Interspecific Offspring Research Articles

Reproductive biology of Sphaeralcea species with ornamental interest

The genus Sphaeralcea belongs to the Malvaceae family and has native species from South America. Their attractive morphological characteristics with ornamental value have not yet been explored. The objective of this work was to know the viability of pollen, stigma receptivity, type of pollination and combining ability of four Sphaeralcea species (S. australis, S. bonariensis, S. crispa and S. mendocina), with the aim to develop new ornamental varieties. Fructification, fertility, seed germination and survival seedlings on intraspecific and reciprocal interspecific offspring were assessed. The highest values ​​of stigma receptivity and pollen viability were obtained at 2:00 pm for the four species. S. mendocina also showed high values ​​of pollen viability at 4:00 pm. The species proved to be self-incompatible and allogamous, with different degrees of reproductive compatibility. The interspecific crosses of S. mendocina and the intraspecific of S. crispa did not produce descendants. The crosses between S. australis and S. bonariensis as maternal parent presented the best combining ability with good fruit production, seed germination and survival. This research provides useful information for the formulation and implementation of breeding strategies, to improve pollination efficiency, and to breed new Sphaeralcea varieties with ornamental potential.

Non-additive effects on the morphology of hybrids between two species of large house spiders, Eratigena saeva and E. duellica (Araneae: Agelenidae)

Hybridization and introgression in the wild between two species in the Eratigena atrica group of large house spiders, E. duellica and E. saeva, are well documented. However, the morphology of known F1 hybrids and subsequent F2 and backcross generations has not previously been explored. The phenotypes of these interspecific offspring have implications for the ease of introgression and for the morphological identification of individuals of hybrid origin. Here, the progeny from laboratory crosses are analysed using both simple characters and multivariate statistical techniques. F1 hybrids in both sexes are, morphologically, significantly biased towards E. duellica but backcross progeny tend to resemble their non-F1 parents more than expected in a model of additive, unlinked quantitative trait loci (QTL). It is possible that loci on the X-chromosomes affect the phenotype or that there are maternal influences. These biases may have consequences for the ease and direction of gene flow between the species. While female F1 hybrids can be distinguished from pure parents, for later generations, and for all generations of males, confusion with the parental species is highly likely and may have affected previous conclusions.

Distribution of 45S rDNA in Modern Rose Cultivars (Rosa hybrida), Rosa rugosa, and Their Interspecific Hybrids Revealed by Fluorescence in situ Hybridization

To elucidate the evolutionary dynamics of the location and number of rDNA loci in the process of polyploidization in the genus Rosa, we examined 45S rDNA sites in the chromosomes of 6 modern rose cultivars (R. hybrida), 5 R. rugosa cultivars, and 20 hybrid progenies by fluorescence in situ hybridization. Variation in the number of rDNA sites in parents and their interspecific hybrids was detected. As expected, 4 rDNA sites were observed in the genomes of 4 modern rose cultivars, while 3 hybridization sites were observed in the 2 others. Two expected rDNA sites were found in 2 R. rugosa cultivars, while in the other 3 R. rugosa cultivars 4 sites were present. Among the 20 R. hybrida × R. rugosa offspring, 13 carried the expected number of rDNA sites, and 1 had 6 hybridization sites, which exceeded the expected number by far. The other 6 offspring had either 2 or 3 hybridization sites, which was less than expected. Differences in the number of rDNA loci were observed in interspecific offspring, indicating that rDNA loci exhibit instability after distant hybridization events. Abnormal chromosome pairing may be the main factor explaining the variation in rDNA sites during polyploidization.

Heterosis and combining ability estimates in isoflavone content using different parental soybean accessions: wild soybean, a valuable germplasm for soybean breeding.

Isoflavone, a group of secondary metabolites in soybean, is beneficial to human health. Improving isoflavone content in soybean seeds has become one of the most important breeding objectives. However, the narrow genetic base of soybean cultivars hampered crop improvement. Wild soybean is an extraordinarily important gene pool for soybean breeding. In order to select an optimal germplasm for breeding programs to increase isoflavone concentration, 36 F1 soybean progenies from different parental accessions (cultivars, wild, Semi-wild and Interspecific) with various total isoflavone (TIF) concentration (High, Middle, Low) were analyzed for their isoflavone content. Results showed that male parents, except for Cultivars, showed positive GCA effects. In particular, wild soybean had higher positive GCA effects for TIF concentration. Both MP and BP heterosis value declined in the hybrid in which male parents were wild soybean, semi-wild soybean, interspecific offspring and cultivar in turn. In general, combining ability and heterosis in hybrids which had relative higher TIF concentration level parents showed better performance than those which had lower TIF concentration level parents. These results indicated characteristics of isoflavone content were mainly governed by additive type of gene action, and wild relatives could be utilized for breeding of soybean cultivars with this trait. A promising combination was found as the best potential hybrid for isoflavone content improvement.

Interspecific offspring killing in owls

In Baranya County (Southern Hungary), tawny owls (Strix aluco) and barn owls (Tyto alba) sequentially use the same nest boxes in a significant number of cases. A total of 460 broods were observed between 1996 and 2003 and, in 12 cases, whole broods of dead tawny owl chicks were registered that had apparently been killed. On investigating the reproductive life characteristics, population sizes, and frequency of killing in these two species, it was concluded that: (1) with growing barn owl population, the number of sequential broods increases but changes in tawny owl population size have no effect on the frequency of sequential broods; (2) the number of killings depends on the number of sequential broods; and (3) with growing barn owl population, the number of killings also grows and this change is unaffected by the size of the tawny owl population. However, no killing occurs as long as 50–60% of the nest boxes are unoccupied. There is no killing either until the percentage of nest boxes occupied by barn owls reaches 40%, although a threshold value like this cannot be shown for the tawny owl. In the cases when a barn owl breeding follows the tawny owl's, the percentage of killing is significantly higher compared to that when barn owls do not breed in the same box. These results indicate that barn owls kill the offspring of tawny owls. By these means, they obtain a breeding place earlier than without killing the chicks of the other species, and this results in higher reproductive success. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 488–494.

Introgression de la résistance à la cécidomyie chez le Blé par croisement avec une souche d'Aegilops ventricosa marocaine

The introduction of alien genetic material through interspecific or intergeneric hybridisation allowed the transfer of resistant genes to many diseases and pests. The Hessian fly Mayetiola destructor is one of the most destructive pests of wheat crops. The Ae. ventricosa is one of the most important sources of alien variation for wheat breeding. For transferring resistance to wheat, interspecific crosses were conducted between Ae. ventricosa resistant accessions with both bread and durum wheat. The low viability and the sterility of the interspecific hybrids F1 and its progenies have a determinant impact on seed set and number of hybrid plants produced. Meiotic analyses showed meiotic irregularities, which are probably causing sterility in the interspecific progenies. Most interspecific offspring maintained were resistant to the Hessian fly. In the fourth generation, some were still showing segregation of the resistance. In the fifth generation, all the progenies analysed were however resistant at 100%.

Transfert à des Blés marocains, à la suite de croisement avec Aegilops squarrosa, de gènes de résistance à la mouche de Hesse

Hessian fly (Mayetiola destructor (Say) is probably the most serious pest on wheat crops (Triticum sp.) in many countries. Interspecific crosses were carried out between durum wheat cultivars and different Ae. squarrosa accessions that are resistant to the Hessian fly. The low viability and the sterility of the interspecific hybrids F1 and its progenies 1st, 2nd and 3rd generations have a determinant impact on seed set and percentages of the interspecific hybrid produced. The rate of univalent percentages decreased clearly in the second generation, in connection with spontaneous chromosomal doubling. Most interspecific offspring were resistant to the Hessian fly. At F4 and F5 they still showed a segregation of resistance. Few interspecific progenies showed higher resistance, especially at the 5th generation.

Growth and reproduction of two species of Akodon and their hybrids.

Growth and reproduction of Akodon molinae (A.m.), A. dolores (A.d.) (Rodentia: Cricetidae), and their hybrids are described. A.d. showed less fertility under animal room conditions, fewer "successful" matings, similar litter sizes, and an altered sex proportion as compared to A.m.; A.d. ovulatory index is supposed to be higher than mean litter size. X-linked lethal gene(s) and chromosome polymorphisms are possible causes of these variations. Interspecific crosses showed a marked seasonal (summer) tendency in parturitions. Intraspecific matings also produced young during winter. F1 hybrids showed a reversed tendency, while F2 matings returned to the parental pattern. A.d. male X A.m. female and F1 crosses presented larger litter sizes than the other pairings. A.m. exhibited sexual differences in weight after 60 days of age. A.d. and F1 hybrids did not show significant differences in weight of both sexes at any age. A.m. males and females were heavier than A.d. individuals except 12 months after birth. F1 hybrids born to A.m. male were heavier at birth than the A.d. female s interspecific offspring, and may be interpreted as a maternal influence of the A.m. females. Hybrids were heavier than their parents at birth and some of them were also heavier at 21 days, and probably is due to pseudoheterosis. The comparison of body measurements between sexes of both species did not give conclusive results. A.m. females were larger than females of A.d. Males of both species showed similar total lengths; A.m. males had larger body lengths and shorter tails. Body measurements were not related to weight variations. However, differences in weight and measurements between sexes appeared simultaneously at 2-6 months. This probably reflected the attainment of maturity.