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.

O principal objetivo deste trabalho foi estudar a variação morfológica do grupo Bufo granulosus, procurando determinar suas unidades evolutivas. Esse grupo, como concebido até o presente, é comporto por 6 espécies (Bufo granulosus, Bufo bergi, Bufo dorbignyi, Bufo fernandezae, Bufo pygmaeus e Bufo beebei), e 10 subespécies de Bufo granulosus (merianae, nattereri, mini, major, barbouri, lutzi, mirandaribeiroi, azarai, humboldti, goeldii). A distribuição geográfica do grupo é bastante ampla e associada a formações abertas, compreendendo a América Central (Panamá) e quase todos os países da América do Sul, com exceção do Chile e do Equador. Foram analisados cerca de 8700 exemplares depositados em diversas coleções nacionais e estrangeiras de cerca de 880 localidades distintas. Caracteres apontados nas descrições das subespécies do grupo e outros, levantados no decorrer no trabalho, foram conferidos com base no estudo de séries de exemplares, comparados por localidade. Foram tomadas medidas de 23 caracteres morfométricos em 2267 indivíduos, utilizados em uma análise estatística multivariada, juntamente com 9 proporções corporais escolhidas como forma de caracterizar os táxons do grupo granulosus. Caracteres osteológicos e miológicos também foram estudados, e foi realizada uma análise das vocalizações (canto de anúncio) disponíveis para o grupo. São reconhecidas 12 espécies para o grupo granulosus: Bufo granulosus (Sudeste e Nordeste do Brasil); Bufo pygmaeus (Rio de Janeiro); Bufo azarai (Argentina, Paraguai e Mato Grosso do Sul); Bufo mirandaribeiroi (Brasil Central); Bufo major (Argentina, Bolívia, Paraguai e Amazônia, Brasil); Bufo fernandezae (Sul do Brasil, Argentina, Uruguai); Bufo dorbignyi (Sul do Brasil, Argentina, Uruguai); Bufo bergi (Argentina, Paraguai, Mato Grosso do Sul); Bufo nattereri (Roraima); Bufo humboldti (Colômbia, Venezuela, Guiana, Suriname); Bufo merianae (Amazônia, Venezuela, Guiana, Suriname); Bufo sp.n. (Panamá). / The Bufo species of the granulosus group are taxonomically reviewed in order to determine their evolutionary units. The granulosus group is composed by 6 species (Bufo granulosus, Bufo bergi, Bufo dorbignyi, Bufo fernandezae, Bufo pygmaeus and B. beebei), and 10 subspecies of Bufo granulosus (merianae, nattereri, mini, major, barbouri, lutzi, mirandaribeiroi, azarai, humboldti, goeldii). The group presents a wide geographical distribution, occurring in Central America (Panama) and in almost all the countries of South America, except for Chile and Ecuador. A total of 8700 specimens deposited in several national and foreign collections were studied representing about 880 different localities. External morphological caracters currently cited in the literature, and others, chosen at the beginning of the work, were compared within the sample series for each locality. Measurements of 23 morphometric characters were taken on 2267 specimens, and were used in an multivariate statistical analysis along with 9 body ratios chosen as a form of characterizing the taxa of the group. Osteological and miological caracters were also analyzed within the taxa, and an analysis of the vocalization (advertisement call) was performed with the available recordings for the group. Twelve species are recognized for the granulosus group, and one is new: Bufo granulosus (Southeast and Northeast Brazil); Bufo pygmaeus (Rio de Janeiro State, Brazil); Bufo azarai (Argentina, Paraguay and Mato Grosso do Sul, Brazil); Bufo mirandaribeiroi (Central Brazillian Savannas); Bufo major (Argentina, Bolivia, Paraguay and Amazonia, Brazil); Bufo fernandezae (South Brazil, Argentina, Uruguay); Bufo dorbignyi (South Brazil, Argentina, Uruguay); Bufo bergi (Argentina, Paraguay and Mato Grosso do Sul); Bufo nattereri (Roraima State, Brazil); Bufo humboldti (Colombia, Venezuela, Guyana, Surinam); Bufo merianae (Amazonia, Venezuela, Guyana, Surinam); Bufo sp. n. (Panama).

The aim of this study was to compare the effects of arginine vasotocin (AVT) administration in the endangered boreal toad (Bufo boreas boreas) and common Fowler’s toad (Bufo fowleri). The objectives of this study were to determine if AVT could elicit: 1) calling, and 2) amplexus behaviors. Toads were paired into single male:female groups and administered AVT at varying concentrations: 0.1, 1.0, 5.0, 10.0 and 25.0 μg/g and in different combinations: 1) only male was treated; 2) only female was treated, and 3) both male and female treated. AVT failed to stimulate any breeding behavior in the boreal toad, but the administration of AVT to both B. Fowleri genders significantly affected the duration of amplexus (p<0.0347). Also, the concentration of AVT significantly affected the length of amplexus (p<0.0429) and call frequency (p<0.0294). These results will be valuable for breeding programs where animals are failing to show natural reproductive behavior.

Currently published data on the role of the lymphatic system in amphibians are inadequate and contradictory. Estimates of the rate of formation of lymph and the role of the lymph hearts in returning this fluid to the circulation are not based on actual volume determinations but rather estimates derived from changes in hematocrit using published values of plasma and blood volume. The lymph hearts are known to be vital to the maintenance of normal fluid compartment physiology and to increase their rate of activity during episodes of hypovolemic stress. Yet, significant redistribution of body fluids following hemorrage appears to occur in animals without lymph hearts. In this study, plasma and blood volumes were determined by the dye dilution technique using injected Evan's blue dye to label the plasma. Eight intact and 6 animals with their lymph hearts destroyed were hemorrhaged to 78% and 75% of their initial blood volumes, respectively. Changes in blood volume were measured following the hemorrhage by analysis of Evan's blue washout and hemodilution.

Many organisms with complex life cycles undergo transition periods associated with increased vulnerability to predation. Several evolutionary adaptations have been proposed as antipredator defenses for organisms during risky transition periods. These include: shortening of the transition period, parental care, cryptic coloration, and synchrony of risky transitions with large numbers of conspecifics. The results of my research support the hypothesis that synchrony of metamorphosis and emergence from the water and aggregation during the period of transformation may be antipredator defenses for the western toad (Bufo boreas). For some anuran species, synchronous metamorphosis may function as an antipredator adaptation by swamping predators during the period of transformation. I examined the levels of synchrony of emergence from the water of metamorphosing western toads (Bufo boreas) in the presence and absence of a live snake predator, the common garter snake (Thamnophis sirtalis) in a laboratory experiment. To compare between the treatments, I measured the time to emergence from the water, the number of metamorphs emerging together, and the level of aggregation (before and during emergence) of the toads in each treatment. There was a difference between the treatments when all three factors were considered. I attributed these differences to a behavioral response in which B. boreas emerged sooner in the presence of the predator, regardless of whether individual toads had reached the point at which they were physically better suited to the terrestrial environment than the larval environment. Since the Pacific treefrog (Hyla regilla) is also preyed upon by T. sirtalis during the vulnerable period of metamorphosis, I conducted a laboratory experiment to test the effects of the presence of T. sirtalis on 1) aggregation of larval and metamorphosing H. regilla, 2) time to metamorphosis, 3) synchrony of metamorphosis, 4) time to emergence from the water and 5) synchrony of emergence from the water. The only significant effect observed in this experiment was a difference between aggregation levels of H. regilla throughout the experiment. There was, however, a strong trend in which the variances around the mean times to metamorphosis and emergence of the frogs in the control treatments were larger than those in the predator treatments. This could indicate a trend toward synchrony of metamorphosis and emergence for H. regilla in the presence of snake predators. / Graduation date: 1998

No description available.

The behavioral and physiological interaction between Bufo bankorensis and its snake predators, Macropisthodon rudis and Dinodon rufozonatum were investigated in this study. Adult M. rudis preferred medium sized toads but neonate favored to small ones. About seized position of different toad sizes, adult snakes attacked large toads head first but neonates did randomly. On the swallow direction with toad sizes, adult snakes had no preference but neonates swallowed large toads head first, so the neonates could change the direction swallowing preys after preys had been seized. Adult and neonate snakes spent similar time in handling toads with head first ingestion costed less handling time. After the large rear-teeth had been grounded, M. rudis would spend more time in handling preys. In all trials, venom secreted from parotid glands did not seem to prolong handling time on adult snake. After forced fed 1 mg/g toad venom to D. rufozonatum, no significant change of Na+, K+, Ca2+ ion concentrations were observed but significant increasing of heart rates. The ECGs of intoxicated snakes showed typical digitalis-like cardioactive effects as sinus arrhythmia, prolonged P-R interval as varying degrees of atrioventricular block and ventricular fibrillation. The LD50 of the venom of B. bankorensis are different between from toads sampled Northern and Southern Taiwan. In comparison with dissected toad-eating snakes D. rufozonatum, M. rudis and Rhabdophis tigrinus formosanus, I didn¡¦t find any nuchal glands on nuchal-dorsal site of D. rufozonatum and M. rudis.

No description available.

To date, the majority of studies into sex determination and sexual development have focused on the mammalian system due to the mouse model being an excellent tool for developmental biology as well as obvious implications to human health and development. However, the focus on the mammalian system has caused a large fraction of other vertebrate groups to be overlooked. The last decade has seen an array of studies into various non-mammalian organisms like fishes, birds, reptiles, and amphibians. These studies have unveiled a remarkably conserved molecular background utilized for sexual differentiation amongst all vertebrates, ranging from the alligator which employs temperature dependent sex determination to the mouse, which employs genotypic sex determination In this project, I implemented molecular methods traditionally used to study model organisms, to investigate an amphibian species, the cane toad (Bufo marinus). The cane toad was chosen due to its invasive status in Australia, as well as being a representative of one of the most successful and specious families of vertebrates, Bufonidae. Since, its introduction, this species has rapidly spread across the continent, adversely effecting native species throughout its introduced range. Recent studies have identified the disruption of the sex-determination pathway as a realistic goal in an otherwise, seemingly futile, effort to curtail their expansion. We decided to approach the study of cane toad sex determination and development on three levels, in order to have a broader understanding of the similarities between toads and other groups, and additionally, to better assess the feasibility of utilizing molecular means to control cane toads in non-native habitats. Firstly, I used a candidate gene approach to clone and characterize five genes which were previously known to be involved in both mammalian as well as amphibian sex determination: Sox9, Dmrt1, p450arom, Sf1, and Dax1. I chose Sox9 and Dmrt1 due to their known involvement in the male-specific pathway of mammals. Dmrt1 was also known to be male specific in other groups, including amphibians. Conversely, I also decided to investigate p450arom and Dax1, due to their affiliation with the female pathway, while Sf1 has a role in both sexes. All of these genes were expressed in the gonads of both sexes of cane toads. However, Sox9 exhibited strong transcriptional up-regulation in testes at the time of sexual differentiation, similar to mammals. Thus, using the candidate gene approach, I was successful in identifying a sex-specific marker which could be utilized in the manipulation of the sex determination pathway (e.g. female to male sex reversal). VIIThe second approach involved the study of sex determination on a cytogenetic level. Traditionally, Bufonids have been assumed to utilize a ZZ/ZW (male homogametic/female heterogametic) sex chromosome system, yet only one recent study has been successful in the identification of sex chromosomes in a toad species. Moreover, the authors identified the sex chromosomes in only one population (of 18 studied), highlighting the scarcity of discernible sex chromosomes in toads. When we began to investigate the karyotype of cane toads, we were able to identify a female-specific length polymorphism in the nucleolus organizer region (NOR) of chromosome 7, making this chromosome pair a strong candidates for the Z and W sex chromosomes. In order to verify our hypothesis, we also performed chromomycin A3 staining to reveal a differential signal between the chromosome pair, indicative of heterochromatin accumulation on the brighter NOR. This study lent strong support to the observed difference between the chromosomes, yet we required further investigation in order to identify the W and the Z chromosomes, specifically. By utilizing comparative genomic hybridization (CGH), I was able to identify a female specific region on the chromosome with the larger NOR, identifying it as the W chromosome. This study was successful in identifying the sex chromosomes in the cane toad. Moreover, it allows us to make a more accurate prediction of the possible sex determination method utilized: either a dosage dependent male determination system, or a female-specific gene in a female determination system. The third approach focused on the Bidder’s organ and its role in sexual development of cane toads. The Bidder’s organ is a gonadal structure comprised of ovary-like tissue, found in both males and females, with no known function. Since our study was focused on female to male sex-reversal of cane toads, we decided to investigate the potential of the Bidder’s organ to interrupt this process. By utilizing the candidate genes, which I had previously cloned, I was able to identify the Bidder’s organ as having an entirely distinct transcriptional pattern in comparison to the gonads of either sex. Additionally, the Bidder’s organ showed significantly higher levels of p450arom expression than the gonads, identifying it as a possible key player in the production of aromatase enzyme for oestrogen production. Moreover, gene expression patterns in the Bidder’s organ strongly correlated with the significant developmental time points in the sexual development of the toads, implying a possible function in the development process of toads. In conclusion, I have performed the first study of the molecular, cytogenetic and anatomical aspects of sexual development in a toad. I was able to verify that cane toads utilize a ZZ/ZW chromosome system and furthermore, likely utilize the mammalian male-linked gene, Sox9, in male development. I was also able to show that the Bidder’s organ is transcriptionally active at key time points, likely indicative of a functional role during development.

Thesis (Ph. D.) -- University of Tennessee, Knoxville, 2005. / Title from title page screen (viewed on Sept. 6, 2005). Thesis advisor: Arthur C. Echternacht. Thesis advisior: Christine R. B. Boake. Document formatted into pages (xvi, 151 p. : ill. (some col.)). Vita. Includes bibliographical references.