Unit 8: Evolution
10.2Darwin’s Observations
- What is Evolution?
Study of ______.
- Theories of Evolution –______
Jean Baptiste Lamarck (1744 – 1829)
►Law of ______
- parts of the body that are used become ______
- unused body parts become ______and eventually ______
►Law of ______
- organisms can pass traits ______to their
offspring
- ex. giraffe evolution
Lamarck’s explanation of how giraffes evolved long neck:
1)In order to reach higher leaves,giraffes ______andacquire long necks. (Law of Useand Disuse)
2) They can pass their ______to their offspring.
(Law of Inheritance of Acquired Characteristics)
3) Eventually, all giraffes ______over time.
Lamarck’s explanation was believed to be ______.
- Theories of Evolution –______
Charles Darwin (1809-1882)
-traveled on ______to ______observing and collecting samples of organisms
Darwin observed that:
1)the Galápagos Islands were ______but had very ______
______.
2)the characteristics of many animals and plants ______
among the different islands of the Galápagos. (ex: _____ species of finches)
Darwin wondered if finches living on different islands had once been members of the
______.
These separate species would have evolved from an original ______ancestor species.
Darwin’s conclusions:
-______in beaks
► ______in beaks in the original flock
► adaptations to ______available on islands
-natural selection for ______
► over many generations, the finches were selected for specific ______
______.
-offspring inherit ______
► accumulation of winning traits: both ______
-separate into different ______
Darwin collected the ______of ancientorganisms, called
______.
Some of those fossils ______organisms that werestill alive. Others looked
______any creature he had ever seen.
Darwin published the book“______” in 1859 (32 years
after the end of his voyage).
Darwin proposed the ______:
individuals with traits ______for a specific environment______
and ______these traits to theiroffspring.
How would Darwin have explained the evolution of giraffe’s long neck differently than
Lamarck?
-Based on Darwin’s theory of natural selection:
1)Long neck giraffes were ______for reaching higher leaves and ______.
2)More long neck giraffes survivedover time and ______
______to their offspring.
3)Short neck giraffes ______because they could not ______with the long neck giraffes.
10.3Theory of Natural Selection
- Several key insights led to Darwin’s idea for ______.
Darwin noticed ______plants and animals seemed to show traits that were not found in their ______.
Breeders of these domesticated plants and animals ______(instead of the ______).
______is the process by which ______select traits through ______. (aka “______”)
Darwin compared processes in ______to artificial selection.
In artificial selection, ______selects the desired traits; while in natural selection, ______(or ______) selects the desired traits.
In nature, there is always ______because of limited resources of ______, ______, and ______.
- ______ explains how evolution can occur.
There are ______main principles to the theory of natural selection.
1)______
A jaguar may produce ______thanthey can survive due to
______.
2)______: ______among individuals.
Jaguar 1 = ______jaws and teeth
Jaguar 2 = ______jaws and teeth
3)______: a feature that allows an organism to ______
______inits environment
Jaguars with larger jaws and teeth have better ______for eating ______, so they are more likely to survive and reproduce better.(______)
4)______: Over time, natural selection will produce more individuals with the ______that are bettersuited for a particular ______.
Larger jaws and teeth become the ______in the population.
Sojaguars’ descendants showed______, or change, over time.
11.2Natural Selection in Populations
- Modern Day Example of Natural Selection
______of peppered moths
- ______in Europe during 1850s affected the natural selection
on ______of the peppered moths
- As the ______changed, the moths that could______
themselves had better chancesof ______.
–early 1800s = pre-industrial England
► ______pollution
► lichen on trees = ______bark
► ______moths survived better
–late 1800s = industrial
► factories = ______coated trees
► killed lichen = ______bark
► ______moths survived better
–mid 1900s = pollution controls
► ______laws
► return of lichen = ______bark
► ______moths survived better again
- Natural selection acts on ______.
A normal distribution, represented by a ______, is generally found in a typical population.
-highest frequency near ______value
- frequencies ______toward each ______value
-Traits not undergoing natural selection have a ______.
-Draw a normal distribution curve in the space below:
- Natural selection can ______the distribution of a trait in one of three ways.
1)______selection
- favors ______phenotype
- ______variations
- Draw the graph of stabilizing selection below:
2)______selection
- favors phenotype at ______
- leads to ______
- Draw the graph of directional selection below:
3)______selection
- favors ______phenotypes; intermediatephenotype is
______
- leads to evolution of ______
- Draw the graph of disruptive selection below:
- Measures of Variation
Calculating the ______for simple data
Measure / Set A2, 2, 3, 5, 5, 7, 8 / Set B
2, 3, 3, 4, 6, 7
Mean:
add up all the data, and then divide this total by the number
of values in the data.
Median:
Put the values in order, then find the middle value. If there are two values in the middle then you find the mean of these two values.
Mode:
The mode is the value which appears the most
often in the data.
Range:
Find the lowest and highest values in the data. Then subtract the lowest value from the highest value.
11.1Genetic Variations within Populations
- Natural selection acts on different ______in a population.
______variation leads to ______variation.
The greater the genetic/phenotypic variations in a population increases the chance
that ______.
Genetic variation is stored in a population’s ______.
-gene pool = all the ______in all individuals in a population
______measure genetic variation.
-measures ______in population
-can be calculated for ______in gene pool
-As allele frequencies and gene pools change over time, the ______evolve.
- Genetic variation comes from several sources.
______is a random change in the DNA of a gene.
-can form ______
- can be passed on to offspring if in ______
Sexual reproduction results in ______. (crossing-over, independent assortment)
- Genetic variation results in different types of adaptations.
Adaptation = variations that improve an organisms’ chances for ______
and ______.
______adaptation (3 types)
1)______:
-carry ______, toxin (ex: skunk)
2)______:
-______= adaptive coloration; blend in with the ______.
-______= resemble another species that ______.
3)______:
-______body form (ex: fangs, claws, spine)
______adaptation
-Actions taken by an organism to ______(ex: running, hiding, migration, hibernating)
11.3Other Mechanism of Evolution
- Five Mechanisms for Evolution
1)______
-changes allele frequencies due to ______.
-Genetic drift causes a ______of genetic diversity.
-It is most common in ______.
-A ______can lead to genetic drift.
It occurs when an event drastically ______.
The ______is genetic drift that occurs after a
bottleneck event.
-The ______can lead to genetic drift.
It occurs when a few individuals ______.
The ______is genetic drift that occurs after start of new population.
Bottleneck Effect Founder Effect
2)______
- ______from one population to another
- changes the ______in a gene pool
-______= movement into the population
-______= movement out of the population
3)______
-permanent change in ______
-______mutations – help an organism ______to its environment
-______mutations – organism ______and ______from population
4)______
-selects for traits that improve ______
5)______
-selects for traits advantageous for ______
11.5Speciation Through Isolation
- The isolation of populations can lead to ______.
-Speciation = the rise of ______from one existing species.
- A species is a group of organisms that ______and produce ______.
- Populations become isolated when there is ______.
Isolated populations adapt to their ______.
______can add up over generations.
•Types of Isolation:
1)______Isolation
- isolated by ______(ex: continental drift, earthquake, volcano)
2) ______Isolation
- differences in ______and ______
3) ______Isolation
- ______of reproductive periods prevents mating
11.6Patterns in Evolution
- Evolution through natural selection is not random.
Natural selection can have direction.
The effects of natural selection add up over time.
•Patterns of evolution:
1)______Evolution
-describes evolution toward similar traits in unrelated species.
2) ______Evolution
- describes evolution toward different traits in closely related species.
3) ______
- Two or more species can ______.
–evolutionary paths become ______
–species evolve in response to ______
–coevolution can occur in ______or ______relationships.
4) ______
- ______evolve from one species
–______species diversifies into many ______species
–descendent species usually adapted to ______
–
- Label the following patterns of evolution:
- Species can become extinct.
–Extinction is the ______from Earth.
–occur at roughly the same rate as ______
–usually affects a ______in a small area
–caused by ______in environment
10.4Evidence of Evolution
- Types of Evidence of Evolution
1) ______– provides a record of the earth’s past life-forms
offers the ______evidence for evolution
shows a ______of early ancestors to their modern descendants
fossil – ______or ______remains (bone, petrified tree, tooth, or shell) or ______of an organism that lived long ago
fossil record is ______– many organisms lived in places where fossils could not form – there are ______in the record
2) ______– changes in ______
- closely related organisms have similar ______
and this also suggests ______
-Example: studying differences in hemoglobin between species
3) ______– comparison of anatomy reveals basic ______
______(even though the ______
may be very different) indicating common ancestry
______:
- ______but used for ______through
evolution
- ex. ______in vertebrates all have the same basic bone structure
- have ______(closely related)
______:
- ______but used for ______through
evolution
- ex: ______wings, ______wings, ______wings
- ______have common origin (not closely related)
- ancestors may have lived in ______with similar
selections
______:
- structures that are ______
- either have ______or have a ______than
they do in other related organisms
– provide evidence of an organism’s ______
- ex. ______in whales, ______in humans
4)______
- comparing embryos of related organisms shows ______
–- similar in ______, but different in ______
- ex: the embryos of ______have similar characteristics during early
development – all develop a ______, ______, buds that become
______, and ______