Academic literature on the topic 'Frogs defensive mechanisms'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Contents
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Frogs defensive mechanisms.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Frogs defensive mechanisms"
1
Caldwell, Janalee, Laurie Vitt, and William Cooper. "Conspicuousness and vestigial escape behaviour by two dendrobatid frogs, Dendrobates auratus and Oophaga pumilio." Behaviour 146, no. 3 (2009): 325–49. http://dx.doi.org/10.1163/156853909x410946.
Full textAbstract:
AbstractAposematic prey are thought to move slowly and openly near predators, but exhibit reduced escape behaviour. We studied conspicuousness and escape by aposematic poison frogs (Dendrobates auratus and Oophaga pumilio). In circles of leaf litter, observers detected poison frogs quickly. Flight initiation distance (FID, predator-prey distance when escape begins) increases with approach speed in non-cryptic palatable prey, but not for frogs in clearings, which permitted close approach. On trails frogs moved slowly into forest and FID in D. auratus increased with approach speed. Distance from cover and handling exposing predators to distastefulness may account for greater reliance on aposematism in clearings. We observed responses to a simulated predator (stick with painted face) in three conditions: not approached, approached, and touched. Latency to hop and time to exit circles decreased and exit from circles was directed further away from the approach path in the order not approached, approached, touched. Oophaga pumilio changed directions less when approached than not; many exhibited no escape behaviour. Aposematic dendrobatids move slowly near predators, but retain risk-assessment mechanisms due to occasional predation. Differences in escape between dendrobatids and palatable Craugastor frogs suggest that dendrobatid defensive behavior may have been molded to maximize the effectiveness of aposematism.
2
CADLE, JOHN E. "Systematics, natural history, and hemipenial morphology of Dendrophidion brunneum (Günther) (Serpentes: Colubridae), a poorly known snake from the Andes of Ecuador and Peru." Zootaxa 2433, no. 1 (April 22, 2010): 1. http://dx.doi.org/10.11646/zootaxa.2433.1.1.
Full textAbstract:
Systematic characters, distribution, natural history, and hemipenial morphology are described for Dendrophidion brunneum (Günther), a poorly known snake from Ecuador and Peru. It has 17 midbody scale rows; 145–165 ventrals; 135–158 subcaudals; a tail 38–44% of total length; a relatively uniform green to brown dorsum; and a maximum length of 1370 mm (700–800 mm SVL). The species occurs from northern Ecuador to 8° S latitude in Peru, primarily on the Pacific slopes of the Andes but with a few documented lowland localities in Peru. Dendrophidion brunneum is diurnal, terrestrial, heliophilic, and oviparous. It occurs in humid montane forests or mixed puna grassland/highland forest. Recorded prey are small terrestrial frogs but a large individual possibly consumed a lizard. Defensive mechanisms include a pseudautotomic tail and behaviors such as striking, biting, and neck inflation. The hemipenis has a short, narrow base, a greatly expanded distal region, and a simple, centrolineal sulcus spermaticus. The expanded region is ornamented with spines, distal to which two flounces completely encircle the organ and another extends partially around one side. The flounces are unusual in being thin, membranous structures and in having mineralized rods (reduced spinules) completely embedded within the membranes. The apex is nude except for a few vestigial calyces. Unusual hemipenial characters are discussed.
3
Chuang, Tsai-Fu, and Yuan-Hsiou Chang. "A New Design Concept of an Ecological Corridor for Frogs to Improve Ecological Conservation." Sustainability 13, no. 20 (October 10, 2021): 11175. http://dx.doi.org/10.3390/su132011175.
Full textAbstract:
Ecological corridors are an essential element in conserving the biodiversity and proper functioning of ecosystems. Without their connectivity, a very large number of species would not have access to all of the habitats needed for their life cycles. Although the concept of an ecological corridor has been discussed for many years, few studies on ecological corridors for frogs have been conducted. Frogs are often considered to be a keystone species. They are a good indicator of habitat health, and they are often the first to be harmed by pollution or ecosystem deterioration. However, there have been reports of frogs crossing ecological corridors and being attacked or consumed by natural enemies. It is vital to create ecological corridors for frogs that allow them to migrate quickly and safely. The purpose of this study was to propose a new ecological corridor design concept for frogs to address the limitations mentioned above. In this paper, grey system theory was employed to offer the necessary information for the frog ladder’s design. In addition, the frog’s high jump capacity and its defense mechanisms against natural enemies were used to determine the rest space and shelter.
4
Patocka, Jiri, Eugenie Nepovimova, Blanka Klimova, Qinghua Wu, and Kamil Kuca. "Antimicrobial Peptides: Amphibian Host Defense Peptides." Current Medicinal Chemistry 26, no. 32 (November 19, 2019): 5924–46. http://dx.doi.org/10.2174/0929867325666180713125314.
Full textAbstract:
Antimicrobial Peptides (AMPs) are one of the most common components of the innate immune system that protect multicellular organisms against microbial invasion. The vast majority of AMPs are isolated from the frog skin. Anuran (frogs and toads) skin contains abundant AMPs that can be developed therapeutically. Such peptides are a unique but diverse group of molecules. In general, more than 50% of the amino acid residues form the hydrophobic part of the molecule. Normally, there are no conserved structural motifs responsible for activity, although the vast majority of the AMPs are cationic due to the presence of multiple lysine residues; this cationicity has a close relationship with antibacterial activity. Notably, recent evidence suggests that synthesis of AMPs in frog skin may confer an advantage on a particular species, although they are not essential for survival. Frog skin AMPs exert potent activity against antibiotic-resistant bacteria, protozoa, yeasts, and fungi by permeating and destroying the plasma membrane and inactivating intracellular targets. Importantly, since they do not bind to a specific receptor, AMPs are less likely to induce resistance mechanisms. Currently, the best known amphibian AMPs are esculentins, brevinins, ranacyclins, ranatuerins, nigrocin-2, magainins, dermaseptins, bombinins, temporins, and japonicins-1 and -2, and palustrin-2. This review focuses on these frog skin AMPs and the mechanisms underlying their antimicrobial activity. We hope that this review will provide further information that will facilitate further study of AMPs and cast new light on novel and safer microbicides.
5
Kuffler, D. P., A. Lyfenko, L. Vyklický, and V. Vlachová. "Cellular Mechanisms of Nociception in the Frog." Journal of Neurophysiology 88, no. 4 (October 1, 2002): 1843–50. http://dx.doi.org/10.1152/jn.2002.88.4.1843.
Full textAbstract:
Cellular mechanisms underlying defense reactions induced by noxious heat and acids were studied in frogs ( Rana pipiens) by measuring whole cell membrane currents in cultured dorsal root ganglion (DRG) neurons. Seventy-eight of 82 DRG neurons exposed to 3-s ramps of increasing temperature to 48°C exhibited an inward current ( I HEAT) of 490 ± 70 pA at −70 mV. I HEAT exhibited reversal at ∼10 mV with a pronounced outward rectification, suggesting opening of nonselective cation channels. In frogs, in contrast to mammals, I HEAT was not influenced by capsaicin (5 μM), capsazepine (10 μM), or ruthenium red (10 μM). In a large proportion (∼80%) of heat-sensitive DRG neurons, acids produced a large slowly inactivating sodium carried current ( I ACID) with average pH50 5.7. I ACIDwas blocked by 1 mM amiloride (to 22%) and was absent if extracellular Na+ was substituted by Cs+. Elevating temperature to 38°C increased I ACID, whereas temperatures >40°C profoundly inhibited it (by 82 ± 2%; n = 42). The inhibition was long-lasting (>30 s) but fully reversible. Phorbol ester myristate acetate (PMA, 1 μM) and forskolin (1 μM) inhibited I ACID to 37 ± 5% ( n = 5) and 78 ± 8% ( n = 4), respectively. It is suggested that I HEAT in frog DRG neurons is carried through capsaicin-insensitive nonselective cation channels distinct from vanilloid receptor in mammals, whereas I ACID is carried through amiloride-sensitive sodium channels that are strongly inhibited by noxious heat, possibly due to activation of the intracellular messenger systems.
6
Paluh, Daniel J., Edward L. Stanley, and David C. Blackburn. "Evolution of hyperossification expands skull diversity in frogs." Proceedings of the National Academy of Sciences 117, no. 15 (March 27, 2020): 8554–62. http://dx.doi.org/10.1073/pnas.2000872117.
Full textAbstract:
Frogs (Anura) are one of the most diverse vertebrate orders, comprising more than 7,000 species with a worldwide distribution and extensive ecological diversity. In contrast to other tetrapods, frogs have a highly derived body plan and simplified skull. In many lineages of anurans, increased mineralization has led to hyperossified skulls, but the function of this trait and its relationship with other aspects of head morphology are largely unexplored. Using three-dimensional morphological data from 158 species representing all frog families, we assessed wide-scale patterns of shape variation across all major lineages, reconstructed the evolutionary history of cranial hyperossification across the anuran phylogeny, and tested for relationships between ecology, skull shape, and hyperossification. Although many frogs share a conserved skull shape, several extreme forms have repeatedly evolved that commonly are associated with hyperossification, which has evolved independently more than 25 times. Variation in cranial shape is not explained by phylogenetic relatedness but is correlated with shifts in body size and ecology. The species with highly divergent, hyperossified skulls often have a specialized diet or a unique predator defense mechanism. Thus, the evolution of hyperossification has repeatedly facilitated the expansion of the head into multiple new shapes and functions.
7
Lawrence, J. P., Bibiana Rojas, Antoine Fouquet, Johanna Mappes, Annelise Blanchette, Ralph A. Saporito, Renan Janke Bosque, Elodie A. Courtois, and Brice P. Noonan. "Weak warning signals can persist in the absence of gene flow." Proceedings of the National Academy of Sciences 116, no. 38 (September 3, 2019): 19037–45. http://dx.doi.org/10.1073/pnas.1901872116.
Full textAbstract:
Aposematic organisms couple conspicuous warning signals with a secondary defense to deter predators from attacking. Novel signals of aposematic prey are expected to be selected against due to positive frequency-dependent selection. How, then, can novel phenotypes persist after they arise, and why do so many aposematic species exhibit intrapopulation signal variability? Using a polytypic poison frog (Dendrobates tinctorius), we explored the forces of selection on variable aposematic signals using 2 phenotypically distinct (white, yellow) populations. Contrary to expectations, local phenotype was not always better protected compared to novel phenotypes in either population; in the white population, the novel phenotype evoked greater avoidance in natural predators. Despite having a lower quantity of alkaloids, the skin extracts from yellow frogs provoked higher aversive reactions by birds than white frogs in the laboratory, although both populations differed from controls. Similarly, predators learned to avoid the yellow signal faster than the white signal, and generalized their learned avoidance of yellow but not white. We propose that signals that are easily learned and broadly generalized can protect rare, novel signals, and weak warning signals (i.e., signals with poor efficacy and/or poor defense) can persist when gene flow among populations, as in this case, is limited. This provides a mechanism for the persistence of intrapopulation aposematic variation, a likely precursor to polytypism and driver of speciation.
8
Boutilier, Robert G. "Mechanisms of metabolic defense against hypoxia in hibernating frogs." Respiration Physiology 128, no. 3 (November 2001): 365–77. http://dx.doi.org/10.1016/s0034-5687(01)00312-7.
Full text
9
Alvarez-Buylla, Aurora, Cheyenne Y. Payne, Charles Vidoudez, Sunia A. Trauger, and Lauren A. O’Connell. "Molecular physiology of pumiliotoxin sequestration in a poison frog." PLOS ONE 17, no. 3 (March 11, 2022): e0264540. http://dx.doi.org/10.1371/journal.pone.0264540.
Full textAbstract:
Poison frogs bioaccumulate alkaloids for chemical defense from their arthropod diet. Although many alkaloids are accumulated without modification, some poison frog species can metabolize pumiliotoxin (PTX 251D) into the more potent allopumiliotoxin (aPTX 267A). Despite extensive research characterizing the chemical arsenal of poison frogs, the physiological mechanisms involved in the sequestration and metabolism of individual alkaloids remain unclear. We first performed a feeding experiment with the Dyeing poison frog (Dendrobates tinctorius) to ask if this species can metabolize PTX 251D into aPTX 267A and what gene expression changes are associated with PTX 251D exposure in the intestines, liver, and skin. We found that D. tinctorius can metabolize PTX 251D into aPTX 267A, and that PTX 251D exposure changed the expression level of genes involved in immune system function and small molecule metabolism and transport. To better understand the functional significance of these changes in gene expression, we then conducted a series of high-throughput screens to determine the molecular targets of PTX 251D and identify potential proteins responsible for metabolism of PTX 251D into aPTX 267A. Although screens of PTX 251D binding human voltage-gated ion channels and G-protein coupled receptors were inconclusive, we identified human CYP2D6 as a rapid metabolizer of PTX 251D in a cytochrome P450 screen. Furthermore, a CYP2D6-like gene had increased expression in the intestines of animals fed PTX, suggesting this protein may be involved in PTX metabolism. These results show that individual alkaloids can modify gene expression across tissues, including genes involved in alkaloid metabolism. More broadly, this work suggests that specific alkaloid classes in wild diets may induce physiological changes for targeted accumulation and metabolism.
10
Toledo, Luís Felipe, and Célio F. B. Haddad. "Colors and Some Morphological Traits as Defensive Mechanisms in Anurans." International Journal of Zoology 2009 (2009): 1–12. http://dx.doi.org/10.1155/2009/910892.
Full textAbstract:
Anurans may be brightly colored or completely cryptic. Generally, in the former situation, we are dealing with aposematism, and the latter is an example of camouflage. However, these are only simple views of what such colorations really mean and which defensive strategy is implied. For instance, a brightly colored frog may be part of a mimicry ring, which could be either Batesian, Müllerian, or Browerian. These are only examples of the diversity of color-usage systems as defensive strategies. Unfortunately, reports on the use of colors as defensive mechanisms are widespread in the available literature, and the possible functions are rarely mentioned. Therefore, we reviewed the literature and added new data to this subject. Then, we the use of colors (as defensive mechanism) into categories. Mimicry was divided into the subcategories camouflage, homotypy, and nondeceitful homotypy, and these groups were also subcategorized. Dissuasive coloration was divided into behavioral display of colors, polymorphism, and polyphenism. Aposematism was treated apart, but aposematic colorations may be present in other defensive strategies. Finally, we propose functions and forms of evolution for some color systems in post-metamorphic anurans and hope that this review can be the basis for future research, even on other animal groups.
Dissertations / Theses on the topic "Frogs defensive mechanisms"
1
Burkart, David. "UNDERSTANDING CHYTRIDIOMYCOSIS RESISTANCE BY INVESTIGATING THE CUTANEOUS DEFENSE MECHANISMS OF MARSUPIAL FROGS." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1835.
Full textAbstract:
Anurans are declining worldwide because of the spread of Batachochytrium dendrobatidis (Bd), the fungus that causes chytridiomycosis. However, some frogs are resistant to this disease, and understanding why may be critical to saving those that are susceptible. In Peru, Gastrotheca excubitor is resistant to chytridiomycosis while Gastrotheca nebulanastes is susceptible. Two anuran skin defenses, symbiotic bacteria and antimicrobial peptides (AMPs), have demonstrated the ability to inhibit Bd in vitro when isolated from certain frogs. We tested if these defenses can explain the difference in susceptibility between the two Gastrotheca species. The cutaneous bacteria and AMPs of both species were collected, tested for their abilities to inhibit the growth of Bd, and analyzed for their compositions. Results indicate that 34%of the strains of skin bacteria from G. excubitor were able to inhibit the growth of Bd whereas only 10% isolated from G. nebulanastes were effective. Gastrotheca excubitor also has stronger anti-Bd skin bacteria. Neither frog species has peptide mixtures capable of completely inhibiting Bd, and overall species did not differ in the anti-Bd abilities of their peptides. These results suggest that the chytridiomycosis resistance experienced by G. excubitor may be attributed to its skin bacteria.
2
Smith, Benjamin Paul Chapman. "Characterisation and function of volatile ’defensive’ secretions of two species of Australian tree-frog." Thesis, 2002. http://hdl.handle.net/2440/63559.
Full textAbstract:
This thesis demonstrates that many frog species, when stressed or challenged, produce odours that are associated with the skin gland secretions, and that the source of these odours can vary. The role of many of these odorous compounds is still unknown. However, it would appear that some odorous compounds have a defensive function and are important components of the secretions.Thesis (Ph.D.) - University of Adelaide, Dept. of Environmental Biology and Dept. of Soil and Water, 2002