scholarly journals Analysis of the Meiotic Segregation in Intergeneric Hybrids of Tilapias

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Etienne Bezault ◽  
Xavier Rognon ◽  
Frederic Clota ◽  
Karim Gharbi ◽  
Jean-Francois Baroiller ◽  
...  
Keyword(s):  
Parental Species ◽  
Genome Structure ◽  
Intergeneric Hybrids ◽  
Interspecific Hybridisation ◽  
Meiotic Segregation ◽  
Apparent Lack ◽  
Cichlid Species ◽  
In The Wild ◽  
Sarotherodon Melanotheron ◽  
Generation Hybrid

Tilapia species exhibit a large ecological diversity and an important propensity to interspecific hybridisation. This has been shown in the wild and used in aquaculture. However, despite its important evolutionary implications, few studies have focused on the analysis of hybrid genomes and their meiotic segregation. Intergeneric hybrids between Oreochromis niloticus and Sarotherodon melanotheron, two species highly differentiated genetically, ecologically, and behaviourally, were produced experimentally. The meiotic segregation of these hybrids was analysed in reciprocal second generation hybrid (F2) and backcross families and compared to the meiosis of both parental species, using a panel of 30 microsatellite markers. Hybrid meioses showed segregation in accordance to Mendelian expectations, independent from sex and the direction of crosses. In addition, we observed a conservation of linkage associations between markers, which suggests a relatively similar genome structure between the two parental species and the apparent lack of postzygotic incompatibility, despite their important divergence. These results provide genomics insights into the relative ease of hybridisation within cichlid species when prezygotic barriers are disrupted. Overall our results support the hypothesis that hybridisation may have played an important role in the evolution and diversification of cichlids.

Phylogeny of the rock wallabies, Petrogale (Marsupialia: Macropodidae). Part II: Detection of hybridisation among macropodines

2010 ◽  
Vol 32 (1) ◽  
pp. 67
Author(s):  
John A. W. Kirsch ◽  
Olivier Gauthier ◽  
Antoine Campeau-Péloquin ◽  
Mark D. B. Eldridge ◽  
François-Joseph Lapointe
Keyword(s):  
Parental Species ◽  
Phylogenetic Position ◽  
Crossing Over ◽  
Interspecific Hybridisation ◽  
Hybrid Speciation ◽  
Detection Criterion ◽  
Hybrid Detection ◽  
Dna Hybridisation ◽  
In Captivity ◽  
In The Wild

Phylogenetic relationships among rock-wallabies, Petrogale (Marsupialia: Macropodidae), have proven difficult to resolve. Given the documented interspecific hybridisation in the wild and the ease with which hybrids can be bred in captivity, introgression and hybrid speciation are likely explanations for these difficulties. In this paper, an attempt is made at using a phylogenetic approach to identify Petrogale hybrids of known origin. The Hybrid Detection Criterion (HDC) test is applied to DNA–DNA hybridisation data for 15 full species, two natural yard-bred hybrids, and two artificial hybrids from the same pairs of parental species. While the yard-bred hybrids elude detection with this technique, the artificial hybrids, consisting of equimolar mixture of parental extracts, are easily identified. Moreover, splitsgraphs constructed from five pairs of natural and artificial hybrids, including those evaluated with HDC, and their parents show that, in all cases but one, these two kinds of hybrids do not group together. Because the HDC assumes an intermediate phylogenetic position of the hybrid between its postulated parents, it is likely that unequal crossing-over, or another recombination event, affects the results of the test. These conclusions cast some doubt on the possibility of accurately detecting Petrogale hybrids with a phylogenetic approach.

Hybridisation Between Black (Pteropods alecto) and Grey- Headed (P. poliocephalus) Flying-Foxes (Megachiroptera: Pteropodidae).

1995 ◽  
Vol 18 (1) ◽  
pp. 19
Author(s):  
N.J. Webb ◽  
C.R. Tidemann
Keyword(s):  
Parental Species ◽  
Interspecific Hybridisation ◽  
Morphological Similarity ◽  
Closely Related Species ◽  
Flying Foxes ◽  
Heterozygous Condition ◽  
Allelic Differences ◽  
In The Wild ◽  
External Characteristics ◽  
Flying Fox

The range of the black flying-fox (Pteropus alecto) in Australia overlaps with two morphologically very similar congenerics: the grey-headed flying-fox (P. poliocephalus) and the spectacled flying-fox (P. conspecillatus). Protein electrophoresis was used to examine cases of apparent hybridisation between P. alecto and these other species. Two loci with fixed allelic differences were identified between P. alecto and P. poliocephalus and were used to confirm three cases of interspecific hybridisation, one of which probably occurred in the wild, and one of backcrossing. Hybrid individuals possessed external characteristics that were intermediate between the parental species. Pteropus alecto and P. conspecillatus showed very little genetic differentiation and only one out of 23 scorable loci showed a fixed allelic difference. A reported interspecific hybrid, and two other flying-foxes, considered to be possible P. alecto/P. conspecillatus hybrids, failed to show the expected heterozygous condition at this locus. Further diagnostic loci need to be sought before a definite conclusion can be made concerning the hybrid status of these individuals. The very close morphological similarity of P. alecto and P. conspecillatus, combined with their genetic similarity, suggests that more discriminating DNA based techniques would be necessary to fully describe the relationships between these closely related species.

Intergeneric hybrids between Thinopyrum and Psathyrostachys (Triticeae)

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 845-849 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Genome Analysis ◽  
Parental Species ◽  
Intergeneric Hybrids ◽  
Meiotic Pairing ◽  
Green Leaves ◽  
Psathyrostachys Juncea ◽  
Basic Genome ◽  
Chromosome Associations ◽  
Thinopyrum Elongatum ◽  
First Time

Intergeneric hybrids were synthesized for the first time from the diploid crosses Thinopyrum elongatum (JeJe) × Psathyrostachys juncea (NjNj), T. elongatum × P. fragilis (NfNf), T. bessarabicum (JbJb) × P. huashanica (NhNh), and T. bessarabicum × P. juncea, as well as from a cross between the amphidiploid of T. bessarabicum × T. elongatum (JbJbJeJe) and P. juncea. Spikes of these hybrids are morphologically intermediate between those of the parental species. Double spikelets occurred occasionally at central nodes of the spikes. Glaucous blue leaves appeared in the F1 only in the cross T. bessarabicum × P. huashanica, suggesting that the gene(s) for glaucous blue leaves in T. bessarabicum is (are) recessive to a gene(s) for green leaves in P. juncea but is (are) dominant to that for yellowish green leaves in P. huashanica. Meiotic pairing at metaphase I in these diploid (JN) and triploid (JJN) hybrids revealed a very low level of homology between the basic J and N genome. Therefore, the J and N genomes are nonhomologous and justifiably represented by different genome symbols. The triploid hybrids exhibited a pattern of chromosome associations that substantiated the earlier conclusion that the genomes in T. bessarabicum and T. elongatum are two versions of a basic genome (J). These hybrids will be useful in genome analysis, forming new Leymus species with the J and N genomes and broadening the diversity in the genus Pascopyrum with the SHJN genomes.Key words: hybrid, Thinopyrum, Psathyrostachys, genome.

scholarly journals Interspecific hybridization can generate functional novelty in cichlid fish

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191621 ◽  
Author(s):  
O. M. Selz ◽  
O. Seehausen
Keyword(s):  
Interspecific Hybridization ◽  
First Generation ◽  
Parental Species ◽  
Cichlid Fish ◽  
Context Dependency ◽  
Functional Variation ◽  
Generate Functional ◽  
Cichlid Species ◽  
Evolutionary Consequences ◽  
African Cichlids

The role of interspecific hybridization in evolution is still being debated. Interspecific hybridization has been suggested to facilitate the evolution of ecological novelty, and hence the invasion of new niches and adaptive radiation when ecological opportunity is present beyond the parental species niches. On the other hand, hybrids between two ecologically divergent species may perform less well than parental species in their respective niches because hybrids would be intermediate in performance in both niches. The evolutionary consequences of hybridization may hence be context-dependent, depending on whether ecological opportunities, beyond those of the parental species, do or do not exist. Surprisingly, these complementary predictions may never have been tested in the same experiment in animals. To do so, we investigate if hybrids between ecologically distinct cichlid species perform less well than the parental species when feeding on food either parent is adapted to, and if the same hybrids perform better than their parents when feeding on food none of the species are adapted to. We generated two first-generation hybrid crosses between species of African cichlids. In feeding efficiency experiments we measured the performance of hybrids and parental species on food types representing both parental species niches and additional ‘novel’ niches, not used by either of the parental species but by other species in the African cichlid radiations. We found that hybrids can have higher feeding efficiencies on the ‘novel’ food types but typically have lower efficiencies on parental food types when compared to parental species. This suggests that hybridization can generate functional variation that can be of ecological relevance allowing the access to resources outside of either parental species niche. Hence, we provide support for the hypothesis of ecological context-dependency of the evolutionary impact of interspecific hybridization.

An intergeneric hybrid in the family Phocoenidae

1998 ◽  
Vol 76 (1) ◽  
pp. 198-204 ◽  
Author(s):  
Robin W Baird ◽  
Pamela M Willis ◽  
Tamara J Guenther ◽  
Paul J Wilson ◽  
Bradley N White
Keyword(s):  
Dna Sequences ◽  
Parental Species ◽  
Intergeneric Hybrid ◽  
Harbour Porpoise ◽  
Colour Pattern ◽  
Phocoena Phocoena ◽  
Female Fetus ◽  
The Family ◽  
In The Wild ◽  
Species Specific

A 60-cm female fetus recovered from a Dall's porpoise (Phocoenoides dalli) found dead in southern British Columbia was fathered by a harbour porpoise (Phocoena phocoena). This is the first report of a hybrid within the family Phocoenidae and one of the first well-documented cases of cetacean hybridization in the wild. In several morphological features, the hybrid was either intermediate between the parental species (e.g., vertebral count) or more similar to the harbour porpoise than to the Dall's porpoise (e.g., colour pattern, relative position of the flipper, dorsal fin height). The fetal colour pattern (with a clear mouth-to-flipper stripe, as is found in the harbour porpoise) is similar to that reported for a fetus recovered from a Dall's porpoise to off California. Hybrid status was confirmed through genetic analysis, with species-specific repetitive DNA sequences of both the harbour and Dall's porpoise being found in the fetus. Atypically pigmented porpoises (usually traveling with and behaving like Dall's porpoises) are regularly observed in the area around southern Vancouver Island. We suggest that these abnormally pigmented animals, as well as the previously noted fetus from California, may also represent hybridization events.

scholarly journals Telomere length is highly heritable and independent of growth rate manipulated by temperature in field crickets

2020 ◽  
Author(s):  
Jelle Boonekamp ◽  
Rolando Rodríguez-Muñoz ◽  
Paul Hopwood ◽  
Erica Zuidersma ◽  
Ellis Mulder ◽  
...  
Keyword(s):  
Growth Rate ◽  
Telomere Length ◽  
Temperature Treatment ◽  
Field Cricket ◽  
Negative Effects ◽  
Human Infants ◽  
Apparent Lack ◽  
Telomere Attrition ◽  
In The Wild ◽  
Telomere Biology

AbstractMany organisms are capable of growing faster than they do. Restrained growth rate has functionally been explained by negative effects on lifespan of accelerated growth. However, the underlying mechanisms remain elusive. Telomere attrition has been proposed as a causal agent and has been studied in endothermic vertebrates. We established that telomeres exist as chromosomal-ends in a model insect, the field cricket, using terminal restriction fragment and Bal 31 methods. Telomeres comprised TTAGGn repeats of 38kb on average, more than four times longer than the telomeres of human infants. Bal 31 assays confirmed that telomeric repeats were located at the chromosome-ends. We tested whether rapid growth is achieved at the expense of telomere length by comparing crickets reared at 23°C with their siblings reared at 28°C, which grew three times faster. Surprisingly, neither temperature treatment nor age affected average telomere length. Concomitantly, the broad sense heritability of telomere length was remarkably high at ~100%. Despite high heritability, the evolvability (a mean standardized measure of genetic variance) was low relative to that of body mass. We discuss the different interpretations of these scaling methods in the context of telomere evolution. It is clear that some important features of vertebrate telomere biology are evident in an insect species dating back to the Triassic, but also that there are some striking differences. The apparent lack of an effect of growth rate and the total number of cell divisions on telomere length is puzzling, suggesting that telomere length could be actively maintained during the growth phase. Whether such maintenance of telomere length is adaptive remains elusive and requires further study investigating the links with fitness in the wild.

scholarly journals Species integrity enhanced by a predation cost to hybrids in the wild

2017 ◽  
Vol 13 (7) ◽  
pp. 20170208 ◽  
Author(s):  
P. Anders Nilsson ◽  
Kaj Hulthén ◽  
Ben B. Chapman ◽  
Lars-Anders Hansson ◽  
Jakob Brodersen ◽  
...  
Keyword(s):  
Related Species ◽  
Parental Species ◽  
Great Cormorant ◽  
Phalacrocorax Carbo ◽  
Hybrid Fitness ◽  
Closely Related Species ◽  
Ecological Selection ◽  
Field Evidence ◽  
In The Wild ◽  
Species Integrity

Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of parental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post-zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of-concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama ) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo ). Scanning for regurgitated tags under cormorant roosts 3–4 years later identified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.

HYBRIDIZATION EXPERIMENTS IN RHODEINE FISHES (CYPRINIDAE, TELEOSTEI): THE INTERGENERIC HYBRIDS OF ACHEILOGNATHUS LANCEOLATA ♂ × ACANTHORHODEUS ATREMIUS ♀ AND TANAKIA TANAGO ♂ × ACHEILOGNATHUS RHOMBEA ♀

1960 ◽  
Vol 38 (6) ◽  
pp. 1171-1173 ◽  
Author(s):  
J. J. Duyvené de Wit
Keyword(s):  
Embryonic Development ◽  
Genetic Factor ◽  
Parental Species ◽  
Intergeneric Hybrids ◽  
Free Swimming ◽  
Phylogenetic Relations ◽  
Male Phenotype

In order to study the phylogenetic relations between rhodeine species a number of interspecific and intergeneric crossings have been performed. This communication deals with the intergeneric hybrids obtained from the combinations Acheilognathus lanceolata ♂ × Acanthorhodeus atremius ♀ and Tanakia tanago ♂ × Acheilognathus rhombea ♀.From the first combination adult hybrids have been obtained which were intermediate between both parental species and showed a male phenotype. The second combination produced larvae, but a deficient yolk supply prevented them from reaching the free-swimming stage.Experimental evidence is presented for the occurrence of a dominant genetic factor in A. rhombea males, which controls the duration of embryonic development in this and other bitterling species.

scholarly journals Protein-Based Genetic Diversity Assessment of Tilapia guineensis and Sarotherodon melanotheron Populations from South-West Nigerian Coastal Waters

2020 ◽  
pp. 9-15
Author(s):  
E. A. Ukenye ◽  
I. Megbowon ◽  
M. M. A. Akinwale ◽  
M. A. Fowora ◽  
I. Chidume ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Similarity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Group Method ◽  
Cichlid Species ◽  
Diversity Assessment ◽  
Sds Page ◽  
Sarotherodon Melanotheron

The present study was carried out to investigate the genetic differences in the Protein banding pattern of Tilapia guineensis and Sarotherodon melanotheron populations in Southwest Nigeria using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Four populations of Tilapia guineensis and three populations of Sarotherodon melanotheron from Ondo and Lagos states were considered for the study. The sarcoplasmic protein of the studied Cichlid species resolved on 12% SDS-PAGE revealed variations in their genetic diversity indices (number of alleles, shanon information index, heterozygosity and percentage polymorphism). T. guineensis had more proteins and higher genetic diversity as was revealed by the genetic diversity parameters and was found to be more polymorphic with a percentage polymorphism of 78.57% than S. melanotheron (57.14%). The two species had similarity coefficient of 0.82 indicating high genetic similarity between them. UPGMA (Unweighted Pair Group Method with Arithmetic Mean) dendrogram also revealed some level of genetic similarity between the studied populations and among the two species. Analysis of molecular variance (AMOVA) confirmed the low genetic variation among the populations of the cichlid species and demonstrated that genetic variation was mostly within populations in both species. It is established from the study that Tilapia guineensis had higher genetic diversity than Sarotherodon melanotheron and the two species are closely related. Further study involving molecular markers is encouraged to complement this finding.

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