scholarly journals Responses of phenology, synchrony and fecundity of breeding by African ungulates to interannual variation in rainfall

2013 ◽  
Vol 40 (8) ◽  
pp. 698 ◽  
Author(s):  
Joseph O. Ogutu ◽  
Hans-Peter Piepho ◽  
Holly T. Dublin
Keyword(s):  
Reproductive Success ◽  
Interannual Variation ◽  
Rainfall Variability ◽  
Gestation Length ◽  
Mating Period ◽  
Rainfall Variation ◽  
Timing Of Births ◽  
African Ungulates ◽  
High Flexibility ◽  
Savanna Ungulates

Context The timing and synchrony of births are important components of fitness among ungulates living in seasonal environments. Aims We investigated the effects of rainfall variation on interannual variation in the timing, synchrony and prolificity of births for six African ungulate species inhabiting an equatorial savanna with bimodal rainfall. Methods We analyse how seasonally and aseasonally breeding African savanna ungulates maintain reproductive success despite rainfall constraints, and adjust the phenology, synchrony and fecundity of their breeding to track interannual variation in rainfall. We use data on six ungulate species inhabiting the Masai Mara National Reserve (Mara) of Kenya to test five hypotheses concerning the influences of seasonality in resources, gestation length and the hider–follower strategy on the timing, synchrony and prolificity of calving. Key results Births were more synchronised for topi, warthog and zebra than for hartebeest, impala, and giraffe. Births occurred in most months, but tended to peak during the early rains when forage quality peaks for all species. The rainfall component exerting the strongest influence on timing of births varied with species. Gestation length, the hider–follower dichotomy, and hence predation, had apparently weak influences on birth synchrony. In drought years with nutritionally deficient forage, births were delayed, less synchronised and fewer. This portrayed protracted calving seasons, suppression of early conceptions, and delayed onset of births, calf losses, reproductive pauses or failures. However, in rainy years with sufficient forage, births peaked early, or were not delayed, and the synchronicity of calving increased for all species. This suggested early breeding by primiparous females; or higher fertility early in the mating period. The prolificity of calving increased with rainfall for topi and warthog but decreased for the remaining species. Conclusions Marked interannual variability in rainfall, plant phenology and forage sufficiency in tropical savannas impose strong constraints on ungulates, favouring flexible timing of births over strictly seasonal reproduction characteristic of temperate latitudes with predictable seasonal resource cues. Implications Despite high flexibility in their timing of births, widening rainfall variability expected to result from global warming could lower reproductive success of tropical ungulates by lowering their fecundity and survival prospects of their calves if droughts became more frequent and severe.

scholarly journals The Ecology of Stress: linking life-history traits with physiological control mechanisms in free-living guanacos

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2640 ◽  
Author(s):  
Ramiro J.A. Ovejero Aguilar ◽  
Graciela A. Jahn ◽  
Mauricio Soto-Gamboa ◽  
Andrés J. Novaro ◽  
Pablo Carmanchahi
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Reproductive Success ◽  
Hpa Axis ◽  
Life History Traits ◽  
Mating Period ◽  
Entire Study ◽  
Non Invasive ◽  
Animal Populations

BackgroundProviding the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life’s challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that prolonged elevated levels of GCs over time can be harmful to individuals, it is predicted that the HPA axis suppresses the HPG axis and causes T levels to decrease, as GCs increase.MethodsAll of the data for individuals were collected by non-invasive methods (fecal samples) to address hormonal activities. This is a novel approach in physiological ecology because feces are easily obtained through non-invasive sampling in animal populations.ResultsAs expected, there was a marked adrenal (p-value = .3.4e−12) and gonadal (p-value = 0.002656) response due to seasonal variation inLama guanicoe. No significant differences were found in fecal GCs metabolites between males/females*season for the entire study period (p-value = 0.2839). Despite the seasonal activity variation in the hormonal profiles, our results show a positive correlation (p-value = 1.952e−11, COR = 0.50) between the adrenal and gonadal system. The marked endocrine (r2 = 0.806) and gonad (r2 = 0.7231) response due to seasonal variation in male guanaco individuals highlights the individual’s energetic demands according to life-history strategies. This is a remarkable result because no inhibition was found between the axes as theory suggests. Finally, the dataset was used to build a reactive scope model for guanacos.DiscussionGuanacos cope with the trade-off between sociability and reproductive benefits and costs, by regulating their GCs and T levels on a seasonal basis, suggesting an adaptive role of both axes to different habitat pressures. The results presented here highlight the functional role of stress and gonad axes on a critical phase of a male mammal’s life—the mating period—when all of the resources are at the disposal of the male and must be used to maximize the chances for reproductive success.

Use of a stochastic model of a calving distribution for beef cows for formulating optimal natural mating strategies

1997 ◽  
Vol 64 (3) ◽  
pp. 413-421 ◽  
Author(s):  
A. B. Pleasants
Keyword(s):  
Probability Distributions ◽  
Live Weight ◽  
Beef Cows ◽  
Mating Strategies ◽  
Conception Rate ◽  
Model Parameters ◽  
Gestation Length ◽  
Mating Period ◽  
Frequency Distributions ◽  
The Cost

AbstractA model of a birthdate distribution for a herd of beef cows is constructed using the probability distributions of the variables that affect reproduction in the cow — anoestrous interval, oestrous cycle length, conception to each oestrus, gestation length, period of mating and the prior calving frequency distribution. The model is general and can be reparamaterized to deal with issues such as intervention to synchronize oestrous cycles among cows in the herd by changing the form of the relevant probability distributions.The model is applied to the question of what time to begin mating in a herd of beef cows. The average calf live weight at day 200, herd conception rate and proportion of cows calving before the planned start of calving were calculated from the model output. The model parameters given by the anoestrous period, conception rate to each oestrus and the regression between prior calving date and anoestrous period, were varied in a factorial design to investigate a range of circumstances found on a farm. Prior calving distributions were generated by random sampling from eight actual calving frequency distributions.Generally starling mating earlier produced an advantage in terms of extra calf live weight and herd conception rate. However, the proportion of the herd calving earlier than expected increased with early mating. Thus, the feasibility of early mating depends on the cost to the farmer of dealing with early calving cows as well as the advantage of heavier older calves.Altering the fixed parameters in the model (variances and covariances, prior calving distributions, mating period) to accommodate the circumstances of herds run under different conditions may produce different results. Model structure allows easy alteration of these parameters and also the introduction of different probability distributions for some variables. This might be necessary to model oestrous synchronization and artificial insemination, issues not considered in this paper.

scholarly journals Interannual Variation of the Late Fall Rainfall in Central Vietnam

2012 ◽  
Vol 25 (1) ◽  
pp. 392-413 ◽  
Author(s):  
Tsing-Chang Chen ◽  
Jenq-Dar Tsay ◽  
Ming-Cheng Yen ◽  
Jun Matsumoto
Keyword(s):  
Large Scale ◽  
Interannual Variation ◽  
Maximum Rainfall ◽  
Vapor Flux ◽  
Low Level ◽  
Rainfall Variation ◽  
Late Fall ◽  
Central Vietnam ◽  
The Individual ◽  
Sst Anomalies

Abstract The heavy rainfall/flood (HRF) event in central Vietnam usually occurs in October–November, the maximum rainfall season. This rainfall maximum undergoes a distinct interannual variation, opposite the interannual variation of sea surface temperature (SST) anomalies averaged over the NOAA Niño-3.4 area—ΔSST(Niño-3.4)—but coincident with the intensification (weakening) of the low-level easterlies at 15°N and westerlies at 5°N. The changes of low-level zonal winds reflect the strengthening (weakening) of the tropical cyclonic shear flow in tropical South/Southeast Asia in response to the tropical Pacific SST anomalies. Because the rainfall maximum in central Vietnam is primarily produced by the HRF cyclone, the interannual rainfall variation in this region should be attributed to the HRF cyclone activity—a new perspective of the climate change in precipitation. On average, one HRF cyclone occurs in each cold late fall. The population of the HRF cyclone may not be an important factor causing the interannual rainfall variation in central Vietnam. During the cold late fall, the rain-producing efficiency of the individual HRF cyclone is statistically almost twice those during warm and normal late falls and the most crucial factor leading to the interannual rainfall variation in central Vietnam. It is shown by further hydrological analysis that the increase (decrease) of the HRF cyclone’s rain-producing efficiency is determined by the large-scale environmental flow through the enhancement (weakening) of the regional convergence of water vapor flux.

scholarly journals The Ecology of Stress: linking life-history traits with physiological control mechanisms in free-living guanacos

2016 ◽  
Author(s):  
Ramiro J.A. Ovejero Aguilar ◽  
Graciela A Jahn ◽  
Mauricio Soto-Gamboa ◽  
Andrés Novaro ◽  
Pablo Carmanchahi
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Reproductive Success ◽  
Hpa Axis ◽  
Life History Traits ◽  
P Value ◽  
Mating Period ◽  
Non Invasive ◽  
Animal Populations

Background-Providing the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life's challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that prolonged elevated levels of GCs over time can be harmful to individuals, it is predicted that the HPA axis suppresses the HPG axis and causes T levels to decrease, as GCs increase. Methods-All of the data for individuals were collected by non-invasive methods (fecal samples) to address hormonal activities. This is a novel approach in physiological ecology because feces are easily obtained through non-invasive sampling in animal populations. Results- As expected, there was a marked adrenal (p-value= .344e-12) and gonadal (p-value= 0.002656) response due to seasonal variation in Lama guanicoe. No significant differences were found in fecal GCs metabolites between males/females*season for the entire study period (p-value= 0.2839). Despite the seasonal activity variation in the hormonal profiles, our results show a positive correlation (p-value= 1.952e-11,COR=0.50) between the adrenal and gonadal system. The marked endocrine (r2 = 0.806) and gonad (r2 = 0.7231) response due to seasonal variation in male guanaco individuals highlights the individual’s energetic demands according to life-history strategies. This is a remarkable result because no inhibition was found between the axes as theory suggests. Finally, the dataset was used to build a reactive scope model for guanacos. Discussion-Guanacos cope with the trade-off between sociability and reproductive benefits and costs, by regulating their GCs and T levels on a seasonal basis, suggesting an adaptive role of both axes to different habitat pressures. The results presented here highlight the functional role of stress and gonad axes on a critical phase of a male mammal's life—the mating period—when all of the resources are at the disposal of the male and must be used to maximize the chances for reproductive success.

scholarly journals The Ecology of Stress: linking life-history traits with physiological control mechanisms in free-living guanacos

2016 ◽  
Author(s):  
Ramiro J.A. Ovejero Aguilar ◽  
Graciela A Jahn ◽  
Mauricio Soto-Gamboa ◽  
Andrés Novaro ◽  
Pablo Carmanchahi
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Reproductive Success ◽  
Hpa Axis ◽  
Life History Traits ◽  
P Value ◽  
Mating Period ◽  
Non Invasive ◽  
Animal Populations

Background-Providing the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life's challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that prolonged elevated levels of GCs over time can be harmful to individuals, it is predicted that the HPA axis suppresses the HPG axis and causes T levels to decrease, as GCs increase. Methods-All of the data for individuals were collected by non-invasive methods (fecal samples) to address hormonal activities. This is a novel approach in physiological ecology because feces are easily obtained through non-invasive sampling in animal populations. Results- As expected, there was a marked adrenal (p-value= .344e-12) and gonadal (p-value= 0.002656) response due to seasonal variation in Lama guanicoe. No significant differences were found in fecal GCs metabolites between males/females*season for the entire study period (p-value= 0.2839). Despite the seasonal activity variation in the hormonal profiles, our results show a positive correlation (p-value= 1.952e-11,COR=0.50) between the adrenal and gonadal system. The marked endocrine (r2 = 0.806) and gonad (r2 = 0.7231) response due to seasonal variation in male guanaco individuals highlights the individual’s energetic demands according to life-history strategies. This is a remarkable result because no inhibition was found between the axes as theory suggests. Finally, the dataset was used to build a reactive scope model for guanacos. Discussion-Guanacos cope with the trade-off between sociability and reproductive benefits and costs, by regulating their GCs and T levels on a seasonal basis, suggesting an adaptive role of both axes to different habitat pressures. The results presented here highlight the functional role of stress and gonad axes on a critical phase of a male mammal's life—the mating period—when all of the resources are at the disposal of the male and must be used to maximize the chances for reproductive success.

Timing of Births and Reproductive Success in Rhesus Monkey Social Groups1

1978 ◽  
Vol 7 (4) ◽  
pp. 202-212 ◽  
Author(s):  
Mark E. Wilson ◽  
Thomas P. Gordon ◽  
Irwin S. Bernstein
Keyword(s):  
Reproductive Success ◽  
Rhesus Monkey ◽  
Timing Of Births

scholarly journals Relation of the South China Sea Precipitation Variability to Tropical Indo-Pacific SST Anomalies during Spring-to-Summer Transition

2014 ◽  
Vol 27 (14) ◽  
pp. 5451-5467 ◽  
Author(s):  
Wenting Hu ◽  
Renguang Wu ◽  
Yong Liu
Keyword(s):  
South China Sea ◽  
South China ◽  
Rainfall Variability ◽  
Walker Circulation ◽  
Tropical Indian Ocean ◽  
Atmospheric Model ◽  
Additional Contribution ◽  
China Sea ◽  
Rainfall Variation ◽  
Sst Anomalies

Abstract The present study investigates the relationship of South China Sea (SCS) precipitation to tropical Indo-Pacific sea surface temperature (SST) during April–June (AMJ), which is the transition season from spring to summer. It is revealed that SCS rainfall anomalies in AMJ are influenced by SST anomalies in the equatorial Pacific (EP), tropical Indian Ocean (TIO), and western North Pacific (WNP). Three types of SST-influenced cases are obtained based on different combinations of SST anomalies in the above three regions. When same-sign EP and TIO SST anomalies are accompanied by opposite WNP SST anomalies, both anomalous cross-equatorial flows from the southwestern TIO induced by negative SST anomalies there and an anomalous Walker circulation forced by negative EP SST anomalies contribute to enhanced convection over the SCS and the surrounding regions with additional contribution from positive WNP SST anomalies via a Rossby wave–type response. In the cases of combined effects of EP and WNP SST anomalies, above-normal SST in the WNP is a direct cause of above-normal SCS rainfall though the WNP SST anomalies are induced by EP SST forcing. In the cases of combined impacts of TIO and EP SST anomalies, the accompanying coastal Sumatra SST anomalies contribute to the SCS rainfall variability via an anomalous cross-equatorial vertical circulation. The negative SST anomalies near the Sumatra coast induce descent over the southeastern TIO and ascent over the SCS and WNP. Model experiments with an atmospheric model confirm the impacts of southern TIO and EP SST anomalies on AMJ rainfall variation over the SCS.

A Critical Analysis of Effect of Projected Temperature and Rainfall for Differential Sowing of Maize Cultivars Under RCP4.5 and RCP6.0 Scenarios for Punjab

2021 ◽  
Author(s):  
Shivani Kothiyal ◽  
Prabhjyot Kaur ◽  
Jatinder Kaur
Keyword(s):  
Minimum Temperature ◽  
Rainfall Variability ◽  
Weather Data ◽  
High Yield ◽  
Strong Negative Correlation ◽  
Rainfall Variation ◽  
Agroclimatic Zone ◽  
Maize Cultivars ◽  
Sowing Dates ◽  
Agroclimatic Zones

Abstract A simulation study was conducted for two cultivars of maize (PMH1 and PMH2) in four agroclimatic zones of Punjab state of India where climate change depicts a consistent rise in temperature and increased variability in amount and distribution of rainfall. The yield assessment was performed for four agroclimatic zones of Punjab comprising of seven locations because variability in temperature rise and rainfall existed from location to location. Corrected ensemble model weather data (temperature and rainfall) for RCP4.5 and RCP6.0 was used as an input in the calibrated and validated CERES-Maize model and yield was simulated for a period of 70 years. The simulated yield for near as well as far-future was statistically assessed to understand the yield trend in Punjab under current dates of sowing and the results indicated a strong negative correlation between the yield and the weather parameters under the two scenarios at the considered four agroclimatic zones of Punjab. An increase in maximum and minimum temperature was observed ranging 0-4°C and 3-8°C, respectively at all the agroclimatic zones except Faridkot (zone V) where the increase in minimum temperature was observed by 0-3°C during the crop growth season while the rainfall variability ranged from 200-800mm under both the scenarios. At agroclimatic zone II and zone III similar results were obtained with higher yields at later dates of sowing and the rainfall at agroclimatic zone III was higher under RCP6.0 (300-600mm) while the yields for agroclimatic zone IV and V (Abohar) with rainfall variation of 270-450mm and 200-400mm, respectively showed no yield increment. Maize at Faridkot performed well with higher yields at early sowing dates. Among the two cultivars PMH1 showed more high yield years than PMH2 for most of the years. The yield under differential sowing dates showed the first fortnight of June and end June to be the best sowing dates for most of the locations as the yield for these dates were higher for most of the years. Thus, the study can be further applied to decide the future sowing window of maize for the agricultural state like Punjab.

scholarly journals Timing of Births and Reproductive Success in Captive Red-tailed Phascogales,Phascogale calura

2008 ◽  
Vol 89 (5) ◽  
pp. 1136-1144 ◽  
Author(s):  
W. K. Foster ◽  
W. Caton ◽  
J. Thomas ◽  
S. Cox ◽  
D. A. Taggart
Keyword(s):  
Reproductive Success ◽  
Timing Of Births

The Effect of a Teaser Bull on the Return to Oestrus of Postpartum Spring Calving Suckler Cows

1994 ◽  
Vol 1994 ◽  
pp. 24-24
Author(s):  
Duncan Pullar ◽  
Peter Rowlinson ◽  
Cheryl Miller ◽  
Joanne Scatcherd
Keyword(s):  
Dairy Cows ◽  
Management Strategies ◽  
Gestation Length ◽  
Calving Interval ◽  
Mating Period ◽  
Oestrus Cycle ◽  
Practical Management ◽  
Optimum Interval

The successful re-breeding of suckler and dairy cows is vital to the economics of farming cattle. The gestation length of cows is 280-290 days, so the optimum interval after calving for the subsequent mating is 75-85 days if a 365 day calving interval is to be achieved. Average calving rates to a given service are of the order of 0.5 to 0.6 (Diskin and Sreenan, 1980). Most practical management strategies allow cows to be mated during a 7-10 week period (giving 3 or 4 opportunities to show oestrus). The chance of conception improves with each oestrus cycle following calving, so the earlier a cow begins to show oestrus activity after calving the more likely she is to be successfully mated, because the early, less fertile oestrus cycles, are likely to happen before the planned mating period.

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