Annual Breeding Season Research Articles

An extreme model of fertility in sheep demonstrates the basis of controversies surrounding antral follicle count and circulating concentrations of anti-Müllerian hormone as predictors of fertility in ruminants

Ovarian ultrasonography and measurement of circulating concentrations of anti-Müllerian hormone (AMH) have been used to estimate follicle number and predict fertility in mammalian females, but no study has evaluated follicle number and circulating concentrations of AMH in ewes known to differ in fertility. We tested the hypothesis that ewes that had failed to lamb (BARREN) in four consecutive annual breeding seasons of 21–35 d have fewer follicles and diminished circulating concentrations of AMH compared to closely matched ewes that consistently produced lambs (FERTILE) under the same breeding protocols. Once identified, BARREN ewes (n = 19) were paired by breed and sire to a FERTILE control ewe (n = 19) and reproductive tracts were recovered at necropsy. Visible antral follicles in both ovaries were counted and a representative cross section of one ovary was embedded for histological evaluation of pre-antral follicle numbers. Paired t-tests indicated that BARREN ewes had fewer antral follicles, fewer primordial follicles, and decreased circulating concentrations of AMH compared to FERTILE ewes (P ≤ 0.01), but there were ewes in each fertility classification that had ovarian phenotypes like the opposite fertility classification. The best technologies we have currently for estimating follicle numbers are ultrasonography and measurement of circulating concentrations of AMH, but no single technique is perfect for predicting fertility. A better understanding of the under-lying biological mechanisms linking AMH, folliculogenesis, and fertility is required to improve the use of measurements of follicle number for predicting fertility in livestock.

Size distribution and reproductive phenology of the invasive Burmese python (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida, USA

The design of successful invasive species control programs is often hindered by the absence of basic demographic data on the targeted population. Establishment of invasive Burmese pythons (Python molurus bivittatus) in the Greater Everglades Ecosystem, Florida USA has led to local precipitous declines (> 90%) of mesomammal populations and is also a major threat to native populations of reptiles and birds. Efforts to control this species are ongoing but are hampered by the lack of access to and information on the expected biological patterns of pythons in southern Florida. We present data from more than 4,000 wild Burmese pythons that were removed in southern Florida over 26 years (1995–2021), the most robust dataset representing this invasive population to date. We used these data to characterize Burmese python size distribution, size at maturity, clutch size, and seasonal demographic and reproductive trends. We broadened the previously described size ranges by sex and, based on our newly defined size-stage classes, showed that males are smaller than females at sexual maturity, confirmed a positive correlation between maternal body size and potential clutch size, and developed predictive equations to facilitate demographic predictions. We also refined the annual breeding season (approx.100 days December into March), oviposition timing (May), and hatchling emergence and dispersal period (July through October) using correlations of capture morphometrics with observations of seasonal gonadal recrudescence (resurgence) and regression. Determination of reproductive output and timing can inform population models and help managers arrest population growth by targeting key aspects of python life history. These results define characteristics of the species in Florida and provide an enhanced understanding of the ecology and reproductive biology of Burmese pythons in their invasive Everglades range.

Soft coral reproductive phenology along a depth gradient: Can "going deeper" provide a viable refuge?

Many species across a wide range of taxa and habitats display phenological shifts and differences in response to both environmental gradients and climate change. Moreover, the wide‐scale decline of numerous ecosystems is leading to increasing efforts to identify zones that might serve as natural refuges from various disturbances, including ocean warming. One such refuge was suggested to be that of the deep coral reefs, but whether depth can provide coral populations with a viable and reproductive refuge remains unclear. Given the global coral‐reef degradation and the key role that corals play as ecosystem engineers, their reproductive ecology has been widely studied. A particular knowledge gap nonetheless exists regarding coral reproductive phenology along a depth gradient. Filling in this gap may uncover the environmental cues that regulate coral reproduction, leading to better predictions of population connectivity, and their possible responses to climate change and other environmental changes. Here, using long‐term in situ observations of the soft coral Rhytisma fulvum's reproductive activity along its entire depth range (0–45 m), we examined the relationship among several environmental factors and the coral's reproductive phenology and activity over five successive annual breeding seasons. Compared with the shallow depths, a lower number of reproducing colonies was found in habitats deeper than 30 m, highlighting possible constraints on coral reproduction at the deeper end of their range. Our results further revealed that an increase in seawater temperature over 1–2‐day intervals during the breeding season correlated with the onset of reproductive activity along the depth gradient, leading to different reproductive periodicities in different depths. These differences suggest that differential temperature regimes and reproductive timing across depth may create intraspecific temporal reproductive segregation, possibly reducing connectivity among populations along a depth gradient. Moreover, we found high variability among years in both the timing of breeding activities and in the level of reproductive synchrony among corals from different depths. Overall, our study questions whether depth can provide a long‐term and viable refuge for corals in the face of global environmental changes.

Impacts of postpartum length at the initiation of the fixed-time artificial insemination protocol on pregnancy rates of Bos indicus beef cows.

The shortest interval between calving and initiation of fixed-time artificial insemination (FTAI) protocols recommended in Brazilian cow–calf systems is 30 d, based on research that characterized uterine involution and incidence of uterine disorders in Bos taurus females. Prevalence of uterine disorders such as subclinical endometritis is limited in Nelore (B. indicus) cows as early as 28 d after calving. We hypothesized that Nelore cows can receive an FTAI protocol as early as 20 d postpartum (DPP) and still experience satisfactory reproductive results. This study evaluated pregnancy rates in 5,258 Nelore cows (n = 1,703 primiparous and 3,555 multiparous) according to DPP at the initiation of the FTAI protocol. Cow body condition score (BCS) was recorded at FTAI, and pregnancy diagnosis was performed ~30 d after FTAI. Cows were ranked within parity by DPP at the initiation of the FTAI protocol and classified according to 5-d intervals (e.g., ≤15 DPP, 16 to 20 DPP, 21 to 26 DPP, until cows with ≥76 DPP). Data were analyzed within parity, using cow as experimental unit and orthogonal polynomial contrasts (linear, quadratic, or cubic) generated using the mean DPP of each DPP class. In both parities, cow BCS at FTAI decreased linearly (P ≤ 0.01) with the advance of DPP (e.g., 4.79, 4.00, and 3.73 in primiparous, and 4.95, 3.70, and 3.23 in multiparous cows classified as ≤15 DPP, 36 to 40 DPP, ≥76 DPP, respectively). The pregnancy rate to FTAI was affected quadratically (P < 0.01) by DPP for both parities. In primiparous cows, the pregnancy rate increased until 36 to 40 DPP (60%), remained near this level until 51 to 60 DPP, and then decreased with the advance of DPP, whereas cows classified as 21 to 25 DPP expressed satisfactory results (41.5%). In multiparous cows, the pregnancy rate increased until 46 to 50 DPP (70.8%), remained near this level until 56 to 60 DPP, and then decreased with the advance of DPP, whereas cows classified as 21 to 25 DPP also expressed satisfactory results (63.6%). Collectively, primiparous and multiparous Nelore cows evaluated herein experienced optimal pregnancy rates when the FTAI protocol was initiated within 30 to 60 DPP, although reasonable outcomes were observed when the FTAI protocol was initiated as early as 21 DPP. Hence, the interval between calving and initiation of the FTAI protocol can be shortened by 10 d in Nelore females and still yield acceptable pregnancy rates, which can be of great value to cows that calve immediately prior to or during the annual breeding season.

176 Are Ovarian Reserve Parameters Related to Reproductive Tract Development and Fertility in Ewes?

Abstract There are differences between cows and ewes in ovarian reserve parameters. No major genes influencing follicle numbers have been identified in cows, whereas several genes have variants reported to influence follicle numbers in ewes. In contrast, antral follicle count is associated with fertility in cows, and we reported that beef cows that failed to conceive in 2 consecutive years had fewer antral follicles and smaller reproductive tracts than cows that had never failed to conceive. In the current study, we tested the hypothesis that ewes that had failed to lamb (BARREN) in 4 consecutive annual breeding seasons of 21– 35 d with rams that had passed a breeding soundness exam have fewer follicles and smaller reproductive tracts than ewes that consistently produced lambs (FERTILE) under the same breeding protocols. BARREN ewes (n = 19) were paired by breed, age, and sire to a FERTILE control ewe (n = 19) and reproductive tracts were recovered at necropsy. All visible antral follicles in both ovaries were counted and a representative cross section of one ovary was embedded for histological evaluation of primordial follicle numbers. The reproductive tract was weighed, and ovulatory status was evaluated. Paired t-tests indicated that BARREN ewes had 25.6 ± 5.0 fewer antral follicles per pair of ovaries, 17.3 ± 4.4 fewer primordial follicles per histological section, and 54.5 ± 18.7 g lighter reproductive tracts than FERTILE ewes (P ≤ 0.01). The odds of FERTILE ewes being ovulatory at necropsy were 2.25 that of BARREN ewes, but this did not differ from expectation by McNemar’s test (P = 0.13). The results indicate that size of the ovarian reserve influences fertility in ewes as it does in cows. USDA is an equal opportunity provider and employer.

Fear of predators in free-living wildlife reduces population growth over generations

Correctly assessing the total impact of predators on prey population growth rates (lambda, λ) is critical to comprehending the importance of predators in species conservation and wildlife management. Experiments over the past decade have demonstrated that the fear (antipredator responses) predators inspire can affect prey fecundity and early offspring survival in free-living wildlife, but recent reviews have highlighted the absence of evidence experimentally linking such effects to significant impacts on prey population growth. We experimentally manipulated fear in free-living wild songbird populations over three annual breeding seasons by intermittently broadcasting playbacks of either predator or nonpredator vocalizations and comprehensively quantified the effects on all the components of population growth, together with evidence of a transgenerational impact on offspring survival as adults. Fear itself significantly reduced the population growth rate (predator playback mean λ = 0.91, 95% CI = 0.80 to 1.04; nonpredator mean λ = 1.06, 95% CI = 0.96 to 1.16) by causing cumulative, compounding adverse effects on fecundity and every component of offspring survival, resulting in predator playback parents producing 53% fewer recruits to the adult breeding population. Fear itself was consequently projected to halve the population size in just 5 years, or just 4 years when the evidence of a transgenerational impact was additionally considered (λ = 0.85). Our results not only demonstrate that fear itself can significantly impact prey population growth rates in free-living wildlife, comparing them with those from hundreds of predator manipulation experiments indicates that fear may constitute a very considerable part of the total impact of predators.

REVENGE OF THE TREES: ENVIRONMENTAL DETERMINANTS AND POPULATION EFFECTS OF INFECTIOUS DISEASE OUTBREAKS ON A BREEDING COLONY OF DOUBLE-CRESTED CORMORANTS (PHALACROCORAX AURITUS) OVER A PERIOD OF 21 YEARS.

During 16 of 21 consecutive annual breeding seasons, two diseases, Newcastle disease and avian cholera, killed approximately 50% of juvenile Double-crested Cormorants (Phalacrocorax auritus) in a large nesting colony in Canada. From 1994 to 2014, we recorded data annually on disease occurrence, causal pathogens, species and age classes affected, total number of breeding pairs of cormorants on the colony site, and other biological parameters. A mathematical model of pathogen transmission was constructed to assess the potential importance of transmission parameters and to test a hypothesis regarding the potential effect of the observed progressive loss of nest trees and the consequent shift from tree-nesting to ground-nesting behavior. The model indicated that juveniles from ground nests were 14 times more likely to die from epidemic disease (50.14% mortality) than were juveniles from nests in trees (3.57% mortality). Additive disease-related mortality of juvenile cormorants in the observed range of 40-60% would reduce a closed cormorant population over time. There was no directional change in the colony population during the study period, suggesting that immigration had compensated for disease-related mortality. Our results highlight the preeminent influence of environmental factors on pathogen transmission and the value of long-term data sets.

Effects of body condition score at initiation of the breeding season on reproductive performance and overall productivity of Bos taurus and B. indicus beef cows

This experiment was conducted to evaluate reproductive and productive responses of Bos indicus and B. taurus beef cows according to body condition score (BCS) at initiation of the annual breeding season. Non-pregnant, suckling multiparous cows were assigned to a fixed-time artificial insemination treatment regimen followed by natural service. Cows were classified as having a BCS < 5.0 (B. taurus, n = 158; B. indicus, n = 248) or BCS ≥ 5.0 (B. taurus, n = 173; B. indicus, n = 122). Calving rate was greater (P < 0.03) in cows with a BCS ≥ 5.0 (93.7 % and 85.1 % in B. taurus, 83.6 % and 73.3 % in B. indicus), which also calved earlier (P < 0.01) compared with cows with a BCS < 5.0. Cows with a BCS ≥ 5.0 weaned more (P ≤ 0.05) calves compared with those with a BCS < 5.0, which were older (P ≤ 0.04) and weighed more (P ≤ 0.09) at weaning (258 and 252 kg in B. taurus, 213 and 203 kg in B. indicus). Kilograms of calf weaned/cow in the breeding herd were greater (P ≤ 0.03) in cows with a BCS ≥ 5.0 compared with those with a BCS < 5.0 (221 and 200 kg in B. taurus, 159 and 129 d in B. indicus). Collectively, cows with a BCS ≥ 5.0 at initiation of the breeding season had greater reproductive and overall productivity during a cow-calf cycle, and these outcomes were observed in B. taurus and B. indicus cowherds.

Linking foraging and breeding strategies in tropical seabirds

The archetypal foraging behaviour of tropical seabirds is generally accepted to differ from that of their temperate and polar breeding counterparts, with the former exhibiting less predictable foraging behaviour associated with the less predictable prey of the tropical marine environment. Similarly, temperate and polar species have predictable, annual breeding seasons, enabling them to profit during periods of the year when prey availability is highest, while tropical seabird species exhibit considerable variability in their breeding strategies. Until now, the reasons for such variation in breeding strategies between tropical seabirds are yet to be investigated. We hypothesise that while some tropical species breed asynchronously in response to unpredictable fluctuations in prey availability, others adopt a seasonal breeding strategy for the same reasons that temperate and polar species do. Consequently, the predictability of seabird foraging behaviour in the tropics may be related to breeding strategy, with populations that breed seasonally exhibiting more predictable foraging behaviour than those that breed aseasonally. To test these predictions, we used GPS tracking to examine the foraging behaviour of two closely related tropical seabird species that colonise the same island yet exhibit markedly different breeding strategies: the asynchronously breeding brown booby Sula leucogaster and the seasonal breeding masked booby Sula dactylatra. We obtained tracks for 251 birds over five years. We found that brown boobies forage less predictably than masked boobies, indicated by larger core foraging areas, lower levels of foraging area overlap between individuals and exhibit more variability between breeding periods. Our results challenge the view that the foraging behaviour of tropical seabirds is always less predictable than that of seabirds breeding in temperate and polar regions and highlight the considerable variability in the breeding and foraging strategies adopted by tropical seabirds which demand further exploration.

Robust circadian and circannual rhythms of expression of clock genes and clock controlled aanat2 gene in the photoreceptive pineal organ of catfish, Clarias gariepinus under natural conditions

ABSTRACT Diurnal changes in daylength and temperature influence circadian rhythm of melatonin synthesis in the fish pineal organ. All core clock genes and clock-controlled aanat2 gene are expressed in the pineal organ of teleosts. However, there is paucity of information on the circadian rhythm of expression of clock genes and any clock-controlled gene in the pineal organ of any tropical/subtropical fish species under natural photoperiod and temperature during different phases of the annual breeding cycle and/or seasons. Therefore, we studied circadian rhythms of expression of clock genes (clock, bmal1, per1, per2, per3, cry1 and cry2) and aanat2 in the pineal organ of the catfish, Clarias gariepinus maintained under natural environmental conditions during different phases of its annual breeding cycle. All clock genes and aanat2 gene invariably exhibited prominent circadian rhythm of expression in the fish pineal organ irrespective of seasons/breeding phases. Further, acrophase, mesor and amplitude of the circadian rhythm of expression of the clock genes and aanat2 gene responded differently to different seasons. Our findings suggest that photoperiod-, temperature- and season-independent circadian rhythm of expression of clock genes and aanat2 gene in the pineal organ enable it to act as a potential master clock in the fish under natural conditions.

Reproductive Biology of Marine Catfish, Arius latiscutatus (Günther, 1864) and Arius gigas (Boulenger, 1911) from the Bays of Guinea

Background and Objectives: Marine catfish are abundant in the bays of Tabounsou and Sangareah in Republic of Guinea, but the knowledge on their biology is still scanty. The reproductive biology of Arius latiscutatus Günther, 1864 and A. gigas Boulenger, 1911 was studied through monthly sampling, from January to December 2016.&#x0D; Methodology: Fish were caught using gill nets in several sampling sites. Five gonadal stages were described, based on macroscopic observation of gonad form, size, weight, color and oocyte diameter.&#x0D; Results: The population was dominated by males (61%) in A. latiscutatus and females (53%) in A. gigas, showing a sex-ratio of 1:1.54 (Chi-square, P &lt; 0.05) and 1:0.88 (P &gt; 0.05), respectively. The length-weight relationship was a positive allometry for A. latiscutatus and A. gigas, and males (35.37 and 35.47 cm, respectively) reached first maturity earlier than females (39.7 and 40.8 cm, respectively). Changes in the gonadosomatic index (GSI) and in stages of gonadal development showed that A. latiscutatus spawned between April and October, while A. gigas spawned in May to November. The peak of condition factor was observed in June (0.68±0.05) and July (0.55±0.04) in females of A. latiscutatus and A. gigas, respectively.&#x0D; Conclusion: Both species, having only one annual breeding season, A. latiscutatus spawns earlier than A. gigas. Coastal fisheries should be restricted in cold season to preserve the ability of broodstock renewal for these species.

Population stability in an unmanaged population of the green and golden bell frog in northern New South Wales, Australia

Population monitoring is required to guide conservation programs. We conducted a capture–mark–recapture study of a population of the vulnerable green and golden bell frog (Litoria aurea) at the northern end of its range. Frogs were captured and marked over three breeding seasons (2015/16, 2016/17, 2017/18) in a large coastal lagoon. We aimed to: (1) produce annual estimates of population size to describe population trajectory, and (2) investigate monthly variation in abundance, capture probability, and temporary emigration to understand how these factors change at a finer temporal scale. Frog abundance varied across the three annual breeding seasons: 60–280 adult males, 120–190 adult females, and 90–420 subadults. We infer that the population is stable because adult abundance estimates were higher after 2015/16. Because our study sampled only half the available breeding habitat, the overall population may number 350–850 adults. Our modelling revealed &gt;40 males but &lt;20 females were detected in the sample area in our monthly samples. Estimates of temporary emigration were high (males: 0.54; females: 0.79), suggesting behaviour that made frogs unavailable for capture between months. Our results suggest that monitoring at greater than annual intervals should be adequate to monitor the future trend of this population.

Site Fidelity of Oyster Reef Blennies and Gobies in Saltmarsh Tidal Creeks

Blennies and gobies are among the most abundant fishes in western Atlantic and Gulf of Mexico estuaries. They establish nests and maintain territories in oyster reefs and around other shallow-water structures during warm months. In this study, site fidelity and movements were determined for adult striped blenny, naked goby, freckled blenny, crested blenny, and feather blenny, in descending order of abundance. Recaptures among 221 tagged fishes at nine intertidal oyster reefs in a southeastern U.S. saltmarsh estuary provided information about fidelity for individual oyster reefs and nest sites as well as the size of territories (areas used) around nest sites. An overall recapture rate of 94% for fishes on reefs where they were tagged indicated high fidelity. Total recapture rates for the four blenny species ranged from 38 to 50%, but the naked goby recapture rate was only 9%. Within a breeding season, fidelity for specific nest sites was 58% for all blennies and 17% for gobies. Movements away from nest sites were limited with 56% of all fishes re-occurring ≤ 1 m from the original tagging site. Territories of 84% of the recaptured fishes. Differences in species composition and abundance between reefs suggested species-specific preferences for habitat features. Crested blenny and freckled blenny were recaptured at nest sites with significantly more oyster cover than nest sites occupied by striped blenny. Blennies occupied nest sites for several months and across annual breeding seasons suggesting continued residency within small areas of individual oyster reefs throughout their lives. Strong fidelity for reefs and nest sites potentially makes blennies more susceptible to disturbances than gobies, but both may be vulnerable to habitat disturbance at scales < 5 m. Thus, blennies and gobies may be useful indicator species for changes within estuarine habitats and ecosystems.

Reproductive life-history strategies in a species-rich assemblage of Amazonian electric fishes.

The reproductive biology of only a small fraction of Neotropical freshwater fishes has been described, and detailed comparative studies of reproductive life-history variation in the Neotropical ichthyofauna are lacking. Here we describe interspecific variation in reproductive life history for a multi-species assemblage of the electric knifefish genus Brachyhypopomus (Hypopomidae: Gymnotiformes: Ostariophysi) from Amazonian floodplain and terra firme stream systems. During a year-round quantitative sampling program, we collected and measured key life-history traits from 3,410 individuals. Based on oocyte size distributions, and on circannual variation in gonadosomatic indices, hepatosomatic indices, and capture-per-unit-effort abundance of reproductive adults, we concluded that all species exhibit a single protracted annual breeding season during which females spawn fractionally. We found small clusters of post-larval individuals in one floodplain species and one terra firme stream species, but no signs of parental care. From analyses of body size-frequency distributions and otolith growth increments, we concluded that five species in our study area have approximately one-year (annual) semelparous life history with a single reproductive period followed by death, while two species have a two-year iteroparous life history, with breeding in both year-groups. Despite predictions from life-history theory we found no salient correlations between life history strategy (semelparity or iteroparity) and habitat occupancy (floodplain or terra firme stream). In the iteroparous species B. beebei, we documented evidence for reproductive restraint in the first breeding season relative to the second breeding season and argue that this is consistent with age-regulated terminal investment.

High-amplitude vocalizations of male northern elephant seals and associated ambient noise on a breeding rookery

Northern elephant seals (Mirounga angustirostris) are massive, land-breeding marine mammals that produce loud, stereotyped calls during annual breeding seasons. To determine vocalization source levels emitted by competing males on a mainland breeding rookery, aerial calls were measured on-axis at 1 m from adult males using three different sound pressure level metrics. Time-averaged (1 min) ambient noise was also measured under variable environmental and social conditions. Results indicate that male northern elephant seals emit high amplitude airborne calls with little variation in call amplitude. Mean source levels ranged from 98 to 114 dB re: 20 μPa [root-mean-square (rms) -fast], 102-116 dB re: 20 μPa (rms-impulse), and 120-131 dB re: 20 μPa (peak) and average standard deviations for all metrics were <2.3 dB. Further, these seal rookeries exhibit high variability in ambient noise (in terms of both spectrum and amplitude) from biotic and environmental sources. Finally, males sampled did not adjust call amplitude to compensate for higher background noise levels and thus did not exhibit a Lombard effect. These findings reinforce the view that the remarkable vocalizations of male northern elephant seals serve as rigid and powerful signals that convey individual identity within noisy breeding colonies rather than as honest indicators of size, status, or motivation.

Early pupping of a sub-Antarctic fur seal at Inaccessible Island, Tristan da Cunha

A sub-Antarctic fur seal, Arctocephalus tropicalis, pup was located on Inaccessible Island in the Tristan da Cunha archipelago (TdC), well before the start of the annual breeding (pupping and mating) season in 2018. It was born a few days before 27 September 2018, at least 59 days before the next pup was observed on the island in 2018 and 75 days before the median birthdate for the species at the TdC. A malfunctioning of the obligate delay of implantation of the blastocyst in its mother was likely the cause of the early birth.

Habitat-Use Patterns among Migrant and Resident Landbirds of Contrasting Dietary Habits in a Southern Mexican Wetland

The distribution of resident and migratory bird abundance across mangrove and marsh patches can produce dynamic and guild-specific habitat-use patterns. Using 32 consecutive months of point counts in a coastal landscape in Oaxaca, Mexico, we studied the annual cycle, non-breeding season (October to March) and breeding season (May to August) of terrestrial birds. For broad trophic guilds of plant-consumers and insectivores, we disclosed seasonal dynamics and assessed the spread of non-breeding season abundance across migratory habit categories and habitat types. To test for habitat-use patterns derived from hypotheses concerning specific trophic resources, we focused on subsets within trophic guilds: frugivores (plant-consumers that mainly eat fruit) and invertebrate gleaners (insectivores that mainly eat terrestrial leaf and stem invertebrates). Drawing on a resourcecentred dietary requirement hypothesis, we predicted lower abundance of migrant frugivores in mangrove, where palatable fruit availability was expected to be low and resident frugivores probably exploited invertebrates to feed nestlings. Based on the competition-oriented nest predation hypothesis, we anticipated a higher proportion of migrant invertebrate gleaners in marsh. We recorded migrant birds in every month of the year. For 20 plant-consumer species, the non-breeding season density was highest among residents in mangrove (> 5 individuals per hectare). For 46 insectivore species, densities were > 5 and > 9 individuals per hectare for migrants and residents, respectively. Comparable average abundances in trophic guilds suggested both migrant and resident species were equally important. For 14 frugivore species, a higher proportion of migrants in marsh (0.90) than mangrove (0.03) resulted from reciprocal between-habitat changes in migrant and resident abundances, as predicted by the dietary requirement hypothesis. For 22 invertebrate gleaners, proportions of migrants in mangrove (0.45) and marsh (0.55) were comparable, as were abundances. Contrary to the nest predation hypothesis, any between-habitat variation in invertebrate gleaner nesting activity did not markedly influence non-breeding season abundance. —Ruiz, M.D.M., Leon-Cortes, J.L., Enriquez, P.L., Garcia-Estrada, C. & Rangel Salazar, J.L. (2019). Habitat-use patterns among migrant and resident landbirds of contrasting dietary habits in a southern Mexican wetland. Ardeola, 66: 291-310.

Structured Breeding Groups for the Transmission of Spontaneous Hypertension in African Green Monkeys

The African Green Monkey (AGM; Chlorocebus aethiops sabaeus) is a nonhuman primate native to the Caribbean island nation of Saint Kitts and Nevis with genetic ancestry in West Africa. We have shown that the AGM develops spontaneous hypertension (HTN) with renal glomerular pathologies and left ventricular hypertrophy. The AGM is also a translational animal model of hypertensive pregnancy disorders and the study of APOL1 genetic variation in HTN and end‐stage renal disease. Our St. Kitts colony of AGMs consists of over 230 wild‐caught animals. This study assesses the selective breeding of normotensive and spontaneously hypertensive animals and strategies for success in breeding paradigms for the potential transmission of HTN. Over the course of 3 years, the breeding groups have produced more than 80 purpose‐bred offspring. We tested the hypothesis that larger breeding groups would lead to greater reproductive success in both percent gravid females and number of live births for socially complex AGM groups. Breeding was established with one male and either 15–25 (large group) or 2–9 (small group) females. We assessed pregnancies and live births over one annual breeding season (November – March). Systolic blood pressure (SBP) and heart rates (HR) were measured via doppler stethoscope and forearm plethysmography. Breeding groups had phenotypes of hypertensive (HT; systolic blood pressure &gt; 140 mmHg) or normotensive (NT; systolic blood pressure &lt; 120 mmHg) male and female adults ages 5–15 years. The percentage of pregnant females for small breeding groups (70.5 ± 38.2%) was similar to that of females for large breeding groups (68.7 ± 21.6%, p&gt;0.05). The average number of annual births for small breeding groups (2.8 ± 2.6 births) was fewer than that for large breeding groups (13.2 ± 10.6 births, p&lt;0.05). Furthermore, when a new male was introduced to a breeding group, the percentage of gravid females was unchanged (p &gt; 0.05). Offspring from breeding groups have been phenotyped for blood pressure and heart rate at 1 and 2 years of age (juveniles before sexual maturity). All juveniles were derived either from a NT mother and HT father (NT x HT) or two HT parents (HT x HT). SBP of NT x HT offspring did not change with age (1.2 years = 106.9 ± 3.4 mmHg, n = 19 vs 2.0 years 103.8 ± 6.8 mmHg, n = 4; p &gt; 0.05). SBP of HT x HT offspring also remained unchanged with age (1.2 years 114.6 ± 7.2 mmHg, n = 5 vs 2.2 years 111.0 ± 9.6 mmHg, n = 3; p &gt; 0.05). HR decreased with age in both groups (NT x HT: 1.2 years 182.5 ± 3.7 bpm, 2.0 years 165.5 ± 7.5 bpm; HT x HT: 1.2 years 188.0 ± 8.0 bpm, 2.2 years 159.0 ± 10.5 bpm; p&lt;0.05). Offspring from HT x HT parents tended to have greater blood pressures than that of NT x HT parents. In conclusion, these data suggest that breeding group size does not affect the rate of successful mating and progeny production in AGMs. With limited space, smaller breeding groups are shown to be effective, but larger breeding groups are useful when space is not a factor. Juvenile age between 1 and 2 years does not affect changes in SBP regardless of maternal parent blood pressure phenotype when paternal phenotype is HT. Future studies will further assess the effect of both NT x NT and HT x HT parental phenotype, including genetic assessment on the development of adolescent HTN.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Energetic investment associated with vitellogenesis induces an oxidative cost of reproduction

Oxidative stress is a potential cost of reproduction, but conclusive evidence for this relationship is lacking. The goal of this study was to serially assess across a seasonal gradient the relationship between reproduction, circulating plasma energy metabolites and oxidative state. Here, we examine a study animal ideally suited to test for the oxidative costs of reproduction: the Allen Cays Rock Iguana. Female rock iguanas reproduce at varying frequencies, often skipping years, allowing for a comparison between reproductive and non-reproductive females during the same narrow, annual breeding season. This feature of iguana life history enabled us to address not just sex and seasonal differences in physiology, but also potential oxidative costs of reproduction in females. Male and female iguanas were sampled during the early (vitellogenic), late (gravid) and post-reproductive seasons. Ultrasound examinations were performed on females to quantify reproductive investment, and blood samples were collected for physiology assays, which included reactive oxygen metabolites (d-ROMs), antioxidants, triglycerides, free glycerol and glucose. The early reproductive season was characterized by significant increases in reproductive female's triglycerides, free glycerol and oxidative stress compared to late and post-reproductive periods and non-reproductive females and males during all sampling periods. Antioxidants were significantly elevated during the early reproductive season for reproductive females, non-reproductive females and males when compared to late and post-season. Follicle number in early reproductive females was positively related to d-ROMs, triglycerides and free glycerol, negatively related to antioxidants and showed no relationship with glucose. Measures of oxidative stress, d-ROMs and oxidative index were positively correlated with circulating levels of the lipid metabolite free glycerol during the early reproductive period, but this relationship weakened in the late season and disappeared in the post-season. Broadly, this study supports the hypothesis that the relationship between reproduction and oxidative stress is driven by energy investment, being greatest during early reproduction when vitellogenesis is occurring.

English

The study was done to examine some aspects of the reproductive biology of Nile tilapia (Oreochromis niloticus) in Tekeze Reservoir a newly man made hydropower reservoir. A total number of 1826 specimens of Nile Tilapia (O. niloticus) were collected from the reservoir from July 2015 to June 2016. Size at first maturity, sex ratio, gonado-somatic index (GSI), breeding season and fecundity were studied. The overall sex-ratio female: Male (F: M) was 1.6:1 which is deviated from the expected 1:1 sex ratio (&chi;2 = 10.13; p&lt;0.05). Length at first maturity was 14 and 15 cm for females and males respectively. The breeding period of females extended from January to September. Two annual breeding seasons were noticed. A minor breeding season which extended from January to March and a major breeding season from July to September and monthly Condition Factor (CF) (mean &plusmn; SD) value of O. niloticus in the reservoir ranged from 1.73&plusmn;0.03 in July to 2.05&plusmn;0.02 in November for males and 1.61&plusmn;0.02 in July to 1.99&plusmn;0.05 in April for females. Fecundity ranged between 399 to 2129 g. Fecundity correlated well with total weight (r = 0.086), total length (r = 0.77) and ovary weight (r = 0.72) than with gonadal weight (r = 0.86). Nile tilapia at Tekeze Reservoir showed isometric growth pattern (b=2.92), indicating that the reservoir was favorable for the fish growth. For proper management of the fish species in the reservoir, it is better for the fishermen not to capture the fish during the breeding season of the year in the reservoir. Key words: Reproductive biology, Oreochromis niloticus, Gonado-somatic index, fecundity. &nbsp