scholarly journals Relative feeding specialization may depress ontogenetic, seasonal, and sexual variations in diet: the endemic lizard Cnemidophorus littoralis (Teiidae)

2003 ◽  
Vol 63 (2) ◽  
pp. 321-328 ◽  
Author(s):  
P. F. Teixeira-Filho ◽  
C. F. D. Rocha ◽  
S. C. Ribas
Keyword(s):  
Sexual Dimorphism ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Analysis Of Covariance ◽  
Head Size ◽  
Head Width ◽  
Adult Males ◽  
Important Prey ◽  
Relative Contribution ◽  
Main Item

We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22º57'S, 43º50'W), Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm³), and grouped in four classes (active, sedentary, and clumped preys, and plant material). The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry). Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA). Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.

Factors driving sexual dimorphism and colour variability in the Achala Copper Lizard (Pristidactylus achalensis), an endemic species to the highland mountains in central Argentina

2020 ◽  
Vol 98 (6) ◽  
pp. 377-389
Author(s):  
S. Naretto ◽  
M. Chiaraviglio
Keyword(s):  
Sex Differences ◽  
Spatial Distribution ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Endemic Species ◽  
Morphological Changes ◽  
Head Size ◽  
Head Width ◽  
Temporal And Spatial Distribution ◽  
Central Argentina

The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whereas other traits, such as colouration, varies seasonally only in males. Our results underline the intriguing possibility of seasonal morphological changes related to mating, and more broadly that sex differences are influenced by sexual selection pressures mediated by temporal variation in mate competition.

Heads or tails? Sexual dimorphism in helodermatid lizards

2007 ◽  
Vol 85 (1) ◽  
pp. 92-98 ◽  
Author(s):  
C.M. Gienger ◽  
Daniel D. Beck
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Morphological Traits ◽  
Tail Length ◽  
Repeated Sequences ◽  
Analysis Of Covariance ◽  
Head Size ◽  
Heloderma Suspectum

We tested the hypothesis that helodermatid lizards (Gila monsters, Heloderma suspectum Cope, 1869, and beaded lizards, H. horridum (Wiegmann, 1829)) show sexual dimorphism in morphological traits related to male–male agonistic behaviors. Male–male combat in helodermatid lizards involves repeated sequences of ritualized grappling. Male Gila monsters use their heads in attempts to gain or maintain a superior position during repeated combat bouts that may last for hours. Pairs of fighting male beaded lizards form spectacular body arches, with abdomens adpressed and snouts, forelimbs, and tail tips contacting the ground. We measured body size, head size, and tail length in 208 preserved H. suspectum, and body size and tail length (but not head size) in 79 live H. horridum, then tested for sexual dimorphism using analysis of covariance. Male Gila monsters had proportionately larger heads than females but did not differ in tail length or body size. Male beaded lizards had proportionately longer tails than females and were larger in body size only when the largest individuals were included in the analysis. Differences in head dimensions (in H. suspectum) and tail length (in H. horridum) are likely the result of sexual selection acting through male–male agonistic behaviors in this unique lizard taxon.

scholarly journals Morfología de las piezas bucales y hábitos alimenticios de Leptonema y Smicridea (Trichoptera: Hydropsychidae) del río Gaira, Sierra Nevada de Santa Marta, Colombia

2017 ◽  
Vol 65 (4) ◽  
pp. 1231 ◽  
Author(s):  
Kevin Daniel Alvarez Soraca ◽  
Cesar Enrique Tamaris Turizo ◽  
Cristian José Guzmán Soto
Keyword(s):  
Sierra Nevada ◽  
Nutrient Dynamics ◽  
Dietary Habits ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Head Width ◽  
Morphometric Measurements ◽  
Monthly Basis ◽  
The Difference ◽  
Del Rio

The genera Leptonema and Smicridea belong to the family Hidropsychidae and constitute one of the most important groups in the nutrient dynamics in the tropical aquatic ecosystems, which diversity of microhabitats is exploited by their larvae. However, there is lack of information concerning the detailed and comparative descriptions of mouthparts between these two genera, and their possible relation with their diet. The aim of this paper was to describe the morphology of the mouthparts and the feeding habits of both genera, in the middle basin of the Gaira River (Sierra Nevada de Santa Marta, Colombia). The samples were collected on a monthly basis, with a surber net, between October and December of 2014, and May of 2015. A total of 15 larvae per genus were taken and the Blue Zen Software was used to determine the morphometric measurements of the cephalic pieces. Measurements were taken on photographs obtained from an AxioCam ERc5s camera adapted to a Nikon SMZ 745T stereoscope. To describe the mouthparts a M205A microscope-stereoscope Leica was used. The dietary habits of 15 individuals in total were evaluated by means of the analysis of stomach contents. A discriminant analysis of Hotelling was applied to the morphometric measurements. There were significant differences in head area (HA), head width (HW3), head length (HL2) and left mandible length (LML). In the morphological descriptions were found differences in: head, labrum and submentum. Dietaries profiles were performed to the stomach contents for both genera and the items with highest percentage for Leptonema was MOPG and MOPF with 38 % and 32 %, respectively, and for Smicridea MOPF (38 %) and MOPG (34 %) with significant differences (F = 8.8298, p < 0.05). This study indicated that the evaluated individuals consume a wide variety of resources and the difference of the diet of both genera can be related to the detected morphological differences.

scholarly journals Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

2020 ◽  
Vol 100 (2) ◽  
pp. 301-313
Author(s):  
Laura Busin Campos ◽  
Xênia Moreira Lopes ◽  
Ednilson da Silva ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Feeding Habits ◽  
Stomach Contents ◽  
Small Fish ◽  
South Eastern ◽  
Important Prey ◽  
Fishing Vessels ◽  
Eastern Brazil ◽  
Significant Difference ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

AbstractThis study evaluated the feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil. Stomach contents were collected from a total of 145 dead specimens found incidentally caught by fishing vessels or stranded between 2005 and 2015. Fish otoliths, cephalopod beaks and whole non-digested prey were used for prey species identification. A total of 9337 prey items were identified, including 26 species of teleost fishes and three species of cephalopods. The most important prey families were Sciaenidae among fish and Loliginidae among cephalopods. Franciscana dolphins tended to feed on small fish (mean = 5.25 cm) and cephalopods (mean = 8.57 cm). The index of relative importance (IRI) showed that Pellona harroweri and Doryteuthis plei were the most important prey for both males and females. The PERMANOVA test confirmed that there is no significant difference between the feeding habits of different sexes, but detected a significant difference among seasons. Overall, our results show that franciscana dolphins are predominantly ichthyophagous and non-selective in relation to the type of prey, feeding on pelagic, demersal and pelagic-demersal prey.

Feeding of tub gurnard Chelidonichthys lucerna (Scorpaeniformes: Triglidae) in the north-east Mediterranean

2011 ◽  
Vol 92 (3) ◽  
pp. 605-612 ◽  
Author(s):  
Marco Stagioni ◽  
Stefano Montanini ◽  
Maria Vallisneri
Keyword(s):  
Diet Composition ◽  
Foraging Behaviour ◽  
Adriatic Sea ◽  
Feeding Habits ◽  
Feeding Activity ◽  
Stomach Contents ◽  
East Mediterranean ◽  
North East ◽  
The North ◽  
Important Prey

The stomach contents of 1096 specimens of Chelidonichthys lucerna were examined in order to analyse their diet composition according to fish size, sex, depth and season. Sampling was carried out from May 2005 to March 2007 during several bottom trawl surveys in the Adriatic Sea (north-east Mediterranean). Feeding activity was more intense in juveniles than in adults. The most important prey was Crustacea (mainly Decapoda: Brachyura, such as Goneplax rhomboides, Liocarcinus spp., Philocheras spp.) and Teleostei (mainly European anchovy Engraulis encrasicolus and black goby Gobius niger). There was no difference between male and female diet. Feeding habits varied with size, with fish dominating the stomach contents of larger specimens. Finally, fish increased in winter and crustaceans in summer. Chelidonichthys lucerna shows a generalist and opportunistic foraging behaviour, preying mainly epibenthic and nectobenthic organisms.

Zeros as a result in diet studies, is this really bad? Rhinoptera steindachneri as a case study

2019 ◽  
Vol 99 (7) ◽  
pp. 1661-1666 ◽  
Author(s):  
N. R. Ehemann ◽  
L. A. Abitia-Cardenas ◽  
A. F. Navia ◽  
P. A. Mejía-Falla ◽  
V. H. Cruz-Escalona
Keyword(s):  
Eating Habits ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Geographic Location ◽  
La Paz ◽  
Important Species ◽  
Mexican Pacific ◽  
Important Prey ◽  
Commercially Important ◽  
Prey Handling

AbstractRhinoptera steindachneri is a commercially important, medium-sized, pelagic migratory batoid fish with benthic feeding habits. It has been considered a specialized predator that feeds on molluscs as well as benthic ophiurids and arthropods off the Mexican Pacific coast. Most biological aspects of this species in La Paz Bay are unknown, despite its being a commercially important species of conservation interest. Therefore, the aim of this study was to characterize the feeding habits of R. steindachneri based on specimens caught in artisanal fisheries. The stomach contents of 310 specimens (146 females and 164 males) were analysed, all captured from 2013 to 2015. The vacuity index was 97.1%, and the most important prey species were Mysidium spp. and Cylichna spp. Because of the high frequency of empty stomachs recorded, it was not possible to describe with precision the general diet of the species. Three hypotheses were developed to try to explain why this characteristic occurred in this species, ranging from eating habits to physiology and prey digestion and geographic location of the study. However, considering the mechanical process of prey handling of R. steindachneri, several hypotheses were formulated, with the hour of capture, chemical processes and physiology and prey digestion being the most probable to explain this high vacuity index reported in this study.

Feeding ecology of little tunny Euthynnus alletteratus in the central Mediterranean Sea

2007 ◽  
Vol 87 (4) ◽  
pp. 999-1005 ◽  
Author(s):  
Manuela Falautano ◽  
Luca Castriota ◽  
Maria Grazia Finoia ◽  
Franco Andaloro
Keyword(s):  
Mediterranean Sea ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Prey Abundance ◽  
Central Mediterranean ◽  
Size Classes ◽  
Larval Stages ◽  
Important Prey ◽  
Predator Size ◽  
Central Mediterranean Sea

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).

Feeding habits of the bullet tuna Auxis rochei in the southern Tyrrhenian Sea

2007 ◽  
Vol 87 (4) ◽  
pp. 1007-1012 ◽  
Author(s):  
E. Mostarda ◽  
D. Campo ◽  
L. Castriota ◽  
V. Esposito ◽  
M.P. Scarabello ◽  
...  
Keyword(s):  
Diet Composition ◽  
Fish Larvae ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Hierarchical Cluster ◽  
Eastern Coast ◽  
Tyrrhenian Sea ◽  
Monthly Basis ◽  
The North ◽  
Important Prey

A total of 235 bullet tunas (Auxis rochei) was caught off the north-eastern coast of Sicily between March 2003 and March 2004 for the purpose of studying their feeding habits. The fish were caught by means of an experimental surface gill-net during fishing surveys carried out on a monthly basis. The stomach contents were analysed and the prey identified, counted and weighed. The importance of the different prey types was assessed utilizing several feeding indices while possible size-related changes of the diet composition were highlighted by means of hierarchical cluster analysis, nMDS and SIMPER analysis. The results of this study showed that the bullet tuna is an epipelagic off-shore predator feeding on whatever abundant resource is available in the environment with a preference for planktonic crustaceans, small cephalopods and fish larvae. Among crustaceans, hyperiidean amphipods were the most important prey, with Anchylomera blossevillei as the dominant species, followed by the euphausiacean Stylocheiron maximum. Among cephalopods, Heteroteuthis dispar was recorded frequently while fish larvae showed high values of all indices. All prey were pelagic organisms. A size-related change in the diet composition was observed, even if it seemed related to the temporal fluctuations of the zooplanktonic assemblage in the environment. The average prey weight per stomach increased significantly in the larger predators which mostly fed on fish larvae belonging to several commercially important demersal and pelagic species.

A STUDY OF THE BLUE GROUSE (DENDRAGAPUS OBSCURUS (SAY)) ON VANCOUVER ISLAND, BRITISH COLUMBIA

1960 ◽  
Vol 38 (4) ◽  
pp. 701-713 ◽  
Author(s):  
C. David Fowle
Keyword(s):  
British Columbia ◽  
Feeding Habits ◽  
Free Water ◽  
Breeding Cycle ◽  
Adult Males ◽  
Seasonal Movements ◽  
Second Growth ◽  
Dendragapus Obscurus ◽  
In Captivity ◽  
Main Item

A study was made of the summer habitat, seasonal movements, fluctuations in populations, population density, breeding cycle, and summer feeding habits of Dendragapus obscurus fuliginosus (Ridgway). During the summer the grouse were found mainly in the early stages of the developing second-growth forests following fire or logging. The birds descended to the lowlands in late March and early April. Most of the adult males returned to the uplands by the end of July, The females and broods left the lowlands by the end of September. There is evidence of several well-marked fluctuations in the numbers of blue grouse in British Columbia since 1904. A density of about.2 adults per acre was recorded in late June and early July. Nesting took place in May and the first young appeared early in June. After the first of July it was not uncommon to see two females with their intermingled broods feeding together. The summer foods of both adults and young were almost entirely vegetable. Grit was the main item in gizzards from birds collected before the middle of July but later it was largely replaced by hard seeds. The grouse were not observed to drink free water except in captivity. There is a rough parallelism between frequency of occurrence of the main items of food in the environment and the proportion of each occurring in the diet.

scholarly journals Diet of Teius oculatus (Sauria, Teiidae) in southern Brazil (Dom Feliciano, Rio Grande do Sul)

2007 ◽  
Vol 97 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Lize Helena Cappellari ◽  
Thales de Lema ◽  
Paulo Prates Jr. ◽  
Carlos Frederico Duarte da Rocha
Keyword(s):  
Diet Composition ◽  
Stomach Contents ◽  
Prey Type ◽  
Adult Males ◽  
Rio Grande Do Sul ◽  
Importance Value Index ◽  
Importance Value ◽  
Important Prey ◽  
Adult Females ◽  
Males And Females

We analyzed stomach contents of 58 specimens of Teius oculatus (D'Orbigny & Bibron, 1837) (20 adult males, 17 adult females and 21 juveniles) captured in Dom Feliciano, RS, Brazil, to evaluate diet composition and sexual and ontogenetic variations in prey consumption. Diet was composed of 15 prey categories, all arthropods. Orthoptera was the most frequent prey type. Quantitatively, termites were the most important prey item (59.5%). There were no significant differences between the diets of adult males and females. Ontogenetic differences were found, mainly concerning volume of prey consumed. Adult lizards ingested significantly larger prey than juveniles (U = 170.00; p < 0.001). Juveniles, although having a comparatively less diverse diet (10 prey types) consumed a larger number of items (45.7% of total). Diet similarity was higher between juveniles and adult males (Ojk = 0.97) and prey diversity was higher in the diet of adult females (H' = 2.65). Based on importance value index the most important item in the diet of T. oculatus was Orthoptera. We conclude that T. oculatus in Dom Feliciano has a relatively generalized diet and it is an opportunist lizard, feeding on arthropods, mainly insects.

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