Search results
Results from the WOW.Com Content Network
Animals avoid inbreeding only rarely. [2] Inbreeding results in homozygosity which can increase the chances of offspring being affected by recessive traits. [3] In extreme cases, this usually leads to at least temporarily decreased biological fitness of a population [4] [5] (called inbreeding depression), which is its ability to survive and ...
It was notable as a dicephalic animal for surviving into adulthood with two perfect heads. Scientists have published in modern journals about dissecting such animals since at least the 1930s. [10] A 1929 paper studied the anatomy of a two-headed kitten. [10] Polycephalic animals, due to their rarity, are a subject of novelty.
[2] [3] In most species with XY sex determination, an organism must have at least one X chromosome in order to survive. [4] [5] The XY system contrasts in several ways with the ZW sex-determination system found in birds, some insects, many reptiles, and various other animals, in which the heterogametic sex is female.
Many animal species have specific mating (or breeding) periods e.g. (seasonal breeding) so that offspring are born or hatch at an optimal time. In marine species with limited mobility and external fertilisation like corals , sea urchins and clams , the timing of the common spawning is the only externally visible form of sexual behaviour.
Most therian mammals have only one pair of sex chromosomes in each cell. Males have one Y chromosome and one X chromosome, while females have two X chromosomes. In mammals, the Y chromosome contains a gene, SRY, which triggers embryonic development as a male. The Y chromosomes of humans and other mammals also contain other genes needed for ...
Haemophilia frequency is about 1 instance in every 10,000 births (or 1 in 5,000 male births) for haemophilia A and 1 in 50,000 births for haemophilia B. [56] About 18,000 people in the United States have haemophilia. Each year in the US, about 400 babies are born with the disorder.
U.S. officials on Thursday approved drugmaker BioMarin's gene therapy for the most common form of hemophilia, a $2.9 million infused treatment that can significantly reduce dangerous bleeding ...
Heteropaternal superfecundation is common in animals such as cats and dogs. Stray dogs can produce litters in which every puppy has a different sire. Though rare in humans, cases have been documented. In one study on humans, the frequency was 2.4% among dizygotic twins whose parents had been involved in paternity suits. [6]