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Some females abort or resorb their own young while they are still in development after a new male takes over; this is known as the Bruce effect. [31] This may prevent their young from being killed after birth, saving the mother wasted time and energy. However, this strategy also benefits the new male.
In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5]
This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental.
Some rodent species (most typically males) will take the chance to kill neonates that are unrelated to them should opportunity permit. There is thought to be several benefits by doing so, which not only include nutrition benefits (particularly where food is in short supply [8]) but also non-direct benefits, such as allowing access to more resources, improving reproductive opportunities and the ...
The Bruce effect, or pregnancy block, [1] [2] is the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male. [3] The effect was first noted in 1959 by Hilda M. Bruce, [4] and has primarily been studied in laboratory mice (Mus musculus). [1]
Human babies are unique in the animal kingdom due to their large head size relative to their bodies. This has an effect on the birthing process for humans as the bipedal gait of a human causes the birthing canal to be relatively narrow and twisted in the middle.
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The larval stage of insect development is considered by some to be a form of altricial development, but it more accurately depicts, especially amongst eusocial animals, an independent phase of development, as the larvae of bees, ants, and many arachnids are completely physically different from their developed forms, and the pre-pupal stages of ...