BIOL 2061 Chapter Notes - Chapter 20: Species Problem, Allele Frequency, Macroevolution
Chapter 20 Notes
Introduction
• Microevolution: Evolution on a small scale as it relates to allele frequencies in a
population
• Macroevolution: Evolutionary changes that produce new species and groups of species
• Species: A group of related organisms that share a distinctive set of attributes in nature
o Members of same species share evolutionary history
â–Ş Makes them more genetically similar
• Speciation: Formation of new species
20.1 Identification of Species
• Common estimates of the total number of species range from 5 to 50 million
• Subspecies: When two or more geographically restricted groups of the same species
display one or more traits that are somewhat different but not enough to count as a
different species
• Ecotypes: Genetically distinct populations that are adapted to their local environment
• Most commonly used characteristic for identifying species are morphological traits, the
ability to interbreed, molecular features, ecological factors, and evolution
relationships
o Morphological Traits: Physical characteristics
o Reproductive Isolation: Prevents one species from successfully interbreeding
with other species
â–Ş Main Problems (4)
• 1. Can be hard to determine if two populations are reproductively
isolated. Especially if they have no overlapping geographic ranges
• 2. When two species can interbreed but consistently maintain
themselves as separate species
• 3. Doesn’t apply to asexual species like bacteria and some forms of
plants and fungi
• 4. Extinct species
â–Ş Has been primarily used to distinguish closely related species of plants
and animals that reproduce sexually
o Molecular Features: Used to determine if two different populations are different
species
o Ecological Factors: When a variety of factors related to an organism’s habitat
may be used to distinguish one species from another.
o Evolutionary Relationships: Are diagrams that describe the relationships between
ancestral species and modern species.
• Species Concept: A way to define the concept of a species and/or of providing an
approach to distinguish one species from another.
• Biological Species Concept: A species as a group of individuals whose members have
the potential to interbreed with one another in nature to produce viable, fertile offspring
but cannot successfully interbreed with members of other species.
• Evolutionary Lineage Concept: An approach to distinguish species based off their
lineage.
find more resources at oneclass.com
find more resources at oneclass.com
