Data from: Post-zygotic selection against parental genotypes during larval development maintains all-hybrid populations of the frog Pelophylax esculentus
| Main Authors: | Reyer, Heinz-Ulrich, Arioli-Jakob, Christian, Arioli, Martina |
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| Format: | info dataset |
| Terbitan: |
, 2015
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/4941917 |
Daftar Isi:
- Background: Hybridization between two species usually leads to inviable or infertile offspring, due to endogenous or exogenous selection pressures. Yet, hybrid taxa are found in several plant and animal genera, and some of these hybrid taxa are ecologically and evolutionarily very successful. One example of such a successful hybrid is the water frog, Pelophylax esculentus which originated from matings between the two species P. ridibundus (genotype RR) and P. lessonae (LL). At the northern border of the distribution all-hybrid populations consisting of diploid (LR) and one or two triploid (LLR, LRR) frog types have been established. Here, the hybrid has achieved reproductive independence from its sexual ancestors and forms a self-sustaining evolutionary unit. Based on the gamete production of these hybrids, certain mating combinations should lead to LL and RR offspring, but these parental forms are absent among the adults. Results: In order to investigate the mechanisms that maintain such an all-hybrid system, we performed a field study and a crossing experiment. In the field we sampled several ponds for water frog larvae at different developmental stages. Genotype compositions were then analysed and life-history differences between the genotypes examined. In the experiment we crossed diploid and triploid males and females from different ponds and determined fertilization success as well as development speed and survival rates of the offspring under high, medium and low food availability. In both parts of the study, we found numerous LL and RR offspring during the egg and early larval stages; but the frequency of these parental genotypes decreased drastically during later stages. In natural ponds almost all of them had disappeared already before metamorphosis; under the more benign experimental conditions the last ones died as juveniles during the following year. Conclusions: From the combined results we conclude that the absence of parental genotypes in all-hybrid populations is due to post-zygotic selection against them, rather than to pre-zygotic mechanisms that might prevent their formation in the first place. For this post-zygotic selection, genetic mechanisms resulting from low genetic diversity and fixation of deleterious mutations seem to be a more likely explanation than ecological factors.
- Reyer_et_al_Fig-3This file provides the data base for Table 1 and Fig. 3, namely the absolute numbers and proportions of 7 genotypes (LL, LLR, LLRR, LR, LRR, RR and uncertain) sampled in natural ponds at 5 developmental stages (eggs, tadpoles, metamorphs, juveniles and adults).Reyer_et_al_Fig-4This file presents the numbers of gamete types produced by the crossed LR, LLR and LRR males and females. Data base for Table 2 and Fig. 4.Reyer_er_al_Fig-5Fertilization success and hatching rates of offspring from different crossing types. Data base for Table 3 and Fig. 5.Reyer_et_al_Fig-6+7aThis file provides the data basis for Table 4a and Figs. 6 and 7a, which analyze and depict tadpole development under different food treatments from the start of the raising Experiment (SURVA0) to shortly before metamorphosis (SURVA10).Reyer_et_al_Fig-7bNumber of surviving froglets from shortly after metamorphosis (Aug 04) to the next summer (July 05). The category "Hyb" includes all hybrid types (LR, LLR, LRR) and the category "Par" the two parental species (LL, RR). Data base for Table 4b and Fig. 7b.