Invasive bullfrogs as predators in a Neotropical assemblage: What frog species do they eat?

2012 ◽  
Vol 62 (4) ◽  
pp. 397-408 ◽  
Author(s):  
Ruben A. Boelter ◽  
Igor L. Kaefer ◽  
Camila Both ◽  
Sonia Cechin
Keyword(s):  
South America ◽  
Stomach Contents ◽  
Relative Importance ◽  
Feeding Preferences ◽  
Prey Category ◽  
American Bullfrog ◽  
Important Prey ◽  
Prey Composition ◽  
Frog Species

Anurans are important prey for the American bullfrog Lithobates catesbeianus, but field assessments of its diet in the context of a local prey assemblage are lacking. We aimed to identify the frog species consumed by an invasive bullfrog population in subtropical South America, and to assess their relative importance among other types of prey. Characterization of the frog assemblage in the study area also allowed us to calculate the degree of electivity of the recorded anuran prey, in order to gain insight regarding bullfrog feeding preferences and to test if the bullfrog prey composition differed from a random sample of the assemblage. A total of 32.6% of the bullfrogs had at least one anuran in the stomach contents, and post-metamorphic anurans represented 49.1% of the relative prey importance for adult bullfrogs. Anurans were preyed on by all size classes, and constituted the volumetrically most important prey category in the diet of individuals heavier than 100 g. Cycloramphidae, Hylidae and Leiuperidae were positively selected, and Hypsiboas pulchellus and Physalaemus cuvieri were the species most often taken. We found a low occurrence of cannibalism, despite the high density of bullfrogs at the study site. Our results showed that the degree of electivity differed among bullfrog prey types, suggesting that some frog species may be preyed on in a higher proportion than their relative abundance in the assemblage. Testing the clues provided by this assemblage-level approach may lead to a better assessment of the interactions between bullfrogs and the native frog fauna.

scholarly journals Identification and characterization of amphibian SLC26A5 using RNA-Seq

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhongying Wang ◽  
Qixuan Wang ◽  
Hao Wu ◽  
Zhiwu Huang
Keyword(s):  
Amino Acid ◽  
Inner Ear ◽  
Hair Cells ◽  
Rana Catesbeiana ◽  
Site Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Rna Seq ◽  
American Bullfrog ◽  
Frog Species

Abstract Background Prestin (SLC26A5) is responsible for acute sensitivity and frequency selectivity in the vertebrate auditory system. Limited knowledge of prestin is from experiments using site-directed mutagenesis or domain-swapping techniques after the amino acid residues were identified by comparing the sequence of prestin to those of its paralogs and orthologs. Frog prestin is the only representative in amphibian lineage and the studies of it were quite rare with only one species identified. Results Here we report a new coding sequence of SLC26A5 for a frog species, Rana catesbeiana (the American bullfrog). In our study, the SLC26A5 gene of Rana has been mapped, sequenced and cloned successively using RNA-Seq. We measured the nonlinear capacitance (NLC) of prestin both in the hair cells of Rana’s inner ear and HEK293T cells transfected with this new coding gene. HEK293T cells expressing Rana prestin showed electrophysiological features similar to that of hair cells from its inner ear. Comparative studies of zebrafish, chick, Rana and an ancient frog species showed that chick and zebrafish prestin lacked NLC. Ancient frog’s prestin was functionally different from Rana. Conclusions We mapped and sequenced the SLC26A5 of the Rana catesbeiana from its inner ear cDNA using RNA-Seq. The Rana SLC26A5 cDNA was 2292 bp long, encoding a polypeptide of 763 amino acid residues, with 40% identity to mammals. This new coding gene could encode a functionally active protein conferring NLC to both frog HCs and the mammalian cell line. While comparing to its orthologs, the amphibian prestin has been evolutionarily changing its function and becomes more advanced than avian and teleost prestin.

Hard prey specialists or opportunistic generalists? An examination of the diet of the cownose ray, Rhinoptera bonasus

2007 ◽  
Vol 58 (1) ◽  
pp. 135 ◽  
Author(s):  
A. B. Collins ◽  
M. R. Heupel ◽  
R. E. Hueter ◽  
P. J. Motta
Keyword(s):  
Feeding Behaviour ◽  
Stomach Contents ◽  
Relative Importance ◽  
Charlotte Harbor ◽  
Severe Damage ◽  
Important Prey ◽  
Cownose Ray ◽  
Rhinoptera Bonasus ◽  
Group Feeding ◽  
Index Of Relative Importance

Atlantic cownose rays (Rhinoptera bonasus) are benthic, suction feeders whose foraging activities have been implicated in severe damage to commercial shellfish industries. With jaws highly modified for durophagy, it has been assumed that R. bonasus are crushing specialists that feed primarily upon hard molluscan prey. Stomach contents from R. bonasus caught within Florida’s Charlotte Harbor estuary between July 2003 and July 2004 were analysed using the index of relative importance (IRI) to determine most important prey types. Prey items were identified from 38 families and fell into nine distinctive groups. The three most dominant prey groups were crustaceans (%IRI = 55.31), polychaetes (%IRI = 25.20) and bivalves (%IRI = 12.58). Shoalmates had more similar diets than non-shoalmates, suggesting group feeding. Most small or softer-bodied prey consumed were relatively intact, indicating lack of prey processing and capture through suction feeding. All larger, harder-bodied prey showed evidence of crushing (fractured and broken shells). Although R. bonasus has been characterised as a hard prey specialist, these results suggest it may behave as an opportunistic generalist, modifying feeding behaviour to consume readily available prey.

scholarly journals Feeding habits of Lithobates megapoda (Anura: Ranidae), a threatened leopard frog used for human consumption, in Lake Chapala, Mexico

2021 ◽  
Vol 20 (1) ◽  
pp. 75-88
Author(s):  
José Luis Barragán-Ramírez ◽  
Benjamín Hernández ◽  
María Guadalupe Velarde-Aguilar ◽  
Oscar Pérez-Flores ◽  
José Luis Navarrete-Heredia ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Dietary Diversity ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Prey Type ◽  
Leopard Frog ◽  
Human Consumption ◽  
Relative Importance ◽  
Prey Category ◽  
Lake Chapala

The Big-footed Leopard Frog (Lithobates megapoda) is a threatened and endemic species from western Mexico. This species has aquatic habits and it is distinguished by its large size, particularly by the length of its legs, reason for which it is captured for human consumption. Also, knowledge about its natural history is scarce and incomplete. In this study, we analyzed the composition of the diet of L. megapoda on the shore of Lake Chapala, the largest lake in Mexico. A total of 69 adult individuals were collected lifeless in fishing nets, during the rainy season (June-October), of which 48 had stomach contents. A total of 96 prey items were identified, which correspond to 13 prey categories. Fish constituted the most dominant prey category in the diet in terms of number, volume, frequency of occurrence, and relative importance. No significant differences were found in the consumption by prey type (aquatic or terrestrial). However, the aquatic preys had a greater relative importance and were more voluminous than the terrestrial ones. The diversity of prey categories, in terms of prey volume, indicates males may have a higher dietary diversity than females, but we not evaluated possible bias. In addition, a significant effect was found in the interaction of size (SVL) of frogs with the average of prey volume. Females (that are larger than males) consumed prey within a wide volume range and, the larger they are, more voluminous are prey. In this way it is possible that intraspecific competition for trophic resources in the environment is reduced. This study helps us understand the trophic ecology of L. megapoda, a frog species that plays an important role in the food web where it lives, as a predator feeding on aquatic and terrestrial organisms.

scholarly journals Diet of Chiasmocleis cordeiroi Caramaschi and Pimenta, 2003 from the Atlantic Rainforest in southern Bahia, Brazil

2020 ◽  
Vol 30 (30) ◽  
pp. 52-56
Author(s):  
Indira Maria Castro ◽  
Caio Vinícius de Mira-Mendes ◽  
Mirco Solé
Keyword(s):  
Atlantic Forest ◽  
Stomach Contents ◽  
Foraging Strategy ◽  
The State ◽  
Atlantic Rainforest ◽  
Prey Category ◽  
Taxonomic Level ◽  
Important Prey ◽  
Southern Bahia ◽  
Prey Items

We studied the diet of a Chiasmocleis cordeiroi population in a fragment of the Atlantic Forest in the state of Bahia, Brazil. Frogs were collected at night after an explosive breeding event and were transferred to the lab where they were measured, weighed and had their stomach contents retrieved following a stomach flushing protocol. Individuals were later released back into the pond from which they had been collected. Stomach contents were measured and identified to the lowest possible taxonomic level. The most important prey category in the diet of C. cordeiroi was Hymenoptera (Formicidae), as has been already observed for other microhylids. The large number of prey items in the stomach and the low niche amplitude suggest that C. cordeiroi is a specialist using an active foraging strategy to detect its prey.

Diet of common dolphins, Delphinus delphis, off the Portuguese continental coast

1999 ◽  
Vol 79 (3) ◽  
pp. 531-540 ◽  
Author(s):  
M.A. Silva
Keyword(s):  
Prey Species ◽  
Stomach Contents ◽  
Foraging Strategies ◽  
Relative Importance ◽  
Target Species ◽  
Delphinus Delphis ◽  
Important Prey ◽  
Size Groups ◽  
Distinct Features ◽  
Common Dolphins

Diet of common dolphins off the Portuguese coast was studied based on the examination of stomach contents of 50 stranded and incidentally caught animals. The relative importance of each prey species was assessed through occurrence, numerical and biomass indices. Common dolphins preyed on a large variety of items but four fish and two cephalopod species appeared to form the basis of their diet. Overall, sardine (Sardina pilchardus) was the most important prey, as given by all the indices used to measure prey relative importance. Although common dolphins preyed mostly on pelagic species, they seemed able to explore habitats with distinct features and employ various foraging strategies. A comparison between the diet of dolphins of different sex and size groups was not indicative of major differences. Common dolphins incidentally caught in fishing nets had taken a higher proportion of sardines, the target species of the fishery.

scholarly journals Prey availability influences the diet of Scinax fuscomarginatus in a Cerrado area, Central Brazil

2020 ◽  
pp. 169-175
Author(s):  
G. Michelin ◽  
K. Ceron ◽  
D. J. Santana
Keyword(s):  
Prey Availability ◽  
Stomach Contents ◽  
Selectivity Index ◽  
Generalist Predators ◽  
Mato Grosso ◽  
Central Brazil ◽  
Important Prey ◽  
Prey Composition ◽  
Generalist Diet ◽  
Mato Grosso Do Sul

Prey availability in an environment may change seasonally and these changes should be considered as determinant factors for the diets of anurans. Scinax species are generalist predators that feed on arthropods, but data concernning their diet in relation to prey availability are lacking. In this study, we describe the diet of Scinax fuscomarginatus by evaluating its possibly generalist diet related to prey availability in its environment. We studied the diet of Scinax fuscomarginatus by analysing the stomach contents of 48 individuals captured in the Campo Grande municipality, Mato Grosso do Sul state, Brazil. We found eight prey categories, the most common and most representative being Hemiptera. The selectivity index of the two most important prey varied inversely between dry and wet seasons. Prey availability also varied between seasons. These results suggest a temporal pattern in prey composition and in the diet of Scinax fuscomarginatus.

Crocodylus johnstoni in the McKinlay River Area, N.T. I. Variation in the Diet, and a New Method of Assessing the Relative Importance of Prey.

1982 ◽  
Vol 30 (6) ◽  
pp. 877 ◽  
Author(s):  
GJW Webb ◽  
SC Manolis ◽  
R Buckworth
Keyword(s):  
Stomach Contents ◽  
Target Size ◽  
Relative Importance ◽  
Wet Season ◽  
Crocodylus Johnstoni ◽  
Important Prey ◽  
Size Groups ◽  
Opportunistic Predator ◽  
Major Shift ◽  
Terrestrial Insects

The stomach contents of 153 C. johnstoni were examined by a modification of the method for stomach contents removal described by Taylor et al. (1978). Prey are analysed on the basis of taxonomy, although more emphasis is placed on prey equivalents, using a concept termed 'target size'. The relative importance of different taxa and prey equivalents is determined by a number of methods, and a ranking method is preferred. The most important prey are aquatic and terrestrial insects, fish and crustaceans. The most important sized organisms are target size 5, animals presenting a maximum area of 1.0-4.0 cm2. With regard to size of prey eaten, three size groups of C. johnstoni (16-25, 26-55 and 56-129 cm snout-vent length) were homogeneous within themselves but were significantly different from each other. With increased body size there was a significant increase in the proportion of aquatic prey eaten. Secondary ingestion did not appear a major bias. C. johnstoni ate appreciably more during the wet season than during the dry season, although seasonal comparisons were restricted due to the samples not coming from the same pools. Vegetation was found in 39.9% of crocodile stomachs, and its presence varied with season but not with crocodile size. Stomach parasites were present in 43.8% of animals, and the number of infected crocodiles varied with season and site. Stones were present in 88.2% of crocodiles; however, when compared with those of C. niloticus the stone loads were relatively small. Most data indicate that C. johnstoni is very much an opportunistic predator at the water's edge, which feeds primarily on small aquatic prey, although it may also take substantial numbers of terrestrial prey organisms. During the wet season there is a major shift in the importance of different prey taxa eaten, although the importance of prey equivalents remains largely unchanged.

scholarly journals Diet of the Bobolink (Dolichonyx oryzivorus) in rice fields on its wintering grounds in Argentina

2019 ◽  
Vol 27 (1) ◽  
pp. 10-16
Author(s):  
Rodrigo E. Lorenzón ◽  
Carolina E. Antoniazzi ◽  
Franco N. Fabre ◽  
Virginia M. Quiroga ◽  
Silvia A. Regner ◽  
...  
Keyword(s):  
Stomach Contents ◽  
Rice Fields ◽  
Cultivated Plants ◽  
Relative Importance ◽  
Santa Fe ◽  
Wintering Grounds ◽  
Dolichonyx Oryzivorus ◽  
Winter Diet ◽  
Number Of Seeds ◽  
Plant Components

AbstractWinter diet of Bobolinks (Dolichonyx oryzivorus), a bird considered a pest of rice fields, is known to consist primarily of seeds. However, it is not yet possible to establish the extent to which non-rice plants and animal components contribute to its diet. To contribute to these issues, we studied the diet of the Bobolink found in rice fields on its wintering grounds in Santa Fe, Argentina, to provide information on (i) the composition of the diet and (ii) the relative importance of plant and animal components in the diet and of the different prey categories. We captured Bobolinks with mist nets and obtained samples of stomach contents by warm water and emetic-based regurgitation to determine the composition of the diet (n = 46 samples) and the importance of the different prey (n = 25 samples), mainly during March, just prior to northbound migration. We confirmed that the Bobolink’s diet in this region during this period is predominantly herbivorous (97%) and rice-based (55%), although it also consumes a large number of seeds of non-cultivated plants that represented 42% of the diet. Invertebrates, although of less importance than plant components (3%), had been consumed by 97% of captured individuais. Our results document the importance of non-cultivated plants and animal prey in the diet of Bobolinks in addition to rice.

Summer foods of Atlantic walrus, Odobenus rosmarus rosmarus, in northern Foxe Basin, Northwest Territories

1997 ◽  
Vol 75 (7) ◽  
pp. 1166-1175 ◽  
Author(s):  
K. I. Fisher ◽  
R. E. A. Stewart
Keyword(s):  
Benthic Invertebrates ◽  
Stomach Contents ◽  
Male And Female ◽  
Foxe Basin ◽  
Important Prey ◽  
Odobenus Rosmarus ◽  
Serripes Groenlandicus ◽  
Gross Energy ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

Stomach contents of Atlantic walrus, Odobenus rosmarus rosmarus, taken by Inuit hunters in northern Foxe Basin in July 1987 and 1988 (n = 105) and September 1988 (n = 2) were examined. In July, 20 of 94 stomachs from immature and adult walrus contained > 5 g of food representing 17 prey taxa, including bivalves, gastropods, holothurians, polychaetes, and brachiopods. The bivalve Mya truncata contributed 81.4% of the total gross energy in the diet, with the bivalve Hiatella arctica, holothurians, and the polychaete Nereis sp. contributing 7.5, 3.5, and 2.8%, respectively. The diets of male and female walrus were similar except that females received a significantly (P < 0.05) greater percentage of gross energy in their diet from H. arctica than did males. Walrus less than 3 years old (n = 11) consumed mostly milk, although some benthic invertebrates were eaten. Analysis of the contents of two stomachs collected in September suggested that walrus may feed more intensively in the fall. Mya truncata was again the predominant prey, contributing 59.9% of total gross energy, with the bivalve Serripes groenlandicus (37.9%) replacing H. arctica (0.3%) as the second most important prey.

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