Chapter 22 - Intro Evolution Flashcards
How did humans get the opsin gene?
through mutation from previous ancestors
When was the earth formed?
4.6 bya (billion years ago)
When did life form?
~3.8 bya
What was early life?
prokaryotic cells
Changes in species can lead to?
a formation of new, separate species
In the simplest sense, what are species?
different kinds of organisms
Individuals of the same _______ share genetic similarity and can (potentially) interbreed
species
all the individuals of the same species occupying a specific area at a particular time
population
Example of populations
black bears and Joshua Trees
What constitutes the Joshua tree species?
all the populations together
explanation for a natural phenomenon
theory
measure of successful reproduction
fitness
All species have descended from other _______. And a single, _______ ancestor lies at base of the evolutionary tree
species; common
Natural Selection is what process?
a trait (or character) that confers reproductive advantage to an individual, spreads in a population over successive generations
Natural selection required understanding the ________ ________ of populations
biotic potential
T/F
Most populations are capable of producing more offspring than can be supported by the environment
true
What is exponential growth?
doubling
Natural selection requires variation in _______
phenotype
Example of phenotypic variation
population of Geospiza fortis, one of Dawrin’s finches
Within populations, there is variation between individuals - some of this variation is _______
heritable
Overtime, beneficial traits ______ through the population
spread
________ is required for natural selection
competition
T/F
Genetic traits that provided an advantage will be spread within a population, but those that do not will be lost from the population
True
What is evolution?
genetically based change of phenotype in a population over successive generations
Species are not fixed entities, but instead are what?
constantly undergoing modification and change
Origin of Species
Perceived ___________ as the primary force driving descent with modification
natural selection
independently developed theory of evolution
Alfred Russel Wallace
Naturalist who believed species were not fixed entities
Jean-Baptiste de Lamarck
What are the five agents of evolution?
Natural selection Sexual selection Gene flow Genetic drift Mutation
more offspring are produced then can be supported by the environment
competition
a change in DNA sequence (change in nucleotides)
mutation
Mutation is an ______ of evolution. How?
agent; Mutations create new alleles
the movement of existing alleles from one population to another by dispersal
gene flow
Example of gene flow
deer populations
chance alteration of allele frequencies in a population
genetic drift
Two forms of genetic drift:
Founder effect and Population bottleneck
New population is started by a few individuals that are not representative of genetic diversity in the original population
Founder effect
What form of genetic drift was seen in red spotted toads?
Founder effect
Following population decline, surviving individuals do not represent genetic diversity of the original population
Population bottleneck
In population bottleneck, survival is _______
random
Example of population bottleneck
elephant seals
Differential reproductive success based on differences in the success of obtaining mates
sexual selection
Example of sexual selection
Female mate choice within guppies
How new species come into being
speciation
Occurs when the geographical range of a species is split into discontinuous parts by formation of barriers to gene flow
Allopatric speciation
In Allopatric speciation, populations can become _______ in many different ways. List a couple
separated; environmental change, dispersal to an isolated area
Allopatric speciation in forest frogs
- Populations become isolated in different areas
- If enough gene flow occurs the populations will remain genetically similar
- If gene flow is lacking, populations diverge
- Overtime, if individuals from the diverging populations can no longer reproduce, speciation has occurred
What occurred almost 500 million years ago?
the Cambrian explosion