REPRODUCTIVE ISOLATION AND MIMETIC DIVERGENCE IN THE POISON FROG RANITOMEYA IMITATOR

Understanding the process of speciation requires examination of various stages of its progress. This work focuses on the early stages of population divergence, where populations of a single species may show varying levels of incipient reproductive isolation. This work focuses on a species of poison frog, Ranitomeya imitator, that has undergone population divergence in color pattern to mimic different model species. This is an example of a Müllerian mimetic radiation, which has led to the establishment of four distinct morphs of R. imitator occurring in different geographic areas. There are two main goals of this research: (1) to examine to what extent (if any), different mimetic morphs are reproductive isolated, and (2) to examine factors influencing variation in the strength of between-morph reproductive isolation. To do this, the work focuses on sampling across three mimetic transition zones. In Chapter 1, by using a combination of color pattern quantification, landscape genetics, and mate choice experiments, results show that a mimetic shift in R. imitator is likely driving incipient speciation among two of these mimetic morphs. In Chapter 2, two additional mimetic transition zones are studied. Results suggest that these mimetic morphs are strongly differentiated in aspects of the mimetic phenotype, but show little neutral genetic divergence, and random mating with respect to mimetic morph at the transition zones, suggesting that mimetic divergence has failed to generate reproductive isolation in the two transition zones studied in this chapter. It is suggested that multifarious selection on both mimetic color-pattern and body size may be responsible for explaining variation in progress toward speciation. In Chapter 3, variation in mating calls among mimetic morphs is studied. While there are shifts in certain aspects of the mating call across two mimetic transition zones, phonotaxis trials indicate that call differences among morphs may not be responsible for generating reproductive isolation. Overall, the this dissertation work supports the idea that mimicry may be driving speciation in Ranitomeya imitator, and provides a basis for future work examining ecological speciation in this system.  Ph.D

The effect of kinship on intraspecific competition in larvae of the poison frog Ameerega bassleri (Anura, Dendrobatidae)

According to inclusive fitness theory, cooperation between related individuals should ameliorate the effect of intraspecific competition. However, close relatedness is also thought to increase similarity between individuals and therefore increase the risk of exploitative competition. Studies of the effects of kinship in larval amphibians have produced mixed results concerning these two hypotheses. We examined the effect of kinship on the mean and variation of mass after 30 days of growth in groups composed of either pure siblings or a mixture of five different sibships in a species of poison frog, Ameerega bassleri. We found no significant differences between sibling and mixed treatments with respect to mass or variation in mass. Our results are consistent with other studies in larval anurans which have found no differences between sibling and mixed treatments, suggesting that the effects of kin selection and genetic similarity between competitors may in some cases cancel each other out

Amphibians in Zootaxa: 20 years documenting the global diversity of frogs, salamanders, and caecilians

Zootaxa is a mega-journal that since its inception, 20 years ago, has contributed to the documentation of the planet?s biodiversity. Its role concerning terrestrial vertebrates has been crucial especially for amphibians, which are the most threatened class of vertebrates. As current editors of the Amphibia section, we reviewed the state of knowledge of taxonomic publications on amphibians over the last two decades (from 2001 to 2020). Our review reveals that 2,533 frogs, 259 salamanders, and 55 caecilians have been named in these 20 years, mainly in the tropical regions of South America, Asia, and Africa. More than half (57%) of these species descriptions were published in only 10 journals. At least 827 species of the new amphibians (29% of the total) were described in Zootaxa. This mega-journal has served also as a place of publication for monographs and systematic reviews, in addition to short articles documenting the vocalizations of anurans and the morphology of embryos and larvae. Its efficient evaluation process, the freedom of manuscript length, including full-color figures, and free of cost for the authors, has made Zootaxa a favorite for amphibian researchers. In an era of accelerating rates of biodiversity loss, documenting, describing, naming, and proposing evolutionary scenarios for species is, more than ever, an urgent task.Fil: Rivera Correa, Mauricio. Universidad de Antioquia; ColombiaFil: Baldo, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Vera Candioti, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Goyannes Dill Orrico, Victor. Universidade Estadual de Santa Cruz; BrasilFil: Blackburn, David C.. University Of Florida. Florida Museum Of History; Estados UnidosFil: Castroviejo Fisher, Santiago. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Chan, Kin Onn. National University of Singapore; SingapurFil: Gambale, Priscilla. Universidade Federal de Goiás; BrasilFil: Gower, David J.. Natural History Museum; Reino UnidoFil: Quah, Evan S. H.. National University of Singapore; SingapurFil: Rowley, Jodi J. L.. University of New South Wales; AustraliaFil: Twomey, Evan. Goethe Universitat Frankfurt; AlemaniaFil: Vences, Miguel. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; Alemani

Current State of Conservation Knowledge on Threatened Amphibian Species in Peru

This study documents the current state of conservation knowledge on threatened amphibian species in Peru. Following the International Union for the Conservation of Nature (IUCN) classification system, we considered species in the following categories: Critically Endangered, Endangered, Vulnerable, and Near Threatened. Even though only the first three categories are regarded as threatened by IUCN, we included the fourth category to make comparisons with the list of threatened species issued by the Peruvian government. We used the Global Amphibian Assessment\u27s database and the list issued in Peru for this comparison. We conducted separate field surveys in 17 regions of Peru to evaluate the presence/absence of threatened amphibian species and species that are potentially threatened. We also used the Declining Amphibian Database-DAPTF, to compare our results with previous assessments on population declines, and the World Wildlife Fund\u27s Wildfinder database, to determine in which Neotropical ecoregion each species occurs. We compiled data on 83 species, 44 of which are recognized as threatened by the IUCN and/or the Peruvian government. The remaining 39 species should be re-assessed as they face various threats. A re-evaluation of current estimates is needed as only 8% of all species recorded in Peru are recognized as threatened by the government, whereas the global estimate of threatened species is about 32%. In addition to using IUCN criteria, this re-assessment should follow national guidelines standardized in Peru and be in accordance with the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Because the habitat of almost 40% of threatened species reported herein still remains unprotected, and data on chytridiomycosis and other threats are lacking for most taxa, it is crucial to develop strategies for habitat conservation and research on disease dynamics in natural populations

Phylogenetic relationships and systematics of the Amazonian poison frog genus Ameerega using ultraconserved genomic elements

The Amazonian poison frog genus Ameerega is one of the largest yet most understudied of the brightly colored genera in the anuran family Dendrobatidae, with 30 described species ranging throughout tropical South America. Phylogenetic analyses of Ameerega are highly discordant, lacking consistency due to variation in data types and methods, and often with limited coverage of species diversity in the genus. Here, we present a comprehensive phylogenomic reconstruction of Ameerega, utilizing state-of-the-art sequence capture techniques and phylogenetic methods. We sequenced thousands of ultraconserved elements from over 100 tissue samples, representing almost every described Ameerega species, as well as undescribed cryptic diversity. We generated topologies using maximum likelihood and coalescent methods and compared the use of maximum likelihood and Bayesian methods for estimating divergence times. Our phylogenetic inference diverged strongly from those of previous studies, and we recommend steps to bring Ameerega taxonomy in line with the new phylogeny. We place several species in a phylogeny for the first time, as well as provide evidence for six potential candidate species. We estimate that Ameerega experienced a rapid radiation approximately 7–11 million years ago and that the ancestor of all Ameerega was likely an aposematic, montane species. This study underscores the utility of phylogenomic data in improving our understanding of the phylogeny of understudied clades and making novel inferences about their evolution

Phenotypic and Genetic Divergence among Poison Frog Populations in a Mimetic Radiation

The evolution of Müllerian mimicry is, paradoxically, associated with high levels of diversity in color and pattern. In a mimetic radiation, different populations of a species evolve to resemble different models, which can lead to speciation. Yet there are circumstances under which initial selection for divergence under mimicry may be reversed. Here we provide evidence for the evolution of extensive phenotypic divergence in a mimetic radiation in Ranitomeya imitator, the mimic poison frog, in Peru. Analyses of color hue (spectral reflectance) and pattern reveal substantial divergence between morphs. However, we also report that there is a “transition-zone� with mixed phenotypes. Analyses of genetic structure using microsatellite variation reveals some differentiation between populations, but this does not strictly correspond to color pattern divergence. Analyses of gene flow between populations suggest that, while historical levels of gene flow were low, recent levels are high in some cases, including substantial gene flow between some color pattern morphs. We discuss possible explanations for these observations

High Levels of Diversity Uncovered in a Widespread Nominal Taxon: Continental Phylogeography of the Neotropical Tree Frog

Species distributed across vast continental areas and across major biomes provide unique model systems for studies of biotic diversification, yet also constitute daunting financial, logistic and political challenges for data collection across such regions. The tree frog Dendropsophus minutus (Anura: Hylidae) is a nominal species, continentally distributed in South America, that may represent a complex of multiple species, each with a more limited distribution. To understand the spatial pattern of molecular diversity throughout the range of this species complex, we obtained DNA sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and the 16S rhibosomal gene (16S) for 407 samples of D. minutus and closely related species distributed across eleven countries, effectively comprising the entire range of the group. We performed phylogenetic and spatially explicit phylogeographic analyses to assess the genetic structure of lineages and infer ancestral areas. We found 43 statistically supported, deep mitochondrial lineages, several of which may represent currently unrecognized distinct species. One major clade, containing 25 divergent lineages, includes samples from the type locality of D. minutus. We defined that clade as the D. minutus complex. The remaining lineages together with the D. minutus complex constitute the D. minutus species group. Historical analyses support an Amazonian origin for the D. minutus species group with a subsequent dispersal to eastern Brazil where the D. minutus complex originated. According to our dataset, a total of eight mtDNA lineages have ranges >100,000 km2. One of them occupies an area of almost one million km2 encompassing multiple biomes. Our results, at a spatial scale and resolution unprecedented for a Neotropical vertebrate, confirm that widespread amphibian species occur in lowland South America, yet at the same time a large proportion of cryptic diversity still remains to be discovered