Chapter 16 Notes - Principles of Evolution
Charles Darwin:
England
traveled on the HMS Beagle as the naturalist
5 year trip around the world — spent time in the Galapagos islands
collected specimens at each stop
evolution - change in living things over time
Darwin developed a theory of biological evolution that offered a scientific explanation for the unity and diversity of life by proposing how modern organisms evolved through descent from common ancestors
Darwin’s work revealed that the living world changes continuously
The evolutionary theory helps us understand and respond to important events such as the emergence of drug-resistant bacteria and new strains of influenza (flu)
Darwin observed 3 patterns of biodiversity on his voyage:
Species vary globally — different, yet ecologically similar species inhabited separated, but ecologically similar, habitats around the globe
Species vary locally — different, yet related species often occupied different habitats within a local area
Species vary over time — the fossil record included many extinct animals that were similar to, yet different from, living species
fossils - the preserved remains or traces of ancient organisms
The Journey Home:
Darwin observed that the characteristics of many animals and plants varied noticeably among the Galapagos Islands
After returning back to England, Darwin wondered if the birds he had collected all belonged to the same species at some time — proving that they had evolved, contradictory to the popular beliefs at the time
James Hutton and Charles Lyell — concluded that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present
Hutton proposed that layers of rock form very slowly and others are pushed up from the sea floor to form mountains
Lyell’s principles of geology: the same process that changed the Earth in the past still operate in the present
ex. volcanoes, erosion
Darwin was influenced by Hutton and Lyell’s work
he reasoned, if the Earth can change over time (earthquakes, volcanoes) maybe life can change too
Lamarck’s Evolution Hypothesis:
Jean-Baptiste Lamarck observed that life changes and species descend from other species
Lamarck had two ideas:
Organisms can alter their bodies by “use and disuse”
Use: use a structure and it will change
Disuse: structures not used will disappear
Acquired characteristics can be inherited
If you increase your muscle mass, your children will inherit your big muscles
→ Although, Lamarck’s ideas were incorrect
He was one of the first people to realize that organisms are adapted to their environments and to propose a theory of evolution
Thomas Mathus was an economist, he published a book which stated that babies were being born faster than people were dying
he reasoned that if the human population continued to grow unchecked, sooner or later, food and living space would run out
Darwin thought this applied to plants and other animals even more because humans usually only have one offspring at a time
Darwin observed that individual organisms differed from one another and that variation could be inherited
farmers and breeders used this
artificial selection - selecting the best organisms to breed and pass on their trait
nature provides the inherited variations, and humans select hose variants they find useful
inherited variations could provide raw material for a natural mechanism that could drive evolution
Darwin realized that organisms compete for resources — struggle for existence
He hypothesized that individuals with certain types of inheritable variation are better suited, or adapted, to life in their environment than others. He noted that organisms better suited to their environment survived to reproduce and pass on their genes
ex. run faster, hide from predators
adaptations - any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment
fitness - the ability of an animal to survive and reproduce in its specific environment
survival of the fittest - more than just staying alive, it means reproducing and passing adaptations on to the next generation
natural selection - the process by which organisms in nature with variations most suited to their local environment survive and leave more offspring
in both artificial and natural selection, only certain individuals produce offspring, but in natural selection it is the environment, not a farmer or breeder, that influences fitness
natural selection occurs in any situation in which more individuals are born than can survive
natural heritable variation affects the ability to survive and reproduce, and fitness varies among individuals
principle of common descent - all species, living and extinct, are united by descent from ancient common, and exhibit diversity due to natural selection and adaptation
A great deal of evolution remains to be learned, however, every scientific test, to date, has supported Darwin’s basic ideas
biogeography - the study of where organisms live now and where they and their ancestor lived in the past
patterns in the distribution of living and fossil species, combined with information from geology, tell us how modern organisms evolved from their ancestors
two potential difficulties for Darwin’s theory involved the age of Earth and gaps in fossil record
radioactive dating indicates that Earth is about 4.5 bil years old — plenty of time for evolution by natural selection to take place
recently discovered fossils form sequences that trace the evolution from extinct common ancestors
homologous structures - similar structures that are shared by related species and have been inherited from a common ancestor
analogous structures - body parts of organisms that share common functions but not common structure and development
ex. wing of a bee and wing of a bird
vestigial structures - inherited from ancestors but have lost much of their original size and function
ex. hipbones of the bottlenose dolphin
similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor
at the molecular level, similarities in the genetic code of all organisms, along with homologous molecules, provide evidence of common descent
Charles Darwin:
England
traveled on the HMS Beagle as the naturalist
5 year trip around the world — spent time in the Galapagos islands
collected specimens at each stop
evolution - change in living things over time
Darwin developed a theory of biological evolution that offered a scientific explanation for the unity and diversity of life by proposing how modern organisms evolved through descent from common ancestors
Darwin’s work revealed that the living world changes continuously
The evolutionary theory helps us understand and respond to important events such as the emergence of drug-resistant bacteria and new strains of influenza (flu)
Darwin observed 3 patterns of biodiversity on his voyage:
Species vary globally — different, yet ecologically similar species inhabited separated, but ecologically similar, habitats around the globe
Species vary locally — different, yet related species often occupied different habitats within a local area
Species vary over time — the fossil record included many extinct animals that were similar to, yet different from, living species
fossils - the preserved remains or traces of ancient organisms
The Journey Home:
Darwin observed that the characteristics of many animals and plants varied noticeably among the Galapagos Islands
After returning back to England, Darwin wondered if the birds he had collected all belonged to the same species at some time — proving that they had evolved, contradictory to the popular beliefs at the time
James Hutton and Charles Lyell — concluded that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present
Hutton proposed that layers of rock form very slowly and others are pushed up from the sea floor to form mountains
Lyell’s principles of geology: the same process that changed the Earth in the past still operate in the present
ex. volcanoes, erosion
Darwin was influenced by Hutton and Lyell’s work
he reasoned, if the Earth can change over time (earthquakes, volcanoes) maybe life can change too
Lamarck’s Evolution Hypothesis:
Jean-Baptiste Lamarck observed that life changes and species descend from other species
Lamarck had two ideas:
Organisms can alter their bodies by “use and disuse”
Use: use a structure and it will change
Disuse: structures not used will disappear
Acquired characteristics can be inherited
If you increase your muscle mass, your children will inherit your big muscles
→ Although, Lamarck’s ideas were incorrect
He was one of the first people to realize that organisms are adapted to their environments and to propose a theory of evolution
Thomas Mathus was an economist, he published a book which stated that babies were being born faster than people were dying
he reasoned that if the human population continued to grow unchecked, sooner or later, food and living space would run out
Darwin thought this applied to plants and other animals even more because humans usually only have one offspring at a time
Darwin observed that individual organisms differed from one another and that variation could be inherited
farmers and breeders used this
artificial selection - selecting the best organisms to breed and pass on their trait
nature provides the inherited variations, and humans select hose variants they find useful
inherited variations could provide raw material for a natural mechanism that could drive evolution
Darwin realized that organisms compete for resources — struggle for existence
He hypothesized that individuals with certain types of inheritable variation are better suited, or adapted, to life in their environment than others. He noted that organisms better suited to their environment survived to reproduce and pass on their genes
ex. run faster, hide from predators
adaptations - any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment
fitness - the ability of an animal to survive and reproduce in its specific environment
survival of the fittest - more than just staying alive, it means reproducing and passing adaptations on to the next generation
natural selection - the process by which organisms in nature with variations most suited to their local environment survive and leave more offspring
in both artificial and natural selection, only certain individuals produce offspring, but in natural selection it is the environment, not a farmer or breeder, that influences fitness
natural selection occurs in any situation in which more individuals are born than can survive
natural heritable variation affects the ability to survive and reproduce, and fitness varies among individuals
principle of common descent - all species, living and extinct, are united by descent from ancient common, and exhibit diversity due to natural selection and adaptation
A great deal of evolution remains to be learned, however, every scientific test, to date, has supported Darwin’s basic ideas
biogeography - the study of where organisms live now and where they and their ancestor lived in the past
patterns in the distribution of living and fossil species, combined with information from geology, tell us how modern organisms evolved from their ancestors
two potential difficulties for Darwin’s theory involved the age of Earth and gaps in fossil record
radioactive dating indicates that Earth is about 4.5 bil years old — plenty of time for evolution by natural selection to take place
recently discovered fossils form sequences that trace the evolution from extinct common ancestors
homologous structures - similar structures that are shared by related species and have been inherited from a common ancestor
analogous structures - body parts of organisms that share common functions but not common structure and development
ex. wing of a bee and wing of a bird
vestigial structures - inherited from ancestors but have lost much of their original size and function
ex. hipbones of the bottlenose dolphin
similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor
at the molecular level, similarities in the genetic code of all organisms, along with homologous molecules, provide evidence of common descent
