which assume that variance is greater than or equal to the mean. However, distributions of reproductive effort are often underdispersed (i.e., variance < mean). When used in hypothesis tests, models that ignore underdispersion will be overly conservative and may fail to detect significant patterns. Here we show that generalized Poisson (GP) and Conway-Maxwell-Poisson (CMP) distributions are better choices for modeling reproductive effort because they can handle both overdispersion and underdispersion; we provide examples of how ecologists can use GP and CMP distributions in generalized linear models (GLMs) and generalized linear mixed models (GLMMs) to quantify patterns in reproduction. Using a new R package, glmmTMB, we construct GLMMs to investigate how rainfall and population density influence the number of fledglings in the warbler Oreothlypis celata and how flowering rate of Heliconia acuminata differs between fragmented and continuous forest. We also demonstrate how to deal with zero-inflation, which occurs when there are more zeros than expected in the distribution, e.g., due to complete reproductive failure by some individuals.