chapter 15 evolution natural selection individuals in a population show variations. variations can...
TRANSCRIPT
![Page 2: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/2.jpg)
Natural Selection
Individuals in a population show variations.
Variations can be inherited.
Organisms have more offspring than can survive on available resources.
Variations that increase reproductive success will have a greater chance of being passed on.
15.1 Darwin’s Theory of Natural Selection
![Page 3: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/3.jpg)
15.2 Evidence of Evolution
Support for Evolution
The fossil record
Glyptodont
Fossils provide a record of species that lived long ago.
Fossils show that ancient species share similarities with species that now live on Earth.
Armadillo
![Page 4: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/4.jpg)
Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors.
Ancestral traits are more primitive features, such as teeth and tails, that do appear in ancestral forms.
Anatomically similar structures inherited from a common ancestor are called homologous structures.
15.2 Evidence of Evolution
![Page 5: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/5.jpg)
Vestigial Structures
Structures that are the reduced forms of functional structures in other organisms.
15.2 Evidence of Evolution
Evolutionary theorypredicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost.
![Page 6: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/6.jpg)
Show that functionally similar features can evolve independently in similar environments
Analogous structures can be used for the same purpose and can be superficially similar in construction, but are notinherited from a common ancestor.
15.2 Evidence of Evolution
![Page 7: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/7.jpg)
Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms.
Comparative Embryology
15.2 Evidence of Evolution
![Page 8: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/8.jpg)
Common ancestry can be seen in the complex metabolic molecules that many different organisms share.
Comparative Biochemistry
15.2 Evidence of Evolution
![Page 9: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/9.jpg)
Geographic Distribution
The distribution of plants and animals that Darwin saw first suggested evolution to Darwin.
Rabbit Mara
15.2 Evidence of Evolution
![Page 10: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/10.jpg)
Types of Adaptation
An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success.
Fitness is a measure of the relative contribution an individual trait makes to the next generation.
15.2 Evidence of Evolution
![Page 11: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/11.jpg)
Camouflage Allows organisms to become almost invisible to predators or prey.
Leafy sea dragon
15.2 Evidence of Evolution
Orchid mantis
![Page 12: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/12.jpg)
Mimicry One species evolves to resemble another species.
Western coral snake California kingsnake
15.2 Evidence of Evolution
![Page 13: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/13.jpg)
Consequences of Adaptations
Some features of an organism might be consequences of other evolved characteristics.
They do not increase reproductive success.
Features likely arose as an unavoidable consequence of prior evolutionary change.
15.2 Evidence of Evolution
![Page 14: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/14.jpg)
15.3 Shaping Evolutionary Theory
Mechanisms of Evolution Population genetics
Hardy-Weinberg principle states that when allelic frequencies remain constant, a population is in genetic equilibrium.
![Page 15: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/15.jpg)
15.3 Shaping Evolutionary Theory
![Page 16: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/16.jpg)
Genetic Drift
A change in the allelic frequencies in a population that is due to chance
In smaller populations, the effects of genetic drift become more pronounced, and the chance of losing an allele becomes greater.
15.3 Shaping Evolutionary Theory
![Page 17: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/17.jpg)
Founder Effect
Occurs when a small sample of a population settles in a location separated from the rest of the population
Alleles that were uncommon in the original population might be common in the new population.
15.3 Shaping Evolutionary Theory
![Page 18: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/18.jpg)
Bottleneck Occurs when a population declines to a very
low number and then rebounds
15.3 Shaping Evolutionary Theory
![Page 19: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/19.jpg)
Gene Flow
Increases genetic variation within a population and reduces differences between populations
Nonrandom Mating
Promotes inbreeding and could lead to a change in allelic proportions favoring individuals that are homozygous for particular traits
15.3 Shaping Evolutionary Theory
![Page 20: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/20.jpg)
Natural Selection
Acts to select the individuals that are best adapted for survival and reproduction
15.3 Shaping Evolutionary Theory
![Page 21: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/21.jpg)
Stabilizing selection operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness.
15.3 Shaping Evolutionary Theory
![Page 22: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/22.jpg)
Directional selection makes an organism more fit.
15.3 Shaping Evolutionary Theory
![Page 23: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/23.jpg)
Disruptive selection is a process that splits a population into two groups.
15.3 Shaping Evolutionary Theory
![Page 24: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/24.jpg)
Sexual selection operates in populations where males and females differ significantly in appearance.
Qualities of sexual attractiveness appear to be the opposite of qualities that might enhance survival.
15.3 Shaping Evolutionary Theory
![Page 25: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/25.jpg)
Obstacle to mating or to fertilization if mating occurs
Prezygotic isolation
behavioral isolation
geographic isolation ecological isolation temporal isolation
mechanical isolation gametic isolation
![Page 26: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/26.jpg)
Postzygotic isolation occurs when fertilization has occurred but a hybrid offspring cannot develop or reproduce.
Prevents offspring survival or reproduction
Liger
15.3 Shaping Evolutionary Theory
![Page 27: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/27.jpg)
Mules are vigorous, but sterile
Postzygotic isolation Reduced hybrid fertility
Even if hybrids can occur they may be sterilechromosomes of parents may differ in
number or structure & meiosis in hybrids may fail to produce normal gametes
Donkeys have 62 chromosomes(31 pairs)
Horses have 64 chromosomes(32 pairs)
Mules have 63 chromosomes!
![Page 28: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/28.jpg)
How do new species originate?Populations must become isolated
geographically isolated reproductively isolated
isolated populations evolve independentlyIsolation
allopatricgeographic separation“other country”
sympatricstill live in same area“same country”
![Page 29: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/29.jpg)
Allopatric Speciation
A physical barrier divides one population into two or more populations.
Abert squirrel Kaibab squirrel
15.3 Shaping Evolutionary Theory
![Page 30: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/30.jpg)
Sympatric Speciation
A species evolves into a new species without a physical barrier.
The ancestor species and the new species live side by side during the speciation process.
15.3 Shaping Evolutionary Theory
![Page 31: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/31.jpg)
Adaptive Radiation
Follows large-scale extinction events
Can occur in a relatively short time when one speciesgives rise to many different species in response to the creation of new habitat or some other ecological opportunity
15.3 Shaping Evolutionary Theory
![Page 32: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/32.jpg)
Coevolution
The relationship between two species might be so close that the evolution of one species affects the evolution of the other species.
Mutualism
Coevolutionary arms race
15.3 Shaping Evolutionary Theory
![Page 33: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/33.jpg)
Unrelated species evolve similar traits even though they live in different parts of the world.
Convergent Evolution
15.3 Shaping Evolutionary Theory
![Page 34: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/34.jpg)
Rate of Speciation
Evolution proceeds in small, gradual steps according to a theory called gradualism.
Punctuated equilibrium explains rapid spurts of genetic change causing species to diverge quickly.
15.3 Shaping Evolutionary Theory
![Page 35: Chapter 15 Evolution Natural Selection Individuals in a population show variations. Variations can be inherited. Organisms have more offspring](https://reader035.vdocuments.net/reader035/viewer/2022062304/56649ea05503460f94ba3119/html5/thumbnails/35.jpg)
15.3 Shaping Evolutionary Theory