Evolution of Homeothermy in Mammals
All mammals and birds are endothermic, by generating and retaining heat internally they can achieve core body temperatures higher than the ambient temperature. This contrasts with other vertebrate classes where at most only a few species have this ability. All mammals are at least sometimes homeothermic, maintaining body temperature within a narrow range of a few degrees. Some mammals can become heterothermic, letting their body temperature decrease towards the ambient temperature by a regulated process, called (daily) torpor if it lasts less than 24 hours, and hibernation for longer periods. This site will be organized into projects, with each examining homeothermy in mammals from a novel perspective.
The Goldilocks Hypothesis
This hypothesis states that all mammals must be homeothermic during part of embryonic development . This requirement may have played a roll in the origin of the evolutionary constraint which results in almost all mammalian species having exactly 7 cervical vertebrae.
Sloppy Systems
Modeling suggests that the parameters that describe the actions of the molecular components and their interactions necessary to accomplish a particular cellular function have a property referred to as sloppiness. Some parameters can only vary slightly without affecting function, but most of the other parameters can vary more widely. This property presumably is favored during evolution because it makes the systems more robust by making many mutations less deleterious. Given this property, the ability to be homeothermic may have allowed more complex interactions between systems to evolve, such as the ability to be selectively heterothermic.
The Seven Cervical Vertebrae Constraint
Pathologies Associated with Cervical Ribs
Pathologies Associated with Heterothermy
The Fossil Record
Development- Gastrula through Pharyngula stages
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