Search results for "Breeding"
showing 10 items of 475 documents
Reproductive biology and conservation implications of three endangered snapdragon species (Antirrhinum, Plantaginaceae)
2009
About 32% of Antirrhinum species are considered to be endangered; however, no field studies have focused on their reproductive biology. In this work, several aspects of the reproductive biology (flowering phenology, floral biology, breeding system) and potential limits on seed quantity and quality (pollen limitation, inbreeding depression) were studied in natural populations of three endangered species of the genus (Antirrhinum charidemi, Antirrhinum subbaeticum, Antirrhinum valentinum). Results disclose that all three species need insect visitors for seed production since fruit set after autonomous self-pollination was lower than under hand cross-pollination. A. charidemi and A. valentinum…
Factors influencing the extent of inbreeding depression: an example from scots pine
1999
Detailed studies suggest that the level of inbreeding depression may vary between populations. In a study of Scots pine from Finland, the level of inbreeding depression was much lower in northern than in southern populations. We have examined theoretically whether population genetic factors, such as the level of selfing, intensity of selection against heterozygotes or homozygotes, level of mutation, a bottleneck, finite population size, or the level of polyembryony could account for this difference. Higher selfing or stronger selection against heterozygotes in the north, both at biologically reasonable levels, appear to produce changes consistent with the observed differences and we conside…
The significance of relatedness and gene flow on population genetic structure in the subsocial spider Eresus cinnaberinus (Araneae: Eresidae)
1998
Interdemic selection, inbreeding and highly structured populations have been invoked to explain the evolution of cooperative social behaviour in the otherwise solitary and cannibalistic spiders. The family Eresidae consists of species ranging from solitary and intermediate subsocial to species exhibiting fully cooperative social behaviour. In this study we, in a hierarchical analysis, investigated relatedness of putative family clusters, inbreeding and population genetic structure of the subsocial spider Eresus cinnaberinus. Five hierarchical levels of investigation ranging from large scale genetic structure (distances of 250 and 50 km level 1 and 2) over microgeographic structure (20 km 2 …
Stepping stones of life: natal dispersal in the group-living but noncooperative speckled warbler
2003
In most cooperatively breeding birds the offspring of one sex, usually male, delays dispersal to remain on the natal territory and helps its parents to rear subsequent young. Thus delayed dispersal could be the first step in the evolution of cooperative breeding. We studied natal dispersal in a population of the group-living speckled warbler, Chthonicola sagittata, based on observations of a colour-banded population over 3 years. Unlike other group-living members of the Acanthizinae, all juvenile males in this population dispersed to settle on foreign territories as subordinates, which do not help rear the young. Speckled warblers showed all the life history traits that are thought to resul…
Food for flight: pre-migratory dynamics of the Lesser Kestrel Falco naumanni.
2014
Capsule The post-reproductive stage of Lesser Kestrel is crucial for migratory fuelling and survival. Aims To describe the summer pre-migratory ecology of the Lesser Kestrel in Sicily and review existing data in Southern Europe. Methods We identified the main summer roosts and then made roost counts every ten days from 2010 to 2012. We used case-sensitive modelling procedures to detect biases in counts (generalized linear mixed models), assess the annual population trends from 2005 to 2012 (TRends and Indices for Monitoring); and to model habitat preferences (generalized linear model). We sampled pellets to describe the birds’ diet during the peak month prior to migration. Results We discov…
Population genetic structure of the butterflyMelitaea didyma(Nymphalidae) along a northern distribution range border
1996
The population genetic structure of the butterfly Melitaea didyma was studied along the northern distribution range border in Central Germany by means of allozyme electrophoresis. Individuals were sampled from a total of 21 habitat patches from four regions, and two provinces. Sampling was designed to estimate local vs. regional differentiation. High levels of variability were found, He= 0.14-0.21. The mean expected sample heterozygosity from one region, Mosel, was significantly lower than from the Hammelburg region, He= 0.17 and 0.19, respectively. Two hierarchical levels of genetic differentiation were found. Within regions individuals sampled from different patches behaved as belonging t…
Generation of homozygosity and genome fixation in pea (Pisum sativum L.)
2013
Pea cultivars are nearly homozygous and thus homogeneous when they are released. The traditional method of selfing is slow and inefficient, taking up to ten generations of inbreeding following a cross to achieve a high level of homozygosity. Current single-seed-descent (SSD) methodologies enable a maximum of three generations per year to be developed in pea. Doubled haploidy and an in vitro based modified SSD technology have been utilised in many important crops for the rapid achievement of homozygosity, and thus acceleration of the breeding process. In pea, due to the lack of robust protocols, none of these technologies is routinely used in a breeding program. The aim of this study was to …
Rumicetum palustris (TIMÁR 1950) W. FISCHER 1978, new plant community from Bidentetea tripartiti R. Tx., LOHM. ET Prsg 1950 class in SW Poland
2016
Natural water reservoirs are very valuable floristic sites in Poland. Among them, the most important for preservation of biodiversity of plant communities are lakes, rivers, oxbow lakes and fishponds. The long-term process of human pressure on habitats of this type caused disturbance to their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of last two hundred years, led to systematic disappearance of localities of many plant communities. Rumicetum palustris (Timár 1950) W. Fischer 1978, of Bidentetea tripartiti R. Tx., Lohm. et Prsg 1950 class, has been described for the first time in Hungary and Germany. This …
Gnaphalio uliginosi-eleocharitetum acicularis Passarge 1999, new plant community in Poland
2017
Zbiorniki wodne są bardzo cennymi miejscami florystycznymi w Polsce. Wśród nich najważniejsze dla zachowania różnorodności biologicznej flory są stawy rybne. Długookresowy proces oddziaływania ludzkiego na tego typu siedliska powodował zakłócenia w ich równowadze biologicznej. Zmiany w systemie wodnym, rozwój przemysłowy i chemizacja rolnictwa, zwłaszcza w okresie ostatnich dwóch stuleci, doprowadziły do zaniku wielu gatunków roślin oraz zbiorowisk roślinnych. Zespół Gnaphalio uliginosi-Eleocharitetum acicularis Passarge 1999 z klasy Isoëto-Nanojuncetea Br.-Bl. et Tx. 1943, po raz pierwszy został opisany w Niemczech. Rośnie na piaszczystych lub mulistych brzegach rzek, starorzeczach i w sta…
Anther culture in Citrus clementina: a way to regenerate tri-haploids
2005
Abstract. Regenerants from anther culture of Citrus clementina Hort. ex Tan. cvv. Nules, SRA 63, and Monreal were obtained in different experiments from 1994 to 2002. Genetic analysis of 37 such regenerants was carried out using 4 microsatellite markers that were heterozygous in the parental genotypes. The results showed that in all cases but one the regenerants carried only one or the other allele of the parental genotype, and were therefore homozygous and produced through a process of gametophytic embryogenesis. Ploidy analysis by flow cytometry of 94 regenerants showed that as many as 82% of them were tri-haploids, rather than haploids or doubled-haploids as expected, with other ploidy …