Anuran radiations and the evolution of tadpole morphospace

Roelants, Kim; Haas, Alexander; Bossuyt, Franky

doi:10.1073/pnas.1100633108

Cited by 74 publications

(87 citation statements)

References 60 publications

(79 reference statements)

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“…We documented patterns in the class I evolutionary trees that indicated trans-species polymorphism had occurred (some allelic lineages on the tree contained sequences from multiple species). The genus Lithobates may be as old as 36-39 million years, while the divergence between A. callidryas and E. prosoblepon dates back to 68-91 million years ago (Roelants et al, 2011). In comparison, the oldest DRB1 allelic lineages in primates are estimated to be B55 million years old (Klein et al, 1998) and allelic lineages are shared between Ruminanta genera that diverged over 30 million years ago (Ballingall et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Genetic diversity of MHC class I loci in six non-model frogs is shaped by positive selection and gene duplication

et al. 2012

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Comparative studies of major histocompatibility complex (MHC) genes across vertebrate species can reveal the evolutionary processes that shape the structure and function of immune regulatory proteins. In this study, we characterized MHC class I sequences from six frog species representing three anuran families (Hylidae, Centrolenidae and Ranidae). Using cDNA from our focal species, we amplified a total of 79 unique sequences spanning exons 2-4 that encode the extracellular domains of the functional alpha chain protein. We compared intra-and interspecific nucleotide and amino-acid divergence, tested for recombination, and identified codon sites under selection by estimating the rate of non-synonymous to synonymous substitutions with multiple codon-based maximum likelihood methods. We determined that positive (diversifying) selection was acting on specific amino-acid sites located within the domains that bind pathogen-derived peptides. We also found significant signals of recombination across the physical distance of the genes. Finally, we determined that all the six species expressed two or three putative classical class I loci, in contrast to the single locus condition of Xenopus laevis. Our results suggest that MHC evolution in anurans is a dynamic process and that variation in numbers of loci and genetic diversity can exist among taxa. Thus, the accumulation of genetic data for more species will be useful in further characterizing the relative importance of processes such as selection, recombination and gene duplication in shaping MHC loci among amphibian lineages.

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Section: Discussionmentioning

confidence: 99%

Genetic diversity of MHC class I loci in six non-model frogs is shaped by positive selection and gene duplication

et al. 2012

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“…Tadpoles of Lepidobatrachus are suctorial (O'Reilly et al 2002) and able to swallow large prey. Roelants et al (2011) found several anuran clades, whose tadpoles are classified as Orton's morphotype IV (Anomocoela, Nobleobatrachia, Natatanura, and Afrobatrachia) occupy contiguous or even overlapping regions in morphospace. Together, these clades are estimated to contain over 80% of modern anuran species, implying that the majority of extant tadpoles are concentrated in a relatively small part of morphospace.…”

Section: Heterocrhony In Ceratophryinesmentioning

confidence: 99%

“…The recent paper by Roelants et al (2011) analyzed the anuran radiations and the evolution of tadpole morphospace and found the slowdown in the morphospace expansion was caused not only by a drop in evolutionary rate after the basal anuran radiation but also by an overall increase in homoplasy in the characters that did evolve during later radiations that may have enhanced tadpole diversity by creating unique combinations of homoplastic traits, but the lack of innovative character changes prevented the exploration of fundamental regions in morphospace.…”

Section: Introductionmentioning

confidence: 98%

Heterochrony in Growth and Development in Anurans from the Chaco of South America

Fabrezi

2011

Evol Biol

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Heterochrony refers to those permutations in timing of differentiation events, and those changes in rates of growth and development through which morphological changes and novelties originate during phyletic evolution. This research analyzes morphological variation during the ontogeny of 18 different anuran species that inhabit semiarid environments of the Chaco in South America. I use field data, collection samples, and anatomical methods to compare larval growth, and sequences of ontogenetic events. Most species present a similar pattern of larval development, with a size at metamorphosis related to the duration of larval period, and disappearance and transformations of larval features that occur in a short period between forelimb emergence and tail loss. Among these 18 species, Pseudis paradoxa has giant tadpole and long larval development that are the results of deviations of rates of growth. In this species events of differentiation that usually occur at postmetamorphic stages have an offset when tail is still present. Tadpoles of Lepidobatrachus spp. reach large sizes at metamorphosis by accelerate developmental rates and exhibit an early onset of metamorphic features. The uniqueness of the ontogeny of Lepidobatrachus indicates that evolution of anuran larval development may occasionally involve mid-metamorphic morphologies conserving a free feeding tadpole and reduction of the morphological-ecological differences between tadpoles and adults.

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“…Early developmental stages of the African clawed frog [X. laevis (Daudin 1802) Pipidae] are commonly used in toxicological studies as surrogates for other aquatic organisms, including amphibians, because of their high sensitivity to pesticides and their availability for use in the laboratory (ASTM 1998;Bantle et al 1998Bantle et al , 1999OECD 2009;Wagner et al 2015). Xenopus larvae [larval type I (pipid type)] are understood as derived within anurans and the larval types IV and III as the phylogenetically basic morphotypes (Roelants et al 2011). This is in good agreement with a lot of their biological features.…”

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confidence: 99%

Acute Toxic Effects of the Herbicide Formulation Focus® Ultra on Embryos and Larvae of the Moroccan Painted Frog, Discoglossus scovazzi

Wagner

Lötters

Veith

et al. 2015

Arch Environ Contam Toxicol

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For regulatory and scientific purposes, there is a need to understand the sensitivity of a wider variety of wild species of amphibians and the sensitivities within their life stages to chemicals of widespread use such as herbicides. We investigated the acute toxic effects of the herbicide formulation Focus Ultra [with the active ingredient (a.i.) cycloxydim plus solvent naphtha and sodium dioctylsulphosuccinate as added substances] on embryos and early stage larvae of the Moroccan painted frog (Discoglossus scovazzi). Different clinical signs (twitching, convulsion, and narcosis) occurred at 40 and 80 mg/L in embryos (4 and 8 mg a.i./L) and narcotic effects (total immobilization or irregular escape responses) at 10, 15, and 20 mg/L in larvae (1, 1.5, and 2 mg a.i./L). Growth inhibition (total length), starting at 20 mg/L in embryos and 2.5 mg/L in larvae (2 and 0.25 mg a.i./L, respectively) was understood as sign of toxicity (retardation) and not as sign of teratogenicity. However, the connection to teratogenesis remained unclear though total length reduction occurred at concentrations <20 % of the 96-h LC50 value and at a minimum concentration that inhibits growth of only 17 % of the 96-h LC50 value. Starting at 20 mg/L, mortality in embryos significantly increased and at 15 mg/L in early larvae (2 and 1.5 mg a.i./L, respectively). Mortality of larvae was enhanced during the first 24 h of exposure to 15 and 20 mg/L (1.5 and 2 mg a.i./L). Morphology of the embryos remained unobtrusive. In contrary, axial malformations significantly increased in the early larvae starting at 10 mg/L (1 mg a.i./L), a concentration free of lethal effects. In all considered end points, larvae were significantly more sensitive than embryos, probably because of developmental and physiological properties or different exposure and bioavailability of the compound. Focus Ultra induced comparable lethal and immobilization effects in D. scovazzi as it does to standard test organisms in pesticide approval. However, to validate the apparent safety in the field, which is based on calculated surface water concentrations of the a.i., more data on real contamination levels is necessary (e.g., peak concentrations, concentrations of added substances). Furthermore, sufficient buffer strips between the farmland and amphibian ponds must be considered, and the effects of the substance on terrestrial life stages have not been assessed yet.

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Anuran radiations and the evolution of tadpole morphospace

Cited by 74 publications

References 60 publications

Genetic diversity of MHC class I loci in six non-model frogs is shaped by positive selection and gene duplication

Genetic diversity of MHC class I loci in six non-model frogs is shaped by positive selection and gene duplication

Heterochrony in Growth and Development in Anurans from the Chaco of South America

Acute Toxic Effects of the Herbicide Formulation Focus® Ultra on Embryos and Larvae of the Moroccan Painted Frog, Discoglossus scovazzi

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