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Some of the earliest examples of parent-offspring conflict were seen in bird broods and especially in raptor species. While parent birds often lay two eggs and attempt to raise two or more young, the strongest fledgling takes a greater share of the food brought by parents and will often kill the weaker sibling ().
Paradox of plenty: Countries with an abundance of natural resources tend to have less economic growth and worse development outcomes than countries with fewer natural resources. The paradox of banknotes: Cash transactions have decreased since the 1940s but the demand of banknotes has increased significantly since the early 2000s.
Induced parthenogenesis of this type in mice and monkeys results in abnormal development. This is because mammals have imprinted genetic regions, where either the maternal or the paternal chromosome is inactivated in the offspring for development to proceed normally. A mammal developing from parthenogenesis would have double doses of maternally ...
In amphibians, the development of the animal-vegetal axis occurs prior to fertilization. [1] Sperm entry can occur anywhere in the animal hemisphere. [2] The point of sperm entry defines the dorso-ventral axis - cells opposite the region of sperm entry will eventually form the dorsal portion of the body. [1] [3]
A freemartin or free-martin (sometimes martin heifer) is an infertile cow with masculinized behavior and non-functioning ovaries. [1] Phenotypically, the animal appears female, but various aspects of female reproductive development are altered due to acquisition of anti-Müllerian hormone from the male twin . [ 2 ]
Neoteny in humans is the slowing or delaying of body development, compared to non-human primates, resulting in features such as a large head, a flat face, and relatively short arms. These neotenic changes may have been brought about by sexual selection in human evolution .
The step lengthens as the pregnancy progresses, due to weight gain and changes in posture. On average, a woman's foot can grow by a half size or more during pregnancy. In addition, the increased body weight of pregnancy, fluid retention, and weight gain lowers the arches of the foot, further adding to the foot's length and width.
A heterotopic pregnancy is a complication of pregnancy in which both extrauterine pregnancy and intrauterine pregnancy occur simultaneously. [2] It may also be referred to as a combined ectopic pregnancy, multiple‑sited pregnancy, or coincident pregnancy. The most common site of the extrauterine pregnancy is the fallopian tube.