scholarly journals Phenotypic Variation in Skull Size and Shape Between Newfoundland and Mainland Populations of North American Black Bears, Ursus americanus

2003 ◽  
Vol 117 (2) ◽  
pp. 236 ◽  
Author(s):  
John A. Virgl ◽  
Shane P. Mahoney ◽  
Kim Mawhinney
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Ursus Americanus ◽  
Population Variation ◽  
Black Bears ◽  
Selection Pressures ◽  
Skull Shape ◽  
Skull Size ◽  
Environmental Selection ◽  
Gape Size

It is well recognized that differences in environmental selection pressures among populations can generate phenotypic divergence in a suite of morphological characteristics and associated life history traits. Previous analysis of mitochondrial DNA and body size have suggested that Black Bears (Ursus americanus) inhabiting the island of Newfoundland represent a different subspecies or ecotype from mainland populations. Assuming that body size covaries positively with skull size, we predicted that skull size would be greater for bears on the island than the mainland, and the distribution of size-related shape components in multivariate space should show a distinct separation between Newfoundland and mainland populations. Measurements of 1080 specimens from Newfoundland, Alberta, New York, and Quebec did not provide unequivocal support for our prediction that skull size in Newfoundland bears would be larger than bears from the mainland populations. After removing ontogenetic effects of skull size, between-population variation in skull shape was greater in females than males, and the analysis significantly separated Newfoundland bears from mainland populations. Explanations for this pattern are numerous, but currently remain hypothetical. Limited covariation between skull size and body size suggests that genetic traits regulating the size of Black Bear skulls are more heritable (i.e., less influenced by environmental selection pressures) than characteristics affecting body size. We hypothesize that if gape size does not limit prey size in solitary terrestrial carnivores, large degrees of among-population variation in body size should be coupled with little covariation in skull size. In general, sexual dimorphism in skull size and shape was marginal for the phenotypic characters measured in our study. We believe that sexual dimorphism in skull size in Black Bears is primarily driven by intrasexual selection in males for increased gape size display, while similarity in skull shape between sexes is associated with the constraints of a temporally-selective, but similar diet.

Predicting nutritional condition in black bears and polar bears on the basis of morphological and physiological measurements

1990 ◽  
Vol 68 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Marc Cattet
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Multiple Regression ◽  
Lipid Content ◽  
Ursus Americanus ◽  
Nutritional Condition ◽  
Black Bears ◽  
Polar Bears ◽  
Regression Equations ◽  
Age Classes

Thirty-eight black bears (Ursus americanus) and 43 polar bears (Ursus maritimus) were dissected to determine equations for predicting body weight (BW) and nonfat body weight (NFBW). Nutritional condition was estimated by calculating a fat to nonfat (FNF) ratio, equalling (BW – NFBW)/NFBW. For each species, BW and NFBW were accurately predicted by multiple regression equations based on morphological measurements. The FNF ratio was independent of body size and thus comparable between sexes and among age-classes. The accuracy of predicting the FNF ratio is limited, and reliable comparisons of nutritional condition among individual bears will require the development of more accurate techniques. Physiological measurements of marrow and intramuscular percent lipid content were also evaluated as potential indicators of nutritional condition, but were determined to be unreliable.

scholarly journals Parental Investment and Sexual Dimorphism in Digger Wasps (Hymenoptera: Sphecidae)

1981 ◽  
Vol 5 ◽  
pp. 58-63
Author(s):  
Howard Evans ◽  
Kevin O'Neill
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Reproductive Success ◽  
Parental Investment ◽  
Mating Success ◽  
Female Body ◽  
Intrasexual Competition ◽  
Mating Strategy ◽  
Selection Pressures ◽  
Female Body Size

While investigating the mating strategy of wasps in the genus Philanthus we have discovered that the major determinant of mating success in males is body size (i.e., larger males are more successful at obtaining matings; this will be summarized further at the end of this report). In vertebrates that display sexual dimorphism and where there is male-male combat involved in the mating strategy, males are usually the larger sex. This is not the case in the Sphecidae where, in the vast majority of species (including Philanthus), the males are smaller, on the average, than females. This is puzzling, given the superiority of larger males in intrasexual competition. Even though larger males show a higher reproductive success than smaller males, there must be stronger selection pressures acting on female body size which promotes larger size in most species of digger wasps.

scholarly journals Pattern and pace of morphological change due to variable human impact: the case of Japanese macaques

Primates ◽  
2021 ◽  
Author(s):  
Madeleine Geiger
Keyword(s):  
Body Size ◽  
Human Impact ◽  
Morphological Variation ◽  
Japanese Macaques ◽  
Linear Measurements ◽  
Skull Shape ◽  
Rates Of Change ◽  
Animal Populations ◽  
Captive Populations ◽  
In Captivity

AbstractHuman impact influences morphological variation in animals, as documented in many captive and domestic animal populations. However, there are different levels of human impact, and their influence on the pattern and rate of morphological variation remains unclear. This study contributes to the ongoing debate via the examination of cranial and mandibular shape and size variation and pace of change in Japanese macaques (Macaca fuscata). This species is ideal for tackling such questions because different wild, wild-provisioned, and captive populations have been monitored and collected over seven decades. Linear measurements were taken on 70 skulls from five populations, grouped into three ‘human impact groups’ (wild, wild-provisioned, and captive). This made it possible to investigate the pattern and pace of skull form changes among the human impact groups as well as over time within the populations. It was found that the overall skull shape tends to differ among the human impact groups, with captive macaques having relatively longer rostra than wild ones. Whether these differences are a result of geographic variation or variable human impact, related to nutritional supply and mechanical properties of the diet, is unclear. However, this pattern of directed changes did not seem to hold when the single captive populations were examined in detail. Although environmental conditions have probably been similar for the two examined captive populations (same captive locality), skull shape changes over the first generations in captivity were mostly different. This varying pattern, together with a consistent decrease in body size in the captive populations over generations, points to genetic drift playing a role in shaping skull shape and body size in captivity. In the captive groups investigated here, the rates of change were found to be high compared to literature records from settings featuring different degrees of human impact in different species, although they still lie in the range of field studies in a natural context. This adds to the view that human impact might not necessarily lead to particularly fast rates of change.

Microsatellite population structure of Newfoundland black bears (Ursus americanus hamiltoni)

2011 ◽  
Vol 89 (9) ◽  
pp. 831-839 ◽  
Author(s):  
H. Dawn Marshall ◽  
Edward S. Yaskowiak ◽  
Casidhe Dyke ◽  
Elizabeth A. Perry
Keyword(s):  
Population Structure ◽  
Ursus Americanus ◽  
Intraspecific Variability ◽  
Black Bears ◽  
Postglacial Colonization ◽  
Correct Assignment ◽  
Hair Samples ◽  
Males And Females ◽  
Two Populations ◽  
F Statistics

We investigated population structure of black bears ( Ursus americanus hamiltoni Cameron, 1957) from insular Newfoundland using the microsatellite profiles of 12 loci from three broadly distributed areas (Northern, Baie Verte, and Bonavista peninsulas). Our goals were to revisit earlier findings of low heterozygosity in Newfoundland and increase knowledge of intraspecific variability in black bears, and make inferences about postglacial colonization and contemporary movements of island black bears. Ninety-three individuals (42 males) were identified among 543 hair samples: 21 from Bonavista, 25 from Northern Peninsula, and 47 from Baie Verte. Genetic diversity is relatively low (HE = 0.42) and decreases from northwest to southeast. Small but significant subpopulation differentiation revealed by F statistics is greatest between Northern and Baie Verte peninsulas; it is lower and comparable in the remaining pairwise comparisons. We hypothesize that postglacial colonization proceeded from the Northern Peninsula southeastward. Bears migrated from the Northern Peninsula to Baie Verte at some more distant time in the past, then diverged by genetic drift. More recently, migration occurred from these two populations to Bonavista, characterized by positive FIS indicative of admixture. Tests of biased dispersal and posterior probability of correct assignment to locality reveal contemporary movements of both males and females with historical dispersal attributable to males.

Sexual dimorphism in human cranial trait scores: Effects of population, age, and body size

2014 ◽  
Vol 154 (2) ◽  
pp. 259-269 ◽  
Author(s):  
Heather M. Garvin ◽  
Sabrina B. Sholts ◽  
Laurel A. Mosca
Keyword(s):  
Body Size ◽  
Sexual Dimorphism

Population variation in skeletal sexual dimorphism

2017 ◽  
Vol 278 ◽  
pp. 407.e1-407.e7 ◽  
Author(s):  
Douglas H. Ubelaker ◽  
Cassandra M. DeGaglia
Keyword(s):  
Sexual Dimorphism ◽  
Population Variation

scholarly journals Environmental Selection Pressures Related to Iron Utilization Are Involved in the Loss of the Flavodoxin Gene from the Plant Genome

2015 ◽  
Vol 7 (3) ◽  
pp. 750-767 ◽  
Author(s):  
Juan J. Pierella Karlusich ◽  
Romina D. Ceccoli ◽  
Martín Graña ◽  
Héctor Romero ◽  
Néstor Carrillo
Keyword(s):  
Plant Genome ◽  
Selection Pressures ◽  
Environmental Selection ◽  
Iron Utilization

Hibernating black bears have blood chemistry and plasma amino acid profiles that are indicative of long-term adaptive fasting

2005 ◽  
Vol 83 (9) ◽  
pp. 1257-1263 ◽  
Author(s):  
T D Lohuis ◽  
T D.I Beck ◽  
H J Harlow
Keyword(s):  
Amino Acids ◽  
Ursus Americanus ◽  
Muscle Protein ◽  
Blood Chemistry ◽  
Black Bears ◽  
Late Winter ◽  
Amino Acid Profiles ◽  
Protein Conservation ◽  
Branched Chain

Blood samples were drawn from six black bears (Ursus americanus Pallas, 1780) active in the summer and six others in early and late hibernation. Plasma urea:creatinine ratios and concentrations of amino acids, alanine aminotransferase, and aspartate aminotransferase dropped during the winter denning season, suggesting a decreased protein breakdown. Fifteen amino acids (3 branched chain and 12 glucogenic) were lower in the early winter than in the summer, but 6 of these amino acids rose back to summer levels by the late denning season. Hydroxyproline and glycine were also elevated during late winter, suggesting an increase in collagen breakdown. This profile suggests a dynamic process of adaptive fasting and protein conservation during the winter with a mobilization of non-myofibrilar collagen and perhaps smooth muscle protein reserves to augment a potential but slight increased breakdown of skeletal muscle during the late winter.

Sperm ultrastructure, morphometry, and abnormal morphology in American black bears (Ursus americanus)

2010 ◽  
Vol 74 (8) ◽  
pp. 1403-1413 ◽  
Author(s):  
L.F.C. Brito ◽  
P.L. Sertich ◽  
G.B. Stull ◽  
W. Rives ◽  
M. Knobbe
Keyword(s):  
Ursus Americanus ◽  
Black Bears ◽  
Sperm Ultrastructure ◽  
Abnormal Morphology ◽  
American Black ◽  
American Black Bears

LEPTOSPIROSIS IN URBAN AND SUBURBAN AMERICAN BLACK BEARS (URSUS AMERICANUS) IN WESTERN NORTH CAROLINA, USA

2019 ◽  
Vol 55 (1) ◽  
pp. 74 ◽  
Author(s):  
Indrani Sasmal ◽  
Nicholas P. Gould ◽  
Krysten L. Schuler ◽  
Yung-Fu Chang ◽  
Anil Thachil ◽  
...  
Keyword(s):  
North Carolina ◽  
Ursus Americanus ◽  
Black Bears ◽  
Western North Carolina ◽  
American Black ◽  
American Black Bears
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