scholarly journals Seasonal changes in recombination rate, crossover interference, and their response to desiccation stress in a natural population of Drosophila melanogaster from India

2020 ◽  
Author(s):  
Dau Dayal Aggarwal ◽  
Sviatoslav Rybnikov ◽  
Shaul Sapielkin ◽  
Eugenia Rashkovetsky ◽  
Zeev Frenkel ◽  
...  
Keyword(s):  
Desiccation Tolerance ◽  
Recombination Rate ◽  
Seasonal Changes ◽  
Life History Traits ◽  
Seasonal Adaptation ◽  
Crossover Interference ◽  
Abiotic Stressors ◽  
Evolutionary Force ◽  
Short Period ◽  
Independent Marker

AbstractEnvironmental seasonality is a potent evolutionary force, capable to maintain polymorphism, promote phenotypic plasticity, and cause bet-hedging. In Drosophila, it has been reported to affect life-history traits, tolerance to abiotic stressors, and immunity. Oscillations in frequencies of alleles underlying fitness-related traits were also documented alongside SNP alleles across genome. Here, we test for seasonal changes in recombination in a natural D. melanogaster population from India using morphological markers of the three major chromosomes. We show that winter flies (collected after the dry season) have significantly higher desiccation tolerance than their autumn counterparts. This difference proved to hold also for hybrids with three independent marker stocks, suggesting its genetic rather than plastic nature. Significant segment-specific changes are documented for recombination rate (in five of 13 intervals) and crossover interference (in five of 16 studied pairs of intervals); both single- and double-crossover rates tended to increase in the winter cohort. The winter flies also display weaker plasticity of recombination characteristics to desiccation. We ascribe the observed differences to indirect selection on recombination caused by directional selection on desiccation tolerance. Our findings suggest that changes in recombination can arise even after a short period of seasonal adaptation (~8–10 generations).

scholarly journals Evolution of the Yeast Recombination Landscape

2018 ◽  
Vol 36 (2) ◽  
pp. 412-422 ◽  
Author(s):  
Haoxuan Liu ◽  
Calum J Maclean ◽  
Jianzhi Zhang
Keyword(s):  
Recombination Rate ◽  
Yeast Species ◽  
Evolutionary Conservation ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Crossover Interference ◽  
Recombination Hotspots ◽  
Genomic Landscape ◽  
Evolutionarily Conserved ◽  
Cold Spots

Abstract Meiotic recombination comprises crossovers and noncrossovers. Recombination, crossover in particular, shuffles mutations and impacts both the level of genetic polymorphism and the speed of adaptation. In many species, the recombination rate varies across the genome with hot and cold spots. The hotspot paradox hypothesis asserts that recombination hotspots are evolutionarily unstable due to self-destruction. However, the genomic landscape of double-strand breaks (DSBs), which initiate recombination, is evolutionarily conserved among divergent yeast species, casting doubt on the hotspot paradox hypothesis. Nonetheless, because only a subset of DSBs are associated with crossovers, the evolutionary conservation of the crossover landscape could differ from that of DSBs. Here, we investigate this possibility by generating a high-resolution recombination map of the budding yeast Saccharomyces paradoxus through whole-genome sequencing of 50 meiotic tetrads and by comparing this recombination map with that of S. cerevisiae. We observe a 40% lower recombination rate in S. paradoxus than in S. cerevisiae. Compared with the DSB landscape, the crossover landscape is even more conserved. Further analyses indicate that the elevated conservation of the crossover landscape is explained by a near-subtelomeric crossover preference in both yeasts, which we find to be attributable at least in part to crossover interference. We conclude that the yeast crossover landscape is highly conserved and that the evolutionary conservation of this landscape can differ from that of the DSB landscape.

scholarly journals Dynamics of recombination modifiers caused by cyclical selection: Interaction of forced and auto-oscillations

1998 ◽  
Vol 72 (2) ◽  
pp. 135-147 ◽  
Author(s):  
A. B. KOROL ◽  
V. M. KIRZHNER ◽  
E. NEVO
Keyword(s):  
Recombination Rate ◽  
Domain Of Attraction ◽  
Forced Oscillations ◽  
Modifier Locus ◽  
Long Period ◽  
Short Period ◽  
Fixed Parameter ◽  
Key Factor ◽  
Limiting Behaviour ◽  
Selection For

Temporally varying selection is considered to be one of the potential mechanisms of recombination evolution. We found earlier that simple cyclical selection for a trait controlled by multiple additive, dominant or semi-dominant loci can result in extremely complex limiting behaviour (CLB) of population trajectories, including ‘supercycles’ and more complex attractors. Recombination rate proved to be a key factor affecting the mode of CLB and the very existence of CLB. Therefore, we considered here a generalized model: the fixed recombination rate was replaced by a polymorphic recombination modifier. The modifier-dependent changes included: (a) supercyclical dynamics due to the recombination modifier in a system that does not manifest CLB when recombination rate is a fixed parameter; (b) appearance of a new level of superoscillations (super-supercycles) in a system that manifests supercycles with a fixed modifier; (c) chaotization of the regular supercyclical dynamics. The domain of attraction of these movements appeared to be quite large. It is noteworthy that the modifier locus is an active participant in the observed non-monotonic limiting movements. Interactions between short-period forced oscillations and the revealed long-period auto-oscillations appeared to result in new regimes of recombination evolution (for some range of linkage between the modifier locus and the selected system), as compared with those caused by the forced oscillations alone.

Effect of early weaning at about 30 days after farrowing on the reproductive characteristics in gilts and sows

1969 ◽  
Vol 72 (2) ◽  
pp. 247-250 ◽  
Author(s):  
Hirokazu Shimizu ◽  
Saburo Takeuchi
Keyword(s):  
Seasonal Changes ◽  
Average Weight ◽  
Early Weaning ◽  
Reproductive Characteristics ◽  
Short Period ◽  
Heat Period

SUMMARYRecords have been analysed from a small herd in which early weaning was practised. Piglets were weaned when average weight was 7–8 kg, at about 30 days old. Decreased feeding of sows, followed by a short period of fasting, was practised at weaning.Mean duration of suckling was 31·5 days and mean interval from weaning to oestrus 6·0 days. 93% of sows conceived to service at the first or second heat period. Mean farrowing interval for all sows was 159·7 days (151·9 days for those holding to the first service). Corresponding annual farrowing frequencies, calculated from these figures, are 2·29 and 2·40.Litter sizes at birth and at weaning were 10·7 and 9·3; corresponding weights of piglets were 1·74 and 7·99 kg. With increase of litter sequence there was a significant decrease of weaning weights; however, there was also an increase in size of litter weaned. Seasonal changes of piglet weight were also found. Early weaning can be considered a useful way to increase production.

scholarly journals Maternal age alters recombination rate in Drosophila pseudoobscura

2020 ◽  
Author(s):  
Keeley A. Pownall ◽  
Hannah N. Taylor ◽  
Ulku H. Altindag ◽  
Laurie S. Stevison
Keyword(s):  
Recombination Rate ◽  
Maternal Age ◽  
Large Scale ◽  
Recombination Analysis ◽  
Recombination Rates ◽  
Crossover Interference ◽  
Choice Of Treatment ◽  
Set Up ◽  
First Time ◽  
Time Point

AbstractAs individuals senesce, factors correlated with fitness, such as fecundity and longevity, decline. Increased age also alters recombination rates in a variety of taxa. Changes in individual recombination rate, or ‘recombination rate plasticity’, can increase meiotic errors. In Drosophila melanogaster, multiple studies on maternal age and recombination rate have found a characteristic pattern where rates initially increase, then decrease, then increase again relative to controls. Here, this phenomenon was investigated in D. pseudoobscura. First, fecundity and survivorship were investigated to guide the choice of treatment age. Then, a large-scale recombination analysis (N=23,559) was set up using three X-linked phenotypic markers. Recombination rate differences in two genomic intervals were measured in females aged to 7 days (control) and 35 days (selected treatment age) prior to mating, with progeny collection continuing for 12 days post-mating in 72 hour timepoints. Results revealed a 3.39% increase in recombination rate due to maternal age (p=0.025), for the first 72 hour time point in one of the two marker intervals. For both genomic intervals, recombination rates were higher in the age treatment for the first time point and lower in later time points of the experiment. Next, these data were used to investigate crossover interference, which decreased with maternal age in the first time point and increased in the last time point. Overall, these results suggest that the mechanisms responsible for recombination rate plasticity may differ between maternal age and stressors, such as temperature.

scholarly journals Hybridization affects life-history traits and host specificity in Diorhabda spp

2017 ◽  
Author(s):  
E.V. Bitume ◽  
D. Bean ◽  
A.R. Stahlke ◽  
R.A. Hufbauer
Keyword(s):  
Biological Control ◽  
Life History ◽  
Host Specificity ◽  
Life History Traits ◽  
Evolutionary Process ◽  
Control Program ◽  
Cross Hybridization ◽  
Evolutionary Force ◽  
Two Generations ◽  
Adult Mass

AbstractHybridization is an influential evolutionary process that has been viewed alternatively as an evolutionary dead-end or as an important creative evolutionary force. In colonizing species, such as introduced biological control agents, hybridization can negate the effects of bottlenecks and genetic drift through increasing genetic variation. Such changes could be beneficial to a biological control program by increasing the chances of establishment success. However, hybridization can also lead to the emergence of transgressive phenotypes that could alter host specificity; an important consideration when assessing potential non-target impacts of planned agents. In a series of lab experiments, we investigated the effects of hybridization between three species of Diorhabda released to control invasive Tamarix (saltcedar) on life history traits through two generations, and through the third generation for one cross. Depending on the cross, hybridization had either a positive or neutral impact on development time, adult mass, and fecundity. We evaluated preference for the target (saltcedar) relative to a non-target host Tamarixaphylla (athel), and found host specificity patterns varied in two of the three hybrids, demonstrating the possibility for hybridization to alter host preference. Importantly, the overall effects of hybridization were inconsistent by cross, leading to unpredictability in the outcome of using hybrids in biological control.

scholarly journals Photoperiod-Induced Neuroplasticity in the Circadian System

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Alessandra Porcu ◽  
Malini Riddle ◽  
Davide Dulcis ◽  
David K. Welsh
Keyword(s):  
Seasonal Changes ◽  
Phase Distribution ◽  
Light Exposure ◽  
Brain Regions ◽  
Day Length ◽  
Light Conditions ◽  
Seasonal Adaptation ◽  
Circadian Oscillators ◽  
Plastic Changes ◽  
Mood And Cognition

Seasonal changes in light exposure have profound effects on behavioral and physiological functions in many species, including effects on mood and cognitive function in humans. The mammalian brain’s master circadian clock, the suprachiasmatic nucleus (SCN), transmits information about external light conditions to other brain regions, including some implicated in mood and cognition. Although the detailed mechanisms are not yet known, the SCN undergoes highly plastic changes at the cellular and network levels under different light conditions. We therefore propose that the SCN may be an essential mediator of the effects of seasonal changes of day length on mental health. In this review, we explore various forms of neuroplasticity that occur in the SCN and other brain regions to facilitate seasonal adaptation, particularly altered phase distribution of cellular circadian oscillators in the SCN and changes in hypothalamic neurotransmitter expression.

scholarly journals Desiccation-induced changes in recombination rate and crossover interference in Drosophila melanogaster: evidence for fitness-dependent plasticity

Genetica ◽  
2019 ◽  
Vol 147 (3-4) ◽  
pp. 291-302 ◽  
Author(s):  
Dau Dayal Aggarwal ◽  
Sviatoslav Rybnikov ◽  
Irit Cohen ◽  
Zeev Frenkel ◽  
Eugenia Rashkovetsky ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Recombination Rate ◽  
Crossover Interference ◽  
Dependent Plasticity ◽  
Induced Changes

scholarly journals Desiccation-induced changes in recombination rate and crossover interference in Drosophila melanogaster: evidence for fitness-dependent plasticity

2018 ◽  
Author(s):  
Dau Dayal Aggarwal ◽  
Sviatoslav R. Rybnikov ◽  
Irit Cohen ◽  
Zeev Frenkel ◽  
Eugenia Rashkovetsky ◽  
...  
Keyword(s):  
Recombination Rate ◽  
Theoretical Models ◽  
Pericentromeric Region ◽  
Chromosome 3 ◽  
Crossover Interference ◽  
Stress Effects ◽  
Response To Stress ◽  
Specific Increase ◽  
Induced Changes ◽  
Benefits And Costs

ABSTRACTMeiotic recombination is evolutionarily ambiguous, as being associated with both benefits and costs to its bearers, with the resultant dependent on a variety of conditions. While existing theoretical models explain the emergence and maintenance of recombination, some of its essential features remain underexplored. Here we focus on one such feature, recombination plasticity, and test whether recombination response to stress is fitness-dependent. We compare desiccation stress effects on recombination rate and crossover interference in chromosome 3 between desiccation-sensitive and desiccation-tolerant Drosophila lines. We show that relative to desiccation-tolerant genotypes, desiccation-sensitive genotypes exhibit a significant segment-specific increase in single- and double-crossover frequencies across the pericentromeric region of chromosome 3. Significant changes (relaxation) in crossover interference were found for the interval pairs flanking the centromere and extending to the left arm of the chromosome. These results indicate that desiccation is a recombinogenic factor and that desiccation-induced changes in both recombination rate and crossover interference are fitness-dependent, with a tendency of less fitted individuals to produce more variable progeny. Such a dependence may play an important role in the regulation of genetic variation in populations experiencing environmental challenges.

scholarly journals Broad geographic sampling reveals the shared basis and environmental correlates of seasonal adaptation in Drosophila

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Heather E Machado ◽  
Alan Bergland ◽  
Ryan W Taylor ◽  
Susanne Tilk ◽  
Emily Behrman ◽  
...  
Keyword(s):  
Allele Frequency ◽  
Weather Conditions ◽  
Frequency Change ◽  
Fluctuating Selection ◽  
Seasonal Adaptation ◽  
Environmental Correlates ◽  
Chromosomal Inversions ◽  
Genome Wide ◽  
Evolutionary Force ◽  
Genomic Response

To advance our understanding of adaptation to temporally varying selection pressures, we identified signatures of seasonal adaptation occurring in parallel among Drosophila melanogaster populations. Specifically, we estimated allele frequencies genome-wide from flies sampled early and late in the growing season from 20 widely dispersed populations. We identified parallel seasonal allele frequency shifts across North America and Europe, demonstrating that seasonal adaptation is a general phenomenon of temperate fly populations. Seasonally fluctuating polymorphisms are enriched in large chromosomal inversions and we find a broad concordance between seasonal and spatial allele frequency change. The direction of allele frequency change at seasonally variable polymorphisms can be predicted by weather conditions in the weeks prior to sampling, linking the environment and the genomic response to selection. Our results suggest that fluctuating selection is an important evolutionary force affecting patterns of genetic variation in Drosophila.

scholarly journals Physiological and life history changes associated with seasonal adaptation in the cactophilic Drosophila mojavensis

2021 ◽  
Author(s):  
Tierney M Shaible ◽  
Luciano M Matzkin
Keyword(s):  
Life History ◽  
Stress Resistance ◽  
Seasonal Changes ◽  
Sonoran Desert ◽  
Drosophila Mojavensis ◽  
Seasonal Adaptation ◽  
Cactophilic Drosophila ◽  
Single Generation ◽  
Multiple Generations ◽  
Larval Stages

Many insects inhabiting temperate climates are faced with changing environmental conditions throughout the year. Depending on the species, these environmental fluctuations can be experienced within a single generation or across multiple generations. Strategies for dealing with these seasonal changes vary across populations. Drosophila mojavensis is a cactophilic Drosophila species endemic to the Sonoran Desert. The Sonoran Desert regularly reaches temperatures of 50°C in the summer months. As individuals of this population are rare to collect in the summer months, we therefore simulated in a temperature and light controlled chamber the cycling temperatures experienced by D. mojavensis in the Sonoran Desert from April to July (four generations) to understand the physiological and life history changes that allow this population to withstand these conditions. In contrast to our hypothesis of a summer aestivation, we found that D. mojavensis continue to reproduce during the summer months, albeit with lower viability, but the longevity of the population is highly reduced during this period. As expected, stress resistance increased during the summer months in both the adult and the larval stages. This study examines several strategies for withstanding the Sonoran Desert summer conditions which may be informative in the study of other desert endemic species.

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