scholarly journals Intralocus conflicts associated with a supergene

2021 ◽  
Author(s):  
Lina Giraldo-Deck ◽  
Jasmine Loveland ◽  
Wolfgang Goymann ◽  
Barbara Tschirren ◽  
Terry Burke ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Reproductive Performance ◽  
Egg Size ◽  
Reproductive Output ◽  
Balancing Selection ◽  
Male Mating ◽  
Captive Population ◽  
Offspring Survival ◽  
Chromosomal Inversions ◽  
Negative Frequency Dependent Selection

Abstract Chromosomal inversions frequently underlie major phenotypic variation maintained by divergent selection within and between sexes. Here we examine whether and how intralocus conflicts contribute to balancing selection stabilizing an autosomal inversion polymorphism in the ruff Calidris pugnax. In this lekking shorebird, three male mating morphs (Independents, Satellites and Faeders) are associated with an inversion-based supergene. We show that in a captive population, Faeder females, who are smaller and whose inversion haplotype has not undergone recombination, have lower average reproductive success in terms of laying rate, egg size and offspring survival than Independent females, who lack the inversion. Satellite females, who carry a recombined inversion haplotype and have intermediate body size, more closely resemble Independent than Faeder females in reproductive performance. We inferred that the lower reproductive output of Faeder females is primarily balanced by higher than average reproductive success of individual Faeder males, driven by negative frequency-dependent selection. These findings suggest that intralocus conflicts may play a major role in the evolution and maintenance of supergene variants.

Overcoming environmental and morphological constraints: egg size and pelvic kinesis in the smallest tortoise, Homopus signatus

2005 ◽  
Vol 83 (10) ◽  
pp. 1343-1352 ◽  
Author(s):  
M D Hofmeyr ◽  
B T Henen ◽  
V J.T Loehr
Keyword(s):  
Body Size ◽  
Southern Africa ◽  
Egg Size ◽  
Reproductive Output ◽  
Selective Advantage ◽  
Arid Environment ◽  
Harsh Environment ◽  
Offspring Survival ◽  
Aridity Gradient ◽  
East West

The small tortoises of southern Africa include the only testudinid taxa that produce single-egg clutches. This group includes the world's smallest tortoise, Homopus signatus (Gmelin, 1789), which inhabits a harsh, arid environment. Climate and body size may influence reproductive output, so we hypothesized that the east–west aridity gradient in southern Africa affects egg and clutch size of the small indigenous tortoises, and that the morphology of H. signatus constrains egg size, preventing the formation of optimal eggs. Here we show that aridity and unpredictable rainfall determine which of these tortoise taxa produce single-egg clutches. Taxa in less predictable environments produce larger eggs relative to body size than do taxa in more predictable environments. Homopus signatus produces the largest egg relative to body size, probably to enhance offspring survival in its harsh environment. Body size, pelvic aperture size, and the narrow anal gap of H. signatus appear to constrain egg size. Despite these constraints, females produce rigid-shelled eggs larger than the pelvic canal and use pelvic kinesis to pass eggs at oviposition; both features are unknown in other chelonians and emphasize the selective advantage of large eggs to H. signatus.

Effects of constant and fluctuating temperatures on egg production in the threespine stickleback (Gasterosteus aculeatus)

1989 ◽  
Vol 67 (6) ◽  
pp. 1599-1602 ◽  
Author(s):  
Vital Boulé ◽  
Gerard J. Fitzgerald
Keyword(s):  
Reproductive Performance ◽  
Egg Production ◽  
Egg Size ◽  
Laboratory Experiments ◽  
Gasterosteus Aculeatus ◽  
Reproduction Number ◽  
Temperature Fluctuations ◽  
Spawning Grounds ◽  
Threespine Sticklebacks ◽  
Fluctuating Temperatures

Female threespine sticklebacks (Gasterosteus aculeatus) spend only 9–15 days on the spawning grounds, an intertidal salt marsh at Isle Verte, Quebec, during a 2-month breeding season. Individuals average only one spawning. However, in the laboratory they lay clutches of several hundred eggs every 3–5 days for several months. We designed laboratory experiments to determine (i) whether daily temperature fluctuations similar to those encountered in the marsh affect reproduction (number of clutches, number of eggs per clutch, and size of eggs) and (ii) whether the amplitude of the fluctuations encountered by the fish affects reproduction. We compared the reproduction of females held in fluctuating temperatures with that of females kept at 20 °C. Fish kept under fluctuating conditions produced more eggs per clutch but had longer interspawning intervals than those at 20 °C. Total seasonal egg production and egg size did not differ between the two groups. Fish in fluctuating temperatures survived longer and were in better condition than those at 20 °C. We conclude that the amplitude of the fluctuations is less important than mean temperature in determining reproductive performance. Fluctuating temperatures on the spawning grounds are not responsible for the short residency there.

Size does not matter for male Marbled Salamanders (Ambystoma opacum)

2015 ◽  
Vol 93 (10) ◽  
pp. 735-740
Author(s):  
D.A. Croshaw ◽  
J.H.K. Pechmann
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Success ◽  
Large Male ◽  
Male Mating ◽  
Ambystoma Opacum ◽  
Positive Assortative Mating ◽  
Important Trait ◽  
Breeding Groups ◽  
Gravid Females

Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.

scholarly journals The effect of pollen source on seed traits and dispersability in the heterocarpic annual Crepis sancta

2020 ◽  
Author(s):  
Efrat Dener ◽  
Hagai Shemesh ◽  
Itamar Giladi
Keyword(s):  
Reproductive Success ◽  
Reproductive Output ◽  
Seed Traits ◽  
Dispersal Strategy ◽  
Physiological Constraints ◽  
Dispersal Traits ◽  
Distant Neighbor ◽  
The Common ◽  
Nonsignificant Effect ◽  
Crepis Sancta

Abstract Aims The evolution and expression of dispersal-related traits are intertwined with those of other life-history functions and are manifested within various physiological constraints. Such a relationship is predicted between inbreeding levels and dispersability, which may be anatomically and ontogenetically linked so that the selection pressures on one may affect the other. While both the effect of inbreeding on reproductive success and on dispersal strategies received much attention, only a few studies considered both simultaneously. Furthermore, such studies often rely on two dichotomic representations of breeding and dispersal: using selfing vs. outcrossing as a representation of breeding level, and dispersal ratio as the sole representation of dispersal strategy. Methods Here we used pollination experiments in the heterocarpic Crepis sancta (Asteraceae) to expand in two different manners on the common practice of using dichotomic representations of breeding and dispersal. First, we used pollination treatments that represent a continuum from selfing through pollination by kin to pollination by a distant neighbor. Second, we measured a whole set of continuous morphological and dispersal-related traits, in addition to measurements of reproductive success and dispersal ratio. Important findings The proportion of developed capitula and the number of both dispersed and non-dispersed achenes were significantly lower in the self-pollination treatment in comparison to the out-crossed treatments. The effect of pollen sources on dispersal ratio was not statistically significant, though self-pollinated plants rarely produced non-dispersing seeds. Achene’s biomass increased with distance between parent plants, but pappus width did not, leading to a nonsignificant effect of pollination on falling velocity. Overall, pollen source affected mainly traits that were associated with reproductive output, but it had no clear effect on predominately dispersal-related traits. Such differences in the response of reproduction and dispersal traits to variation in pollen source suggest that dispersal-related selection is probably weak and/or masked by other forces.

scholarly journals Polygyny and Extra-Pair Paternity in a Population of Southwestern Willow Flycatchers

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 571-578
Author(s):  
Talima Pearson ◽  
Mary J. Whitfield ◽  
Tad C. Theimer ◽  
Paul Keim
Keyword(s):  
Reproductive Success ◽  
Microsatellite Markers ◽  
Mating Strategy ◽  
Male Reproductive Success ◽  
Offspring Survival ◽  
Extra Pair Paternity ◽  
Study Population ◽  
Willow Flycatcher ◽  
Empidonax Traillii ◽  
Disproportionate Number

Abstract Although polygyny can potentially increase male reproductive success, the benefits of this strategy could be offset by losses to extra-pair paternity or reduced offspring survival. We developed microsatellite markers to assess the influence of extra-pair offspring (EPO) on reproductive success and paternity in monogamous and polygynous pairs of the facultatively polygynous Southwestern Willow Flycatcher (Empidonax traillii extimus). Based on genotypes of 140 offspring from 56 clutches over six years, 14% of nestlings in our study population were extra-pair offspring, with 23% of all successful nests containing at least one EPO. We found that polygynous males produced 2.11 ± 0.35 offspring per season, compared to 1.15 ± 0.18 for monogamous males. This increased reproductive success was due primarily to the increased number of nests of polygynous males, as the number of offspring per pair did not differ between monogamous and polygynous males. Twenty of the 140 genotyped nestlings were extra-pair offspring. Sires could be assigned to 16 of these; one polygynous male sired two EPO in one nest, two monogamous males sired eight EPO in two nests, and four nonterritorial males sired six EPO in four nests. Overall, these results indicate that in this population, females of polygynous males did not raise a disproportionate number of EPO as a result of the polygynous mating strategy of their mate, and that both territorial and nonterritorial males sired EPO.

scholarly journals Balancing selection maintains polymorphisms at neurogenetic loci in field experiments

2017 ◽  
Vol 114 (14) ◽  
pp. 3690-3695 ◽  
Author(s):  
Eija Lonn ◽  
Esa Koskela ◽  
Tapio Mappes ◽  
Mikael Mokkonen ◽  
Angela M. Sims ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Population Density ◽  
Arginine Vasopressin ◽  
Field Experiments ◽  
Balancing Selection ◽  
Regulatory Region ◽  
Natural Populations ◽  
Myodes Glareolus ◽  
Sexual Antagonism ◽  
Reproductive Behaviors

Most variation in behavior has a genetic basis, but the processes determining the level of diversity at behavioral loci are largely unknown for natural populations. Expression of arginine vasopressin receptor 1a (Avpr1a) and oxytocin receptor (Oxtr) in specific regions of the brain regulates diverse social and reproductive behaviors in mammals, including humans. That these genes have important fitness consequences and that natural populations contain extensive diversity at these loci implies the action of balancing selection. In Myodes glareolus, Avpr1a and Oxtr each contain a polymorphic microsatellite locus located in their 5′ regulatory region (the regulatory region-associated microsatellite, RRAM) that likely regulates gene expression. To test the hypothesis that balancing selection maintains diversity at behavioral loci, we released artificially bred females and males with different RRAM allele lengths into field enclosures that differed in population density. The length of Avpr1a and Oxtr RRAMs was associated with reproductive success, but population density and the sex interacted to determine the optimal genotype. In general, longer Avpr1a RRAMs were more beneficial for males, and shorter RRAMs were more beneficial for females; the opposite was true for Oxtr RRAMs. Moreover, Avpr1a RRAM allele length is correlated with the reproductive success of the sexes during different phases of reproduction; for males, RRAM length correlated with the numbers of newborn offspring, but for females selection was evident on the number of weaned offspring. This report of density-dependence and sexual antagonism acting on loci within the arginine vasopressin–oxytocin pathway explains how genetic diversity at Avpr1a and Oxtr could be maintained in natural populations.

scholarly journals Negative frequency dependent selection contributes to the maintenance of a global polymorphism in mitochondrial DNA

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Zorana Kurbalija Novičić ◽  
Ahmed Sayadi ◽  
Mihailo Jelić ◽  
Göran Arnqvist
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Variation ◽  
Life History ◽  
Balancing Selection ◽  
Food Resource ◽  
Ecological Processes ◽  
Central Process ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection

Abstract Background Understanding the forces that maintain diversity across a range of scales is at the very heart of biology. Frequency-dependent processes are generally recognized as the most central process for the maintenance of ecological diversity. The same is, however, not generally true for genetic diversity. Negative frequency dependent selection, where rare genotypes have an advantage, is often regarded as a relatively weak force in maintaining genetic variation in life history traits because recombination disassociates alleles across many genes. Yet, many regions of the genome show low rates of recombination and genetic variation in such regions (i.e., supergenes) may in theory be upheld by frequency dependent selection. Results We studied what is essentially a ubiquitous life history supergene (i.e., mitochondrial DNA) in the fruit fly Drosophila subobscura, showing sympatric polymorphism with two main mtDNA genotypes co-occurring in populations world-wide. Using an experimental evolution approach involving manipulations of genotype starting frequencies, we show that negative frequency dependent selection indeed acts to maintain genetic variation in this region. Moreover, the strength of selection was affected by food resource conditions. Conclusions Our work provides novel experimental support for the view that balancing selection through negative frequency dependency acts to maintain genetic variation in life history genes. We suggest that the emergence of negative frequency dependent selection on mtDNA is symptomatic of the fundamental link between ecological processes related to resource use and the maintenance of genetic variation.

scholarly journals Multi-Farm Analyses Indicate a Novel Boar Pheromone Improves Sow Reproductive Performance

Animals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 37
Author(s):  
John McGlone ◽  
Arlene Garcia ◽  
Anoosh Rakhshandeh
Keyword(s):  
Reproductive Success ◽  
Reproductive Performance ◽  
Cost Effective ◽  
Experimental Unit ◽  
Commercial Farm ◽  
Treatment Interaction ◽  
And Performance ◽  
Meta Analyses

The objective of this study was to examine the effectiveness of a novel 3-molecule boar pheromone (BOARBETTER®, BB,) to improve sow reproductive performance (breeding, conception, farrowing rates, pigs born alive, stillborn, mummies and total born). Data from 12 commercial farm sites were used to evaluate the effectiveness of BB. Each farm was used as the experimental unit in the meta-analyses. Individual sows records were collected, merged and analyzed in overall analyses. Relative to CON, BB increased the number of total born pigs per litter (13.81 ± 0.11 vs. 14.30 ± 0.11 pigs/litter, respectively; p < 0.01) and the number of pigs born alive (12.76 ± 0.14 vs. 13.13 ± 0.14 pigs/litter, respectively; p < 0.05). In the merged dataset analyses, the parity by treatment interaction was significant for total pigs and pigs born alive per litter (p < 0.01). In parities one through three, treatment with BB increased total pigs born by 0.88 per litter, and pigs born alive per litter by 0.73 pigs per litter (p < 0.05). However, BB had no effect on these parameters in sows from parities four through six. BOARBETTER® increased reproductive success, is cost effective, safe, and can meaningfully improve sow reproductive success and performance.

Annual Reproductive Yield in the Cooperative Pygmy Nuthatch (Sitta pygmaea)

The Auk ◽  
1988 ◽  
Vol 105 (1) ◽  
pp. 70-77 ◽  
Author(s):  
William J. Sydeman ◽  
Marcel Güntert ◽  
Russell P. Balda
Keyword(s):  
Reproductive Success ◽  
Cooperative Breeding ◽  
Reproductive Output ◽  
Breeding Birds ◽  
Overwinter Survival ◽  
Northern Arizona ◽  
Floral Diversity ◽  
Indirect Fitness ◽  
The Difference ◽  
The Relationship

Abstract We studied cooperative-breeding Pygmy Nuthatches (Sitta pygmaea) for 4 yr in northern Arizona. Breeding units contained 2-5 birds. Helpers were found at about 30% of all nests. All helpers that later bred on the study area were male. Helpers were mostly yearlings, and offspring or siblings of the birds that they aided, but often aided at least one unrelated breeder. Breeding units with helpers produced significantly more young than those without helpers. Breeding units in habitats with the greatest floral diversity and structural maturity fledged significantly more young than those in other habitats. Habitat did not influence the effect of helpers. Year effects increased the strength of the relationship between helpers and annual reproductive output. Previous breeding experience and pair-bond duration were not related to reproductive success. Total brood loss, although rare, was responsible for the difference in reproductive output among pairs with and without helpers and between habitats. Breeding birds with helpers benefit by an increase in direct fitness. The advantage to the helpers is not clear but may be an increase in indirect fitness associated with aiding relatives. Helpers may benefit directly, however, by sharing roosting cavities on a group territory thereby enhancing overwinter survival.

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