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J.d. Roberts - One of the best experts on this subject based on the ideXlab platform.
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Investigating patterns in the spermiation response of eight Australian frogs administered human chorionic gonadotropin (hCG) and luteinizing hormone-releasing hormone (LHRHa)
General and comparative endocrinology, 2012Co-Authors: Aimee J. Silla, J.d. RobertsAbstract:Exogenous LHRHa and hCG are routinely employed to induce spermiation in vivo in anurans. To date, however, few studies have directly compared the efficacy of these two hormones. The aim of this study was threefold. First to quantify the spermiation response of eight Australian anuran species (Crinia glauerti, Crinia georgiana, Crinia pseudinsignifera, GeoCrinia rosea, Heleioporus albopunctatus, Heleioporuseyrei, Neobatrachus pelobatoides and Pseudophryne guentheri) administered LHRHa and hCG. Second, to determine whether variance in spermiation responses is related to a species' reproductive mode (aquatic vs. terrestrial) or family (Limnodynastidae vs. Myobatrachidae). Third, to compare the quantity and quality of spermatozoa obtained via hormone administration (LHRHa and hCG) to spermatozoa obtained via testis removal and maceration. There was no significant difference in the viability of spermatozoa obtained from hCG or LHRHa administration in any of the eight study species. The sperm viability of samples ranged from 28-84% in C. georgiana and G. rosea, respectively. The hormone that induced the release of the highest number of spermatozoa differed among species, with all five species belonging to the family Myobatrachidae responding better to LHRHa, and the three species from the family Lymnodynastidae releasing a greater number of spermatozoa in response to hCG. Importantly, these results provide the first preliminary evidence that hCG and LHRHa efficacy in anurans may be predicted by phylogeny. Understanding such broad-scale patterns in the response of anurans to exogenous hormones will expedite the application of assisted reproductive technologies to novel species.
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Fitness consequences of variable maternal provisioning in quacking frogs (Crinia georgiana).
Journal of evolutionary biology, 2006Co-Authors: Martin A. Dziminski, J.d. RobertsAbstract:Variable maternal provisioning may evolve when there is variation in the quality of offspring environments. The frog Crinia georgiana has high variability in egg size both within and between clutches, independent of female phenotype. It breeds in ponds with high spatial and temporal variation in habitat quality. Egg size strongly affected offspring fitness in good and poor quality offspring environments, whether the egg size difference was from between or within clutches. Since there is a trade-off in egg size and number, these fitness consequences translate to strong effects on maternal fitness. In the variable and unpredictable offspring environment of C. georgiana, the maintenance of variable maternal provisioning both within and between clutches is likely to be an evolved response to the offspring environment.
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Call matching in the quacking frog (Crinia georgiana)
Behavioral Ecology and Sociobiology, 2000Co-Authors: H. C. Gerhardt, J.d. Roberts, Mark A. Bee, Joshua J. SchwartzAbstract:Males of the quacking frog Crinia georgiana produce calls consisting of 1–11 notes. Playback experiments using synthetic calls showed that males tend to match the number of notes in 2-note and 4-note stimuli; however, males tended to produce more than 1 note in response to a 1-note stimulus and fewer than 8 notes in response to an 8-note stimulus. Successive playbacks of two, 4-note calls from separate speakers indicate that males are likely to match the combined number of notes in the calls of two neighbors, even if they are not equidistant from the focal male. The results are compared with the few other studies of matching in anurans, and interpreted in terms of hypotheses developed to explain matching in songbirds. One attractive and testable hypothesis for call matching in C. georgiana is that males are attempting to produce calls that are at least as attractive to females as those of rivals, without wasting energy.
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Does multiple paternity improve fitness of the frog Crinia georgiana
Evolution; international journal of organic evolution, 2000Co-Authors: Phillip G. Byrne, J.d. RobertsAbstract:Abstract In the Australian myobatrachid frog Crinia georgiana simultaneous polyandry occurs in about half of all matings, which leads to multiple paternity, but reduced fertilization success and occasional female mortality. Multiple paternity may provide benefits to females that compensate for these costs, for example, through enhanced genetic diversity of a clutch. In nature, embryos and tadpoles of C. georgiana develop in shallow, temporary pools and may be exposed to fluctuating water levels and the risk of desiccation between rain events. Fertilization by genetically diverse sires may act as a bet hedge against these conditions. To evaluate this hypothesis, females were artificially mated with one or two males in the field and eggs and larvae reared in the laboratory under constant or fluctuating developmental conditions. Experiment 1 exposed embryos from single- and multiple-paternity clutches to conditions where eggs were completely covered during development or eggs sat in air on a moist substrate....
Phillip G. Byrne - One of the best experts on this subject based on the ideXlab platform.
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Intrasexual selection and group spawning in quacking frogs (Crinia georgiana)
2014Co-Authors: Phillip G. Byrne, Dale J RobertsAbstract:In the Australian frog Crinia georgiana, matings frequently involve a single female and multiple males (group spawning). The aim of the present study was to demonstrate a connection between variation in the intensity of intrasexual competition, measured by using male density and operational sex ratio (OSR), and the incidence of group spawning. Over a 3-month breeding period, male density and OSR varied substantially and were significantly influenced by climatic conditions. The frequency of agonistic interactions between males was higher in denser choruses. Fights were typically over the possession of sites used to broadcast advertisement calls and were almost always won by larger males. At higher densities, males allocated significantly less time to calling to attract females and spent more time as nonmoving satellites or roaming through an aggregation (searching). However, large males always called more than did small males. The number of males involved in a spawning correlated positively with variation in both male density and OSR. Observation of group spawnings revealed that they generally arose when a satellite male joined a mating pair after a female chose to mate with a calling male or when a female was seized by a searching male and the pair was joined by other searching males. These findings, coupled with past research documenting costs but no benefits of multiple paternity to females, suggest that competitively inferior males force group spawns. Key words: forced copulation, frogs, group spawning, sexual conflict. [Behav Ecol 15:872–882 (2004)] Disparity in mating interests between the sexes conven-tionally arises because males have a higher potential reproductive rate than do females. Consequently, female
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Heavy metal pollution negatively correlates with anuran species richness and distribution in south-eastern Australia
Austral Ecology, 2012Co-Authors: Kristina L. G. Ficken, Phillip G. ByrneAbstract:Heavy metal pollution has likely played an important role in global biodiversity decline, but there remains a paucity of information concerning the effects of metals on amphibian diversity. This study assessed anuran species richness and distribution in relation to sediment metal content and water chemistry in wetlands located along the Merri Creek corridor in Victoria, south-eastern Australia. Anurans were present in 60% (21/35) of study sites, with a total of six species detected: the eastern common froglet (Crinia signifera), the eastern sign-bearing froglet (Crinia parinsignifera), the southern brown tree frog (Litoria ewingii), the growling grass frog (Litoria raniformis), the eastern banjo frog (Limnodynastes dumerilii) and the spotted marsh frog (Limnodynastes tasmaniensis). Mean species richness was 1.77 ± 0.32 per site, and species richness ranged from zero to six species per site. Across sites, species richness correlated negatively with sediment concentrations of six heavy metals: copper, nickel, lead, zinc, cadmium and mercury. Species richness also correlated negatively with wetland water electrical conductivity (a proxy for salinity) and concentrations of orthophosphate. Distributions of the three most commonly observed frog species (C. signifera, L. tasmaniensis and L. ewingii) were significantly negatively associated with the total level of metal contamination at individual sites. The study is the first to provide evidence for an association between metal contamination and anuran species richness and distribution in the southern hemisphere, adding to a small but growing body of evidence that heavy metal pollution has contributed to global amphibian decline.
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Intrasexual selection and group spawning in quacking frogs (Crinia georgiana)
Behavioral Ecology, 2004Co-Authors: Phillip G. Byrne, J. Dale RobertsAbstract:In the Australian frog Crinia georgiana, matings frequently involve a single female and multiple males (group spawning). The aim of the present study was to demonstrate a connection between variation in the intensity of intrasexual competition, measured by using male density and operational sex ratio (OSR), and the incidence of group spawning. Over a 3-month breeding period, male density and OSR varied substantially and were significantly influenced by climatic conditions. The frequency of agonistic interactions between males was higher in denser choruses. Fights were typically over the possession of sites used to broadcast advertisement calls and were almost always won by larger males. At higher densities, males allocated significantly less time to calling to attract females and spent more time as nonmoving satellites or roaming through an aggregation (searching). However, large males always called more than did small males. The number of males involved in a spawning correlated positively with variation in both male density and OSR. Observation of group spawnings revealed that they generally arose when a satellite male joined a mating pair after a female chose to mate with a calling male or when a female was seized by a searching male and the pair was joined by other searching males. These findings, coupled with past research documenting costs but no benefits of multiple paternity to females, suggest that competitively inferior males force group spawns. Key words: forced copulation, frogs, group spawning, sexual conflict. [Behav Ecol 15:872–882 (2004)]
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Does multiple paternity improve fitness of the frog Crinia georgiana
Evolution; international journal of organic evolution, 2000Co-Authors: Phillip G. Byrne, J.d. RobertsAbstract:Abstract In the Australian myobatrachid frog Crinia georgiana simultaneous polyandry occurs in about half of all matings, which leads to multiple paternity, but reduced fertilization success and occasional female mortality. Multiple paternity may provide benefits to females that compensate for these costs, for example, through enhanced genetic diversity of a clutch. In nature, embryos and tadpoles of C. georgiana develop in shallow, temporary pools and may be exposed to fluctuating water levels and the risk of desiccation between rain events. Fertilization by genetically diverse sires may act as a bet hedge against these conditions. To evaluate this hypothesis, females were artificially mated with one or two males in the field and eggs and larvae reared in the laboratory under constant or fluctuating developmental conditions. Experiment 1 exposed embryos from single- and multiple-paternity clutches to conditions where eggs were completely covered during development or eggs sat in air on a moist substrate....
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Intrasexual selection and group spawning in quacking frogs (Crinia georgiana)
1Co-Authors: Phillip G. Byrne, Dale J RobertsAbstract:In the Australian frog Crinia georgiana, matings frequently involve a single female and multiple males (group spawning). The aim of the present study was to demonstrate a connection between variation in the intensity of intrasexual competition, measured by using male density and operational sex ratio (OSR), and the incidence of group spawning. Over a 3-month breeding period, male density and OSR varied substantially and were significantly influenced by climatic conditions. The frequency of agonistic interactions between males was higher in denser choruses. Fights were typically over the possession of sites used to broadcast advertisement calls and were almost always won by larger males. At higher densities, males allocated significantly less time to calling to attract females and spent more time as nonmoving satellites or roaming through an aggregation (searching). However, large males always called more than did small males. The number of males involved in a spawning correlated positively with variation in both male density and OSR. Observation of group spawnings revealed that they generally arose when a satellite male joined a mating pair after a female chose to mate with a calling male or when a female was seized by a searching male and the pair was joined by other searching males. These findings, coupled with past research documenting costs but no benefits of multiple paternity to females, suggest that competitively inferior males force group spawns. Copyright 2004.forced copulation; frogs; group spawning; sexual conflict
J. Dale Roberts - One of the best experts on this subject based on the ideXlab platform.
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Natural Hybrid between the Frogs Crinia pseudinsignifera and Crinia subinsignifera (Myobatrachidae) from Southwestern Australia Defined by Allozyme Phenotype and Call
Journal of Herpetology, 2010Co-Authors: J. Dale RobertsAbstract:Advertisement calls of the West Australian frogs Crinia pseudinsignifera and Crinia subinsignifera are distinct. I report a natural hybrid between C. subinsignifera and C. pseudinsignifera based on initial detection of an intermediate call and confirmed by allozyme data. I discuss patterns of hybridization among C. subinsignifera, C. pseudinsignifera, and Crinia insignifera.
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Fitness consequences of parental compatibility in the frog Crinia georgiana.
Evolution; international journal of organic evolution, 2008Co-Authors: Martin A. Dziminski, J. Dale Roberts, Leigh W SimmonsAbstract:Theory suggests that multiple mating by females can evolve as a mechanism for acquiring compatible genes that promote offspring fitness. Genetic compatibility models predict that differences in fitness among offspring arise from interactions between male and female haplotypes. Using a cross-classified breeding design and in vitro fertilization, we raised families of maternal and paternal half-siblings of the frog Crinia georgiana, a species with a polyandrous breeding system and external fertilization. After controlling for variation in maternal provisioning, we found significant effects of interacting parental haplotypes on fertilization success, and nonadditive genetic effects on measures of offspring fitness such as embryo survival, and survival to, size at, and time to metamorphosis. Additive genetic variation due to males and females was negligible, and not statistically significant for any of the fitness traits measured. Combinations of parental haplotypes that resulted in high rates of fertilization produced offspring with higher embryo survival and rapid juvenile development. We suggest that a gamete recognition mechanism for selective fertilization by compatible sperm may promote offspring fitness in this system.
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Intrasexual selection and group spawning in quacking frogs (Crinia georgiana)
Behavioral Ecology, 2004Co-Authors: Phillip G. Byrne, J. Dale RobertsAbstract:In the Australian frog Crinia georgiana, matings frequently involve a single female and multiple males (group spawning). The aim of the present study was to demonstrate a connection between variation in the intensity of intrasexual competition, measured by using male density and operational sex ratio (OSR), and the incidence of group spawning. Over a 3-month breeding period, male density and OSR varied substantially and were significantly influenced by climatic conditions. The frequency of agonistic interactions between males was higher in denser choruses. Fights were typically over the possession of sites used to broadcast advertisement calls and were almost always won by larger males. At higher densities, males allocated significantly less time to calling to attract females and spent more time as nonmoving satellites or roaming through an aggregation (searching). However, large males always called more than did small males. The number of males involved in a spawning correlated positively with variation in both male density and OSR. Observation of group spawnings revealed that they generally arose when a satellite male joined a mating pair after a female chose to mate with a calling male or when a female was seized by a searching male and the pair was joined by other searching males. These findings, coupled with past research documenting costs but no benefits of multiple paternity to females, suggest that competitively inferior males force group spawns. Key words: forced copulation, frogs, group spawning, sexual conflict. [Behav Ecol 15:872–882 (2004)]
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Molecular Phylogeny of the Australian Frog Genera Crinia, GeoCrinia, and Allied Taxa (Anura: Myobatrachidae)
Molecular phylogenetics and evolution, 2001Co-Authors: Kathryn Read, J. Dale Roberts, J. Scott Keogh, Ian A. W. Scott, Paul DoughtyAbstract:We present a mitochondrial gene tree for representative species of all the genera in the subfamily Myobatrachinae, with special emphasis on Crinia and GeoCrinia. This group has been the subject of a number of long-standing taxonomic and phylogenetic debates. Our phylogeny is based on data from approximately 780 bp of 12S rRNA and 676 bp of ND2, and resolves a number of these problems. We confirm that the morphologically highly derived monotypic genera MetaCrinia, Myobatrachus, and Arenophryne are closely related, and that Pseudophryne forms the sister group to these genera. Uperoleia and the recently described genus Spicospina are also part of this clade. Our data show that Assa and GeoCrinia are reciprocally monophyletic and together they form a well-supported clade. GeoCrinia is monophyletic and the phylogenetic relationships with the genus are fully resolved with two major species groups identified: G. leai, G. victoriana, and G. laevis; and G. rosea, G. alba, and G. vitellina (we were unable to sample G. lutea). We confirm that Taudactylus forms the sister group to the other myobatrachine genera, but our data are equivocal on the phylogenetic position of ParaCrinia. The phylogenetic relationships among Crinia species are well resolved with strong support for a number of distinct monophyletic clades, but more data are required to resolve relationships among these major Crinia clades. Crinia tasmaniensis and Bryobatrachus nimbus form the sister clade to the rest of Crinia. Due to the lack of generic level synapomorphies for a Bryobatrachus that includes C. tasmaniensis, we synonymize Bryobatrachus with Crinia. Crinia georgiana does not form a clade distinct from other Crinia species and so our data do not support recognition of the genus Ranidella for other Crinia species. Crinia subinsignifera, C. pseudinsignifera, and C. insignifera are extremely closely related despite differences in male advertisement call. A preliminary investigation of phylogeographic substructure within C. signifera revealed significant divergence between samples from across the range of this species.
John H. Bowie - One of the best experts on this subject based on the ideXlab platform.
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Structural and activity changes in three bioactive anuran peptides when Asp is replaced by isoAsp.
Peptides, 2012Co-Authors: Antonio N. Calabrese, Katarina Markulic, Ian F. Musgrave, Hui Guo, Lixin Zhang, John H. BowieAbstract:Abstract The Asp and iso Asp isomers of three bioactive peptides, Crinia angiotensin 11 [APGDRIYHPF(OH)], uperin 1.1 [pEADPNAFYGLM(NH 2 )] and citropin 1.1 [GLFDVIKKVASVIGGL(NH 2 )] were tested for changes in (i) susceptibility towards proteolytic cleavage, (ii) activity (smooth muscle activity for Crinia angiotensin 11 and uperin 1.1 isomers, and antimicrobial activity for the two isomers of citropin 1.1), and (iii) 3D structures in water, trifluoroethanol-d 3 /water (1:1) and DPC micelles as determined by 2D nuclear magnetic resonance spectroscopy. Proteolytic cleavage with trypsin was identical for each pair of Asp/ iso Asp isomers. Cleavage with chymotrypsin was the same for the Crinia angiotensin and uperin 1.1 isomeric pairs, but different for the two Asp/ iso Asp citropin 1.1 isomers. Chymotrypsin cleaved at Phe3 (adjacent to Asp4) for citropin 1.1, but not at Phe3 (adjacent to iso Asp4) for iso Asp citropin 1.1. The smooth muscle activity of the iso Asp isomer of Crinia angiotensin 11 was less than that of the Asp isomer. The smooth muscle activity of iso Asp3-uperin 1.1 is greater than that of the Asp isomer at low concentration ( −9 M) but no different from the Asp isomer at concentrations > 10 −9 M. Citropin 1.1 is a wide-spectrum antibiotic against Gram positive organisms, while the iso Asp isomer is inactive against the test pathogens Staphylococcus aureus and Bacillus subtilis . The observed changes in activity are accompanied by changes in the 3D structures of isomers as determined by 2D nuclear magnetic resonance spectroscopy.
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Skin peptide and cDNA profiling of Australian anurans: Genus and species identification and evolutionary trends
Peptides, 2010Co-Authors: Rebecca J. Jackway, Tara L. Pukala, Stephen C. Donnellan, Patrick J. Sherman, Michael J. Tyler, John H. BowieAbstract:Host defense peptides of 35 species of Australian frogs from the hylids Cyclorana and Litoria, and the myobatrachids Crinia, Limnodynastes and Uperoleia have been identified. The biological activities of the majority of these peptides have been determined and include hormones, neuropeptides, opioids, immunomodulators, membrane active peptides [including antimicrobial, anticancer, antiviral (enveloped viruses like HIV and Herpes) and antifungal peptides], neuronal nitric oxide synthase inhibitors, pheromones and individual peptides with other specific activities. The host defense peptide skin profile can be diagnostic at both the species and higher taxonomic levels; for example, species of Crinia, Litoria and Uperoleia each produce quite different types of peptides. Species of Cyclorana and Limnodynastes are more difficult to characterize by skin peptides alone: species of both genera produce similar peptides with no apparent activity. The skin peptide profiles of frogs from the genera Crinia, Litoria and Uperoleia may be used together with morphological and cognate methods, to differentiate between sub-species and even different population clusters of the same species. Nucleotide sequencing of cDNAs of precursors (pre-pro peptides) of bioactive peptides from the skin glands of various species of the genus Litoria show that the majority of these peptides originated from a single ancestor gene before the break away of Australia from Gondwana. The exceptions are the caerulein neuropeptides {e.g. caerulein [pEQDY(SO3H)TGWMDF(NH2)]} which have a different origin to that of other Litoria peptides. Disulfide containing peptides from skin glands of species of Crinia show a different evolutionary route to peptides from species of Litoria.
Martin A. Dziminski - One of the best experts on this subject based on the ideXlab platform.
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Intraspecific Competition in the Larvae of Quacking Frogs (Crinia georgiana)
Copeia, 2009Co-Authors: Martin A. DziminskiAbstract:Abstract Intraspecific competition during the larval stage has important consequences on growth and development resulting in fitness loss at higher densities in many anuran species. Larvae of Crinia georgiana can complete metamorphosis without feeding, which may make the effects of intraspecific competition potentially less significant in this species. The aim of this experiment was to determine if intraspecific competition occurs and results in fitness loss in larvae of C. georgiana. Larvae were raised at high and low densities in mesocosms in the laboratory that simulated natural ponds in the field. Offspring at higher densities metamorphosed at significantly smaller sizes and suffered higher mortality rates than larvae in the low density treatment. Despite this species possessing an egg with a large yolk content in comparison to most anuran species with exotrophic larvae, and having the ability to complete metamorphosis without feeding, intraspecific competition results in important density dependent f...
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Fitness consequences of parental compatibility in the frog Crinia georgiana.
Evolution; international journal of organic evolution, 2008Co-Authors: Martin A. Dziminski, J. Dale Roberts, Leigh W SimmonsAbstract:Theory suggests that multiple mating by females can evolve as a mechanism for acquiring compatible genes that promote offspring fitness. Genetic compatibility models predict that differences in fitness among offspring arise from interactions between male and female haplotypes. Using a cross-classified breeding design and in vitro fertilization, we raised families of maternal and paternal half-siblings of the frog Crinia georgiana, a species with a polyandrous breeding system and external fertilization. After controlling for variation in maternal provisioning, we found significant effects of interacting parental haplotypes on fertilization success, and nonadditive genetic effects on measures of offspring fitness such as embryo survival, and survival to, size at, and time to metamorphosis. Additive genetic variation due to males and females was negligible, and not statistically significant for any of the fitness traits measured. Combinations of parental haplotypes that resulted in high rates of fertilization produced offspring with higher embryo survival and rapid juvenile development. We suggest that a gamete recognition mechanism for selective fertilization by compatible sperm may promote offspring fitness in this system.
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Fitness consequences of variable maternal provisioning in quacking frogs (Crinia georgiana).
Journal of evolutionary biology, 2006Co-Authors: Martin A. Dziminski, J.d. RobertsAbstract:Variable maternal provisioning may evolve when there is variation in the quality of offspring environments. The frog Crinia georgiana has high variability in egg size both within and between clutches, independent of female phenotype. It breeds in ponds with high spatial and temporal variation in habitat quality. Egg size strongly affected offspring fitness in good and poor quality offspring environments, whether the egg size difference was from between or within clutches. Since there is a trade-off in egg size and number, these fitness consequences translate to strong effects on maternal fitness. In the variable and unpredictable offspring environment of C. georgiana, the maintenance of variable maternal provisioning both within and between clutches is likely to be an evolved response to the offspring environment.