Genome dosage effect and colouration features in hybridogenetic water frogs of the Pelophylax esculentus complex

Abstract

There are three taxons of central European water frogs of the Pelophylax esculentus complex: two morphologically distinct species, Pelophylax lessonae (LL) and Pelophylax ridibundus (RR), and hybrids Pelophylax esculentus, which can be either diploid (RL) or triploid (LLR or RRL). The morphology of hybrids is supposed to follow genome dosage effect. We describe colouration of water frogs with genome composition verified by chromosome analysis. Typical colouration features in LL were: spots on the ventral side, brown limbs, “weak” femur spotting pattern, brown dorsal folds and yellow-green colour in “waist”. Typical RR had dark-green or olive-green limbs, “full” femur spotting pattern, no hip spot and no yellow colour in “waist”. For all hybrids the most typical features were strong spots on the ventral side and a mosaic of green and brown colour on limbs. Typical LLR had brown-greenish dorsal folds underlined by a partial black line, “weak” femur spotting pattern and yellow-greenish colour in “waist” and on femur. Typical RL had greenish hind limbs, green dorsal folds, no yellow colour in “waist”, and no hip spot. Typical RRL was similar to RL, but had a continuous black line under dorsal folds. There were, however, numerous exceptions to these trends, with the most prominent being much higher than expected variability of colouration of Pelophylax lessonae. Therefore caution must be advised when trying to estimate genome composition of water frogs solely on the basis of colouration.

Natural Pathways towards Polyploidy in Animals: The <b><i>Squalius alburnoides</i></b> Fish Complex as a Model System to Study Genome Size and Genome Reorganization in Polyploids

“…In central and southern populations, when comparing the AA genomotype with the distinct hybrid combinations (PA, PAA and PPA) and with the pure PP ( S. pyrenaicus ), only the extreme genomotypes are identifiable with confidence. Such patterns seem to result from a dosage effect of parental genome contributions [see also Kierzkowski et al, 2011] and are particularly visible regarding the number of scales (slightly higher in AA, when compared with the PP extreme), number and size of gill rakers (higher in AA), position of the mouth (more terminal in AA), and body coloration. The latter of which, in AA individuals, includes a clearly visible longitudinal dark stripe that is lighter in the hybrid genomes and nonexistent in S. pyrenaicus [reviewed in Collares-Pereira and Coelho, 2010].…”

Surveys on populations of green frogs (Pelophylax) of Western Tuscany sites with molecular and morphometric methods

“…The difficulty of establishing a close correspondence between geno- typic composition and external morphology of green frogs is likely due to the high morphological variability of these species (Hotz and Bruno, 1980;Gubányi and Korsos, 1992;Gün-ther and Plötner, 1994;Lode and Pagano, 2000). A number of papers have focused on the identification and characterization of genetic variability, DNA contents, and genomic composition of RanalPelophyiax hybrids and their parental forms (Uzzell and Hotz, 1979;Ragghianti et al, 1995Ragghianti et al, , 2007Bucci et al, 2000;Ogielska, Kierzkowski and Rybacki, 2004;Kierzkowski et al, 2011Kierzkowski et al, , 2013Marracci et al, 2011). Also, studies that address ecological and habitat features have provided interesting results.…”

“…Delimiting valid morphological characteristics to discriminate parental species and hybrid forms is, however, rather challenging. The green frog complex is undoubtedly very variable from a morphological and a genetic point of view (Kierzkowski et al, 2011;Hauswaldt et al, 2012). Recent papers have shown that the L (= lessonae) haplotype has a greater influence on morphology than the R (= ridibundus) haplotype, all the hybrid individuals being morphologically more similar to P. lessonae than to P. ridibundus (Kierzkowski et al, 2011(Kierzkowski et al, , 2013.…”

“…The green frog complex is undoubtedly very variable from a morphological and a genetic point of view (Kierzkowski et al, 2011;Hauswaldt et al, 2012). Recent papers have shown that the L (= lessonae) haplotype has a greater influence on morphology than the R (= ridibundus) haplotype, all the hybrid individuals being morphologically more similar to P. lessonae than to P. ridibundus (Kierzkowski et al, 2011(Kierzkowski et al, , 2013. Interestingly, it has also been found that environmental parameters affect the genotype composition of all-hybrid populations less than populations of the parental species (Jakob et al, 2010).…”

Variability of NOR patterns in European water frogs of different genome composition and ploidy level

“…Artificial crosses and rearing of progeny were done according to standard protocol for water frogs (Berger et al 1994). Taxonomic identity of individuals was determined by morphology (Berger 1983, Plötner 2005, Kierzkowski et al 2011) and at least one of the following methods: actinomycin D (AMD)-DAPI staining (Schweitzer 1976, Heppich et al 1982, Ogielska et al 2004), LDH electrophoresis and 17 microsatellite loci (both methods described in Hauswaldt et al 2012). …”