scholarly journals A review of chemical defense in harlequin toads (Bufonidae; Atelopus)

2021 ◽  
Author(s):  
Kannon Pearson ◽  
Rebecca Tarvin
Keyword(s):  
Chemical Defense ◽  
Small Molecule ◽  
Chemical Defenses ◽  
Evolutionary Perspective ◽  
Unique Combination ◽  
Selective Pressures ◽  
Environmental Toxin ◽  
Biological Sources ◽  
Biochemical Research ◽  
Existing Data

Toads of the genus Atelopus are chemically defended by a unique combination of endogenously synthesized cardiotoxins (bufadienolides) and what are likely exogenously sequestered neurotoxins (guanidinium alkaloids). Investigation into Atelopus small-molecule chemical defenses has been primarily concerned with identifying and characterizing various forms of these toxins while largely overlooking their ecological roles and evolutionary implications. In addition to describing the extent of knowledge about Atelopus toxin structures, pharmacology, and biological sources, we review the detection, identification, and quantification methods used in studies of Atelopus toxins to date and conclude that many known toxin profiles are unlikely to be comprehensive because of methodological and sampling limitations. Patterns in existing data suggest that both environmental (toxin availability) and genetic (capacity to synthesize or sequester toxins) factors influence toxin profiles. From an ecological and evolutionary perspective, we summarize the possible selective pressures acting on Atelopus toxicity and toxin profiles, including predation, intraspecies communication, disease, and reproductive status. Ultimately, we intend to provide a basis for future ecological, evolutionary, and biochemical research on Atelopus.

scholarly journals Ecología y evolución de la polinización por engaño

2017 ◽  
pp. 57
Author(s):  
Reyna A. Castillo ◽  
Carlos Cordero ◽  
César A. Domínguez
Keyword(s):  
Theoretical Framework ◽  
Evolutionary Perspective ◽  
Frequency Dependent ◽  
Selective Pressures ◽  
Deceit Pollination ◽  
Different Types ◽  
Main Components

In this work we reviewed the biology of deceit pollination from an ecological and evolutionary perspective. Species pollinated by deceit are characterized because a percentage of their flowers do not produce rewards, and therefore these species get the advantages derived from pollinators without paying the costs. In this review, we first described the different types of deceit occurring in nature, as well as the selective pressures involved on its evolution. We then reviewed and discussed the theoretical framework of deceit pollination and the relevant aspects of its main components: frequency-dependent se lection, flower resemblance, and the sensorial capacities of pollinators.

The Evolution of Monogamy in Large Primates: a New Hypothesis and Some Crucial Tests

Behaviour ◽  
1990 ◽  
Vol 115 (1-2) ◽  
pp. 30-61 ◽  
Author(s):  
C.P. VAN SCHAIK ◽  
R.I.M. Dunbar
Keyword(s):  
Reproductive Output ◽  
Selective Pressures ◽  
Male Care ◽  
Feeding Area ◽  
New Hypothesis ◽  
Existing Data

AbstractMonogamy among the large primates is not accompanied by high levels of male care for infants. The selective pressures that have led to its evolution in this case are far from clear. In this paper, we evaluate and test four different hypotheses. Monogamy in these species did not evolve because males are unable to defend access to more than one female. Hence, it must be related to behavioural services provided by the male which substantially increase the female's reproductive output. Existing data argue against the suggestion that these services involve protection against predators or defence of an exclusive feeding area. We propose that the male's service consists primarily in protecting the female against infanticide by other males. Tests that would differentiate this hypothesis unequivocally from other hypotheses are suggested. To the extent that these predictions can be tested with the data currently available, the evidence supports the infanticide hypothesis. We speculate that infanticide avoidance is also responsible for the near-universal occurrence among primates of male-female bonds.

scholarly journals Morphological and biomechanical disparity of crocodile-line archosaurs following the end-Triassic extinction

2013 ◽  
Vol 280 (1770) ◽  
pp. 20131940 ◽  
Author(s):  
Thomas L. Stubbs ◽  
Stephanie E. Pierce ◽  
Emily J. Rayfield ◽  
Philip S. L. Anderson
Keyword(s):  
Late Cretaceous ◽  
Morphological Variation ◽  
Late Triassic ◽  
Complex Relationship ◽  
Ecological Diversity ◽  
Unique Combination ◽  
Morphological Disparity ◽  
Selective Pressures ◽  
Feeding Modes ◽  
Jaw Biomechanics

Mesozoic crurotarsans exhibited diverse morphologies and feeding modes, representing considerable ecological diversity, yet macroevolutionary patterns remain unexplored. Here, we use a unique combination of morphological and biomechanical disparity metrics to quantify the ecological diversity and trophic radiations of Mesozoic crurotarsans, using the mandible as a morpho-functional proxy. We recover three major trends. First, the diverse assemblage of Late Triassic crurotarsans was morphologically and biomechanically disparate, implying high levels of ecological variation; but, following the end-Triassic extinction, disparity declined. Second, the Jurassic radiation of marine thalattosuchians resulted in very low morphological disparity but moderate variation in jaw biomechanics, highlighting a hydrodynamic constraint on mandibular form. Third, during the Cretaceous terrestrial radiations of neosuchians and notosuchians, mandibular morphological variation increased considerably. By the Late Cretaceous, crocodylomorphs evolved a range of morphologies equalling Late Triassic crurotarsans. By contrast, biomechanical disparity in the Cretaceous did not increase, essentially decoupling from morphology. This enigmatic result could be attributed to biomechanical evolution in other anatomical regions (e.g. cranium, dentition or postcranium), possibly releasing the mandible from selective pressures. Overall, our analyses reveal a complex relationship between morphological and biomechanical disparity in Mesozoic crurotarsans that culminated in specialized feeding ecologies and associated lifestyles.

scholarly journals Rapid and independent evolution of ancestral and novel defenses in a genus of toxic plants (Erysimum, Brassicaceae)

2019 ◽  
Author(s):  
Tobias Züst ◽  
Susan R. Strickler ◽  
Adrian F. Powell ◽  
Makenzie E. Mabry ◽  
Hong An ◽  
...  
Keyword(s):  
Related Species ◽  
Chemical Defenses ◽  
Evolutionary Time ◽  
Closely Related Species ◽  
Selective Pressures ◽  
Toxic Plants ◽  
Trade Offs ◽  
Plant Chemical ◽  
Plant Chemical Defenses ◽  
Redundant Functions

AbstractPhytochemical diversity is thought to result from coevolutionary cycles as specialization in herbivores imposes diversifying selection on plant chemical defenses. Plants in the speciose genus Erysimum (Brassicaceae) produce both ancestral glucosinolates and evolutionarily novel cardenolides as defenses. Here we test macroevolutionary hypotheses on co-expression, co-regulation, and diversification of these potentially redundant defenses across this genus. We sequenced and assembled the genome of E. cheiranthoides and foliar transcriptomes of 47 additional Erysimum species to construct a highly resolved phylogeny, revealing that cardenolide diversity increased rapidly rather than gradually over evolutionary time. Concentrations, inducibility, and diversity of the two defenses varied independently among species, with no evidence for trade-offs. Closely related species shared similar cardenolide traits, but not glucosinolate traits, likely as a result of specific selective pressures acting on distinct molecular diversification mechanisms. Ancestral and novel chemical defenses in Erysimum thus appear to provide complementary rather than redundant functions.

scholarly journals Rapid toxin sequestration modifies poison frog physiology

2021 ◽  
pp. jeb.230342
Author(s):  
Lauren A. O'Connell ◽  
Jeremy D. O'Connell ◽  
Joao A. Paulo ◽  
Sunia A. Trauger ◽  
Steven P. Gygi ◽  
...  
Keyword(s):  
Small Molecule ◽  
Chemical Defenses ◽  
Protein Abundance ◽  
Poison Frog ◽  
Poison Frogs ◽  
Toxin Binding ◽  
Physiological Adaptations ◽  
Molecule Transport ◽  
Protein Classes ◽  
Small Molecule Transport

Poison frogs sequester chemical defenses from their diet of leaf litter arthropods for defense against predation. Little is known about the physiological adaptations that confer this unusual bioaccumulation ability. We conducted an alkaloid-feeding experiment with the Diablito poison frog (Oophaga sylvatica) to determine how quickly alkaloids are accumulated and how toxins modify frog physiology using quantitative proteomics. Diablito frogs rapidly accumulated the alkaloid decahydroquinoline within four days, and dietary alkaloid exposure altered protein abundance in the intestines, liver, and skin. Many proteins that increased in abundance with decahydroquinoline accumulation are plasma glycoproteins, including the complement system and the toxin-binding protein saxiphilin. Other protein classes that change in abundance with decahydroquinoline accumulation are membrane proteins involved in small molecule transport and metabolism. Overall, this work shows poison frogs can rapidly accumulate alkaloids, which alter carrier protein abundance, initiate an immune response, and alter small molecule transport and metabolism dynamics across tissues.

scholarly journals Chemical Defense Mechanisms and Ecological Implications of Indo-Pacific Holothurians

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4808
Author(s):  
Elham Kamyab ◽  
Sven Rohde ◽  
Matthias Y. Kellermann ◽  
Peter J. Schupp
Keyword(s):  
Chemical Defense ◽  
Defense Mechanisms ◽  
Sea Cucumber ◽  
Pathogenic Bacteria ◽  
Ecological Factors ◽  
Chemical Defenses ◽  
Sea Cucumbers ◽  
Defense Compounds ◽  
Crude Extracts ◽  
Pharmacologically Active

Sea cucumbers are slow-moving organisms that use morphological, but also a diverse combination of chemical defenses to improve their overall fitness and chances of survival. Since chemical defense compounds are also of great pharmaceutical interest, we pinpoint the importance of biological screenings that are a relatively fast, informative and inexpensive way to identify the most bioactive organisms prior to further costly and elaborate pharmacological screenings. In this study, we investigated the presence and absence of chemical defenses of 14 different sea cucumber species from three families (Holothuriidae, Stichopodidae and Synaptidae) against ecological factors such as predation and pathogenic attacks. We used the different sea cucumber crude extracts as well as purified fractions and pure saponin compounds in a portfolio of ecological activity tests including fish feeding assays, cytotoxicity tests and antimicrobial assays against environmental pathogenic and non-pathogenic bacteria. Furthermore, we quantified and correlated the concentrations of sea cucumber characteristic saponin compounds as effective chemical defensive compounds in all 14 crude extracts by using the vanillin–sulfuric acid test. The initial results revealed that among all tested sea cucumber species that were defended against at least one ecological threat (predation and/or bacterial attack), Bohadschiaargus, Stichopuscholoronotus and Holothuria fuscopunctata were the three most promising bioactive sea cucumber species. Therefore, following further fractionation and purification attempts, we also tested saponin-containing butanol fractions of the latter, as well as two purified saponin species from B. argus. We could demonstrate that both, the amount of saponin compounds and their structure likely play a significant role in the chemical defense strategy of the sea cucumbers. Our study concludes that the chemical and morphological defense mechanisms (and combinations thereof) differ among the ecological strategies of the investigated holothurian species in order to increase their general fitness and level of survival. Finally, our observations and experiments on the chemical ecology of marine organisms can not only lead to a better understanding of their ecology and environmental roles but also can help in the better selection of bioactive organisms/compounds for the discovery of novel, pharmacologically active secondary metabolites in the near future.

scholarly journals Chemotaxis and chemical defenses in seaweed susceptibility to herbivory

2000 ◽  
Vol 60 (3) ◽  
pp. 405-414 ◽  
Author(s):  
R. C. PEREIRA ◽  
R. DONATO ◽  
V. L. TEIXEIRA ◽  
D. N. CAVALCANTI
Keyword(s):  
Chemical Defense ◽  
Brown Alga ◽  
Sea Urchins ◽  
Feeding Preference ◽  
Chemical Defenses ◽  
Feeding Deterrent ◽  
Limited Mobility ◽  
Dictyota Menstrualis ◽  
Close Relationship ◽  
Herbivore Species

Recent studies have show that small marine herbivores with limited mobility (mesograzers) often feed on macroalgae chemically defended against fishes or sea-urchins. In order to verify the involved mechanisms of chemotaxis or chemical defense into this process in Brazilian littoral, two species of brown alga Dictyota menstrualis and Dictyota mertensii were studied against the limited mobility herbivores, the amphipod Parhyale hawaiensis and the crab Pachygrapsus transversus. These two species were studied in order to verify the action of their crude extracts in the defense and chemotaxis processes related to limited mobility of these herbivores. Feeding preference assays revealed that P. hawaiensis do not eaten these Dictyota species. P. transversus do not eaten D. menstrualis either, but consumed large amounts of D. mertensii. Chemical deterrence assays showed that extracts of these species act as feeding deterrent to both species of herbivores. In addition, chemotaxis assays demonstrated that both herbivores are significantly negative chemotactic probably due to the presence of complementary metabolites into artificial foods. Considering that both Dictyota species exhibit active extracts against these small herbivores, we suppose that the non-occurrence of these herbivore species in close relationship with the seaweeds D. menstrualis and D. mertensii may explain the defense action of both extracts related to these mesograzers.

scholarly journals Ancient RNA virus epidemics through the lens of recent adaptation in human genomes

2020 ◽  
Vol 375 (1812) ◽  
pp. 20190575 ◽  
Author(s):  
David Enard ◽  
Dmitri A. Petrov
Keyword(s):  
Rna Virus ◽  
Human Populations ◽  
Evolutionary Perspective ◽  
Arms Races ◽  
Selective Pressures ◽  
The Past ◽  
1000 Genomes ◽  
Human Genomes ◽  
Different Types ◽  
Health And Disease

Over the course of the last several million years of evolution, humans probably have been plagued by hundreds or perhaps thousands of epidemics. Little is known about such ancient epidemics and a deep evolutionary perspective on current pathogenic threats is lacking. The study of past epidemics has typically been limited in temporal scope to recorded history, and in physical scope to pathogens that left sufficient DNA behind, such as Yersinia pestis during the Great Plague. Host genomes, however, offer an indirect way to detect ancient epidemics beyond the current temporal and physical limits. Arms races with pathogens have shaped the genomes of the hosts by driving a large number of adaptations at many genes, and these signals can be used to detect and further characterize ancient epidemics. Here, we detect the genomic footprints left by ancient viral epidemics that took place in the past approximately 50 000 years in the 26 human populations represented in the 1000 Genomes Project. By using the enrichment in signals of adaptation at approximately 4500 host loci that interact with specific types of viruses, we provide evidence that RNA viruses have driven a particularly large number of adaptive events across diverse human populations. These results suggest that different types of viruses may have exerted different selective pressures during human evolution. Knowledge of these past selective pressures will provide a deeper evolutionary perspective on current pathogenic threats. This article is part of the theme issue ‘Insights into health and disease from ancient biomolecules’.

scholarly journals Antipredator defenses predict diversification rates

2015 ◽  
Vol 112 (44) ◽  
pp. 13597-13602 ◽  
Author(s):  
Kevin Arbuckle ◽  
Michael P. Speed
Keyword(s):  
Chemical Defense ◽  
Large Scale ◽  
Empirical Test ◽  
Chemical Defenses ◽  
Extinction Rates ◽  
Cryptic Coloration ◽  
Threatened Taxa ◽  
Speciation Rates ◽  
Adaptive Radiations ◽  
And Behavior

The “escape-and-radiate” hypothesis predicts that antipredator defenses facilitate adaptive radiations by enabling escape from constraints of predation, diversified habitat use, and subsequently speciation. Animals have evolved diverse strategies to reduce the direct costs of predation, including cryptic coloration and behavior, chemical defenses, mimicry, and advertisement of unprofitability (conspicuous warning coloration). Whereas the survival consequences of these alternative defenses for individuals are well-studied, little attention has been given to the macroevolutionary consequences of alternative forms of defense. Here we show, using amphibians as the first, to our knowledge, large-scale empirical test in animals, that there are important macroevolutionary consequences of alternative defenses. However, the escape-and-radiate hypothesis does not adequately describe them, due to its exclusive focus on speciation. We examined how rates of speciation and extinction vary across defensive traits throughout amphibians. Lineages that use chemical defenses show higher rates of speciation as predicted by escape-and-radiate but also show higher rates of extinction compared with those without chemical defense. The effect of chemical defense is a net reduction in diversification compared with lineages without chemical defense. In contrast, acquisition of conspicuous coloration (often used as warning signals or in mimicry) is associated with heightened speciation rates but unchanged extinction rates. We conclude that predictions based on the escape-and-radiate hypothesis must incorporate the effect of traits on both speciation and extinction, which is rarely considered in such studies. Our results also suggest that knowledge of defensive traits could have a bearing on the predictability of extinction, perhaps especially important in globally threatened taxa such as amphibians.

scholarly journals High evolutionary potential in the chemical defenses of an aposematic Heliconius butterfly

2020 ◽  
Author(s):  
Anniina L. K. Mattila ◽  
Chris D. Jiggins ◽  
Øystein H. Opedal ◽  
Gabriela Montejo-Kovacevich ◽  
Érika de Castro ◽  
...  
Keyword(s):  
Chemical Defense ◽  
Host Plant ◽  
Environmental Gradients ◽  
Common Garden ◽  
Color Pattern ◽  
Chemical Defenses ◽  
Color Patterns ◽  
Wild Populations ◽  
Evolutionary Potential ◽  
Chemical Defences

2.ABSTRACTChemical defences against predators underlie the evolution of aposematic coloration and mimicry, which represent classic examples of adaptive evolution. Yet, unlike color patterns, little is known about the evolutionary potential of chemical defences. Neotropical Heliconius butterflies exhibit incredibly diverse warning color patterns and widespread mimicry. Their larvae feed exclusively on cyanogenic Passiflora vines, can metabolize and sequester host plant toxins, as well as biosynthesize defensive cyanogenic toxins themselves. Here, we investigate variation in biosynthesized toxicity both in wild populations along environmental gradients and in common-garden broods and feeding treatments in Heliconius erato, together demonstrating considerable intraspecific variation and evolutionary potential in this important chemical defense trait. Toxicity varied markedly among wild populations from Central and South America. Within wild populations, the distribution of toxicity was consistently skewed, indicative of automimic “cheaters” that may exploit, and consequently deplete, the protection of the warning coloration. In a common-garden rearing design comprising more than 300 butterflies across 20 broods, variation in host-plant nutritional quality or cyanogen levels did not translate into differences in toxicity of butterflies feeding on these plants. Instead, toxicity had a significant heritable genetic component, in part explained by maternal inheritance. The evolvability of toxicity was high (eµ=1.55%), suggesting that toxicity can evolve rapidly. Through its link with the evolution of warning color pattern mimicry, the high evolutionary potential of cyanogenic toxicity may have facilitated diversification and ecological speciation in Heliconius, highlighting the importance of understanding the evolution of chemical defense in aposematic and mimetic species.

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