A Reconsideration of Aspects of Growth, Reproduction, and Behavior of the White Whale (Delphinapterus leucas), with Reference to the Cumberland Sound, Baffin Island, Population

1971 ◽  
Vol 28 (9) ◽  
pp. 1309-1318 ◽  
Author(s):  
P. F. Brodie
Keyword(s):  
Body Size ◽  
Sexual Maturity ◽  
Delphinapterus Leucas ◽  
Corpora Lutea ◽  
Island Population ◽  
Baffin Island ◽  
White Whale ◽  
Cumberland Sound ◽  
And Behavior ◽  
Commercial Hunting

The beluga or white whale, Delphinapterus leucas (Pallas), was studied in Cumberland Sound, Baffin Island. Layering in teeth and mandibles plus body size were used to determine age. Sexual maturity is attained at 5 years for females and at 8 years for males, with potential life span estimated to be 30 years. Whitening of the skin begins after 6 years.Multiple ovulations and accessory corpora lutea are typical of beluga. The breeding season is in May, and after 14.5 months gestation single births occur in late July or early August. Lactation lasts about 2 years, resulting in a 3-year reproductive cycle. Tooth eruption begins late in the 2nd year with partial eruption by the 3rd. This population appears to have been overexploited by commercial hunting. Productivity estimates for this species are 43% of those implied in previous studies.

Ontogenetic Shifts in Brain Organization in the Bluespotted Stingray Neotrygon kuhlii (Chondrichthyes: Dasyatidae)

2017 ◽  
Vol 89 (2) ◽  
pp. 68-83 ◽  
Author(s):  
Thomas J. Lisney ◽  
Kara E. Yopak ◽  
Victoria Camilieri-Asch ◽  
Shaun P. Collin
Keyword(s):  
Body Size ◽  
Sexual Maturity ◽  
Initial Growth ◽  
Brain Growth ◽  
Olfactory Bulbs ◽  
Brain Areas ◽  
Brain Organization ◽  
Ontogenetic Shifts ◽  
And Behavior ◽  
The Brain

Fishes exhibit lifelong neurogenesis and continual brain growth. One consequence of this continual growth is that the nervous system has the potential to respond with enhanced plasticity to changes in ecological conditions that occur during ontogeny. The life histories of many teleost fishes are composed of a series of distinct stages that are characterized by shifts in diet, habitat, and behavior. In many cases, these shifts correlate with changes in overall brain growth and brain organization, possibly reflecting the relative importance of different senses and locomotor performance imposed by the new ecological niches they encounter throughout life. Chondrichthyan (cartilaginous) fishes also undergo ontogenetic shifts in habitat, movement patterns, diet, and behavior, but very little is known about any corresponding shifts in the size and organization of their brains. Here, we investigated postparturition ontogenetic changes in brain-body size scaling, the allometric scaling of seven major brain areas (olfactory bulbs, telencephalon, diencephalon, optic tectum, tegmentum, cerebellum, and medulla oblongata) relative to the rest of the brain, and cerebellar foliation in a chondrichthyan, i.e., the bluespotted stingray Neotrygon kuhlii. We also investigated the unusual morphological asymmetry of the cerebellum in this and other batoids. As in teleosts, the brain continues to grow throughout life, with a period of rapid initial growth relative to body size, before slowing considerably at the onset of sexual maturity. The olfactory bulbs and the cerebellum scale with positive allometry relative to the rest of the brain, whereas the other five brain areas scale with varying degrees of negative allometry. None of the major brain areas showed the stage-specific differences in rates of growth often found in teleosts. Cerebellar foliation also increases at a faster rate than overall brain growth. We speculate that changes in the olfactory bulbs and cerebellum could reflect increased olfactory and locomotor capabilities, which may be associated with ontogenetic shifts in diet, habitat use, and activity patterns, as well as shifts in behavior that occur with the onset of sexual maturity. The frequency distributions of the three cerebellar morphologies exhibited in this species best fit a 2:1:1 (right-sided:left-sided:intermediate) distribution, mirroring previous findings for another stingray species.

THE »EARLY-ANDROGEN« SYNDROME; ITS DEVELOPMENT AND THE RESPONSE TO HEMI-SPAYING

1964 ◽  
Vol 45 (1) ◽  
pp. 1-12 ◽  
Author(s):  
H. E. Swanson ◽  
J. J. van der Werff ten Bosch
Keyword(s):  
Sexual Maturity ◽  
Compensatory Growth ◽  
Testosterone Propionate ◽  
Single Injection ◽  
Weight Increase ◽  
Corpora Lutea ◽  
Transition Stage ◽  
Adult Females

ABSTRACT The »early-androgen« syndrome in the rat – i. e. anovulatory ovaries in adult females after a single injection of testosterone propionate (TP) within a week of birth – may not become apparent until some time after the attainment of sexual maturity. Large doses (50 or 100 μg) of TP were effective earlier than lower doses (5 or 10 μg). Rats which received 5 μg TP were ovulating at 10 weeks of age, mated but were infertile at 13 weeks of age, and were anovulatory at 21 weeks. In rats between 10 and 13 weeks old there was a marked fall in the number of corpora lutea in the ovaries of animals which had been given 5 μg TP. Hemi-spaying was followed by compensatory growth of the remaining ovary which consisted of corpora lutea in ovulating, and of follicles in anovulatory rats; little or no compensatory weight increase occurred in animals which seemed to be in the transition stage from the ovulatory to the anovulatory condition.

scholarly journals Independent evolution towards larger body size in the distinctive Faroe Island mice

2021 ◽  
Author(s):  
Ricardo Wilches ◽  
William H Beluch ◽  
Ellen McConnell ◽  
Diethard Tautz ◽  
Yingguang Frank Chan
Keyword(s):  
Body Size ◽  
Meta Analysis ◽  
Small Body ◽  
Laboratory Mouse ◽  
Large Body ◽  
Natural Populations ◽  
Size Variation ◽  
Phenotypic Traits ◽  
Island Population ◽  
Multiple Loci

Abstract Most phenotypic traits in nature involve the collective action of many genes. Traits that evolve repeatedly are particularly useful for understanding how selection may act on changing trait values. In mice, large body size has evolved repeatedly on islands and under artificial selection in the laboratory. Identifying the loci and genes involved in this process may shed light on the evolution of complex, polygenic traits. Here, we have mapped the genetic basis of body size variation by making a genetic cross between mice from the Faroe Islands, which are among the largest and most distinctive natural populations of mice in the world, and a laboratory mouse strain selected for small body size, SM/J. Using this F2 intercross of 841 animals, we have identified 111 loci controlling various aspects of body size, weight and growth hormone levels. By comparing against other studies, including the use of a joint meta-analysis, we found that the loci involved in the evolution of large size in the Faroese mice were largely independent from those of a different island population or other laboratory strains. We hypothesize that colonization bottleneck, historical hybridization, or the redundancy between multiple loci have resulted in the Faroese mice achieving an outwardly similar phenotype through a distinct evolutionary path.

scholarly journals Emergence ecology of the critically endangered Urothemis edwardsii in a new colonized site in El Kala National Park (Algeria): conservation implications

2019 ◽  
pp. 137-142
Author(s):  
Baaloudj Affef
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Sexual Size Dimorphism ◽  
The Body ◽  
Microhabitat Selection ◽  
Conservation Implications ◽  
And Behavior ◽  
The Relationship ◽  
The Vertical Distribution ◽  
Dragonfly Species

Urothemis edwardsii is one of the most threatened dragonfly species in the Mediterranean. Recent investigations and conservation efforts have increased the local geographic distribution of the species in Northeast Algeria, where a new population (named El Graeate) has been discovered. In the absence of information about the biology and behavior of U. edwardsii in this new site, a study was conducted on the emergence ecology of the species taking into account the temporal pattern of emergence, sex ratio, body size and microhabitat selection. Emergence, which was quite asynchronous, lasted for 50 days, with 50% of the population emerging within the first half of the period. Sex ratio at emergence was slightly female biased despite the absence of sexual size dimorphism, suggesting that size is not the only driving force behind mortality bias during the larval stage. There was a slight seasonal increase in the body size of exuviae (exoskeletons) in both sexes. Microhabitat selection, assessed as the vertical stratification of exuviae at ecdysis, was positively correlated with the height of supporting plants, but the relationship reached a plateau suggesting that there are predetermined limits to the vertical distribution of exuviae. These data will be essential for the future species protection, restoration and management attempts in the region.

scholarly journals Population dynamics of the threatened Cumberland Sound beluga (Delphinapterus leucas) population

2020 ◽  
Author(s):  
Cortney Watt ◽  
Marianne Marcoux ◽  
Steven H. Ferguson ◽  
Mike Hammill ◽  
Cory Matthews
Keyword(s):  
Scientific Evidence ◽  
Marine Ecosystem ◽  
Ecological Integrity ◽  
Beluga Whale ◽  
Delphinapterus Leucas ◽  
Commercial Harvest ◽  
Abundance Estimates ◽  
Long Term Trends ◽  
Cumberland Sound ◽  
Reproductive Rates

Current scientific evidence indicates the threatened Cumberland Sound beluga (Delphinapterus leucas) population is genetically differentiated and spatially segregated from other beluga whale populations. This population has been hunted for subsistence for centuries by Inuit who now live in the community of Pangnirtung, Nunavut, Canada, and was harvested commercially from 1860 until 1966. The commercial harvest removed at least 10,000 individuals from the population. Visual and photographic aerial surveys were flown during August 2014 and 2017 and produced beluga whale abundance estimates of 1,151 (CV = 0.214; 95% Confidence Interval [CI] = 760-1,744) and 1,381 (CV = 0.043; CI = 1,270-1,502), respectively. Long-term trends in abundance were examined by fitting a Bayesian surplus-production population model to a time series of abundance estimates (n = 5), flown between 1990 and 2017, taking into account reported subsistence harvests (1960-2017). The model suggests the population is declining. Engaged co-management of the Cumberland Sound beluga population and information on demographic parameters, such as reproductive rates, and age and sex composition of the harvest, are needed to restore the ecological integrity of the Cumberland Sound marine ecosystem.

Abstract P119: High Stress Reasons for Immigration Affect Diabetes Risk, Body Size and Behavior: The Africans in America Study

Circulation ◽  
2018 ◽  
Vol 137 (suppl_1) ◽  
Author(s):  
Sara M Briker ◽  
J Damascene Kabakambira ◽  
Rafeal L Baker ◽  
Christopher W DuBose ◽  
Lilian S Mabundo ◽  
...  
Keyword(s):  
Body Size ◽  
Sleep Duration ◽  
Allostatic Load ◽  
High Stress ◽  
The United States ◽  
Washington Dc ◽  
Subsaharan Africa ◽  
Medical Histories ◽  
And Behavior ◽  
Visceral Adipose

Introduction: Leaving Africa to live in the United States is stressful. Due to oversecretion of glucocortoids and catecholamines, stress has biologic consequences. No data exists on whether Africans who come to America for reasons associated with high stress have a higher rate of conditions such as obesity, diabetes and hypertension than Africans who come for low stress reasons. Goals: Working with the Africans in America cohort and using allostatic load score (ALS) to measure biologic stress, our objectives were to (a) rank by ALS the 5 most common reasons for immigration (work, study, asylum/refugee, family unification and lottery); (b) divide the cohort in to 2 groups: high stress (combining the individuals with the 3 reasons with the highest ALS) and low stress (combining the individuals with the lowest ALS); (c) compare body size, visceral adipose tissue (VAT), glucose, BP, sleep duration and smoking in Africans with high and low stress. Methods: OGTT and abdominal CT scans were performed in 114 African immigrants (68% male, age 41±10, range22-62y) born in subSaharan Africa but living in Washington, DC. Results: Ranked from highest to lowest, ALS for each reason for immigration was: work 3.18±1.71; asylum/refugee 2.68±1.46; study 2.66±1.88; family 1.77±1.27; lottery 1.60±1.27. Hence, high stress reasons for immigration were: work, asylum/refugee and study. Low stress reasons were: family and lottery. ALS in high vs. low stress reasons for immigration were: 2.81±1.74 vs. 1.72±1.25, P<0.01. BP did not vary by group. However, Africans with high stress had a higher BMI, more VAT and hyperglycemia than Africans with low stress (Table). Africans with high stress also had a greater tendency to sleep <7h per night and smoke (Table). Conclusions: High stress reasons for immigration include work, asylum/refugee and study. As obesity, hyperglycemia, and behaviors such as decreased sleep duration and smoking are associated with high stress reasons for immigration, medical histories when possible should include reason for immigration.

Body Size and the Timing of Sexual Maturity

2017 ◽  
pp. 341-374
Author(s):  
Kim Hill ◽  
A. Magdalena Hurtado
Keyword(s):  
Body Size ◽  
Sexual Maturity

Body size, diet and reproductive ecology of Coluber hippocrepis in the Rif (Northern Morocco)

2004 ◽  
Vol 25 (3) ◽  
pp. 287-302 ◽  
Author(s):  
Juan Pleguezuelos ◽  
Soumia Fahd
Keyword(s):  
Body Size ◽  
Sexual Maturity ◽  
Prey Size ◽  
Reproductive Ecology ◽  
Size Difference ◽  
Southern Europe ◽  
Strait Of Gibraltar ◽  
Dietary Shift ◽  
Intersexual Difference ◽  
Whip Snake

AbstractAlthough it is generally assumed that the Horseshoe Whip Snake (Coluber hippocrepis) originated in northern Africa, its biology and ecology has been studied mainly in southern Europe. In this paper we report on morphology, feeding, and reproductive ecology of Coluber hippocrepis in the Rif region (northern Morocco). Males attained larger sizes than did females, but there was no body-size difference between populations separated by the Strait of Gibraltar. The species feeds exclusively on vertebrates: mammals (45%), reptiles (28%), birds (17%), and amphibians (10%). There was an ontogenetic dietary shift in terms of frequency of prey consumed and in terms of prey size; moreover, an intersexual difference in prey frequency was found. Sexual maturity was attained at 540 mm snout-vent length (SVL) in males, and 720 mm SVL in females. Males showed a vernal spermatogenic cycle. Oviposition occurred at the beginning of summer, and offspring were observed in the field during September.

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