Introgressive Hybridization between Color Morphs in a Population of Cichlid Fishes Twelve Years after Human-Induced Secondary Admixis

In the extremely species-rich haplochromine cichlid fishes of the East African Great Lakes, prezygotic isolation between closely related species is often maintained by color-assortative mating. In 1998, local fisherman working for the ornamental fish trade released different color morphs of the cichlid genus Tropheus into a small harbor basin in the southern part of Lake Tanganyika. This artificial amalgamation of color morphs provides a unique possibility to study mating patterns in cichlids in a natural environment over time. In a precursor study, we analyzed genotypes and phenotypes of almost 500 individuals sampled between 1999 and 2001 and uncovered a marked degree of color-assortative mating, which depended on the level of color pattern dissimilarity between morphs. Twelve years after introduction of nonindigenous morphs, we again sampled Tropheus individuals from the harbor basin and an adjacent, originally pure population and analyzed phenotypes (coloration) and genotypes (mitochondrial control region and 9 microsatellite loci) to assess the current status of the admixed population. Principal component analyses of color score data and population assignment tests demonstrate an increasing level of introgressive hybridization between morphs but also some ongoing color-assortative mating within morphs. The observed mating pattern might have been influenced by fluctuating environmental conditions such as periodic algal blooms or increased sedimentation causing turbid conditions in an otherwise clear lak

Mating and Parental Care in Lake Tanganyika's Cichlids

Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay

Embryogenesis in microspore culture of Vitis subspecies

Embryoid structures showing epidermal layers have been regenerated from isolated Vitis microspores. Experiments were carried out on 8 genotypes of Vitis including different donor plant growth conditions, chilling of microspores (4 °C), heat shock (35 °C) and colchicine exposure (10, 25 and 50 mg/l) as induction treatments and incubation of the cultures on 87 different solid and liquid NN and LS media. The reactions of the cultured microspores included enlargement and thickening of the exine, formation of microcalli, calli, globular proembryos and embryoid structures displaying cell differentiation. Callus formation took place mainly on solid LS media with 3 % or 12 % sucrose, whereas most of the embryoids developed on NN media with 3 % sucrose. Both, callus and embryoid formation, were promoted by colchicine treatment. 8 months after transfer of calli and embryoids to subculture media, 4 embryoids still showed cell proliferation

Genotyping of grapevine and rootstock cultivars using microsatellite markers

Sixty-six grapevine and rootstock cultivars from an Austrian germplasm collection were genotyped using the following 10 microsatellite loci: VVS1, VVS2, VVS3, VVS4 (THOMAS and SCOTT 1993), VVS29 (THOMAS, pers. comm.), VVMD5, VVMD7 (BOWERS et al. 1996), VVMD28, VVMD32 and VVMD36 (BOWERS and MEREDITH, pers, comm.). All cultivars except those which are thought to be closely related (e.g. Portugieser blau and Portugieser grun) provided unique allelic profiles. A phenogram based on pairwise similarity values revealed the separation of rootstock cultivars from the Vitis vinifera varieties. The probability for the presence of null alleles was estimated from heterozygote deficiencies and null alleles were statistically excluded at 9 of the 10 loci. In order to demonstrate the distinctive power of the microsatellite markers investigated, gene diversity (GD) values were calculated. For both grapevine and rootstock cultivars we estimated a GD range from 0.70 to 0.91, while GD values for grapevines only range from 0.52 to 0.87 and values for rootstocks from 0.29 to 0.86

The ART of mating : alternative reproductive tactics and mating success in a nest-guarding fish

Fish use different modalities to access mates for reproduction, often referred to as Alternative Reproductive Tactics (ARTs). ARTs are an example of coexisting phenotypes, which have to hold some degree of reproductive success to persist in a population. In the Mediterranean damselfish (Chromis chromis), territorial males colonise nests on rocky reefs, competing for females, while sneaker males attempt to parasitically spawn in those nests. Here we combine behavioural observations in the field with molecular analyses, using bi-parentally and maternally inherited markers, to investigate reproductive success patterns of the two observed male ARTs in terms of number of eggs sired and number of females contributing to each nest. Cuckoldry was observed in every nest sampled, with at least two and up to seven sneakers per nest; however, the nesting male always significantly fathered the large majority of the eggs (on average 49%) in each clutch. Each sneaker fathered around 7% of the clutch. The average number of females whose eggs were fertilised by nesting males was 6.76 (ranging 2-13), while each sneaker on average fertilised the eggs of 1.74 (range 1-8) females. Using this sibship reconstruction, we investigated some of the factors involved in the regulation of the dynamic equilibrium of reproductive success between the two ARTs showed by C. chromis males. Our results show that the sneakers’ reproductive success was positively linked to egg clutch size; the density of individuals in the nesting area negatively affected the size of egg clutches; the rate of defence behaviours performed by nesting males negatively influenced the number of females contributing to each nest

Genetic diversity of wild and cultivated grapevine accessions from southeast Turkey

INRA UMR 1334 AGAP, Equipe DAVEM = Diversité et Adaptation de la Vigne et des Espèces MéditerranéennesWild grapevine genetic diversity in southeast Turkey has not been documented to date. In the present work, in order to clarify the relationships between wild and cultivated grape accessions from southeastern Turkey, 22 nuclear and three chloroplast microsatellite loci were used on 21 wild grapevine Vitis vinifera L. ssp. sylvestris (Gmelin) and 13 cultivated grapevine Vitis vinifera ssp. sativa accessions. The number of alleles per SSR locus ranged from 4 (VVIn16) to 20 (VVIv67) and the mean allele number per locus was 10.09. Expected locus heterozygosity ranged from 0.586 (locus VVIb01) to 0.898 (locus (VVIv67)). The three cpSSR molecular markers presented variation in size both in cultivars and in wild Turkish accessions. Two size variants were detected for cpSSR3 (106 and 107 bp) for cpSSR5 (104 and 105 bp), and for cpSSR10 (115 and 116 bp). The six alleles in wild grapevines fell into three haplotypes B, C and D. A genetic structure according to accessions taxonomic status (wild or cultivated) was revealed by UPGMA analysis. This highlighted a clear separation between domesticated and wild accessions in Turkish germplasm. The results pointed out the need to further collect and characterize this wild and cultivated grapevine germplasm

Nuclear and mitochondrial data reveal different evolutionary processes in the Lake Tanganyika cichlid genus Tropheus

<p>Abstract</p> <p>Background</p> <p>Cichlid fishes are notorious for their wealth of intra- and interspecific colour pattern diversity. In Lake Tanganyika, the endemic genus <it>Tropheus </it>represents the most impressive example for geographic variation in the pattern and hue of integument colouration, but the taxonomy of the over 100 mostly allopatric colour morphs remains to a large degree unresolved. Previous studies of mitochondrial DNA sequence data revealed polyphyly of the six nominally described species and complex phylogeographic patterns influenced by lake level fluctuations and population admixture, and suggested the parallel evolution of similar colour patterns in divergent evolutionary lineages. A gene tree of a rapidly radiating group may be subject to incomplete and stochastic lineage sorting, and to overcome this problem we used multi-locus, nuclear AFLP data in comparison with mtDNA sequences to study diversification, migration and introgression in <it>Tropheus </it>colour morphs in Lake Tanganyika.</p> <p>Results</p> <p>Significant incongruence between phylogenetic reconstructions from mitochondrial and AFLP data suggested incomplete sorting of mitochondrial haplotypes as well as frequent introgression between differentiated lineages. In contrast to the mitochondrial phylogeny, the AFLP phenogram was largely congruent with species classifications, colour pattern similarities, and in many cases also with the current geographic distribution of populations, and did not produce evidence of convergent colour pattern evolution. Homoplasy in the AFLP data was used to identify populations that were strongly affected by introgression.</p> <p>Conclusion</p> <p>Different evolutionary processes were distinguished by the combination of mitochondrial and AFLP data. Mitochondrial phylogeographic patterns retained signals of large-scale migration events triggered by historical, major lake level fluctuations, whereas AFLP data indicated genetic cohesion among local groups of populations resulting from secondary contact of adjacent populations in the course of the more frequently occurring, minor lake level fluctuations. There was no support for the parallel evolution of similar colour patterns in the AFLP data. Genetic signatures of introgression and hybridisation detected in several populations suggest that lake level fluctuations drove the stunning diversification of <it>Tropheus </it>morphs not only through population fragmentation, but also by promoting hybridisation between differentiated morphs in secondary contact.</p

Genetic continuity of brood-parasitic indigobird species

Speciation in brood-parasitic indigobirds (genus Vidua ) is a consequence of behavioural imprinting in both males and females. Mimicry of host song by males and host fidelity in female egg laying result in reproductive isolation of indigobirds associated with a given host species. Colonization of new hosts and subsequent speciation require that females occasionally lay eggs in the nests of novel hosts but the same behaviour may lead to hybridization when females parasitize hosts already associated with other indigobird species. Thus, retained ancestral polymorphism and ongoing hybridization are two alternative explanations for the limited genetic differentiation among indigobird species. We tested for genetic continuity of indigobird species using mitochondrial sequences and nuclear microsatellite data. Within West Africa and southern Africa, allopatric populations of the same species are generally more similar to each other than to sympatric populations of different species. Likewise, a larger proportion of genetic variation is explained by differences between species than by differences between locations in alternative hierarchical amovas, suggesting that the rate of hybridization is not high enough to homogenize sympatric populations of different species or prevent genetic differentiation between species. Broad sharing of genetic polymorphisms among species, however, suggests that some indigobird species trace to multiple host colonization events in space and time, each contributing to the formation of a single interbreeding population bound together by songs acquired from the host species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75693/1/j.1365-294X.2005.02492.x.pd

Identification and relationship of the autochthonous ‘Romé’ and ‘Rome Tinto’ grapevine cultivars

The ‘Romé’ variety is considered an Andalusian (southern region in Spain) autochthonous black grape cultivar. However, several white and black grapevine accessions are known by this name, according to Vitis International Variety Catalogue. The aim of the present work was to clarify the identity of the ‘Romé’ and ‘Rome Tinto’ as black grapevine cultivar. Eight accessions known as ‘Romé’ and two as ‘Rome Tinto’ were analyzed using 30 OIV descriptors and 22 SSR loci. The morphologic and genetic analysis showed that all accessions studied presented the same genotype and phenotype and grouped with South Spanish cultivars. This study helps to clarify the confusion over the identity of ‘Romé’ grapevine cultivar, and provides a solid basis to develop a germplasm collection to protect grapevine diversity and to recover cultivars that may be in danger of extinction

Evolutionary History of Lake Tanganyika's Predatory Deepwater Cichlids

Hybridization among littoral cichlid species in Lake Tanganyika was inferred in several molecular phylogenetic studies. The phenomenon is generally attributed to the lake level-induced shoreline and habitat changes. These allow for allopatric divergence of geographically fragmented populations alternating with locally restricted secondary contact and introgression between incompletely isolated taxa. In contrast, the deepwater habitat is characterized by weak geographic structure and a high potential for gene flow, which may explain the lower species richness of deepwater than littoral lineages. For the same reason, divergent deepwater lineages should have evolved strong intrinsic reproductive isolation already in the incipient stages of diversification, and, consequently, hybridization among established lineages should have been less frequent than in littoral lineages. We test this hypothesis in the endemic Lake Tanganyika deepwater cichlid tribe Bathybatini by comparing phylogenetic trees of Hemibates and Bathybates species obtained with nuclear multilocus AFLP data with a phylogeny based on mitochondrial sequences. Consistent with our hypothesis, largely congruent tree topologies and negative tests for introgression provided no evidence for introgressive hybridization between the deepwater taxa. Together, the nuclear and mitochondrial data established a well-supported phylogeny and suggested ecological segregation during speciation