Dispersal is an important factor in animal ecology. Anurans (frogs and toads) are often philopatric (home loving) but some specimens in a population usually have the capacity to disperse relatively long distances. In this study I investigated the colonization of newly constructed ponds in the southwest of Sweden by three anuran species: The common toad (Bufo bufo), the moor frog (Rana arvalis) and the common frog (Rana temporaria). The ponds were constructed between two and five years ago and were now as frequently occupied as older source ponds in the area. For the common toad and the common frog there was no correlation between distance to source populations and degree of colonization. The moor frog was more common in ponds that were situated in the vicinity of older source ponds with ample populations. The main impression was that these species rapidly colonize newly constructed ponds, at least within moderate distances from source populations. There were some differences between the species though and it seems like the moor frog have more limited dispersal abilities than the other two species.

Detta arbete syftar till att svara på hypotesen som säger att det är skillnader i tillväxt, storlek, dödlighet och deformationer hos besläktade yngel av grönfläckig padda (Bufo viridis) gentemot obesläktade yngel vid uppfödning. Tidigare australiensisk studie visar att kemiska ämnen som paddorna själva utsöndrar påverkar tillväxt och överlevnad. Det förekommer även att syskon favoriserar och känner igen varandra och således blir konkurrensen syskon emellan inte lika stark. Yngel från fem olika honor delades in i grupper och placerats i akvarietankar med antingen besläktade individer från en och samma hona eller blandade. Där har de vuxit upp från ägg till yngel. De yngel som föddes upp tillsammans med sina syskon var större än yngel som fötts upp med obesläktade yngel. Det var ingen skillnad i procentuell tillväxt över tid mellan besläktade och obesläktade individer. Vid de första mättillfällena var det skillnad i storlek, viket indikerar att mekanismen som styr tillväxt är som starkast i ett tidigt utvecklingsskede för att sedan avta. Tidigare studie på grönfläckig padda i Sverige visar på liknande resultat och dessa motsäger resultat från en australiensisk studie där tillväxten varit mindre i början och större i slutet. Dödligheten från ägg till yngel var större hos de obesläktade individerna. Sammantaget ger det en indikation om att mekanismen bakom exempelvis storlek, tillväxt och dödlighet är mer komplexa än vad som framkommit i tidigare arbeten. Resultatet visar på skillnader som kan ligga till grund för utvecklandet av nya metoder vid uppfödning av grönfläckig padda och som även kan hjälpa till vid bevarandet av den svenska populationen. / This work aims to respond to the hypothesis that says that there are differences in growth, size, mortality and deformation in the kin of green toad (Bufo viridis) between unrelated egg and later on juveniles when breeding. A previous Australian studie demonstrates that chemical substances that the toads themselves secrete affect growth and survival. It also appears that the siblings chemically recognize and favours each other, and thus competition for food between siblings is not as strong. Eggs and later on juveniles of five different females have been divided into groups and placed in aquariumtanks. Either with related individuals from a single female or mixed. The juveniles reared together with their siblings had on average larger bodies than juveniles reared with unrelated brood. There were no difference in growth over time between the different rearing methods. There where, however, differences in growth during the first measurements, which indicates that the mechanisms that differentiates the growth is strongest in an early stage of development. Mortality from egg to juvenile where larger in the unrelated individuals than within the siblings. Previous Swedish study show similar results and these contradicts result from Australian studies. Overall, it gives an indication that the mechanism that affect size, growth and mortality is more complex than what transpired in the previous work. The result points to differences that may form the basis for the development of new methods for the breeding of European Green Toad, and which can also help in the preservation of the Swedish population.

This project aims to study fossil amphibian and reptile (herpetofaunal) remains from Quaternary sites in the British Isles. This neglected group of vertebrates hold great potential for Quaternary Science. Collectively, they cover a wide range of ecological tolerances, although individual species often have very specific tolerances. The biology and ecology of individual species are discussed (Chapter 2) to facilitate their use in Quaternary palaeoenvironmental reconstructions, and an account of previous work on fossil herpetofaunas is given (Chapter 3). Very little work on fossil herpetofaunas has been carried out in the British Isles, mainly due to a lack of the required osteological expertise. The preparation and study of a modern osteological collection (Chapter 4), for comparative purposes, has therefore constituted a large and essential part of the project. The resulting manual for the identification of fossil herpetofaunal remains, appropriately illustrated with SEMs and hand-drawn figures, is presented (Chapter 5). The difficulties encountered in identifying some taxa are discussed in detail, and points of caution are stressed where necessary.

This thesis contains brief knowledge about homing and migration in amphibians. In practical part this thesis is studied fidelity and movement yellow-bellied toad (Bomnina variegata) in observed lokality. It is maped relative quantity during four seasons. Habitat preferences of yellow-bellied toad are researched depend on chosen paramerts (maximal depth, area, vegetation). This thesis also devote a pattern maps, special technice for marking amphibians. This method was used for marking individuals of yellow-bellied toad in field experiment.

abstract: Non-native consumers can significantly alter processes at the population, community, and ecosystem level, and they are a major concern in many aquatic systems. Although the community-level effects of non-native anuran tadpoles are well understood, their ecosystem-level effects have been less studied. Here, I tested the hypothesis that natural densities of non-native bullfrog tadpoles (Lithobates catesbeianus) and native Woodhouse's toad tadpoles (Anaxyrus woodhousii) have dissimilar effects on aquatic ecosystem processes because of differences in grazing and nutrient recycling (excretion and egestion). I measured bullfrog and Woodhouse's carbon, nitrogen, and phosphorus nutrient recycling rates. Then, I determined the impact of tadpole grazing on periphyton biomass (chlorophyll a) during a 39-day mesocosm experiment. Using the same experiment, I also quantified the effect of tadpole grazing and nutrient excretion on periphyton net primary production (NPP). Lastly I measured how dissolved and particulate nutrient concentrations and respiration rates changed in the presence of the two tadpole species. Per unit biomass, I found that bullfrog and Woodhouse's tadpoles excreted nitrogen and phosphorus at similar rates, though Woodhouse's tadpoles egested more carbon, nitrogen, and phosphorus. However, bullfrogs recycled nutrients at higher N:C and N:P ratios. Tadpole excretion did not cause a detectable change in dissolved nutrient concentrations. However, the percent phosphorus in mesocosm detritus was significantly higher in both tadpole treatments, compared to a tadpole-free control. Neither tadpole species decreased periphyton biomass through grazing, although bullfrog nutrient excretion increased areal NPP. This result was due to higher biomass, not higher biomass-specific productivity. Woodhouse's tadpoles significantly decreased respiration in the mesocosm detritus, while bullfrog tadpoles had no effect. This research highlights functional differences between species by showing non-native bullfrog tadpoles and native Woodhouse's tadpoles may have different effects on arid, aquatic ecosystems. Specifically, it indicates bullfrog introductions may alter primary productivity and particulate nutrient dynamics. / Dissertation/Thesis / Masters Thesis Biology 2015

Made available in DSpace on 2016-06-02T19:23:01Z (GMT). No. of bitstreams: 1 6358.pdf: 1461364 bytes, checksum: 88df144bc77432e6c6026f8cd985fa7a (MD5) Previous issue date: 2014-08-29 / Universidade Federal de Minas Gerais / The hypocretin or orexin A plays an important role in the modulation of respiratory control in mammals, but there are no data available for the role of Orexins in the peripheral and central chemoreception of non-mammalian vertebrates. Thus, the present study was designed to evaluate the location of orexinergic neurons in toads (Rhinella schneideri). In addition, we investigate if the orexinergic system of this species is important to hypoxic (5% O2 and N2 for balance) and hypercarbic (5% CO2, 21% O2 and N2 for balance) drive to breath. We assessed the role of the orexinergic system on respiratory responses by using intracerebroventricular injection of SB-334867 (orexin A receptor antagonist) during the light and the dark phase. Our results demonstrated that orexinergic neurons of Rhinella schneideri are located in the suprachiasmatic nucleus of diencephalon. Additionally, the injection of the orexin antagonist attenuated the ventilatory response to hypercarbia during the dark phase by acting on tidal volume and breathing frequency, while in the light phase, there was an attenuation in the ventilatory response to hypoxia by acting just in the tidal volume. We conclude that central orexin A contributes to hypercarbic and to hypoxic chemoreflex in toads Rhinella schneideri. / A orexina ou hipocretina exerce uma importante modulação no controle respiratório em mamíferos, mas nenhum estudo verificou a participação das orexinas na quimiorrecepção central e periférica em vertebrados não-mamíferos. Em vista disso, o objetivo do presente estudo foi avaliar a imunorreatividade para orexina para localização dos neurônios orexinérgicos no encéfalo de sapos (Rhinella schneideri) e investigar se o sistema orexinérgico desta espécie participa nas respostas respiratórias à hipóxia (5% O2 e N2 balanço) e à hipercarbia (5% CO2, 21%O2 e N2 balanço). A participação da neurotransmissão orexinérgica na regulação respiratória em sapos (Rhinella schneideri) foi avaliada por meio de microinjeções intracerebroventriculares (i.c.v.) de SB-334867 (antagonista de receptores OX1R) em duas doses (5 mM e 10mM) no ventrículo lateral durante as fases clara e escura desses animais. Nossos resultados mostram que os neurônios orixinérgicos de sapos Rhinella schneideri estão localizados no núcleo supraquiasmático no diencéfalo. Adicionalmente, a injeção do antagonista orexinérgico atenua a resposta ventilatória à hipercarbia na fase escura, devido tanto à diminuição do volume corrente quanto da frequência respiratória, enquanto, na fase clara, atenua a resposta ventilatória à hipóxia devido a uma redução no volume corrente. Concluímos, portanto, que a Orexina A participa na modulação dos quimiorreflexos central e periférico em sapos Rhinella schneideri.

The San Luis Valley is a large valley formation in Colorado surrounded on either side by mountain ranges exceeding 4,267 m. Within the Valley, two of the 14 amphibian and reptile species are dwarfed: the short-horned lizard (Phrynosoma hernandesi) and the Great Plains toad (Anaxyrus cognatus). Since its initial reporting in 1968 and confirmation in 1981, no research further investigating this dwarfism has been conducted. I collected morphological measurements to determine the extent and patterns of dwarfism of both species. I then investigated the genetics of both species using mitochondrial DNA to determine whether they are genetically distinct, their colonization histories within the Valley, and whether the Valley functions as a reproductive barrier. Lastly, I report life/natural-history data to determine the effects of dwarfism. Phrynosoma hernandesi and A. cognatus were significantly dwarfed and showed an increase in sexual size dimorphism compared to populations surrounding the Valley. Valley populations of P. hernandesi show high amounts of genetic divergence from populations surrounding the Valley while A. cognatus shows minimal genetic variation throughout its range. Based on the variable distribution of genetic variation in the Valley, historic climate patterns, and fossil records, there are two most likely colonization histories for P. hernandesi: 1.) populations colonized the Valley during a singular event and have since diverged or 2.) populations colonized the Valley during two events that correlate with the two warm, dry periods within the last 0.8 MYA. Dwarfed P. hernandesi consumed diets similar to populations outside the Valley although there is local variation in the diversity of prey items consumed. Phrynosoma hernandesi at Zapata Ranch showed annual variation in body size and morphology while population dynamics correlate with the timing of precipitation. Also, females show a reduced reproductive output, producing fewer neonates but of equal size to non-dwarfed neonates. Collectively, findings from this study suggest that Valley populations represent unique taxa and should be considered for further genetic study to determine their taxonomic and conservation status.

Batrachochytrium dendrobatidis (Bd) is a fungus that causes chytridiomycosis in amphibians. This fungus is an invasive species that has spread all over the world and is causing mass deaths in many areas. Bd has an efficient life cycle which targets suitable hosts and causes disturbances in amphibian osmoregulation and eventually death. It has caused more than 90 presumed extinctions worldwide. However, even though this fungus is commonly found in Sweden, no cases of chytridiomycosis has been found in the wild. This raises the questions i) what factors makes the infection in amphibians more severe and ii) does temperature affect the severity of Bd infection? According to the thermal mismatch hypothesis pathogens should be more efficient at temperatures where the performance gap between the host and pathogen is the widest. We chose the common toad as a study organism since it can be found all over Sweden and is generally considered to be adapted to colder climates. Our aim was to test the thermal mismatch hypothesis and see if the effect of infection differed between different temperatures. Common toad eggs were collected from two ponds in southern Sweden, raised in the laboratory and metamorphosed juvenile toads were reared in three different temperature rooms, either 14℃, 18℃ or 22℃. There they were either infected with Bd or exposed to a sham infection and monitored for 40 days. We show that Bd infection negatively affects growth and survival of common toads in accordance with previous studies. Furthermore, we found that temperature affects the effect of infection and shows patterns of the thermal mismatch hypothesis.

No description available.

We tested the adequacy of standard 30 m riparian buffers for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas boreas) as an example. We monitored toad populations in south-central Utah using radio telemetry during the summers of 2003 and 2004. We found 30 m buffers inadequate for protecting boreal toads and suggest this is likely true for other species as well. Managers must consider several factors when constructing buffers: (1) Buffer requirements may vary by time of year. While we located toads most often in wet habitats, toads commonly utilized upland habitats in late summer, occasionally at distances greater than 100 m from water. (2) A single year's observation may not be sufficient to establish adequate buffers. Toads moved into upland habitats more often and at greater distances from water (> or = 30 m) during the wetter, cooler weather conditions of 2004 than in 2003. (3) Buffer requirements may differ by sex. Male toads appeared to have stronger selection for wetland habitats than females. Females moved greater distances from water than males, often outside of buffer areas. (4) Buffer requirements may differ by location. 30 m buffers contained 82.4% of all observations, though results varied between 50.0 and 97.2%, depending on breeding location. Finally (5) All habitat requirements should be considered when establishing buffers. Many small, unmapped streams and seeps utilized by toads for hibernation were located outside buffer zones. After ground truthing and extending 30 m buffers around these habitats, the percentage of all observations within 30 m buffers increased to 92.4%. Managers need to be aware of the accuracy of digital and other mapping sources used in creating buffers and to incorporated all critical habitats in conservation buffers. Our boreal toad example suggests that ground truthing may be the most important factor in establishing effective buffer zones.