divergent selection
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Sexual selection plays a key role in the diversification of numerous animal clades and may accelerate trait divergence during speciation. However, much of our understanding of this process comes from phylogenetic comparative studies, which rely on surrogate measures such as dimorphism that may not represent selection in wild populations. In this study, we assess sexual selection pressures for multiple male visual signals across four barn swallow (Hirundo rustica) populations. Our sample encompassed 2400 linear km and two described subspecies: European H. r. rustica (in the Czech Republic and Romania) and eastern Mediterranean H. r. transitiva (in Israel), as well as a potential area of contact (in Turkey). We demonstrate significant phenotypic differentiation in four sexual signalling axes, despite very low-level genomic divergence and no comparable divergence in an ecological trait. Moreover, the direction of phenotypic divergence is consistent with differences in sexual selection pressures among subspecies. Thus, H. r. transitiva, which have the darkest ventral plumage of any population, experience directional selection for darker plumage. Similarly, H. r. rustica, which have the longest tail feathers of any population, experience directional selection for elongated tail feathers and disruptive selection for ventral plumage saturation. These results suggest that sexual selection is the primary driver of phenotypic differentiation in this species. Our findings add to growing evidence of phenotypic divergence with gene flow. However, to our knowledge, this is the first study to relate direct measures of the strength and targets of sexual selection to phenotypic divergence among closely related wild populations.
- MeSH
- fenotyp MeSH
- fylogeneze * MeSH
- sexuální výběr u zvířat * MeSH
- tok genů * MeSH
- vlaštovkovití * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- Izrael MeSH
- Rumunsko MeSH
1. Changes in embryonic development and growth were analysed in relation to direct changes in postnatal growth and correlated responses in egg parameters using Japanese quail lines selected for more than 30 generations for high (HG) and low (LG) relative gain of body weight (BW) between 11 and 28 d of age, and constant BW at 49 d of age. 2. During the first 42 h as well as at the end of incubation, LG embryos were developmentally accelerated in comparison with their HG counterparts. An expected increase of line divergence across generations was observed only in traits analysed at the end of incubation. 3. In contrast to early generations, LG embryos continuously exhibited a higher BW than HG embryos and this difference temporarily disappeared only around incubation d 8. Analogous to early generations, the HG compared with LG embryos showed two periods of transient growth retardation compensated subsequently by a higher growth rate (incubation d 3-8 and 8-16). 4. More pronounced growth retardation of HG versus LG embryos in late versus early generations corresponded to more distinct decrease of HG versus LG growth rate during the first post-hatch days. Likewise, a disappearance of line BW differences on incubation d 8 characterising the late generations corresponded to the elimination of line differences in adult BW. 5. Alterations of growth pattern were associated with changes of egg size. While HG quail maintained a relatively constant adult BW and egg size across generations, the gradually increasing incidence of large eggs in the LG line allowed selection of birds with higher growth potential, which in turn amplified the line differences in the embryonic BW and eliminated the line differences in adult BW. Line differences in egg composition (larger albumen with lower density in LG compared with HG eggs) apparently contributed to the strengthening of line developmental divergence during incubation. 6. Transient lack of nutrient supply to HG embryos due to their developmental delay is probably responsible for a higher HG versus LG embryo mortality.
- MeSH
- časové faktory MeSH
- Coturnix embryologie genetika růst a vývoj MeSH
- embryonální vývoj genetika MeSH
- selekce (genetika) * MeSH
- tělesná hmotnost genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12 ± 1°C and 55% relative humidity) and incubation conditions (37.5 ± 0.2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28 d of age, respectively, and constant body weight at 49 d of age. 2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406 h after egg setting, respectively). 3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1 d storage: 96.0 vs. 82.5%; 5 d storage: 88.7 vs. 72.7%, respectively). 4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation. 5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation.
1. Hatching time, hatchability of fertile eggs and embryo mortality in relation to (1) physical quality of fresh eggs and (2) embryonic development during storage and incubation periods were analysed after egg storage for 1, 5 or 10 d at 30°C in the meat-type lines of Japanese quail, HG and LG, divergently selected for high and low relative weight gain between 11 and 28 d of age, respectively, and constant body weight at 49 d of age. 2. In both lines, the increase of egg storage temperature from 12°C (standard level) to 30°C increased the egg weight loss during storage, shortened the incubation period and reduced the hatching success. 3. Similar to standard egg storage temperature, LG quail hatched earlier than HG quail after egg storage at 30°C and early and late mortality of both lines increased with a prolonged period of egg storage. In contrast to the standard egg storage conditions, no line differences in hatchability were observed. 4. The results did not identify a relationship between the decrease in hatchability or embryo viability and line differences in external egg parameters as well as any important role of undesirable changes induced by a high storage temperature on albumen viscosity. 5. The pattern of embryonic death, low developmental rate of embryos and a dichotomy between the development of the extra-embryonic vascular system and the embryo itself during egg storage at high temperature implied that an insufficient nutrient supply in consequence of developmental delay could represent a key factor in increasing early and late embryo mortality.
- MeSH
- časové faktory MeSH
- Coturnix embryologie genetika fyziologie MeSH
- embryo nesavčí embryologie fyziologie MeSH
- oviparie MeSH
- ovum fyziologie MeSH
- selekce (genetika) * MeSH
- teplota MeSH
- vysoká teplota MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Understanding the mechanisms and selective forces leading to adaptive radiations and origin of biodiversity is a major goal of evolutionary biology. Acrocephalus warblers are small passerines that underwent an adaptive radiation in the last approximately 10 million years that gave rise to 37 extant species, many of which still hybridize in nature. Acrocephalus warblers have served as model organisms for a wide variety of ecological and behavioral studies, yet our knowledge of mechanisms and selective forces driving their radiation is limited. Here we studied patterns of interspecific gene flow and selection across three European Acrocephalus warblers to get a first insight into mechanisms of radiation of this avian group. RESULTS: We analyzed nucleotide variation at eight nuclear loci in three hybridizing Acrocephalus species with overlapping breeding ranges in Europe. Using an isolation-with-migration model for multiple populations, we found evidence for unidirectional gene flow from A. scirpaceus to A. palustris and from A. palustris to A. dumetorum. Gene flow was higher between genetically more closely related A. scirpaceus and A. palustris than between ecologically more similar A. palustris and A. dumetorum, suggesting that gradual accumulation of intrinsic barriers rather than divergent ecological selection are more efficient in restricting interspecific gene flow in Acrocephalus warblers. Although levels of genetic differentiation between different species pairs were in general not correlated, we found signatures of apparently independent instances of positive selection at the same two Z-linked loci in multiple species. CONCLUSIONS: Our study brings the first evidence that gene flow occurred during Acrocephalus radiation and not only between sister species. Interspecific gene flow could thus be an important source of genetic variation in individual Acrocephalus species and could have accelerated adaptive evolution and speciation rate in this avian group by creating novel genetic combinations and new phenotypes. Independent instances of positive selection at the same loci in multiple species indicate an interesting possibility that the same loci might have contributed to reproductive isolation in several speciation events.
- MeSH
- biodiverzita MeSH
- biologická evoluce MeSH
- fenotyp MeSH
- genetická variace MeSH
- hybridizace genetická MeSH
- pohlavní chromozomy * MeSH
- reprodukční izolace MeSH
- selekce (genetika) * MeSH
- tok genů * MeSH
- vznik druhů (genetika) MeSH
- zpěvní ptáci genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa MeSH
Population divergence in geographic isolation is due to a combination of factors. Natural and sexual selection may be important in shaping patterns of population differentiation, a pattern referred to as 'isolation by adaptation' (IBA). IBA can be complementary to the well-known pattern of 'isolation by distance' (IBD), in which the divergence of closely related populations (via any evolutionary process) is associated with geographic isolation. The barn swallow Hirundo rustica complex comprises six closely related subspecies, where divergent sexual selection is associated with phenotypic differentiation among allopatric populations. To investigate the relative contributions of selection and geographic distance to genome-wide differentiation, we compared genotypic and phenotypic variation from 350 barn swallows sampled across eight populations (28 pairwise comparisons) from four different subspecies. We report a draft whole-genome sequence for H. rustica, to which we aligned a set of 9493 single nucleotide polymorphisms (SNPs). Using statistical approaches to control for spatial autocorrelation of phenotypic variables and geographic distance, we find that divergence in traits related to migratory behaviour and sexual signalling, as well as geographic distance, together explain over 70% of genome-wide divergence among populations. Controlling for IBD, we find 42% of genomewide divergence is attributable to IBA through pairwise differences in traits related to migratory behaviour and sexual signalling alone. By (i) combining these results with prior studies of how selection shapes morphological differentiation and (ii) accounting for spatial autocorrelation, we infer that morphological adaptation plays a large role in shaping population-level differentiation in this group of closely related populations.
- MeSH
- biologická evoluce * MeSH
- fenotyp MeSH
- genom MeSH
- populační genetika * MeSH
- reprodukční izolace MeSH
- selekce (genetika) * MeSH
- vlaštovkovití genetika MeSH
- zeměpis MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Behavioural isolation may lead to complete speciation when partial postzygotic isolation acts in the presence of divergent-specific mate-recognition systems. These conditions exist where Mus musculus musculus and M. m. domesticus come into contact and hybridize. We studied two mate-recognition signal systems, based on urinary and salivary proteins, across a Central European portion of the mouse hybrid zone. Introgression of the genomic regions responsible for these signals: the major urinary proteins (MUPs) and androgen binding proteins (ABPs), respectively, was compared to introgression at loci assumed to be nearly neutral and those under selection against hybridization. The preference of individuals taken from across the zone regarding these signals was measured in Y mazes, and we develop a model for the analysis of the transition of such traits under reinforcement selection. The strongest assortative preferences were found in males for urine and females for ABP. Clinal analyses confirm nearly neutral introgression of an Abp locus and two loci closely linked to the Abp gene cluster, whereas two markers flanking the Mup gene region reveal unexpected introgression. Geographic change in the preference traits matches our reinforcement selection model significantly better than standard cline models. Our study confirms that behavioural barriers are important components of reproductive isolation between the house mouse subspecies.
- MeSH
- alely MeSH
- chování zvířat MeSH
- genetické lokusy genetika MeSH
- genetické markery MeSH
- hybridizace genetická MeSH
- modely genetické MeSH
- myši MeSH
- posilování (psychologie) MeSH
- pravděpodobnostní funkce MeSH
- savčí chromozomy genetika MeSH
- selekce (genetika) MeSH
- zeměpis MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Geografické názvy
- Evropa MeSH
Background: Children's creativity and motor competence are expandable factors that are related to convergent and divergent thinking processes. Objective: This study aimed to investigate the effect of games based on divergent and convergent thinking on motor competence and creativity in children aged 7-8 years. Methods: Participants aged 7.41 ± 0.39 years (n = 34) were selected based on inclusion criteria and were divided randomly into three groups (divergent thinking, convergent thinking, and control). Participants performed their group interventions in eighteen training sessions (six weeks period). The nonlinear training approach was used to manipulate divergent thinking and linear training was used in the group of manipulating convergent thinking. Each child completed the Movement Assessment Battery for Children - Second Edition to assess motor competence. The Bertsch Test was used to assess motor creativity. Results: In motor competence, the results revealed significant main effects for groups (p < .001) and time (p < .001) as well as significant groups by time interaction effect (p < .001). The divergent thinking group (M = 32.50) was significantly better than the control group (M = 24.79, p < .001), and the convergent thinking group (M = 28.81, p = .003). In motor creativity, the results revealed significant main effects for groups (p < .001) and time (p < .001) as well as significant groups by time interaction effect (p < .001). The divergent thinking group (M = 13.27, p < .001) and the convergent thinking group (M = 12.36, p = .016) were significantly better than the control group (M = 10.63). However, no significant difference was found between the divergent thinking and convergent thinking groups. Conclusions: Physical education teachers and educators are recommended to use the divergent thinking training approach to promote students' motor competence. Also, simple adjustments in the exercise program in the form of games can help children's motor creativity. However, more research is suggested to explore divergent and convergent learning mechanisms.
- Klíčová slova
- divergent thinking, convergent thinking,
- MeSH
- kreativita MeSH
- motorické dovednosti MeSH
- myšlení * klasifikace MeSH
- techniky cvičení a pohybu metody psychologie MeSH
- tělesná výchova * MeSH
- Publikační typ
- klinická studie MeSH
A highly divergent 16S rRNA gene was found in one of the five ribosomal operons present in a species complex currently circumscribed as Scytonema hyalinum (Nostocales, Cyanobacteria) using clone libraries. If 16S rRNA sequence macroheterogeneity among ribosomal operons due to insertions, deletions or truncation is excluded, the sequence heterogeneity observed in S. hyalinum was the highest observed in any prokaryotic species thus far (7.3-9.0%). The secondary structure of the 16S rRNA molecules encoded by the two divergent operons was nearly identical, indicating possible functionality. The 23S rRNA gene was examined for a few strains in this complex, and it was also found to be highly divergent from the gene in Type 2 operons (8.7%), and likewise had nearly identical secondary structure between the Type 1 and Type 2 operons. Furthermore, the 16S-23S ITS showed marked differences consistent between operons among numerous strains. Both operons have promoter sequences that satisfy consensus requirements for functional prokaryotic transcription initiation. Horizontal gene transfer from another unknown heterocytous cyanobacterium is considered the most likely explanation for the origin of this molecule, but does not explain the ultimate origin of this sequence, which is very divergent from all 16S rRNA sequences found thus far in cyanobacteria. The divergent sequence is highly conserved among numerous strains of S. hyalinum, suggesting adaptive advantage and selective constraint of the divergent sequence.
- MeSH
- bakteriální RNA chemie genetika MeSH
- DNA bakterií genetika izolace a purifikace MeSH
- fylogeneze MeSH
- konformace nukleové kyseliny MeSH
- operon * MeSH
- promotorové oblasti (genetika) MeSH
- ribozomy metabolismus MeSH
- RNA ribozomální 16S chemie genetika MeSH
- sinice klasifikace genetika MeSH
- Publikační typ
- časopisecké články MeSH
