Search results
Results From The WOW.Com Content Network
Occasionally, chimeras arise from loss or gain of individual chromosomes or chromosome fragments owing to misdivision. [42] More commonly cytochimeras have simple multiple of the normal chromosome complement in the changed layer. There are various effects on cell size and growth characteristics.
Having multiple sets of chromosomes is called polyploidy. Polyploidy is usually fatal in animals where extra chromosome sets upset fetal development, but is often found in plants. [17] A form of hybrid speciation that is relatively common in plants occurs when an infertile hybrid becomes fertile after doubling of the chromosome number.
The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons.
Hybridization without change in chromosome number is called homoploid hybrid speciation. It is considered very rare but has been shown in Heliconius butterflies [83] and sunflowers. Polyploid speciation, which involves changes in chromosome number, is a more common phenomenon, especially in plant species. [citation needed]
A mule is a sterile hybrid of a male donkey and a female horse.Mules are smaller than horses but stronger than donkeys, making them useful as pack animals.. In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction.
A sex-determination system in which the sex of an individual organism is determined by the number of sets of chromosomes it possesses: offspring which develop from fertilized eggs are diploid and female, while offspring which develop from unfertilized eggs are haploid and male, with half as many chromosomes as the females.
An image of multiple chromosomes, taken from many cells. Plant genetics is the study of genes, genetic variation, and heredity specifically in plants. [1] [2] It is generally considered a field of biology and botany, but intersects frequently with many other life sciences and is strongly linked with the study of information systems.
Most plants, as well as many groups of animals, lack heteromorphic sex chromosomes. [136] The absence of heteromorphic sex chromosomes results in slower accumulation of reproductive isolation, [ 137 ] [ 138 ] and may hence enable hybridization between phylogenetically more distant taxa.