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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.
In one experimental population of zebra finches, there was increased singing activity by the male after breeding. [9] This increase is positively correlated with the partner's reproductive investment. The female finches were bred in cages with two subsequent males that differed with varying amounts of song output.
The zebra finch genome was the second bird genome to be sequenced, in 2008, after that of the chicken. [32] The Australian zebra finch uses an acoustic signal to communicate to embryos. It gives an incubation call to its eggs when the weather is hot—above 26 °C (79 °F)—and when the end of their incubation period is near.
The Australian zebra finch is used worldwide in several research fields (e.g. neurobiology, physiology, behaviour, ecology and evolution) as individuals are easy to maintain and breed in captivity. [12] Zebra finches are more social than many migratory birds, generally traveling in small bands and sometimes gathering in larger groups. [13]
Darwin's finches with different sized beaks that were suited for different seed types. Another example of directional selection is the beak size in a specific population of finches. Darwin first observed this in the publication of his book, On the Origin of Species, and he details how the size of the finches beak differs based on environmental ...
Example of a pedigree chart using Ahnentafel numbering. A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes [jargon] of a particular gene or organism and its ancestors from one generation to the next, [1] [2] [3] [unreliable source?] most commonly humans, show dogs, and race horses.
The phenotype of a homozygous dominant pair is 'A', or dominant, while the opposite is true for homozygous recessive. Heterozygous pairs always have a dominant phenotype. [ 11 ] To a lesser degree, hemizygosity [ 12 ] and nullizygosity [ 13 ] can also be seen in gene pairs.
A notable example in birds is the zebra finch. These birds have lateralised brain structures in the face of a common steroid signal, providing strong evidence for a non-hormonal primary sex mechanism regulating brain differentiation.