Rebecca Vaught | Monash University (original) (raw)
Papers by Rebecca Vaught
Evolutionary theory predicts maternal inheritance of the mitochondria will lead to the accumulati... more Evolutionary theory predicts maternal inheritance of the mitochondria will lead to the accumulation of mutations in the mitochondrial DNA (mtDNA) that impair male fertility, but leave females unaffected. The hypothesis has been referred to as 'Mother's Curse'. There are many examples of mtDNA mutations or haplotypes, in humans and other metazoans, associated with decreases in sperm performance, but seemingly few reports of associations involving female reproductive traits; an observation that has been used to support the Mother's Curse hypothesis. However, it is unclear whether apparent signatures of male bias in mitochondrial genetic effects on fertility reflect an underlying biological bias or a technical bias resulting from a lack of studies to have screened for female effects. Here, we conduct a systematic literature search of studies reporting mitochondrial genetic effects on fertility-related traits in gonochoristic metazoans (animals with two distinct sexes). Studies of female reproductive outcomes were sparse, reflecting a large technical sex bias across the literature. We were only able to make a valid assessment of sex specificity of mitochondrial genetic effects in 30% of cases. However, in most of these cases, the effects were male biased, including examples of male bias associated with mtDNA mutations in humans. These results are therefore consistent with the hypothesis that maternal inheritance has enriched mtDNA sequences with mutations that specifically impair male fertility. However, future research that redresses the technical imbalance in studies conducted per sex will be key to enabling researchers to fully assess the wider implications of the Mother's Curse hypothesis to male reproductive biology. Reproduction (2018) 155 R159–R168
The Biological bulletin, 2015
Larvae in aquatic habitats often develop in environments different from those they inhabit as adu... more Larvae in aquatic habitats often develop in environments different from those they inhabit as adults. Shrimp in the Atyidae exemplify this trend, as larvae of many species require salt or brackish water for development, while adults are freshwater-adapted. An exception within the Atyidae family is the "anchialine clade," which are euryhaline as adults and endemic to habitats with subterranean fresh and marine water influences. Although the Hawaiian anchialine atyid Halocaridina rubra is a strong osmoregulator, its larvae have never been observed in nature. Moreover, larval development in anchialine species is poorly studied. Here, reproductive trends in laboratory colonies over a 5-y period are presented from seven genetic lineages and one mixed population of H. rubra; larval survivorship under varying salinities is also discussed. The presence and number of larvae differed significantly among lineages, with the mixed population being the most prolific. Statistical differe...
Journal of Crustacean Biology, 2014
Color variation among and within crustacean species is primarily due to morphological and physiol... more Color variation among and within crustacean species is primarily due to morphological and physiological differences in specialized cells called chromatophores. Within Atyidae, individuals of Halocaridina rubra Holthuis, 1963, which is endemic to anchialine habitats (coastal ponds of mixohaline water under marine and terrestrial influences) of the Hawaiian Islands, range from bright red to nearly translucent in color. While H. rubra encompasses (at least) eight genetically diverged lineages based on analyses of mitochondrial genes, whether this phenotypic variation in coloration correlates to genetic background or if it statistically differs between lineages is unknown. Furthermore, if such properties in H. rubra exhibit plasticity under the environmental extremes that can be encountered in anchialine habitats has not been determined. Using previously published protocols for another atyid species, chromatosomal morphology and chromatic properties were quantified and statistically analyzed from 240 individuals of H. rubra, representing seven of the eight genetic lineages as well as one naturally mixed population (n = 30 per group), maintained under standardized laboratory conditions for >6 years. Analogous analyses were also conducted on animals before and after exposure to environmental extremes, including anoxia, desiccation, decreased salinity and high and low temperatures. Overall, the genetic lineages of H. rubra statistically differed from one another in varying numbers of chromatosomal properties while exposure to environmental extremes also elicited significant changes. Furthermore, these properties statistically differed among body parts of H. rubra in a manner inconsistent with previous studies. Notably, data on chromosomal properties generated via a streamlined protocol were well correlated with those from the previously published approach utilized here, suggesting such analyses for H. rubra (or other crustacean/atyid species) might be successfully conducted under field settings.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2014
Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial... more Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Caveadapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO 2 declined, resulting in a decline in VO 2 during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans.
Evolutionary theory predicts maternal inheritance of the mitochondria will lead to the accumulati... more Evolutionary theory predicts maternal inheritance of the mitochondria will lead to the accumulation of mutations in the mitochondrial DNA (mtDNA) that impair male fertility, but leave females unaffected. The hypothesis has been referred to as 'Mother's Curse'. There are many examples of mtDNA mutations or haplotypes, in humans and other metazoans, associated with decreases in sperm performance, but seemingly few reports of associations involving female reproductive traits; an observation that has been used to support the Mother's Curse hypothesis. However, it is unclear whether apparent signatures of male bias in mitochondrial genetic effects on fertility reflect an underlying biological bias or a technical bias resulting from a lack of studies to have screened for female effects. Here, we conduct a systematic literature search of studies reporting mitochondrial genetic effects on fertility-related traits in gonochoristic metazoans (animals with two distinct sexes). Studies of female reproductive outcomes were sparse, reflecting a large technical sex bias across the literature. We were only able to make a valid assessment of sex specificity of mitochondrial genetic effects in 30% of cases. However, in most of these cases, the effects were male biased, including examples of male bias associated with mtDNA mutations in humans. These results are therefore consistent with the hypothesis that maternal inheritance has enriched mtDNA sequences with mutations that specifically impair male fertility. However, future research that redresses the technical imbalance in studies conducted per sex will be key to enabling researchers to fully assess the wider implications of the Mother's Curse hypothesis to male reproductive biology. Reproduction (2018) 155 R159–R168
The Biological bulletin, 2015
Larvae in aquatic habitats often develop in environments different from those they inhabit as adu... more Larvae in aquatic habitats often develop in environments different from those they inhabit as adults. Shrimp in the Atyidae exemplify this trend, as larvae of many species require salt or brackish water for development, while adults are freshwater-adapted. An exception within the Atyidae family is the "anchialine clade," which are euryhaline as adults and endemic to habitats with subterranean fresh and marine water influences. Although the Hawaiian anchialine atyid Halocaridina rubra is a strong osmoregulator, its larvae have never been observed in nature. Moreover, larval development in anchialine species is poorly studied. Here, reproductive trends in laboratory colonies over a 5-y period are presented from seven genetic lineages and one mixed population of H. rubra; larval survivorship under varying salinities is also discussed. The presence and number of larvae differed significantly among lineages, with the mixed population being the most prolific. Statistical differe...
Journal of Crustacean Biology, 2014
Color variation among and within crustacean species is primarily due to morphological and physiol... more Color variation among and within crustacean species is primarily due to morphological and physiological differences in specialized cells called chromatophores. Within Atyidae, individuals of Halocaridina rubra Holthuis, 1963, which is endemic to anchialine habitats (coastal ponds of mixohaline water under marine and terrestrial influences) of the Hawaiian Islands, range from bright red to nearly translucent in color. While H. rubra encompasses (at least) eight genetically diverged lineages based on analyses of mitochondrial genes, whether this phenotypic variation in coloration correlates to genetic background or if it statistically differs between lineages is unknown. Furthermore, if such properties in H. rubra exhibit plasticity under the environmental extremes that can be encountered in anchialine habitats has not been determined. Using previously published protocols for another atyid species, chromatosomal morphology and chromatic properties were quantified and statistically analyzed from 240 individuals of H. rubra, representing seven of the eight genetic lineages as well as one naturally mixed population (n = 30 per group), maintained under standardized laboratory conditions for >6 years. Analogous analyses were also conducted on animals before and after exposure to environmental extremes, including anoxia, desiccation, decreased salinity and high and low temperatures. Overall, the genetic lineages of H. rubra statistically differed from one another in varying numbers of chromatosomal properties while exposure to environmental extremes also elicited significant changes. Furthermore, these properties statistically differed among body parts of H. rubra in a manner inconsistent with previous studies. Notably, data on chromosomal properties generated via a streamlined protocol were well correlated with those from the previously published approach utilized here, suggesting such analyses for H. rubra (or other crustacean/atyid species) might be successfully conducted under field settings.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2014
Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial... more Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Caveadapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO 2 declined, resulting in a decline in VO 2 during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans.