Reyer
Fakultäten » Mathematisch-naturwissenschaftliche Fakultät » Evolutionsbiologie und Umweltwissenschaften, Institut für » Ecology & Environment » Prof. Dr. Heinz-Ulrich Reyer (emeritiert) » Reyer
Completed research project
| Title / Titel | Spatial structure and temporal dynamics of hybridogenetic frog populations | ||
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| Abstract (PDF, 14 KB) | |||
| Summary / Zusammenfassung | I am interested in patterns of biological variation in space and time and the processes that create and maintain them. My research exploits water frogs as a model system to investigate how the structure and dynamics of populations and species associations is determined by the behaviour of individuals. Rana esculenta (genotype LR), originally a hybrid between R. lessonae (LL) and R. ridibunda (RR), eliminates one parental genome (usually L, in some areas the R) prior to meiosis and produces only gametes that carry the unrecombined remaining genome (R or L; “hybridogenesis”). In most areas LR can reproduce successfully only by mating with the parental species whose genome it excludes (which restores hybridity), whereas parentals are only successful when they avoid mating with hybrids. Using a combination of comparative field studies, experiments and theoretical models we have shown how the outcome of this conflict determines the composition of these mixed sexual parasite (LR) and sexual host (LL) populations and why this composition differs considerably among ponds but remains stable within ponds across years. The responsible factors for this spatial variability and temporal stability include habitat-specific larval performance (i.e. genotype x environment interactions), mating preference of both female types for LL males, more regular breeding of LL than LR females, and decreased fertilization success of hybrid sperm. Presently, we focus on pure hybrid populations in countries around the Baltic Sea where the parental species LL and RR are not present. Their role as a sexual host for the diploid (2n) LR has been taken over by triplod (3n) hybrids LLR or LRR) which exclude the rarer of the three genomes prior to meiosis (R or L) and produce gametes of the remaining type (L or R). Matings between males and females of different ploidies produce offspring of those genotypes that are also present among adults, while matings between individuals of the same ploidy result in larvae (but not in adults) of the parental species LL and RR, respectively. We are conducting field studies, crossing experiments and genetic analyses to find out why the parental types do not survive. The system seems to represent one of the rare cases where selection acts against two parental species, rather than against the hybid between them. Weitere Informationen |
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| Publications / Publikationen | REYER, H.-U., FREI, G. & SOM, C. (1999): Cryptic female choice: frogs reduce clutch size when amplexed by undesired males. Proc. R. Soc. Lond. B 266: 2101-2107.ALTWEGG, R., REYER H.-U. (2003): Patterns of natural selection on size at metamorphosis in water frogs. Evolution 37: 872-882. REYER, H.-U., NIEDERER, B., HETTYEY, A. (2003): Variation in fertilisation abilities between hemiclonal hybrid and sexual parental males of sympatric water frogs (Rana lessonae, R. esculenta, R. ridibunda). Behav. Ecol. Sociolbiol. 54: 274-284REYER, H.-U., WÄLTI, M.O., BÄTTIG, I., ALTWEGG, R. & HELLRIEGEL, B. (2004): Low proportions of reproducing hemiclonal females increase the stability of a sexual parasite-host system (Rana esculenta, R. lessonae). J. Anim. Ecol. 73: 1089-1101.Weitere Informationen |
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| Keywords / Suchbegriffe | population dynamics, population structure, ecology, genetics, competition, hybrid, mating behavior, sexual parasite, sexual host, Rana lessonae, Rana esculenta, Rana ridibunda | ||
| Project leadership and contacts / Projektleitung und Kontakte |
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| Other links to external web pages | http://www.uli-reyer.ch/hemiclonal_waterfrogs.htm | ||
| Funding source(s) / Unterstützt durch |
SNF (Personen- und Projektförderung) |
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| Duration of Project / Projektdauer | Oct 2001 to Sep 2008 |