Four trials were conducted to investigate factors controlling the seasonal onset of reproductive activity in red deer hinds. Firstly (Chapter 4), the role of photorefractoriness to long daily photoperiods in the initiation of the seasonal reproductive activity in breeding red deer hinds was examined. Red deer hinds (n=10) were prematurely exposed to a long daily photoperiod of 15.3 h from 22 July to 8 November 1986 i.e. winter-spring (EPW), or maintained under natural photoperiods (NP). Six hinds experienced the natural changes in daily photoperiod until mid-summer but were exposed to a 15.5 h of light each day from 30 January to 30 April 1987, i.e. summer-autumn (EPS), whilst hinds in the other groups experienced naturally decreasing daily photoperiods. On 5 occasions (July 1986, January, February, March and April 1987), blood samples were collected from 4 NP and 4 EPW hinds every 20 minutes for 4 h to monitor secretion of luteinising hormone and half hourly for another 4 h following an i.v. injection of 2 µg GnRH to measure pituitary responsiveness. In January, March and April 1987 EPS hinds were also intensively sampled for 4 h. Plasma progesterone concentrations and mean date of calving indicated that the onset of breeding activity was not affected by light treatment in the EPW hinds but was delayed by 3 weeks in the EPS hinds. In contrast, supplementary lighting caused a premature elevation of plasma prolactin concentrations and advanced pelage moulting in EPW hinds only. Plasma LH secretion patterns indicated that LH pulse frequency and mean LH concentrations were greater during the breeding season than during pregnancy or, seasonal or postpartum, anoestrus. The reduction in LH secretion was partially explained by a diminished pituitary responsiveness to GnRH. Daily plasma melatonin secretion patterns indicated that the duration of the nocturnal increase in melatonin concentrations was responsive to changes in photoperiod and provided a suitable endocrine signal for measuring day length. The results suggest that, unlike the sheep and prepubertal red deer hind, the onset of seasonal breeding activity in breeding red deer hinds is not affected by long daily photoperiods in spring but is delayed if the autumnal decrease in daily photoperiod is delayed. Therefore neither the development of photorefractoriness nor the spring increase in daily photoperiods initiated the transition from seasonal anoestrus to reproductive activity in the breeding hind. However, long daily photoperiods may have entrained the annual cycle of pelage shedding and prolactin secretion. It is possible that the neuroendocrine pathway by which photoperiodic signals entrain the seasonal cycle of reproduction is separate from those which regulate other seasonal events in the breeding red deer hind. Secondly (Chapter 5), in a study of seasonality of reproduction, 4 pubertal hinds were monitored for live weight and plasma LH and progesterone concentrations from December 1987 to October 1988 (i.e. 12-22 months of age). In addition the pattern of LH secretion was also studied in 4 ovariectomised pubertal hinds implanted s.c. with controlled release implants containing 12 mg oestradiol-17β between 4 March and 25 May and between 15 June and 19 September, 1988. On several occasions (15 December, 29 February, 15 March, 24 April, 14 June, 29 June, 18 September (all hinds) and 3 October (ovariectomised hinds only) blood samples were collected every 20 minutes for 4 h to monitor secretion of luteinising hormone and following an i.v. injection of 2 µg GnRH to measure pituitary responsiveness. Plasma progesterone profiles indicated that 4-6 ovarian cycles, lasting about 19 d each, occurred in each intact hind. Regular ovarian cycles commenced in late April (26 April ± 3.4 d, mean ± s.e.m.) and ceased 3 months later in July (21 July ± 7.2 d). The number of LH pulses in the intact hinds was higher in June (1-2 pulses/4 h) than in the non-breeding season (< 1 pulse/4 h) probably due to a seasonal increase in GnRH secretion. It appears that the seasonal increase in LH pulsatility and onset of reproductive activity in the entire hinds were temporally related to a reduction in the sensitivity of LH secretion to the negative feedback effects of oestradiol in ovariectomised pubertal hinds. In the third trial (Chapter 6), 20 male and 20 female red deer calves were immunised at birth against a melatonin conjugate or injected with adjuvant only (controls). Booster injections were given on 5 occasions over the next 2 years. Stags which produced significant melatonin binding activity in response to immunisation, were heavier than the controls between 7 and 11 months of age and at 16, 20, 30 and 34 months of age. A similar but smaller effect on live weight was seen in the immunised hinds. Immunisation against melatonin did not affect the calving date of the hinds or antler development and time of casting of antlers in the stags. These results indicated that disruption of the photoperiodic signal by immunisation against melatonin may have prevented the entrainment of annual rhythms in feed intake and growth but without affecting the seasonal cycles in antler growth and ovarian activity. Finally in a series of 3 trials (Chapter 7), anoestrous red deer hinds were induced to ovulate with the GnRH analogue, buserelin. Hinds were pre-treated with intravaginal devices containing 0.6 g progesterone (CIDR-Type S) for 14 days prior to CIDR withdrawal on 4 March. In Year 1, 15 hinds were treated with 1 CIDR each and 8 hinds were injected i.m. with 4 µg buserelin (a GnRH analogue) at CIDR removal followed by 2nd injection of 10 µg 48 h later. In Year 2, 16 hinds were treated with 2 CIDRs each and 8 hinds were injected Lm. with 4, 3, 2, 2 and 10 µg buserelin at -48, -24, 0, 24 and 48 h respectively from CIDR withdrawal. In Year 3, 15 hinds were treated with 2 CIDRs and 11 hinds (Groups Band BO) injected with buserelin identical to the protocol in Year 2. At CIDR withdrawal 6 of these buserelin treated hinds (Group BO) and 4 other progesterone-primed hinds (Group 0) were injected with 500 µg oestradiol benzoate. In addition, during the breeding season, 4 hinds (Group C) were treated with double CIDRs only for 14 d from 1 April. When oestrous behaviour and the pattern of plasma LH secretion were monitored in Year 3, oestrous behaviour was less noticeable and delayed in Group B hinds and peak LH levels were lower and increased later relative to Group 0, BO and C hinds. Two weeks after CIDR withdrawal, 6 buserelin-treated hinds in both Year 1 and Year 2, and 3/5 B, 2/4 0, 3/6 BO and 4/4 C group hinds in Year 3 had a single corpus luteum present. Plasma progesterone concentrations were elevated for about 12 d in most hinds with a corpus luteum in Year 2 and in most B, BO and C Group hinds in Year 3. However, progesterone secretion was low in several Year 1 and all Group 0 hinds in Year 3 indicating that the induced corpora lutea in these hinds were functionally subnormal. There was no evidence that any of the buserelin-induced ovulations resulted in pregnancy, probably because the induced ovulations were not accompanied by normal hormonal and behavioural patterns. The experiments described in this thesis have contributed to our understanding of the regulation of seasonal breeding in red deer hinds. This knowledge may eventually enable reproductive activity to be effectively manipulated, thereby improving the efficiency of deer production systems.

Reproduction is the process whereby an animal ensures the continuous existence of their genes in the population by procreation. Reproduction presents a series of obstacles for both males and females. Males have to ensure they are in peak physical condition in order to establish dominance and compete for the attention of the opposite sex. Females need enough energy to support their bodily needs whilst supplying energy to the growing foetuses and suckling young. The current thesis investigated the pattern of ovulation in female as well as the effect of photoperiod and food restriction on male gonadal development in wild caught South African spiny mice (Acomys spinosissimus) from the Limpopo province in South Africa by using faecal samples to measure hormone concentrations. A novel method, using faecal samples to monitor reproductive function in Acomys spinosissimus was validated during this study. It was shown that reproductive function can reliably be monitored in both sexes using enzyme immunoassays for 17-oxo-androgens in males and 20-oxopregnanes in females, respectively. Females were randomly assigned to one of three treatments. Seven females were housed completely separated from any male stimuli and represented the control group. The two experimental groups were each made up of seven females. The separated treatment was housed in visual and olfactory contact with intact males, separated by wire mesh. The paired treatment was housed with vasectomized males, allowing full contact between the two sexes. Females from all three treatment groups underwent normal follicular development with corpora lutea of ovulation recorded for one female from the control and one female from the paired treatment. Progesterone concentrations were compared between the different treatments using faecal hormone metabolite levels. The progesterone concentrations were not affected by the different treatments; however, the day of faecal sample collection influenced progesterone levels. The findings from the ovarian histology and faecal progestagens strongly suggest a spontaneous pattern of ovulation. To investigate the effects of photoperiod and food restriction, males were randomly assigned to one of four treatment groups. The first two groups, consisting of six males each, were subjected to a 14L: 10D (LD) photoperiod. Within the LD treatment, one group was fed ad libitum (NR) whilst the other group was subjected to a 10% food restriction (R). The remaining two cohorts were subjected to the same feeding regime as mentioned above, but they were kept on a 10L: 14D (SD) photoperiod. Male spiny mice exposed to a long photoperiod had significantly greater testes volume and seminiferous tubule diameters when compared to the males exposed to a short photoperiod. Total body fat did not differ significantly when compared between the different treatments. Males exposed to the long photoperiod also had significantly higher testosterone concentrations when compared to the males exposed to the short photoperiod. Feeding regime did not have any significant effect on any of the reproductive parameters investigated in this study. During this study it was concluded that Acomys spinosissimus is a spontaneous ovulator that is strongly photoperiodic with the availability of food resources enhancing the photoperiodic effect. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Zoology and Entomology / Unrestricted

Le Système Nord du Courant de Humboldt (SNCH) est le lieu d’une forte activité biologique due à un upwelling côtier intense. Il abrite l’une des plus grandes populations de l’anchois du Pérou soumis à la plus grande pêcherie monospécifique au monde. Le SNCH héberge aussi de grandes et variables, populations d’oiseaux, composées de trois espèces sympatriques productrices de guano : le cormoran guanay (Phalacrocorax bougainvillii), le fou péruvien (Sula variegata) et le pélican péruvien (Pelecanis thagus), qui se nourrissent principalement d’anchois. Dans ce travail, nous examinons les fluctuations de ces trois populations d’oiseaux marins, en nous concentrant sur le cycle saisonnier de leur reproduction, pour aborder les questions suivantes : Dans quelle mesure les saisonnalités de reproduction diffèrent elles entre espèces ? Dans quelle mesure sont-elles plastiques dans le temps et dans l’espace ? Qu’est ce qui, des conditions environnementales et des activités anthropogéniques affecte le plus la reproduction des oiseaux marins ? Nous abordons ces questions en utilisant des données de présence de reproducteurs (1) dans 30 sites péruviens répartis entre 06°S-18°S (2003-2014) ; et (2) dans un site, pendant trois périodes (1952-1968, 1972-1989, 2003-2014). Nous utilisons des covariables environnementales décrivant les conditions océanographiques, l’abondance, l’accessibilité et la condition des proies, ainsi que des covariables décrivant la pression de pêche. Nous utilisons des modèles d’occupation multi-saisonniers pour caractériser la saisonnalité de la reproduction et la relier aux covariables environnementales. Nous utilisons aussi des analyses en composantes principales fonctionnelles pour classifier les différences de saisonnalité entre sites, et des forêts aléatoires de régression pour analyser la contribution relative des covariables à la variabilité de la saisonnalité de reproduction.Nous mettons en évidence qu’en moyenne, la reproduction démarre au cours de l’hiver austral / début de printemps et prend fin en été / début d’automne, ce patron étant plus marqué chez les fous et pélicans que chez les cormorans. La reproduction est calée dans le temps de telle sorte à ce que les jeunes prennent leur indépendance lorsque les conditions de production primaire, d’abondance et d’accessibilité des proies sont maximales. Ce patron est unique en comparaison avec les autres écosystèmes d’upwelling et peut être expliqué par les fortes abondances absolues de proies disponibles tout au long de l’année dans le SNCH.La saisonnalité de reproduction diffère entre les sites de nidification. Les oiseaux se reproduisent plus tôt et avec de plus fortes probabilités lorsque les colonies sont plus grandes, situées sur des îles à moins de 20 km des côtes, aux plus basses latitudes, et présentant une production primaire plus élevée. Alors, la saisonnalité de la reproduction est davantage influencée par les conditions environnementales locales que par les gradients environnementaux de grande échelle.Les oiseaux marins adaptent aussi la saisonnalité de leur reproduction aux changements drastiques causés dans l’écosystème par les changements de régime. Les cormorans font preuve de la plus grande plasticité, en modulant la date te l’amplitude de la saisonnalité de leur reproduction, cela est probablement permis par leur plus grande flexibilité de fourragement. Les dates et amplitudes fixes observées chez les fous peuvent être liées aux spécificités de leur stratégie de fourragement et à des changements de proies lorsque le stock d’anchois est bas. Les différences spécifiques dans les adaptations de la saisonnalité de reproduction permettent aux oiseaux de profiter différemment des conditions locales de proies, et de faire face aux changements de régime avec des stratégies différentes. Une méthodologie de capture-recapture en parallèle des comptages mensuels est proposée pour élargir les horizons de l’évaluation des dynamiques d’une population. / The Northern Humboldt Current System (NHCS) is a place of a high biological activity due to an intense coastal upwelling. It supports one of the biggest forage fish populations, the Peruvian anchovy, and the world-leading monospecific fishery in terms of landings. The NHCS also hosts large, although variable, seabird populations, composed among others by three guano-producing sympatric species: the Guanay cormorant (Phalacrocorax bougainvillii), the Peruvian booby (Sula variegata) and the Peruvian pelican (Pelecanus thagus), which all feed primarily on anchovy.In this work we reviewed the fluctuations of these three seabird populations, focusing on the seasonal cycle of their breeding, to address the following questions: How different are the seasonality of reproduction among species? To what extent may they be plastic in space and time? What from the natural environment and the anthropogenic activities impact more the breeding of seabirds?We addressed these questions using the monthly occupancy of breeders (1) in >30 Peruvian sites between 06°S and 18°S and from 2003 to 2014; and (2) in one site during three decadal periods (1952-1968, 1972-1989, 2003-2014). We also used environmental covariates from satellite and at-sea monitoring such as oceanographic conditions, prey abundance, availability and body conditions, and fisheries pressure covariates. We used multiseason occupancy models to characterize the seasonality of breeding and relate it with environmental covariates. We also used functional principal component analysis for classifying the differences in seasonality among sites, and random forest regression for analyzing the relative contribution of covariates in the variability of the seasonal breeding.We found that in average seasonal breeding mainly started during the austral winter/ early spring and ended in summer/ early fall, this pattern being stronger in boobies and pelicans than in cormorants. The breeding onset of seabirds is timed so that fledging independence occurs when primary production, prey conditions and availability are maximized. This pattern is unique compared with other upwelling ecosystems and could be explained by the year-round high abundances of anchovy in the NHCS.The average seasonal breeding may differ among nesting sites. Seabirds breed earlier and are more persistent when colonies are larger, located on islands, within the first 20km of the coast, at lower latitudes and with greater primary production conditions. These results suggest that in the NHCS, the seasonality of breeding is more influenced by local environmental conditions than by large-scale environmental gradients. These results provides critical information to a better coordination of guano extraction and conservancy policies.Seabirds may also adapt the seasonality of their breeding to drastic ecosystem changes caused by regime shifts. We found that the three study species exhibited a gradient of plasticity regarding the seasonality of their breeding. Cormorants showed a greater plasticity, modulating the timing and magnitude on their breeding seasonality. This is probably authorized by the greater foraging flexibility offered its great diving capacities. Fixed onset and magnitudes of breeding in boobies may be related to their specific foraging strategy and/or to changes of prey items when anchovy stock was low. We also suggested that boobies may adapt other fecundity traits as growth rate of chicks to lower abundance of anchovy.The specific differences in the adaptation of seasonal breeding allow seabirds to take profit differently from local prey conditions or to face differently regime shifts. Further researches, implementing a large-scale capture-recapture methodology in parallel with monthly census, are proposed in order to fulfill gaps in the basic knowledge on vital traits (adult survival, first age at reproduction, and juvenile recruitment) which are critical parameters to evaluate the dynamic of a population.