scholarly journals Intraspecific variation in the diet of the Mexican garter snakeThamnophis eques

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4036 ◽  
Author(s):  
Javier Manjarrez ◽  
Martha Pacheco-Tinoco ◽  
Crystian S. Venegas-Barrera
Keyword(s):  
Intraspecific Variation ◽  
Resource Competition ◽  
Prey Availability ◽  
General Pattern ◽  
Stomach Contents ◽  
Large Prey ◽  
Male And Female ◽  
Males And Females ◽  
Prey Items

The Mexican Garter Snake (Thamnophis eques)is a terrestrial-aquatic generalist that feeds on both aquatic and terrestrial prey. We describe size-related variation and sexual variation in the diet ofT. equesthrough analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The snakeT. equeswe studied consumed mostly fish, followed in lesser amounts by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the frequency of consumption of various prey items differed between the categories of age but not between sex of snakes, and the general pattern was a reduction of prey item diversity with size of snake. Snake length was correlated positively with mass of ingested prey. Large snakes consumed large prey and continued to consume smaller prey. In general, no differences were found between the prey taxa of male and female snakes, although males ate two times more tadpoles than females. Males and females did not differ in the mass of leeches, earthworms, fishes, frogs and tadpoles that they ate, and males and females that ate each prey taxon were similar in length. We discuss proximate and functional determinants of diet and suggest that the observed intraspecific variation inT. equescould be explored by temporal variation in prey availability, proportions of snake size classes and possible sexual dimorphism in head traits and prey dimensions to assess the role of intersexual resource competition.

scholarly journals Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques

2016 ◽  
Author(s):  
Javier Manjarrez ◽  
Martha Pacheco-Tinoco ◽  
Crystian S Venegas-Barrera
Keyword(s):  
Intraspecific Variation ◽  
Resource Competition ◽  
Prey Availability ◽  
General Pattern ◽  
Stomach Contents ◽  
Garter Snake ◽  
Large Prey ◽  
Garter Snakes ◽  
Males And Females ◽  
Prey Items

The Mexican Garter Snake (Thamnophis eques) is a terrestrial-aquatic generalist because it feeds on both aquatic and terrestrial prey. We describe size-related variation and slight sexual variation in the diet of Thamnophis eques through analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The Mexican Garter Snakes we studied ate prey items mostly fish, followed in lesser amounts, respectively, by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the frequency of consumption of various prey items differed between the categories of age and sex of snakes, and the general pattern was a reduction of prey item diversity with size of snake. Snake length was correlated positively with mass of ingested prey. Large snakes consumed large prey and continued to consume smaller prey. In general, no differences were found between the prey taxa of male and female snakes, although males ate two times more tadpoles than females. Males and females did not differ in the mass of leeches, earthworms, fishes, frogs and tadpoles that they ate, and males and females that ate each prey taxon were similar in length. We discuss proximate and functional determinants of diet and suggest that the observed intraspecific variation in Mexican Garter Snakes could be explored by temporal variation in prey availability, proportions of snake size classes and possible sexual dimorphism in head traits and prey dimensions to assess the role of intersexual resource competition.

scholarly journals Intraspecific variation in the diet of the Mexican garter snake Thamnophis eques

2016 ◽  
Author(s):  
Javier Manjarrez ◽  
Martha Pacheco-Tinoco ◽  
Crystian S Venegas-Barrera
Keyword(s):  
Intraspecific Variation ◽  
Resource Competition ◽  
Prey Availability ◽  
General Pattern ◽  
Stomach Contents ◽  
Garter Snake ◽  
Large Prey ◽  
Garter Snakes ◽  
Males And Females ◽  
Prey Items

The Mexican Garter Snake (Thamnophis eques) is a terrestrial-aquatic generalist because it feeds on both aquatic and terrestrial prey. We describe size-related variation and slight sexual variation in the diet of Thamnophis eques through analysis of 262 samples of identifiable stomach contents in snakes from 23 locations on the Mexican Plateau. The Mexican Garter Snakes we studied ate prey items mostly fish, followed in lesser amounts, respectively, by leeches, earthworms, frogs, and tadpoles. Correspondence analysis suggested that the frequency of consumption of various prey items differed between the categories of age and sex of snakes, and the general pattern was a reduction of prey item diversity with size of snake. Snake length was correlated positively with mass of ingested prey. Large snakes consumed large prey and continued to consume smaller prey. In general, no differences were found between the prey taxa of male and female snakes, although males ate two times more tadpoles than females. Males and females did not differ in the mass of leeches, earthworms, fishes, frogs and tadpoles that they ate, and males and females that ate each prey taxon were similar in length. We discuss proximate and functional determinants of diet and suggest that the observed intraspecific variation in Mexican Garter Snakes could be explored by temporal variation in prey availability, proportions of snake size classes and possible sexual dimorphism in head traits and prey dimensions to assess the role of intersexual resource competition.

Response of summerform pear psylla (Hemiptera: Psyllidae) to male- and female-produced odors

2011 ◽  
Vol 143 (3) ◽  
pp. 245-253 ◽  
Author(s):  
Christelle Guédot ◽  
David R. Horton ◽  
Peter J. Landolt
Keyword(s):  
Chemical Signals ◽  
Male Attraction ◽  
Male And Female ◽  
Volatile Chemicals ◽  
Sex Attraction ◽  
Pear Psylla ◽  
Males And Females

AbstractWe examined the role of chemical signals in sex attraction of pear psylla, Cacopsylla pyricola (Förster), assessing the response of summerform male and female psyllids to male- and female-produced volatile chemicals. Male psyllids were attracted to odors from live females and pentane extracts of females. Extracts of females were as attractive to males as live females, suggesting that the female-produced volatile chemicals responsible for male attraction might be isolated by extracting females with pentane. Females were not attracted to odorants from live females and tended to avoid odorants from extracts of females. Furthermore, summerform males and females were not attracted or repelled by male-produced odorants from live males or extracts of males. Results of olfactometer assays using male summerform C. pyricola are consistent with results from earlier studies with the winterform morphotype of this species.

Nestling foods of the savannah sparrow

1984 ◽  
Vol 62 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Marie Meunier ◽  
Jean Bédard
Keyword(s):  
Breeding Season ◽  
Temporal Changes ◽  
Prey Abundance ◽  
Large Prey ◽  
Passerculus Sandwichensis ◽  
Main Prey ◽  
Savannah Sparrow ◽  
Close Relationship ◽  
Males And Females ◽  
Prey Items

The diet of savannah sparrow (Passerculus sandwichensis) nestlings was monitored at Îsle Verte, Québec, during the 1980 breeding season. Adults carried exclusively arthropods to the nest. The main prey types found were Lepidoptera and Hymenoptera larvae, larval and adult Diptera and Homoptera. The proportion of different prey types in the diet varied during the season but there was no close relationship between temporal changes in the indices of prey abundance in the habitat and the type of prey chosen by the adult birds. Both the type and size of prey brought to the nest changed with the age and number of nestlings (aged 4–10 days). The proportion of Homoptera in the diet decreased sharply with age while that of Lepidoptera and Diptera increased. Adults feeding broods of four brought a larger proportion of large prey items (Lepidoptera and Hymenoptera larvae) than those feeding broods of a lesser size; to these they brought a larger proportion of smaller items such as Diptera and adult Lepidoptera. Males and females brought the same major prey types to the nest but not in the same proportions.

You Can Tell by the Nose—Judging Sex from an Isolated Facial Feature

Perception ◽  
1995 ◽  
Vol 24 (8) ◽  
pp. 969-973 ◽  
Author(s):  
Edward P Chronicle ◽  
Mei-Yin Chan ◽  
Charlotte Hawkings ◽  
Karen Mason ◽  
Kathryn Smethurst ◽  
...  
Keyword(s):  
Analysis Of Variance ◽  
Significant Interaction ◽  
Facial Feature ◽  
Male And Female ◽  
Males And Females ◽  
Physical Variables ◽  
Female Subjects

Measurements taken from the nose are among the most important physical variables which discriminate statistically between male and female faces, yet several investigators have claimed that it is difficult to judge sex on the basis of noses presented in isolation. Previous work on the isolated nose has, however, involved the use of frontal views only, which may have obscured important physical differences between the noses of males and females. An investigation of the accuracy of judgments of the sex of isolated noses observed in frontal, profile, and three-quarter views by male and female subjects is reported. Judgment of sex was performed significantly more accurately than chance in all cases except for frontal views of female noses, where judgment was significantly less accurate than chance. Analysis of variance demonstrated a significant interaction of sex of nose and view of nose, such that male noses were identified better in frontal and in profile views, but female noses better in the three-quarter view. It is suggested that one possible reason for the seemingly contradictory role of the nose in previous studies of sex judgment is that all noses look more male in frontal views. For a nose to be perceived as female, its distinctive shape must be made available to the perceiver; this is most likely from the three-quarter view.

Trophic ecology of a benthic intertidal hydroid, Tubularia crocea, at Mar del Plata, Argentina

2005 ◽  
Vol 85 (2) ◽  
pp. 307-312 ◽  
Author(s):  
Gabriel N. Genzano
Keyword(s):  
Trophic Ecology ◽  
Feeding Rate ◽  
Prey Availability ◽  
Stomach Contents ◽  
Dry Weight ◽  
Benthic Organisms ◽  
Food Items ◽  
The Mean ◽  
The Relationship ◽  
Prey Items

The trophic ecology and seasonal changes in the diet of the intertidal hydrozoan Tubularia crocea were studied analysing the enteron contents of hydranths collected each season of the year. The relationship between feeding rate, prey availability, and re-suspension processes caused by tidal currents was also assessed. The most prevalent food items were diatoms and crustaceans. The most remarkable differences occurred during summer, when crustaceans were more abundant than diatoms. Conversely, diatoms were the most abundant prey during other seasons, and they were almost the only prey found during winter. There was no relationship between abundances of primary prey items in the water column and their occurrences in stomach contents. Instead, most prey items consisted of benthic organisms, primarily two species of diatoms (Grammatophora marina and Licmophora abreviatta) and fragments (usually appendages) of the amphipods Caprella sp. and Jassa falcata. Most food items were digested within 4–4·5 hours. The mean number of items captured per polyp per day was determined to be 115·2±19·2 in summer, 93·6±14·4 in autumn, 76·8±21·6 in winter and 199·2±31·2 in spring. Prey biomass (dry weight) polyp−1 d−1 was 5·1 μg in summer, 2·3 μg in autumn, 1·8 μg in winter, and 6·3 μg in spring. These values, in relation to hydranth biomass (55·3 μg; dry weight), were equivalent to a food intake polyp−1 d−1 of 9·3%, 4·2%, 3·2% and 11·5% of its own weight, respectively.

scholarly journals Influence of environmental colors and long-term sex isolation on zebrafish shoaling behavior

2019 ◽  
Vol 71 (2) ◽  
pp. 329-337
Author(s):  
Christian Lenzi ◽  
Chiara Grasso ◽  
Mircea Nicoara ◽  
Alexandra Savuca ◽  
Alin Ciobica ◽  
...  
Keyword(s):  
Social Interactions ◽  
Potential Influence ◽  
Male Fish ◽  
Male And Female ◽  
Shoaling Behavior ◽  
Males And Females ◽  
Complex Social Behavior ◽  
Selection Of

Zebrafish has a complex social behavior and little is known about the role of sexual preference and their environmental social interactions. In this study we investigated the potential influence of environmental colors and shoaling preferences of zebrafish male and female populations, with a focus on visual communication. Males and females were kept for 7 days in gender-isolated tanks, with a specific habitat color for each group: green for males and red for females. After the pre-test period, all the animals were kept separated and 8 noninvasive behavioral tests were conducted in a T-maze, with the application of different visual stimuli. We did not observe any clear influence of environmental coloring on social zebrafish choices. Significant sex-related differences were found in shoaling partner preference (i.e. same sex vs. other sex, one fish vs. three fish) as follows: females showed a tendency to avoid other females and spent more time with males. Male fish did not display a preference between one or three fish stimuli and they shoaled more with another male and less with a potential sexual partner. There was an obvious difference between males and females in responses and selection of shoaling partners.

Depression and Law Violation: Gendered Responses to Gendered Stresses

2005 ◽  
Vol 48 (2) ◽  
pp. 155-187 ◽  
Author(s):  
Stacy De Coster
Keyword(s):  
General Pattern ◽  
Future Research ◽  
Stress Process ◽  
Youth Survey ◽  
Differential Vulnerability ◽  
Limited Support ◽  
Different Types ◽  
Differential Exposure ◽  
Males And Females

This article unites arguments from the sociology of mental health, criminology, and the sociology of gender to explore the role of gender in the stress process. The author proposes that gender acts upon the stress process in three ways. First, males and females may report exposure to different types of stresses. Second, males and females may be vulnerable to different types of stresses. Third, males and females may respond to stress in different ways—law violation versus depression. Arguments are tested about the relative importance of differential exposure versus differential vulnerability to various stresses for understanding the gender gaps in law violation and depression using the National Youth Survey, OLS regression, and Kessler's method for decomposing differences in exposure and vulnerability to stress. The results provide limited support for these arguments, suggesting that females report more exposure than do males to some communal stresses, whereas males report more exposure than do females to the agentic stresses included in this study. Vulnerability to these stresses also varies across gender, with females generally expressing greater vulnerability to communal stresses in the form of depression and males expressing greater vulnerability to agentic stresses in the form of law violation. Some deviations from this general pattern are discussed, and recommendations for future research follow.

Parental care in the savannah sparrow

1983 ◽  
Vol 61 (12) ◽  
pp. 2836-2843 ◽  
Author(s):  
Jean Bédard ◽  
Marie Meunier
Keyword(s):  
Parental Care ◽  
Dry Weight ◽  
Food Delivery ◽  
Male And Female ◽  
Passerculus Sandwichensis ◽  
Short Period ◽  
Savannah Sparrow ◽  
Gross Energy ◽  
Males And Females ◽  
Prey Items

The apportioning of parental care by male and female during the nestling stage was studied in the savannah sparrow (Passerculus sandwichensis). Brooding by both parents amounted to 66% of the daylight period during the first 2 days after hatching and decreased to 12% toward the end of the nestling stage. Broods of two received more brooding care than broods of either three or four nestlings during the last 2 days of rearing. We monitored the identity, size, and number of all the prey items (exclusively arthropods) brought by 32 nesting pairs during 628 h of observation. These estimates were later converted to estimates of dry weight of food transported (in milligrams per nestling per hour) by using weight measurements of standard prey items. The number of food deliveries increased steadily with nestling age. Males and females contributed nearly equally in this respect, with some exceptions. Estimates of gross energy carried to the nestlings peaked markedly on days 5 and 6 and decreased afterwards. During this short period, the male contributed significantly more than the female in terms of gross food energy transported. We conclude that the birds can tune their feeding contribution to the nest in subtle ways that the monitoring of food delivery rates alone cannot adequately describe.

Impact of age and sex on response to ischemic preconditioning in the rat heart: differential role of the PI3K–AKT pathway

2013 ◽  
Vol 91 (8) ◽  
pp. 640-647 ◽  
Author(s):  
Veronika Ledvenyiova ◽  
Dezider Pancza ◽  
Jana Matejiková ◽  
Miroslav Ferko ◽  
Iveta Bernatova ◽  
...  
Keyword(s):  
Ischemic Preconditioning ◽  
Ischemia Reperfusion ◽  
Akt Pathway ◽  
Female Rat ◽  
Adult Males ◽  
Male And Female ◽  
Males And Females ◽  
The Impact ◽  
Old Females

Sex and aging represent important factors that determine morbidity and mortality due to cardiovascular diseases in the human population. This study aimed to investigate the impact of aging on the response to ischemia–reperfusion in male and female rat hearts, and to explore a potential role of the PI3K–Akt pathway in the cardioprotective effects of ischemic preconditioning (IPC) in the myocardium of younger and older adult males and females. Langendorff-perfused nonpreconditioned and preconditioned hearts of 12- and 18-week-old male and female Wistar rats were subjected to regional ischemia and reperfusion with or without prior perfusion with the PI3K inhibitor wortmannin for the evaluation of ischemia-induced arrhythmias and the size of myocardial infarction (infarct size; IS). Aging did not modify IS in both sexes; however, it markedly increased susceptibility to arrhythmias. Although IPC effectively reduced IS in males and females of both ages, only the hearts of males and 18-week-old females benefited from its antiarrhythmic effect. In the preconditioned 12-week-old females, but not the 18-week-old females, and in males of both ages, wortmannin blunted the anti-infarct effect of IPC. In conclusion, activation of the PI3K–Akt pathway plays an important role in protection against lethal injury conferred by IPC in males irrespective of age. The IS-limiting effect of IPC appears to be PI3K–Akt-dependent only in the 12-week-old females.

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