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•A new molecular phylogeny for species in the genus Thoropa is presented.•Thoropa species show deep divergences, beginning in the Oligocene and continuing until the Pleistocene.•The ...phylogeny for this genus shows 12 deeply divergent lineages across the four species analyzed.•The species Thoropa miliaris was paraphyletic with respect to Thoropa taophora.•A single sample of Thoropa lutzi included in the study calls into question the monophyly of the genus Thoropa.
The Brazilian Atlantic coastal forest is one of the most heterogeneous morphoclimatic domains on earth and is thus an excellent region in which to examine the role that habitat heterogeneity plays in shaping diversification of lineages and species. Here we present a molecular phylogeny of the rock frogs of the genus Thoropa Cope, 1865, native to the Atlantic forest and extending to adjacent campo rupestre of Brazil. The goal of this study is to reconstruct the evolutionary history of the genus using multilocus molecular phylogenetic analyses. Our topology reveals 12 highly supported lineages among the four nominal species included in the study. Species T. saxatilis and T. megatympanum are monophyletic. Thoropa taophora is also monophyletic, but nested within T. miliaris. Populations of T. miliaris cluster in five geographically distinct lineages, with low support for relationships among them. Although all 12 lineages are geographically structured, some T. miliaris lineages have syntopic distributions with others, likely reflecting a secondary contact zone between divergent lineages. We discuss a biogeographic scenario that best explains the order of divergence and the distribution of species in Atlantic forest and adjacent areas, and outline the implications of our findings for the taxonomy of Thoropa.
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•Thoropa miliaris is monophyletic and the sister taxon to T. taophora.•Thoropa miliaris harbors at least seven evolutionarily independent lineages.•Four of the seven lineages of ...Thoropa miliaris show some genetic admixture.•The eight lineages of Thoropa miliaris + T. taophora complex have little ongoing gene flow in sympatry.•Divergences occurred mostly in Pliocene-Pleistocene.
Species delimitation can be challenging and affected by subjectivity. Sibling lineages that occur in sympatry constitute good candidates for species delimitation regardless of the adopted species concept. The Thoropa miliaris + T. taophora species complex exhibits high genetic diversity distributed in several lineages that occur sympatrically in the southeastern Atlantic Forest of Brazil. We used 414 loci obtained by anchored hybrid enrichment to characterize genetic variation in the Thoropa miliaris species group (T. saxatilis, T megatympanum, T. miliaris, and T. taophora), combining assignment analyses with traditional and coalescent phylogeny reconstruction. We also investigated evolutionary independence in co-occurring lineages by estimating gene flow, and validated lineages under the multispecies coalescent. We recovered most previously described lineages as unique populations in assignment analyses; exceptions include two lineages within T. miliaris that are further substructured, and the merging of all T. taophora lineages. We found very low probabilities of gene flow between sympatric lineages, suggesting independent evolution. Species tree inferences and species delimitation yielded resolved relationships and indicate that all lineages constitute putative species that diverged during the Pliocene and Pleistocene, later than previously estimated.
Two of the most fundamental questions in tadpole biology, also applicable to most small, under‐studied organisms are: (1) ‘Why are they built the way they are?’ and (2) ‘Why do they live where they ...do?’ Regrettably, despite significant progress in most aspects of tadpole biology, the answers to these questions are not much better now than they were in the last century. We propose that an autecological approach, that is the careful observation of individuals and how they interact with the environment, is a potential path towards a fuller understanding of tadpole ecomorphology and evolution. We also discuss why more attention should be given to studying atypical tadpoles from atypical environments, such as torrential streams, water‐filled cavities of terrestrial plants and wet rock surfaces neighbouring streams. Granted, tadpoles are rare in these settings, but in those unusual habitats the physical environments can be well described and characterized. In contrast, the more common ponds where tadpoles are found are typically too structurally complex to be easily delineated. This makes it difficult to know exactly what individual tadpoles are doing and what environmental parameters they are responding to. Our overall thesis is that to understand tadpoles we must see exactly what they are doing, where they are doing it, and how they are doing it. This takes work, but we suggest it is feasible and could greatly advance our understanding of how anuran larvae have evolved. The same strategies for studying tadpoles that we encourage here can be applied to the study of many other small and fast‐moving animals.
中文摘要
为什么蝌蚪拥有自己独特的形态以及它们怎样适应不同的生境，是蝌蚪生物学的两个基本问题。尽管我们对蝌蚪的研究在过去几十年中获得了长足进步，但对这些问题仍需更加深入的理解。在此文中，我们建议基于个体生态学，对蝌蚪个体以及它们与环境的相互关系进行仔细观察和记录，从而全面地理解蝌蚪中不同生态型的演化。我们特别讨论了适应于非典型生境(例如，湍急的溪流、陆生植物的积水和溪流附近的潮湿表面)的蝌蚪，以及研究它们形态及功能特化的重要意义。基于对自然状态下的蝌蚪的观察和研究，可以有效推进我们对无尾类幼体多样性及演化的理解；类似策略也适用于对其他小型动物的研究。
Resumen
Dos de las preguntas más fundamentales en biología de renacuajos, también aplicables a la mayoría de los organismos pequeños y poco estudiados son: (1) ‘¿Por qué son construidos cómo son?’ y (2) ‘¿Por qué viven dónde viven?’ Lamentablemente, pese al significativo progreso en la mayoría de los aspectos de la biología de los renacuajos, las respuestas a esas preguntas no son mucho mejores ahora que en el siglo passado. Nosotros proponemos que un enfoque autoecológico, que es la observación cuidadosa de individuos y cómo ellos interactuam con el ambiente, es um camino potencial en la dirección de un entendimiento más completo de la ecomorfología y la evolución de los renacuajos. También discutimos por qué se debe prestar más atención al estudio de los renacuajos atípicos de ambientes atípicos, como los arroyos torrenciales, las cavidades de plantas terrestres llenas de água y las superficies rocosas húmedas cercanas a arroyos.Es cierto, renacuajos son raros en estas conformaciones, pero en esos hábitats inusuales el ambiente físico puede ser bien descrito y caracterizado. Al contrario, los estanques más comunes de encontrar renacuajos son tipicamente muy complejos estructuralmente para seren facilmente delineados. Eso dificulta saber exactamente qué los renacuajos individuales están haciendo y qué parâmetros ambientales ellos están respondiendo. Nuestra tesis general es que para comprender los renacuajos necesitamos ver exactamente lo que ellos están haciendo, dónde lo están haciendo, y cómo lo están haciendo. Eso requiere trabajo, pero sugerimos que es factible y puede mejorar nuestro entendimiento de cómo las larvas de anuros evolucionaron. Las mismas estratégias para estudiar renacuajos que estamos alentando aquí pueden ser aplicadas al estudio de muchos otros animales pequeños y rápidos.
The evolutionary success of anurans can be partially explained by the occurrence of free‐living larvae. Tadpoles occupy several distict habitats, including the terrestrial environment. ...Semiterrestriality appears to have evolved seven times in anurans, and tadpoles of distantly related lineages have converged in a set of phenotypic characters, such as a depressed body, ventral mouth, massive, well‐keratinized and laterally compressed jaw sheaths, low fins, and well‐developed hind limbs. The semiterrestrial tadpoles of the South American family Cycloramphidae remain poorly studied. In this work, we perform a comparative analysis of the external and internal morphology of these larvae, we comment on the systematic and evolutionary implications for the family, and finally, we discuss the convergent evolution of semiterrestrial tadpoles in anurans. We studied the external, buccopharyngeal, and musculoskeletal morphology of semiterrestrial tadpoles of 14 species of Cycloramphidae. These tadpoles are highly modified and present several character‐states associated with semiterrestrial life. Most of them are unique and restricted to the family, such as the novel configuration of the muscles subarcualis rectus I, rectus abdominis, and levator arcuum branchialium III. We propose 13 new synapomorphies for Cycloramphidae and one for Thoropa. The presence of similar, homoplastic, character‐states in all semiterrestrial tadpoles of unrelated phylogenetic lineages seems to suggest that these character‐states are adaptations for semiterrestriality.
Resumo
O sucesso evolutivo dos anuros pode ser parcialmente explicado pela ocorrência de larvas de vida livre. Os girinos ocupam vários habitats distintos, incluindo o ambiente terrestre. A semiterrestrialidade parece ter evoluído sete vezes em anuros, e girinos de linhagens distantemente relacionadas apresentam uma série de caracteres fenotípicos convergentes, como corpo deprimido, boca ventral, lâminas mandibulares maciças, fortemente queratinizadas e comprimidas lateralmente, nadadeiras baixas e membros posteriores desenvolvidos. Entretanto, os girinos semiterrestres da família sul‐americana Cycloramphidae permanecem pouco estudados. Neste estudo, fazemos uma análise comparativa da morfologia externa e interna dessas larvas, comentamos as implicações sistemáticas e evolutivas para a família e, por fim, discutimos a evolução convergente de girinos semiterrestres em anuros. Estudamos a morfologia externa, bucofaríngea e musculoesquelética de girinos semiterrestres de 14 espécies de Cycloramphidae. Esses girinos são altamente modificados e apresentam vários estados de caráter associados à vida semiterrestre. A maioria deles são estados únicos e restritos à família, como a nova configuração dos músculos subarcualis rectus I, rectus abdominis e levato arcuum branchialium III. Propomos 13 novas sinapomorfias para Cycloramphidae e uma para Thoropa. A presença de estados de caráter homoplásticos semelhantes em todos os girinos semiterrestres de linhagens filogenéticas não relacionadas parece sugerir que esses estados de caráter são adaptações para a semiterrestrialidade.
Semiterrestriality in tadpoles is rare, having evolved only seven times across Anura. We studied the semiterrestrial tadpoles of Cycloramphidae. After a detailed examination of their external morphology, buccopharyngeal cavity, chondrocranium, musculature, and viscera, we studied the evolution of larval characters in this family. We identified 13 novel synapomorphies for Cycloramphidae, including several unique, previously unknown character‐states, and one for the genus Thoropa. Additionally, we assessed the functional significance of these characters and their convergent evolution in the semiterrestrial tadpoles.
Amphibian parasites of the Order Dermocystida (Ichthyosporea) are widespread pathogens known mainly from Europe and North America, which cause primarily a disease of skin and subcutaneous tissue in ...their hosts. The taxonomy of these organisms has been problematic given their conserved morphology, similar clinical disease and pathology. Currently recognized taxa belong to the three closely related genera, Amphibiocystidium, Amphibiothecum, and Rhinosporidium, whereas species of Dermocystidium and Sphaerothecum destruens include fish parasites. Here, we review the taxonomy of Dermocystida based on a molecular phylogenetic analysis, principally of amphibian parasites, including DNA sequences obtained from amphibian hosts collected in the central-eastern region of South America. A new taxonomic arrangement is proposed, which includes the designation of type material for Dermocystidium pusula, synonymization of Amphibiothecum with Dermocystidium, and the restriction of Amphibiocystidium to its type species A. ranae. We also review the taxonomic status of Dermosporidium hylarum until the present work included in the synonymy of the human and animal pathogen R. seeberi, and considered herein as a valid taxon, however. In addition, a new species of Sphaerothecum parasitic to amphibians is described, being the first record of this genus in the southern hemisphere and in an amphibian host.
Abstract
Semiterrestrial tadpoles live on wet rock surfaces and have evolved independently in at least seven anuran families. They have a flat venter, laterally compressed keratinized jaws and ...elongated, largely finless tails. When threatened, they can jump. Here, we describe the kinematics of locomotion for semiterrestrial tadpoles of the genera Cycloramphus and Thoropa (Cycloramphidae). Forward locomotion can be accomplished solely by the upper jaw cyclically engaging and disengaging from the substrate. Undulating tail movements, in contrast, cause the tadpoles to move laterally, like sidewinding snakes, rather than forwards. Jumping is an explosive escape behaviour with an unpredictable trajectory. Jumping requires rapid elevation of the head and extension of the torso and tail. This is made possible by epaxial musculature that extends onto the cranium and movement of the tail in the sagittal plane. Tadpoles near metamorphosis extend their hindlimbs symmetrically when jumping, even when the limbs are too small to provide thrust. The rapid rostral elevation of the snout, extension of the trunk and symmetrical extension of the hindlimbs is a kinematic pattern shared with post-metamorphic frogs when they jump. This suggests that semiterrestrial tadpoles use essentially the same neural programme as that used by frogs to jump.
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