Mechanisms of Microevolution adapted from http evolution berkeley

Mechanisms of Microevolution (adapted from: http: //evolution. berkeley. edu/evolibrary/article/0_0_0/evo_39) • Three (3) examples of mechanisms that contribute to Microevolutionary change. – Mutation – Migration (emigration and/or immigration) – Predation • ALL of the above produce VARIATION in populations. • VARIATION is the “fuel” for NATURAL SELECTION

EXAMPLE: Beetle Color • You are observing a population of beetles • Over time, you observe 2 changes in the beetle population – An increase in the frequency brown beetles – A decrease in the frequency of green beetles in the beetle population.

Example: Beetle Color (2) • As genes determine characteristics, you generate 2 related hypotheses based on your observations – The gene that makes beetles brown has increased in frequency in the population – The gene that makes beetles green has decreased.

Example: Beetle Color (3) • Any combination of the Microevolutionary Mechanisms might be responsible for the observed changed in the frequency of green and brown beetles

Contributing Microevolutionary Mechanisms • Mutation as the source of observed variation in beetle color – Some "green genes" randomly mutated to "brown genes“ – Since any particular mutation is rare, this process alone cannot account for a big change in gene frequency over one generation but can account for big changes of multiple generations.

Contributing Microevolutionary Mechanisms (2) • Migration (or Gene Flow) (Ref: Invasive species) – Some beetles with brown genes immigrated from another population, OR – Some beetles carrying green genes emigrated.

Contributing Microevolutionary Mechanisms (3) • Predation (Ref: Kettlewell) – Beetles with brown genes escaped predation (being eaten by a bird) and survived to reproduce more frequently than beetles with green genes – So more brown genes got into the next generation.