Sex biases in parasitism of neotropical bats by bat flies (Diptera: Streblidae)

2008 ◽  
Vol 24 (4) ◽  
pp. 387-396 ◽  
Author(s):  
Bruce D. Patterson ◽  
Carl W. Dick ◽  
Katharina Dittmar
Keyword(s):  
Sex Differences ◽  
Sexual Size Dimorphism ◽  
Species Level ◽  
Male And Female ◽  
Size Dimorphism ◽  
Bat Flies ◽  
Neotropical Bats ◽  
Males And Females ◽  
Heavy Loads ◽  
Sex Biases

AbstractWe describe levels of parasitism of ectoparasitic bat flies (Hippoboscoidea: Streblidae) on male and female bats from an extensive Neotropical survey. The collection resulted from coordinated vertebrate-parasite surveys undertaken by the Smithsonian Venezuelan Project (SVP) from 1965–1968, which sexed 24 978 bats of 130 species. Streblid parasites were recovered from 6935 individuals of 87 bat species, but only 47 species were captured frequently enough (≥ 20 infested individuals) to permit reliable estimates of streblid parasitism on males and females. Well-sampled species included 39 phyllostomids, four mormoopids, two noctilionids, one natalid and one molossid. Prevalence of streblid parasitism (proportion of individuals infested) of male and female bats was generally not significantly different, and averaged 0.34 across infested species. In species-level analyses assessed against captures, significant sex differences in infestation levels were noted in six species; all had mean prevalence below 0.5 and females were parasitized disproportionately in each. Sex differences in total numbers of flies were noted in 21 species, and in 16 of these, females carried disproportionately heavy loads. Sex differences were also found for eight species of bat in the number of fly species infesting an individual; seven of eight showed heavier female parasitism. In analyses weighted by infestation levels, sex differences in total number of flies were found in only 12 species, with seven showing excessive parasitism of females, and no species showed sex differences in the number of fly species infesting them. These significant biases were not associated with sexual size dimorphism among the bat species. Generally higher levels of parasitism among female bats accords with theory, given their generally higher survivorship and enhanced probabilities of lateral and vertical transmission of host-specific parasites, but contrasts with patterns shown by many other parasitic arthropods. Future analyses should target social groupings of bats, not passively sampled foragers, to better address the mechanisms responsible for this pattern.

scholarly journals Sex-specific microhabitat use is associated with sex-biased thermal physiology in Anolis lizards

2020 ◽  
pp. jeb.235697
Author(s):  
Michael L. Logan ◽  
Lauren K. Neel ◽  
Daniel J. Nicholson ◽  
Andrew J. Stokes ◽  
Christina L. Miller ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Habitat Use ◽  
Thermal Tolerance ◽  
Sexual Size Dimorphism ◽  
Microhabitat Use ◽  
Thermal Physiology ◽  
Male And Female ◽  
Size Dimorphism ◽  
Heterogeneous Habitats ◽  
Males And Females

If fitness optima for a given trait differ between males and females in a population, sexual dimorphism may evolve. Sex-biased trait variation may affect patterns of habitat use, and if the microhabitats used by each sex have dissimilar microclimates, this can drive sex-specific selection on thermal physiology. Nevertheless, tests of differences between the sexes in thermal physiology are uncommon, and studies linking these differences to microhabitat use or behavior are even rarer. We examined microhabitat use and thermal physiology in two ectothermic congeners that are ecologically similar but differ in their degree of sexual size dimorphism. Brown anoles (Anolis sagrei) exhibit male-biased sexual size dimorphism and live in thermally heterogeneous habitats, whereas slender anoles (Anolis apletophallus) are sexually monomorphic in body size and live in thermally homogeneous habitats. We hypothesized that differences in habitat use between the sexes would drive sexual divergence in thermal physiology in brown anoles, but not slender anoles, because male and female brown anoles may be exposed to divergent microclimates. We found that male and female brown anoles, but not slender anoles, used perches with different thermal characteristics and were sexually dimorphic in thermal tolerance traits. However, field-active body temperatures and behavior in a laboratory thermal arena did not differ between females and males in either species. Our results suggest that sexual dimorphism in thermal physiology can arise from phenotypic plasticity or sex-specific selection on traits that are linked to thermal tolerance, rather than from direct effects of thermal environments experienced by males and females.

scholarly journals Degree of anisogamy is unrelated to the intensity of sexual selection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Judit Mokos ◽  
István Scheuring ◽  
András Liker ◽  
Robert P. Freckleton ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Life History ◽  
Parental Care ◽  
Sex Roles ◽  
Sexual Size Dimorphism ◽  
Ecological Factors ◽  
Size Dimorphism ◽  
Wide Range ◽  
Males And Females

AbstractMales and females often display different behaviours and, in the context of reproduction, these behaviours are labelled sex roles. The Darwin–Bateman paradigm argues that the root of these differences is anisogamy (i.e., differences in size and/or function of gametes between the sexes) that leads to biased sexual selection, and sex differences in parental care and body size. This evolutionary cascade, however, is contentious since some of the underpinning assumptions have been questioned. Here we investigate the relationships between anisogamy, sexual size dimorphism, sex difference in parental care and intensity of sexual selection using phylogenetic comparative analyses of 64 species from a wide range of animal taxa. The results question the first step of the Darwin–Bateman paradigm, as the extent of anisogamy does not appear to predict the intensity of sexual selection. The only significant predictor of sexual selection is the relative inputs of males and females into the care of offspring. We propose that ecological factors, life-history and demography have more substantial impacts on contemporary sex roles than the differences of gametic investments between the sexes.

scholarly journals Stem cell treatment improves post stroke neurological outcomes: a comparative study in male and female rats

2021 ◽  
pp. svn-2020-000834
Author(s):  
Koteswara Rao Nalamolu ◽  
Bharath Chelluboina ◽  
Casimir A Fornal ◽  
Siva Reddy Challa ◽  
David M Pinson ◽  
...  
Keyword(s):  
Stem Cells ◽  
Sex Differences ◽  
Motor Function ◽  
Infarct Volume ◽  
Female Rats ◽  
Human Umbilical Cord ◽  
Male And Female ◽  
Post Stroke ◽  
Male And Female Rats ◽  
Males And Females

Background and purposeThe therapeutic potential of different stem cells for ischaemic stroke treatment is intriguing and somewhat controversial. Recent results from our laboratory have demonstrated the potential benefits of human umbilical cord blood-derived mesenchymal stem cells (MSC) in a rodent stroke model. We hypothesised that MSC treatment would effectively promote the recovery of sensory and motor function in both males and females, despite any apparent sex differences in post stroke brain injury.MethodsTransient focal cerebral ischaemia was induced in adult Sprague-Dawley rats by occlusion of the middle cerebral artery. Following the procedure, male and female rats of the untreated group were euthanised 1 day after reperfusion and their brains were used to estimate the resulting infarct volume and tissue swelling. Additional groups of stroke-induced male and female rats were treated with MSC or vehicle and were subsequently subjected to a battery of standard neurological/neurobehavioral tests (Modified Neurological Severity Score assessment, adhesive tape removal, beam walk and rotarod). The tests were administered at regular intervals (at days 1, 3, 5, 7 and 14) after reperfusion to determine the time course of neurological and functional recovery after stroke.ResultsThe infarct volume and extent of swelling of the ischaemic brain were similar in males and females. Despite similar pathological stroke lesions, the clinical manifestations of stroke were more pronounced in males than females, as indicated by the neurological scores and other tests. MSC treatment significantly improved the recovery of sensory and motor function in both sexes, and it demonstrated efficacy in both moderate stroke (females) and severe stroke (males).ConclusionsDespite sex differences in the severity of post stroke outcomes, MSC treatment promoted the recovery of sensory and motor function in male and female rats, suggesting that it may be a promising treatment for stroke.

Sex Differences in Expected Guilt Reactions to Hypothetical Behaviors of Sexual, Hostile, and Moral Substance

1975 ◽  
Vol 40 (2) ◽  
pp. 409-410 ◽  
Author(s):  
Robert H. Heying ◽  
Karen Korabik ◽  
David C. Munz
Keyword(s):  
Sex Differences ◽  
Sentence Completion ◽  
Male And Female ◽  
Response Alternatives ◽  
Males And Females ◽  
Moral Nature

Differences between male and female guilt reactions to hypothetical guilt-inducing situations of a sexual, hostile, and moral nature were investigated. Two independent samples of Ss (56 men, 56 women; and 34 men, 62 women) reported the intensity of their anticipated guilt reactions to 60 hypothetical behavior situations presented in sentence-completion format through the use of scaled response alternatives. Across both samples there were specific behaviors in which stable sex differences were evidenced, i.e., females' reactions were more intense for those behaviors reflecting sexual transgressions. However, males and females were highly similar in their reactions to hostile and moral guilt-provoking situations. Implications of these results for research on trait-guilt were discussed.

scholarly journals Bigger Males, Bigger Females? Pigeons’ Sexual Size Dimorphism

2020 ◽  
pp. 20-24
Author(s):  
P. M. Parés- Casanova ◽  
A. Kabir
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Sexual Size Dimorphism ◽  
Wing Length ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Neck Thickness ◽  
Males And Females ◽  
Domestic Pigeons

Sexual dimorphism, defined as phenotypic differences between males and females, is a common phenomenon in animals. In this line, Rensch’s rule states that sexual size dimorphism increases with increasing body size when the male is the larger sex and decreases with increasing average body size when the female is the larger sex. Domesticated animals offer excellent opportunities for testing predictions of functional explanations of Rensch’s theory. Pigeon breeds encounters many different functional purposes and selective constraints, which could influence strongly their morphology. The aim of this paper is to examine, for first time, Rensch’s rule among domestic pigeons. It was compiled a database of 12 quantitative traits (body weight, body height, beak thickness, beak length, neck length, neck thickness, wing length, rump width, tail length, tarsus length, tarsus thickness and middle toe length) for males and females of 11 different domestic pigeon breeds: Bangladesh Indigenous, Racing Homer, Turkish Tumbler, Indian Lotan, Kokah, Mookee, Indian Fantail, Bokhara Trumpeter, Bombai, Lahore and Hungarian Giant House; Rock Pigeon (Columba livia) was also considered as wild relative for comparative purposes. Comparative results between males and females showed that only body weight, wing length and neck thickness were consistent with Rensch’s rule. The rest of trait did not present correlations. Among domestic pigeons, there can appear different expressions of dimorphism according to each trait, so it must be considered that Rensch’s rule vary when considering other traits than body weight.

Field Dependence among Male and Female Alcoholics: II. Norms for the Rod-and-Frame Test

1976 ◽  
Vol 43 (2) ◽  
pp. 399-402 ◽  
Author(s):  
George R. Jacobson ◽  
Ann Van Dyke ◽  
Theodore G. Sternbach ◽  
Russell Brethauer
Keyword(s):  
Sex Differences ◽  
Field Dependence ◽  
Normative Data ◽  
Male And Female ◽  
Field Dependent ◽  
Perceptual Style ◽  
Males And Females ◽  
Rod And Frame Test ◽  
Rod And Frame

402 males and 160 females hospitalized for treatment of alcoholism were tested in a standardized manner on the Rod-and-frame test as a means of supplementing an earlier report of normative data on perceptual style among male alcoholics. When their performance was contrasted with that of normal and psychiatric samples, alcoholics were clearly the most field dependent of all groups studied. Statistically significant sex differences justify the need for separate norms for males and females.

Size-Dependent Selective Mechanisms on Males and Females and the Evolution of Sexual Size Dimorphism in Frogs

2014 ◽  
Vol 184 (6) ◽  
pp. 727-740 ◽  
Author(s):  
Renato C. Nali ◽  
Kelly R. Zamudio ◽  
Célio F. B. Haddad ◽  
Cynthia P. A. Prado
Keyword(s):  
Sexual Size Dimorphism ◽  
Size Dimorphism ◽  
Size Dependent ◽  
Males And Females

Egg size, prey size, and sexual size dimorphism in digger wasps (Hymenoptera: Sphecidae)

1985 ◽  
Vol 63 (9) ◽  
pp. 2187-2193 ◽  
Author(s):  
Kevin M. O'Neill
Keyword(s):  
Body Size ◽  
Selection Pressure ◽  
Sexual Size Dimorphism ◽  
Species Selection ◽  
Male Size ◽  
Size Dimorphism ◽  
Female Body Size ◽  
Mean Size ◽  
Males And Females ◽  
Apparent Association

Female digger wasps invest substantially in each of their offspring, laying relatively few, large eggs and providing the young with the insect prey on which they depend for food. In a study of six species in the genera Philanthus, Bembecinus, and Bembix, it was found that within each species, there is a positive correlation between female body size and both the size of their ovarial eggs and the size of the prey they provision. In five of the six species, females were larger than males on average. It is suggested that the apparent association between body size and certain aspects of parental investment by females may provide the directional selection pressure that results in the evolution of sexual size dimorphism in digger wasps. In one species, males and females have the same mean size, probably because, in this species, selection pressure on male size is similar to that on females.

Egg-laying site, fecundity and degree of sexual size dimorphism in frogs

2020 ◽  
Vol 131 (3) ◽  
pp. 600-610
Author(s):  
Nelson Rodrigues Silva ◽  
Bianca V M Berneck ◽  
Helio R da Silva ◽  
Célio F B Haddad ◽  
Kelly R Zamudio ◽  
...  
Keyword(s):  
Sexual Size Dimorphism ◽  
Egg Laying ◽  
Female Size ◽  
Selective Force ◽  
Size Dimorphism ◽  
Body Sizes ◽  
Space Limitation ◽  
Males And Females ◽  
Similar Body ◽  
Oviposition Sites

Abstract Female fecundity is an important selective force leading to female-biased sexual size dimorphism (SSD) in frogs. Because anurans exhibit diverse reproductive modes, we investigated whether variation in SSD and fecundity are related with oviposition site. We asked whether arboreal breeding species show pronounced female-biased SSD and if, paradoxically, females have lower fecundity because of the costs of carrying oocytes and amplectant males. Conversely, we tested whether species that deposit eggs in concealed sites show less pronounced SSD, because females do not carry males and space limitation may reduce female size and fecundity. Our results showed that, in general, males were approximately 20% smaller than females. However, for species with hidden oviposition sites, males and females exhibited more similar body sizes and arboreal hylids showed more pronounced female-biased SSD. Overall, fecundity was higher in aquatic breeders, as expected, but in hylids, fecundity was smaller in arboreal breeders, which suggests that arboreality may impose restrictions on fecundity. By analysing SSD in a broader and more specific lineage (Hylidae), we found that reproductive microhabitat may also influence female size and fecundity, playing an important role in the evolution of SSD in frogs at different evolutionary scales.

Effects of Sex of Pressuring Group, Perception of Ability, and Sex of Communicator Influencing Perceived Ability on Conformity of Males and Females

1979 ◽  
Vol 44 (3) ◽  
pp. 719-726 ◽  
Author(s):  
Diane R. Follingstad
Keyword(s):  
Sex Differences ◽  
Male And Female ◽  
Differential Effects ◽  
Female Data ◽  
Males And Females ◽  
Group Perception ◽  
Independent Behavior ◽  
Male Subjects ◽  
Better Than ◽  
Female Subjects

This study assessed the differential effects of sex of pressuring confederates and perception of ability on conforming behavior of males and females. Varying male and female sources of the communication to influence subjects' views of their ability was expected to produce less conformity in females receiving the information from a male rather than a female. Data on undergraduates showed 64 females did not conform significantly more than 64 males, but male subjects conformed more in the presence of male confederates while females conformed significantly more when led to believe that males were more accurate on the task. Only the male source influencing females to believe they were superior on the task resulted in significantly less conformity in female subjects. Considering sex differences is essential due to the finding that the sexes responded to different variables present in most conformity experiments. The decrease in conformity produced in females when told by a male that females do better than males has implications for the use of male sources of communication to increase independent behavior of women.

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