Unexpected long-term changes in chromosome inversion frequencies in a Neotropical Drosophila species

Abstract

Several long-term studies on Drosophila chromosome inversion polymorphisms have shown that inversions can be a valuable tool to monitor rapid genetic shifts with climate change. However, so far, no study has assessed the effects of climate change in populations of Neotropical Drosophila species. After more than 2 decades, new samples were collected from the Parque Nacional do Itatiaia, Rio de Janeiro, to assess any changes in inversion frequencies and to detect possible global warming effects on the inversion polymorphism of the second chromosome of D. mediopunctata. Our results show unexpected simultaneous changes in inversion frequencies associated with climate change. Perhaps climatic variables other than temperature underlying the process caused such change, although potential genetic drift effects or demographic factors cannot be excluded. Further studies assessing population genetic structure may help clarify the changes observed.

Comparative analysis of adaptive and neutral markers ofDrosophila mediopunctatapopulations dispersed among forest fragments

“…We could not find a consistent pattern of geographical variation for any microsatellite locus. In contrast, inversion polymorphism showed clinal variations congruent with previous findings (Ananina et al, ; Batista et al, ). This highlights that for a complete understanding of how the fragmentation process is affecting a species, studies should be carried out using different genetic markers to evaluate the joint effects of natural selection, migration and genetic drift.…”

“…Surprisingly, we found a strong and significant correlation between DI and longitude ( r = − 0.95) as shown in Table . This gene arrangement also showed significant correlation with altitude in samples of 2007–2010 from the Itatiaia population (Batista et al, ). The biological meaning of this correlation is an open question that should be further analyzed, perhaps involving biotic factors.…”

“…However, it also could be caused by drastic changes in thermal regime associated with forest fragmentation process—the monthly average temperature for April 2007 was 24.1°C; while for June 2008 was 18.8°C. This difference in thermal regime may induce a seasonal cycle of inversion DA, since this inversion showed a seasonal cycle in IT population since the 1980s (Ananina et al, ; Batista et al, ).…”

“…They allow insights on the action of natural selection in both natural and laboratory populations by monitoring inversion frequency shifts (Dobzhansky, ; Dobzhansky & Levene, ). These shifts in natural populations are often associated with seasonal (Wellenreuther, Rosenquist, Jaksons, & Larson, ) and long‐term variation (Batista, Ananina, & Klaczko, ; Etges, Arbckle, & Levitan, ; Orengo, Puerma, & Aguadé, ). Similarly, assessing geographical variation one can unveil patterns, which might be interpreted as prima facie evidence of natural selection (Ayala et al, ; Simões, Calabria, Picão‐Osório, Balanyà, & Pascual, ).…”

Drosophila Chromosomal Polymorphism: From Population Aspects to Origin Mechanisms of Inversions

“…Considering the climatic changes that occurred during these two decades in the region of Itatiaia Park, this suggest that temperature change has little influence on the seasonal changes in the frequencies of inversions in this species. Climate changes may have affected other genetic or morphological features, which may be more directly related to the inversions in chromosome II of D. mediopunctata [23][24][25][26].…”