ABSTRACT
The environment is changing faster than anticipated due to climate change, making species more vulnerable to its impacts. The level of vulnerability of species is influenced by factors such as the degree and duration of exposure, as well as the physiological sensitivity of organisms to changes in their environments, which has been shown to vary among species, populations, and individuals. Here, we compared physiological changes in fecundity, critical thermalmaximum (CTmax), respiratory quotient (RQ), and DNA damage in ovaries in response to temperature stress in two species of fruit fly, Drosophila melanogaster (25 vs. 29.5 °C) and Drosophila pseudoobscura (20.5 vs. 25 °C). The fecundity of D. melanogaster was more affected by high temperatures when exposed during egg through adult development, while D. pseudoobscura was most significantly affected when exposed to high temperatures exclusively during egg through pupal development. Additionally, D. melanogaster males exhibited a decrease of CTmax under high temperatures, while females showed an increase of CTmax when exposed to high temperatures during egg through adult development. while D. pseudoobscura females and males showed an increased CTmax only when reared at high temperatures during egg through pupae development. Moreover, both species showed an acceleration in oogenesis and an increase in apoptosis due to heat stress. These changes can likely be attributed to key differences in the geographic range, thermal range, development time, and other different factors between these two systems. Through this comparison of variation in physiology and developmental response to thermal stress, we found important differences between species and sexes that suggest future work needs to account for these factors separately in understanding the effects of constant increased temperatures.
Subject(s)
Drosophila melanogaster , Drosophila , Humans , Male , Female , Animals , Drosophila melanogaster/physiology , Drosophila/physiology , Temperature , Fertility , Heat-Shock ResponseABSTRACT
BACKGROUND: As in other model organisms, genetic background in the non-human primates Macaca mulatta and Macaca fascicularis is an experimental variable that affects the response of other study variables. Genetic background in model organisms is manipulated by breeding schemes but is generally pre-determined by the source population used to found captive stocks. In M. fascicularis three such sources have been distinguished, however, these are not routinely taken into consideration when designing research. METHODS: We exemplify a mitochondrial DNA (mtDNA)-based strategy to trace the maternal geographic origins of M. fascicularis animals of unspecified origins. RESULTS: Macaca fascicularis of unspecified origins kept at primate research centers carry mtDNA haplotypes representing all three major genetic subdivisions. CONCLUSIONS: We suggest that the genetic background of study animals could be better specified in the future using an mtDNA-based approach, which would enable informed selection of study animals and help reduce variation within and among studies.
Subject(s)
Macaca fascicularis/genetics , Macaca mulatta/genetics , Amino Acid Sequence , Animals , Asia, Southeastern , Base Sequence , DNA, Mitochondrial/chemistry , DNA, Mitochondrial/genetics , Female , Genetic Variation , Haplotypes , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction/veterinary , RNA, Ribosomal/chemistry , RNA, Ribosomal/genetics , RNA, Ribosomal, 16S/chemistry , RNA, Ribosomal, 16S/genetics , RNA, Transfer, Val/chemistry , RNA, Transfer, Val/genetics , Sequence AlignmentABSTRACT
In Drosophila melanogaster and Drosophila simulans, positive Darwinian selection drives high rates of evolution of male reproductive genes, and accessory gland proteins (Acps) in particular. Here, we tested whether 13 X-linked male-specific genes, 4 Acps and 9 non-Acps, are under selective forces in the Drosophila pseudoobscura species group, much as those in the D. melanogaster group. We observed a statistically significant correlation in relative rates of nonsynonymous evolution between the two species groups tested. One Acp examined had a higher rate of nonsynonymous substitution than predicted by a neutral model in both species groups, suggesting its divergence was driven by positive Darwinian selection. To further test for the signature of selection, we examined polymorphism of three Acps within D. pseudoobscura. From this test, no Acp individually bore the signature of positive selection, but the 3 Acps together possessed an excess of nonsynonymous differences between species, relative to polymorphism within species. We conclude that faster evolution of Acps in the D. pseudoobscura group appears to be driven by positive selection, as previously suggested in the D. melanogaster group.
