University:
University of Cincinnati
Course:
BIOL 2084C | Evolution and Ecology
Academic year:

2023
Views:

133

Pages:

2
Author:

Marcus Zimmerman

Evolution and Community Ecology Notes Black and White, and Spread All Over • • • Zebra mussels and quagga mussels were accidentally introduced into Lake St. Clair in the late 1980s. They have since spread throughout the Great Lakes system and connecting rivers. The invasive mussels have a high economic and ecological cost. Examples of Invasive Species Other invasive species in our area of the world: • • • Japanese honeysuckle Japanese kudzu Asian carp Evolution and Natural Selection Evolution is simply change over time Gene: A sequence of DNA that codes for a particular trait Gene pool: All the genes present in a population Biological evolution: The change in a population’s gene pool over time 4 primary mechanisms of evolution: 1. 2. 3. 4. Mutation Migration Genetic drift Natural Selection Mechanisms of Biological Evolution: Mutation and Migration 1. Mutation Accidental change in DNA that can give rise to variation among individuals. Can be passed on to new generation 2. Migration (gene flow) Movement of individuals into (immigration) or out of (emigration) a population 3. Genetic Drift Evolution that occurs by chance (luck) Ex: fishing net kills or separates fish, bugs get squashed. 4. Natural Selection Process by which traits useful for survival and reproduction are passed on more frequently than those that are not Conditions of Natural Selection 1. Organisms produce more offspring than can survive. “struggle for existence” 2. Individuals vary in characteristics, some of which are heritable. 3. Individuals vary in fitness, or reproductive Success. SURVIVAL OF THE FITTEST! Artificial Selection Selection under human direction Throughout history, humans have chosen and bred animals and plants with beneficial traits. Speciation • • • Process by which new species are generated Can occur in a number of different ways; the most important way is called allopatric speciation: geographic separation Has resulted in every form of life on Earth— today and in the past Extinction The disappearance of species from Earth Generally occurs gradually, one species at a time, when environmental conditions change more rapidly than the species can adapt There are five known mass extinction events, each of which wiped out a large proportion of Earth’s species.