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Brooks OL, Talbott‐Swain EN, Rimmele BN, Dugas MB. Tadpole plasticity shapes the potential benefits of egg feeding to poison frog parents. Ethology 2023. [DOI: 10.1111/eth.13358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Olivia L. Brooks
- School of Biological Sciences Illinois State University Normal Illinois USA
| | | | - Brianne N. Rimmele
- School of Biological Sciences Illinois State University Normal Illinois USA
| | - Matthew B. Dugas
- School of Biological Sciences Illinois State University Normal Illinois USA
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Paitz RT, Dugas MB. Steroid levels in frog eggs: Manipulations, developmental changes, and implications for maternal steroid effects. J Exp Zool Pt A 2022; 337:293-302. [PMID: 34905660 DOI: 10.1002/jez.2566] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/21/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Exposure to maternally derived steroids during embryonic development can elicit phenotypic effects in the resulting offspring. Studies of maternal steroid effects, especially rich in mammals and birds, have offered exciting insights into the evolution of maternal effects in vertebrates. To extend this literature, we quantified levels of steroids in the eggs of four neotropical dendrobatid frogs that lay terrestrial clutches, a reproductive strategy that has evolved multiple times in amphibians. Building on our observational results, we then manipulated levels of pregnenolone and progesterone in eggs of one species and examined how this affected steroid levels during development. Eggs of all four species had detectable steroids levels, with progestogens being more abundant than androgens and glucocorticoids. Estrogens could not be detected. Immersion of frog eggs in a solution containing pregnenolone and progesterone resulted in elevated levels of both steroids early in development, but levels declined and were similar to those in unmanipulated eggs by the end of development. Treated eggs also exhibited a transient increase in levels of steroids that can be produced from pregnenolone and progesterone. Overall, our findings demonstrate that frog eggs contain steroids similar to what has been observed in other egg-laying vertebrates. During development, steroid levels are dynamic, further suggesting developing embryos regulate exposure to maternal steroids. These results set the stage for investigating the causes and consequences of maternal steroid effects in frogs.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Matthew B Dugas
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
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Dugas MB, Border SE. Effects of a novel ectoparasite on condition and mouth coloration of nestling barn swallows. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Parasites have profound and widespread implications for the ecology and evolution of hosts, and human activity has increased the frequency of interactions between hosts and parasites that have not co-evolved. For example, by building habitat attractive for nesting, humans might have facilitated range expansion by cliff swallows (Petrochelidon pyrrhonata) and barn swallows (Hirundo rustica) in North America, concurrently allowing a haematophagous ectoparasite of cliff swallows, the swallow bug (Oeciacus vicarious), to infest the nests of barn swallows. We found that in barn swallow nests infested with swallow bugs, nestlings weighed less and had lower haematocrit, and the within-brood variation in body mass and tarsus length was higher. Information about these negative effects might be available to parents via mouth coloration, a condition-dependent component of the begging signal. We found that nestlings from infested broods had lower-intensity carotenoid-based and ultraviolet mouth colours, although most elements of colour were unrelated to parasites. Host switching by the swallow bug offers excellent opportunities to understand the direct and indirect effects of a novel parasite and might also afford insights into how parasites cope with selective pressures exerted by closely related hosts with key ecological differences.
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Affiliation(s)
- Matthew B Dugas
- Department of Zoology, University of Oklahoma, Norman, OK, USA
- School of Biological Sciences, Illinois State University, Normal, IL, USA
| | - Shana E Border
- School of Biological Sciences, Illinois State University, Normal, IL, USA
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Saporito RA, Russell MW, Richards-Zawacki CL, Dugas MB. Experimental evidence for maternal provisioning of alkaloid defenses in a dendrobatid frog. Toxicon 2019; 161:40-43. [PMID: 30790578 DOI: 10.1016/j.toxicon.2019.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/23/2019] [Accepted: 02/07/2019] [Indexed: 01/19/2023]
Abstract
Dendrobatid frogs sequester alkaloid defenses from dietary arthropods. Here, we provide experimental evidence that mother strawberry poison frogs (Oophaga pumilio) provision alkaloids to tadpoles. Captive-raised females were fed the synthetic alkaloid decahydroquinoline (DHQ), which we subsequently quantified in their skin, eggs, and developing tadpoles. DHQ quantity was positively associated with tadpole mass/development, suggesting high sequestration rates by tadpoles. These data confirm that tadpoles obtain nutrition and alkaloids by feeding exclusively on maternally provisioned eggs.
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Affiliation(s)
- Ralph A Saporito
- Department of Biology, John Carroll University, 1 John Carroll Boulevard, University Heights, Ohio 44118, USA.
| | - Matthew W Russell
- Department of Biology, John Carroll University, 1 John Carroll Boulevard, University Heights, Ohio 44118, USA
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Building, New Orleans, LA 70118, USA
| | - Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Building, New Orleans, LA 70118, USA; School of Biological Sciences, Illinois State University, Normal, IL, 61790, USA
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Yang Y, Blomenkamp S, Dugas MB, Richards-Zawacki CL, Pröhl H. Mate Choice versus Mate Preference: Inferences about Color-Assortative Mating Differ between Field and Lab Assays of Poison Frog Behavior. Am Nat 2019; 193:598-607. [PMID: 30912970 DOI: 10.1086/702249] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Codivergence of mating traits and mate preferences can lead to behavioral isolation among lineages in early stages of speciation. However, mate preferences limit gene flow only when expressed as mate choice, and numerous factors might be more important than preferences in nature. In the extremely color polytypic strawberry poison frog (Oophaga pumilio), female mate preferences have codiverged with color in most allopatric populations tested. Whether these lab-assayed preferences predict mating (gene flow) in the wild remains unclear. We observed courting pairs in a natural contact zone between red and blue lineages until oviposition or courtship termination. We found color-assortative mating in a disturbed habitat with high population density but not in a secondary forest with lower density. Our results suggest color-assortative O. pumilio mate choice in the wild but also mating patterns that do not match those predicted by lab-assayed preferences.
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Yang Y, Dugas MB, Sudekum HJ, Murphy SN, Richards-Zawacki CL. Male-male aggression is unlikely to stabilize a poison frog polymorphism. J Evol Biol 2018; 31:457-468. [PMID: 29345026 DOI: 10.1111/jeb.13243] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/18/2017] [Accepted: 01/09/2018] [Indexed: 12/13/2022]
Abstract
Phenotypic polymorphism is common in animals, and the maintenance of multiple phenotypes in a population requires forces that act against homogenizing drift and selection. Male-male competition can contribute to the stability of a polymorphism when males compete primarily with males of the same phenotype. In and around a contact zone between red and blue lineages of the poison frog Oophaga pumilio, we used simulated territorial intrusions to test the nonexclusive predictions that males would direct more aggression towards males of (i) their own phenotype and/or (ii) the phenotype that is most common in their population. Males in the monomorphic red and blue populations that flank the contact zone were more aggressive towards simulated intruders that matched the local coloration. However, males in the two polymorphic populations biased aggression towards neither their own colour nor the colour most common in their population. In sympatry, the rarer colour morph gains no advantage via reduced male-male aggression from territorial males in these O. pumilio populations, and so male aggression seems unlikely to stabilize colour polymorphism on its own. More broadly, these results suggest that the potential for divergent male aggression biases to maintain phenotypic diversity depends on the mechanism(s) that generate the biases and the degree to which these mechanisms persist in sympatry.
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Affiliation(s)
- Y Yang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - M B Dugas
- Watershed Studies Institute and Department of Biological Sciences, Murray State University, Murray, KY, USA
| | - H J Sudekum
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
| | - S N Murphy
- Smithsonian Tropical Research Institute, Balboa, Ancon, República de Panamá
| | - C L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.,Smithsonian Tropical Research Institute, Balboa, Ancon, República de Panamá
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Yang Y, Richards-Zawacki CL, Devar A, Dugas MB. Poison frog color morphs express assortative mate preferences in allopatry but not sympatry. Evolution 2016; 70:2778-2788. [PMID: 27704539 DOI: 10.1111/evo.13079] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 09/12/2016] [Accepted: 09/20/2016] [Indexed: 11/29/2022]
Abstract
The concurrent divergence of mating traits and preferences is necessary for the evolution of reproductive isolation via sexual selection, and such coevolution has been demonstrated in diverse lineages. However, the extent to which assortative mate preferences are sufficient to drive reproductive isolation in nature is less clear. Natural contact zones between lineages divergent in traits and preferences provide exceptional opportunities for testing the predicted evolutionary consequences of such divergence. The strawberry poison frog (Oophaga pumilio) displays extreme color polymorphism in and around the young Bocas del Toro archipelago. In a transition zone between red and blue allopatric lineages, we asked whether female preferences diverged along with coloration, and whether any divergent preferences persist in a zone of sympatry. When choosing among red, blue and phenotypically intermediate males, females from monomorphic red and monomorphic blue populations both expressed assortative preferences. However, red, blue, and intermediate females from the contact zone all preferred red males, suggesting that divergent preferences may be insufficient to effect behavioral isolation. Our results highlight the complexity of behavioral isolation, and the need for studies that can reveal the circumstances under which divergent preferences do and do not contribute to speciation.
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Affiliation(s)
- Yusan Yang
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.,Current Address: Department of Biological Sciences, University of Pittsburgh, 2429 Fifth Ave, Pittsburgh, Pennsylvania, 15260
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.,Smithsonian Tropical Research Institute, Balboa, Ancon, Republica de Panama
| | - Anisha Devar
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118
| | - Matthew B Dugas
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, 44106
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Abstract
When an individual can selfishly cannibalize a relative or altruistically set it free, the benefits of altruism will be positively associated with the relative's fitness prospects (the benefits it receives from altruism). We tested the prediction that altruism should be preferentially directed toward high-quality relatives using larvae of the New Mexican spadefoot toad (Spea multiplicata), a species in which tadpoles plastically express omnivore and carnivore ecomorphs. In a no-choice design, we presented carnivores with sibling or nonsibling omnivores varying in developmental stage, which is positively associated with survival in this toad's ephemeral larval environment. There was a significant interaction between relatedness and developmental stage on the probability of cannibalism: carnivores were overall more likely to cannibalize less developed omnivores, but this effect was exaggerated when the potential victim was a sibling. This evidence that altruists favor relatives with high fitness prospects highlights the numerous factors shaping altruism's payoffs.
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Dugas MB. Detectability matters: conspicuous nestling mouth colours make prey transfer easier for parents in a cavity nesting bird. Biol Lett 2015; 11:rsbl.2015.0771. [PMID: 26538540 DOI: 10.1098/rsbl.2015.0771] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An often underappreciated function of signals is to notify receivers of the presence and position of senders. The colours that ornament the mouthparts of nestling birds, for example, have been hypothesized to evolve via selective pressure generated by parents' inability to efficiently detect and feed nestlings without such visually conspicuous targets. This proposed mechanism has primarily been evaluated with comparative studies and experimental tests for parental allocation bias, leaving untested the central assumption of this detectability hypothesis, that provisioning offspring is a visually challenging task for avian parents and conspicuous mouths help. To test this assumption, I manipulated the mouths of nestling house sparrows to appear minimally and maximally conspicuous, and quantified prey transfer difficulty as the total duration of a feeding event and the number of transfer attempts required. Prey transfer to inconspicuous nestlings was, as predicted, more difficult. While this suggests that detectability constraints could shape nestling mouth colour evolution, even minimally conspicuous nestlings were not prohibitively difficult for parents to feed, indicating that a more nuanced explanation for interspecific diversity in this trait is needed.
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Affiliation(s)
- Matthew B Dugas
- Department of Zoology, University of Oklahoma, Norman, OK 73019, USA Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
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Dugas MB, Wamelink CN, Killius AM, Richards-Zawacki CL. Parental care is beneficial for offspring, costly for mothers, and limited by family size in an egg-feeding frog. Behav Ecol 2015. [DOI: 10.1093/beheco/arv173] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dugas MB, Moore MP, Wamelink CN, Richards-Zawacki CL, Martin RA. An experimental test for age-related improvements in reproductive performance in a frog that cares for its young. Naturwissenschaften 2015; 102:48. [PMID: 26286323 DOI: 10.1007/s00114-015-1302-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/06/2015] [Accepted: 08/09/2015] [Indexed: 11/24/2022]
Abstract
Reproductive performance often increases with age in long-lived iteroparous organisms, a pattern that can result from within-individual increases in effort and/or competence. In free-living populations, it is typically difficult to distinguish these mechanisms or to isolate particular features of reproduction-influencing outcomes. In captive Oophaga pumilio, a frog in which mothers provide extended offspring provisioning via trophic eggs, we experimentally manipulated the age at which females started breeding and then monitored them across repeated reproductive events. This experiment allowed us to decouple age and experience and isolate maternal care as the proximate source of any differences in performance. Younger first-time mothers produced larger broods than older first-time mothers, but did not rear more offspring to independence. Across repeated reproductive events, maternal age was unassociated with any metric of performance. At later reproductive events, however, mothers produced fewer metamorphs, and a lower proportion of individuals in their broods reached independence. These patterns suggest that performance does not improve with age or breeding experience in this frog, and that eventual declines in performance are driven by reproductive activity, not age per se. Broadly, age-specific patterns of reproductive performance may depend on the proximate mechanism by which parents influence offspring fitness and how sensitive these are to effort and competence.
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Affiliation(s)
- Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA,
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Dugas MB, Halbrook SR, Killius AM, del Sol JF, Richards-Zawacki CL. Colour and Escape Behaviour in Polymorphic Populations of an Aposematic Poison Frog. Ethology 2015. [DOI: 10.1111/eth.12396] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew B. Dugas
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
| | - Susannah R. Halbrook
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
| | - Allison M. Killius
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
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Dugas MB, Richards-Zawacki CL. A captive breeding experiment reveals no evidence of reproductive isolation among lineages of a polytypic poison frog. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12571] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew B. Dugas
- Department of Ecology and Evolutionary Biology; Tulane University; 400 Lindy Boggs Building New Orleans LA 70118 USA
| | - Corinne L. Richards-Zawacki
- Department of Ecology and Evolutionary Biology; Tulane University; 400 Lindy Boggs Building New Orleans LA 70118 USA
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Dugas MB, Yeager J, Richards-Zawacki CL. Carotenoid supplementation enhances reproductive success in captive strawberry poison frogs (Oophaga pumilio). Zoo Biol 2013; 32:655-8. [PMID: 24151130 DOI: 10.1002/zoo.21102] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/12/2013] [Accepted: 09/20/2013] [Indexed: 11/10/2022]
Abstract
Amphibians are currently experiencing the most severe declines in biodiversity of any vertebrate, and their requirements for successful reproduction are poorly understood. Here, we show that supplementing the diet of prey items (fruit flies) with carotenoids has strong positive effects on the reproduction of captive strawberry poison frogs (Oophaga pumilio), substantially increasing the number of metamorphs produced by pairs. This improved reproduction most likely arose via increases in the quality of both the fertilized eggs from which tadpoles develop and trophic eggs that are fed to tadpoles by mothers. Frogs in this colony had previously been diagnosed with a Vitamin A deficiency, and this supplementation may have resolved this issue. These results support growing evidence of the importance of carotenoids in vertebrate reproduction and highlight the nuanced ways in which nutrition constrains captive populations.
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Affiliation(s)
- Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana
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