Question

Discuss the patterns and processes associated with the evolution of body size in mammals. In your answer, compare and contrast the biological and physical factors (e.g., feeding adaptations, heat regulation, skeletal adaptations, behaviours, and anything else you think is important) associated with optimal body size in the insectivores, proboscideans, and cetaceans.

Answer 1

Patterns and process associated with evolution of body size in mammals:

• Divergent evolution: where one ancestral species splits into two descendant species
• Co-evolution: changes in one species leads to reciprocal changes in the other- the two species exert selection pressures on each other.
• Adaptive radiation: where a range of new species evolves from a common ancestral species filing vacant ecological niches
• Punctuated equilibrium: Long periods of little evolutionary change in species (stasis) followed by short bursts of speculation
• Gradualism: Slow accumulation of genetic change over a long period of time, resulting in gradual change of the species.
• Convergent evolution: Where two species have similar adaptations due to similar selection pressures, not because they shared a common ancestor from which they derived these adaptations
• Directional selection: Individuals at one end of the Phenotypic range survive or have greater reproductive success(selection for one extreme)
• Clade: The set of species descended from a particular common ancestor
• Founder effect: A change in allele frequencies that occurs after a founder event, due to genetic drift.
• Common Ancestor: An ancestor that is shared by two descendent species
• Founder event: the establishment of a new populatipon, usually by a small number of individuals
• Genetic drift: Where chance variation in survival or RS cause changes in allele frequencies from one generation to the next.
• Homology: Similarity in characteristics between species resulting from inheritance of traits from a common ancestor
• Analogous structures: Structures serving the serving the same function but not found in a shared common ancestor(they are examples of convergent evolution)
• Natural selection: where some individuals have a greater reproductive success because they possess a beneficial variation in phenotype.
• Stabilising selection: A type of selection which occurs when individuals with intermediate values of a trait have higher fitness