Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


This content will become publicly available on December 1, 2026

Title: Poison frog chemical defences are influenced by environmental availability and dietary selectivity for ants
Abstract The ability to use small molecule alkaloids as defensive chemicals, often acquired via trophic interactions, has evolved in many organisms. Animals with diet‐derived defences must balance food choices to maintain their defence reservoirs along with other physiological needs. Poison frogs accumulate skin alkaloids from their arthropod diet, but whether they show selectivity for specific prey remains unexplored.We investigated the role of leaf litter prey availability and dietary selectivity in shaping poison frog chemical defences along a geographic gradient. Specifically, we examined skin alkaloid composition, stomach contents and leaf litter ants in aposematic diablito frogs (Oophaga sylvatica) at five sites in north‐western Ecuador and in sympatric, cryptic Chimbo rocket frogs (Hyloxalus infraguttatus) at one site.Our results show that differential availability of leaf litter ants influenced alkaloid profiles across diablito populations, and low levels of alkaloids were observed in the sympatric, ‘undefended’ Chimbo rocket frog. Ants were the primary dietary component of the defended species, while the ‘undefended’ species ate other prey categories including beetles and larvae in addition to ants.A prey selection analysis suggested that defended and ‘undefended' frogs both feed on a high proportion of specific small ant genera that naturally contain alkaloids, suggesting that selectivity for toxic prey is not restricted to classically aposematic and highly toxic species.These findings suggest that poison frogs’ use of feeding resources relative to availability may be an understudied and important selection factor in the evolution of acquired defences.  more » « less
Award ID(s):
2337580
PAR ID:
10671854
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley
Date Published:
Journal Name:
Journal of Animal Ecology
Volume:
94
Issue:
12
ISSN:
0021-8790
Page Range / eLocation ID:
2476 to 2490
Subject(s) / Keyword(s):
alkaloids, Dendrobatidae, diet, prey availability
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, PLOS ONE)
    Haque, Mainul (Ed.)
    The ability to acquire chemical defenses through the diet has evolved across several major taxa. Chemically defended organisms may need to balance chemical defense acquisition and nutritional quality of prey items. However, these dietary preferences and potential trade-offs are rarely considered in the framework of diet-derived defenses. Poison frogs (Family Dendrobatidae) acquire defensive alkaloids from their arthropod diet of ants and mites, although their dietary preferences have never been investigated. We conducted prey preference assays with the Dyeing Poison frog ( Dendrobates tinctorius ) to test the hypothesis that alkaloid load and prey traits influence frog dietary preferences. We tested size preferences (big versus small) within each of four prey groups (ants, beetles, flies, and fly larvae) and found that frogs preferred interacting with smaller prey items of the fly and beetle groups. Frog taxonomic prey preferences were also tested as we experimentally increased their chemical defense load by feeding frogs decahydroquinoline, an alkaloid compound similar to those naturally found in their diet. Contrary to our expectations, overall preferences did not change during alkaloid consumption, as frogs across groups preferred fly larvae over other prey. Finally, we assessed the protein and lipid content of prey items and found that small ants have the highest lipid content while large fly larvae have the highest protein content. Our results suggest that consideration of toxicity and prey nutritional value are important factors in understanding the evolution of acquired chemical defenses and niche partitioning. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, bioRxiv)
    Abstract Diverse organisms use toxins as antipredator defenses. Although many taxa synthesize their toxins, dietary toxin acquisition is less documented, particularly in vertebrates. In poison frogs (Dendrobatidae), efficient sequestration of dietary alkaloids evolved at least three times from ancestors that bore at most trace concentrations of skin alkaloids. Yet molecular mechanisms underlying poison-frog sequestration remain poorly understood. We used two approaches to address this. First, we performed a broad phylogenetic analysis of the serpinA gene family, which includesserpina1-like/alkaloid-binding globulin (ABG), the putative dendrobatid alkaloid transporter, and biliverdin-binding serpins (BBSs), which bind and spectrally tune biliverdin in blue-green arboreal frogs. Second, we used an evolutionarily narrower but discovery-oriented liver gene-expression analysis, contrasting seven populations from two sequesteringEpipedobatesspecies, the most recent origin of sequestration among dendrobatids (<15 mya), with two trace-accumulating lineages,SilverstoneiaandHyloxalus. Phylogenetic analyses revealed extensive diversification of ABGs and BBS-like genes in Dendrobatidae, forming two and five major clades, respectively. These expansions reveal broader ligand-binding serpin diversity than previously recognized and indicate that alkaloid sequestration may involve multiple ABG paralogs. Gene-expression analyses revealed 23 candidate genes associated with small-molecule transport, xenobiotic metabolism, and immune response, includingserpina1-like, which was overexpressed inEpipedobates. A co-expression network analysis independently placed 20 of the 23 candidates into four key modules (enriched for differentially-expressed genes, containing ≥1 candidate, and correlated with sequestration). Our findings point to ligand-binding-protein diversification and coordinated gene-expression changes as major contributors to the evolution of alkaloid defenses in poison frogs. 
    more » « less
  3. ; ; ; ; ; ; ; (, New Phytologist)
    Summary Plant‐specialized metabolism is complex, with frequent examples of highly branched biosynthetic pathways, and shared chemical intermediates. As such, many plant‐specialized metabolic networks are poorly characterized.TheN‐methyl Δ1‐pyrrolinium cation is a simple pyrrolidine alkaloid and precursor of pharmacologically important tropane alkaloids. Silencing of pyrrolidine ketide synthase (AbPyKS) in the roots ofAtropa belladonna(Deadly Nightshade) reduces tropane alkaloid abundance and causes highN‐methyl Δ1‐pyrrolinium cation accumulation. The consequences of this metabolic shift on alkaloid metabolism are unknown. In this study, we utilized discovery metabolomics coupled withAbPyKSsilencing to reveal major changes in the root alkaloid metabolome ofA. belladonna.We discovered and annotated almost 40 pyrrolidine alkaloids that increase whenAbPyKSactivity is reduced. Suppression of phenyllactate biosynthesis, combined with metabolic engineeringin planta, and chemical synthesis indicates several of these pyrrolidines share a core structure formed through the nonenzymatic Mannich‐like decarboxylative condensation of theN‐methyl Δ1‐pyrrolinium cation with 2‐O‐malonylphenyllactate. Decoration of this core scaffold through hydroxylation and glycosylation leads to mono‐ and dipyrrolidine alkaloid diversity.This study reveals the previously unknown complexity of theA. belladonnaroot metabolome and creates a foundation for future investigation into the biosynthesis, function, and potential utility of these novel alkaloids. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Animal Ecology)
    Abstract Growing evidence suggests that organisms with narrow niche requirements are particularly disadvantaged in small habitat patches, typical of fragmented landscapes. However, the mechanisms behind this relationship remain unclear. Dietary specialists may be particularly constrained by the availability of their food resources as habitat area shrinks. For herbivorous insects, host plants may be filtered out of small habitat fragments by neutral sampling processes and deterministic plant community shifts due to altered microclimates, edge effects and browsing by ungulates.We examined the relationship between forest fragment area and the abundance of dietary‐specialist and dietary‐generalist larval Lepidoptera (caterpillars) and their host plants in the northeastern USA. We surveyed caterpillars and their host plants over 3 years in equal‐sized plots within 32 forest fragments varying in area between 3 and 1014 ha. We tested whether the abundances and species richness of dietary specialists increased more than those of dietary generalists with increasing fragment area and, if so, whether the difference could be explained by reduced host plant availability or increased browsing by white‐tailed deer (Odocoileus virginianus).The overall abundance of dietary specialists was positively related to fragment area; the relationship was substantially weaker for dietary generalists. There was notable variation among species within diet breadth groups, however. There was no effect of fragment area on the diversity of dietary‐specialist or dietary‐generalist caterpillars. Deer activity was not related to the abundances of either dietary‐generalist or dietary‐specialist caterpillars.Plant community composition was strongly associated with fragment area. Larger fragments were more likely to include host plants for both dietary‐specialist and dietary‐generalist caterpillars. Deer activity was correlated with decreased host plant availability for both groups, with a slightly stronger impact on host plants of dietary specialists. Although dietary specialists were more likely to lack host plants in fragments, the relationship between fragment area and host availability did not depend on caterpillar diet breadth.This study provides further evidence that decreasing patch area disproportionately impacts specialist consumers. Because this relationship was derived from equal‐sized plots, it is robust to some criticisms levelled at fragmentation research. The mechanisms for specialist consumer declines, however, remain elusive. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Ecology)
    Abstract Litter decomposition is a key ecological process that determines carbon (C) and nutrient cycling in terrestrial ecosystems. The initial concentrations of C and nutrients in litter play a critical role in this process, yet the global patterns of litter initial concentrations of C, nitrogen (N) and phosphorus (P) are poorly understood.We employed machine learning with a global database to quantitatively assess the global patterns and drivers of leaf litter initial C, N and P concentrations, as well as their returning amounts (i.e. amounts returned to soils).The medians of litter C, N and P concentrations were 46.7, 1.1, and 0.1%, respectively, and the medians of litter C, N and P returning amounts were 1.436, 0.038 and 0.004 Mg ha−1 year−1, respectively. Soil and climate emerged as the key predictors of leaf litter C, N and P concentrations. Predicted global maps showed that leaf litter N and P concentrations decreased with latitude, while C concentration exhibited an opposite pattern. Additionally, the returning amounts of leaf litter C, N and P all declined from the equator to the poles in both hemispheres.Synthesis: Our results provide a quantitative assessment of the global concentrations and returning amounts of leaf litter C, N and P, which showed new light on the role of leaf litter in global C and nutrients cycling. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email