Chapter 21 - Evidence and Mechanisms of Evolution Flashcards
What year is the beginning of the “Modern Era of Biology?”
1859
The Origin of Species was published by whom?
Charles Darwin
What did The Origin of Species contain?
Darwin’s theory of evolution
What did Darwin observe during his 5 year voyage on the Galapagos Islands?
He observed that the animals on each island differed from island to island.
What did Darwin theorize about the animals among the different islands of the Galapagos?
Theorized that some animals had come from mainland South America and then undergo changes on each of the islands.
What was the common opinion about living creatures during the 19th century?
Living creatures are immutable products of a sudden creation. They existed now in precisely the form in which they always existed.
What did Darwin’s observations from his visit to South America and Galapagos Islands disprove?
His observations disproved the fixity of species - the common opinion during the 19th century about living creatures being immutable products of a sudden creation.
What was the guiding factor that Darwin believed determined the course of change?
Natural Selection - the guiding factor that determines the course of change.
What is Evolution?
the Process in which the form and overall genetic structure of an organisms change with time.
What evidence did Darwin use to combat the static view of creationism?
1) Fossils, 2) Resemblances between living species, 3) Changes produced in domesticated plants and animals
What kind of bones were dug up in South America by Charles Darwin?
Darwin dug up bones of extinct GIANT ARMADILLOS and GROUND SLOTHS
What conclusion did Darwin come to when he reconstructed the skeletons of the fossils that he dug up?
Darwin came to the conclusion that the extinct version of the bones and the modern version of the bones were similar so they seemed to be related.
What did Darwin conclude from the resemblances of different species when compared?
Darwin came to the conclusion that resemblance suggested that all these species descended from a common ancestor, each with their own DISTINCTIVE MODIFICATION.
What is Artificial Selection?
A process in which humans consciously select FOR or AGAINST particular features in organisms.
(Example: the human may allow only organisms with the desired feature to reproduce or may provide more resources to the organisms with the desired feature. This process causes evolutionary change in the organism and is analogous to natural selection, only with humans, not nature, doing the selecting.)
What is Natural Selection?
The guiding force in evolution; one of the basic mechanisms of evolution, along with MUTATION, MIGRATION, and GENETIC DRIFT
What is the meaning of Immutable?
not subject to change
What is the meaning of Species?
Series of populations within which significant gene flow occurs under natural conditions, but which is genetically isolated; it is a kind of animal, plant, or organism; the basic unit of biological classification.
What is Population?
Localized group of individuals belonging to the same species.
What is Population Genetics?
Study of gene pools and genetic variation in biological populations.
What is Gene Pool?
All of the genes in a population or species, thus its genetic constitution. The alleles present and their relative frequencies.
What is Gene Flow?
Movement of alleles between populations through interbreeding; any movement of genes from one population to another and is an important source of genetic variation; also known as “migration”
What are the smallest units that can evolve?
POPULATIONS (not individual organisms) are the smallest units that can evolve.
What makes up a Scientific Name?
1) Genus and 2) Species Epithet
What is a Theory?
Generalization supported by MUCH evidence.
What kind of science (anatomy) did Darwin use to come to the conclusion of natural selection?
Darwin used the science of COMPARATIVE ANATOMY to come to a conclusion that all species had a common ancestor and this was support for the resemblances between living species.
What are (2) important facts that have to do with NATURAL SELECTION?
1) organisms vary, and these variations are inherited (at least in part) by their offspring. 2) organisms produce more offspring than can survive.
Describe Natural Selection’s creative force.
On average, offspring that vary most strongly in directions favored by environment will survive and propagate FAVORABLE VARIATION will therefore accumulate in populations by Natural Selection. Offspring that DO NOT vary most strongly in directions favored by environment will die.
Jean Baptiste de Lamarck
Pre-Darwinian; theorized (2) mechanisms that fostered evolutionary change: 1) PRINCIPLE OF USE & DISUSE 2) INHERITANCE OF ACQUIRED CHARACTERISTICS
Describe the PRINCIPLE OF USE AND DISUSE
Body parts grow in proportion to how much they are used and structures not often used get weaker and shrink.
(Example: muscles do grow larger through continued use; most structures don’t respond in a Lamarckian way; Lamarck refers to somatic changes)
Describe INHERITANCE OF ACQUIRED CHARACTERISTICS
Changes that an animal acquires during its lifetime are inherited by its offspring.
What German evolutionary biologist disproved Lamarck?
August Weismann (1834-1914)
August Weismann
German Evolutionary Biologist; disproved Lamarckism; Contributed the GERM PLASM THEORY - inheritance only takes place by means of the germ cells (the gametes or egg and sperm cells).
Is it possible for organisms of different species to reproduce?
Yes, BUT they have to be very similar species genetically for them to be able to reproduce, and it is likely that their offspring will be sterile, but not always, making it highly unlikely for the offspring to survive and reproduce.
What is the Hardy Weinberg Theorem?
Law of population genetics stating that in the absence of selection, nonrandom mating, and other conditions, heredity tends to stabilize allelic frequencies in a population.
It also predicts phenotypic ratios from genotypic ratios in a randomly mating population.
Who is Alfred Russel Wallace?
a British naturalist, explorer, geographer, anthropologist and biologist that also came up with the ideas of natural selection and evolution and pushed for Darwin to publish The Origin of Species.
What is Hardy Weinberg Equilibrium?
The Hardy-Weinberg theorem states that the frequency of the dominant allele and the frequency of the recessive allele for a given population will not change, given that a certain set of circumstances are met;
A model that provides a base line from which evolutionary departures take place. It is important in evolution since it tells use what will happen in a NONEVOLVING population.
It also describes a reference point with which to compare the frequencies of Alleles and genotypes of natural populations whose gene pools may be changing.
4)Random mating, no sexual selection 5)No natural selection
What does Hardy Weinberg Equilibrium describe?
It describes genetics of an idealized population. This situation never exists in nature (under natural conditions).
What are the (5) conditions that need to be met for Hardy Weinberg Equilibrium to be maintained?
1) Population is very large (infinitely large), so that there is NO GENETIC DRIFT.
2) Population is isolated. No immigration or emigration; no coming or going. (NO MIGRATION or GENE FLOW IN OR OUT)
3) No net changes in gene pool due to mutations. (NO MUTATIONS)
4) Mating is random. (NO SEXUAL SELECTION.)
5) All genotypes are equal to reproductive success. (NO NATURAL SELECTION)
What is Allele Frequency?
How common an allele is in a given population…
What is Genetic Drift?
A change in the population’s allele frequency due to chance.
Example: natural disaster
What does ‘p’ refer to in the Hardy Weinberg Theorem?
p = frequency of the dominant allele
