Ivari jelzések információtartalma és szerepe territoriális gyíkok szaporodási sikerében = Information content of sexual signals in territorial lizards, and their role in reproductive success

A kutatás fő célja a fizikai színek és a kémiai szignálok szexuális szelekcióban betöltött szerepének vizsgálata volt. Modellfajnak a zöld gyíkot (Lacerta viridis) választottuk, mivel a faj hímjei kék torokfoltot viselnek a szaporodási idő alatt, és a hímek femorális szekrétumában nagy mennyiségű E vitamin található. Eddigi eredményeink alapján a torokszínezet ultraibolya (UV) komponense fontos ivari jelzés: mind a hölgyválaszban, mind a hímek küzdelmében fontos, pozitív szerepe van. Emellett az UV intenzitás negatívan függött össze az egyedek kondíciójával (a territorialitást nem befolyásolta), tehát a jelzés feltehetőleg költséges, és ezért őszinte. Az UV jelzés környezet-függését kísérletesen bizonyítottuk, ha csökkentettük az optimális testhőmérséklet fenntarthatóságának napi intervallumát, a hímek kevésbé intenzív UV színt fejlesztettek. Kimutattunk emellett a nőstények preferenciáját a nagyobb E vitamin koncentrációjú hím szekrétumok felé. Összességében bizonyítottuk a fizikai színek és kémiai jelzések kiemelkedő szerepét a szexuális szelekcióban, egy, a szexuális szelekciós kutatásokban méltatlanul alulreprezentált állatcsoportot vizsgálva. Az eddig még ki nem értékelt adatokból további eredmények várhatóak a színezeti és kémiai jelzések kapcsolatáról, összefüggéseikről a parazitáltsággal, illetve az anyai befektetésekről (az utódokba) az apa preferáltságának függvényében. | The main goal of the project was to investigate the role of structural colours and chemical signals in sexual selection. Our model was the European green lizard (Lacerta viridis), where males develop blue nuptial throat patches during the reproductive season and invest large amounts of vitamin E into their femoral secretions. Our results have proven so far that the ultraviolet (UV) component of the nuptial throat patch is indeed a sexual signal, having a positive role in both female mate choice and male-male fights. The UV chroma of the throat patch showed a negative correlation with body condition of male lizards (and no relationship with territoriality), suggesting that the signal is costly, and thus honest. We proved the environment-dependence of the annual development of the UV signal experimentally: decreasing the daily time range when optimal body temperature was maintainable affected the UV development negatively. In addition, we showed that females prefer male secretions with high vitamin E concentration. Taken together, we showed how important role structural colours and chemical signals play in sexual selection, using a reptile – a taxon largely underrepresented in sexual selection studies – as a model. Based on our yet unanalysed data, further results are expected about the relationship between visual and chemical signals, the effects of parasites on those signals, and about maternal investments depending on the fathers' preferredness

Responses in the diet composition of the Common frog (Rana temporaria) to the stochastic gradation of Autumnal moth (Epirrita autumnata) larvae

We studied the feeding ecology of the common frog Rana temporaria in a population located at the subarctic taiga-tundra frontier in Finland over two consecutive years (2002, 2003). In the summer of 2003, an unexpected gradation of autumnal moth (Epirrita autumnata) larvae occurred at our study site. This situation allowed us to study the changes in the diet composition of the same common frog population between a presumably average and an extraordinary year with respect to the gradation of one of the prey species. We found clear evidence for the opportunistic feeding behaviour of common frogs in a natural population, as reflected by the mass appearance of Epirrita autumnata larvae in the frogs’ stomach content in 2003. Further, our results draw attention to the fact that a one-year study on the feeding ecology of an opportunistic species can result in flawed conclusions

Parallel morphological evolution and habitat-dependent sexual dimorphism in cave- vs. surface populations of the Asellus aquaticus (Crustacea: Isopoda: Asellidae) species complex

Studying parallel evolution (repeated, independent evolution of similar phenotypes in similar environments) is a powerful tool to understand environment-dependent selective forces. Surface-dwelling species that repeatedly and independently colonized caves provide unique models for such studies. The primarily surface-dwelling Asellus aquaticus species complex is a good candidate to carry out such research, because it colonized several caves in Europe. By comparing 17 functional morphological traits between six cave and nine surface populations of the A. aquaticus species complex, we investigated population divergence in morphology and sexual dimorphism. We found habitat-dependent population divergence in 10 out of 17 traits, likely reflecting habitat-driven changes in selection acting on sensory systems, feeding, grooming, and antipredator mechanisms. Sexual dimorphism was present in 15 traits, explained by sexual selection acting on male traits important in male-male agonistic behavior or mate guarding and fecundity selection acting on female traits affecting offspring number and nursing. In eight traits, the degree of sexual dimorphism was habitat dependent. We conclude that cave-related morphological changes are highly trait- and function-specific and that the strength of sexual/fecundity selection strongly differs between cave and surface habitats. The considerable population variation within habitat type warrants further studies to reveal cave-specific adaptations besides the parallel patterns

The relationship between DRD4 polymorphisms and phenotypic correlations of behaviors in the collared flycatcher

There is increasing evidence that the genetic architecture of exploration behav- ior includes the dopamine receptor D4 gene ( DRD4 ). Such a link implies that the within-individual consistency in the same behavior has a genetic basis. Behavioral consistency is also prevalent in the form of between-individual cor- relation of functionally different behaviors; thus, the relationship between DRD4 polymorphism and exploration may also be manifested for other behav- iors. Here, in a Hungarian population of the collared flycatcher, Ficedula albi- collis , we investigate how males with distinct DRD4 genotypes differ in the consistent elements of their behavioral displays during the courtship period. In completely natural conditions, we assayed novelty avoidance, aggression and risk-taking, traits that were previously shown repeatable over time and correlate with each other, suggesting that they could have a common mechanistic basis. We identified two single-nucleotide polymorphisms (SNP554 and SNP764) in the exon 3 of the DRD4 gene by sequencing a subsample, then we screened 202 individuals of both sexes for these SNPs. Focusing on the genotypic variation in courting males, we found that “AC” heterozygote individuals at the SNP764 take lower risk than the most common “AA” homozygotes (the “CC” homo- zygotes were not represented in our subsample of males). We also found a con- siderable effect size for the relationship between SNP554 polymorphism and novelty avoidance. Therefore, in addition to exploration, DRD4 polymorphisms may also be associated with the regulation of behaviors that may incur fear or stress. Moreover, polymorphisms at the two SNPs were not independent indi- cating a potential role for genetic constraints or another functional link, which may partially explain behavioral correlations

Quantitative genetic analysis of brain size variation in sticklebacks: support for the mosaic model of brain evolution

The mosaic model of brain evolution postulates that different brain regions are relatively free to evolve independently from each other. Such independent evolution is possible only if genetic correlations among the different brain regions are less than unity. We estimated heritabilities, evolvabilities and genetic correlations of relative size of the brain, and its different regions in the three-spined stickleback (Gasterosteus aculeatus). We found that heritabilities were low (average h2 = 0.24), suggesting a large plastic component to brain architecture. However, evolvabilities of different brain parts were moderate, suggesting the presence of additive genetic variance to sustain a response to selection in the long term. Genetic correlations among different brain regions were low (average rG = 0.40) and significantly less than unity. These results, along with those from analyses of phenotypic and genetic integration, indicate a high degree of independence between different brain regions, suggesting that responses to selection are unlikely to be severely constrained by genetic and phenotypic correlations. Hence, the results give strong support for the mosaic model of brain evolution. However, the genetic correlation between brain and body size was high (rG = 0.89), suggesting a constraint for independent evolution of brain and body size in sticklebacks

The relationship between DRD4 polymorphisms and phenotypic correlations of behaviors in the collared flycatcher

There is increasing evidence that the genetic architecture of exploration behavior includes the dopamine receptor D4 gene (DRD4). Such a link implies that the within-individual consistency in the same behavior has a genetic basis. Behavioral consistency is also prevalent in the form of between-individual correlation of functionally different behaviors; thus, the relationship between DRD4 polymorphism and exploration may also be manifested for other behaviors. Here, in a Hungarian population of the collared flycatcher, Ficedula albicollis, we investigate how males with distinct DRD4 genotypes differ in the consistent elements of their behavioral displays during the courtship period. In completely natural conditions, we assayed novelty avoidance, aggression and risk-taking, traits that were previously shown repeatable over time and correlate with each other, suggesting that they could have a common mechanistic basis. We identified two single-nucleotide polymorphisms (SNP554 and SNP764) in the exon 3 of the DRD4 gene by sequencing a subsample, then we screened 202 individuals of both sexes for these SNPs. Focusing on the genotypic variation in courting males, we found that “AC” heterozygote individuals at the SNP764 take lower risk than the most common “AA” homozygotes (the “CC” homozygotes were not represented in our subsample of males). We also found a considerable effect size for the relationship between SNP554 polymorphism and novelty avoidance. Therefore, in addition to exploration, DRD4 polymorphisms may also be associated with the regulation of behaviors that may incur fear or stress. Moreover, polymorphisms at the two SNPs were not independent indicating a potential role for genetic constraints or another functional link, which may partially explain behavioral correlations