Darwin’s Theory Of Evolution Analysis – Flashcards

Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.

Abraham Lincoln. They both were born on February 12, 1809.

Evolution is the process of change over time.

Darwin’s work shows how the living world is constantly changing, which helps us understand things like drug-resistant bacteria and newly emerging diseases.

Darwin’s journey began in 1831 and was a 5 year trip from Western Europe to South America, New Zealand, around the Cape of Good Hope in southern Africa and back to Europe.

(1) Species vary globally, (2) Species vary locally, and (3) Species vary over time.

The rhea and the emu are flightless birds that look like ostriches. Darwin noticed that species vary globally.

Darwin meant that different, yet ecologically similar, animal species inhabited separate, but ecologically similar, habitats around the globe.

He meant that different, yet related, animal species often occupied different habitats within a local area.

The turtles from Isabela Island have dome-shaped shells and short necks, because the vegetation on the island is close to the ground.

The turtles of Hood Island are curved and open around their long necks and legs, which allows them to reach the Island’s sparse, high vegetation.

Biogeography is the study of where organisms live now and where they and their ancestors lived in the past.

First, a pattern in which closely related species differentiate in slightly different climates (e.g., the shell shape of different tortoises).
Second, a pattern in which very distantly related species develop similarities in similar environments (e.g., rheas, ostriches, and emus),

Darwin noticed that some fossils didn’t look anything like living organisms, but some fossils of extinct animals were similar to living species. It lead him to conclude that species vary over time.

Structures that are shared by related species and that have been inherited from a common ancestor. For example, the front limbs of reptiles and birds are more similar to each other than either is to the front limb of an amphibian or mammal.

Biologists test whether structures are homologous by studying anatomical details, the way structures develop in embryos, and the pattern in which they appeared over evolutionary history.

Body parts that share a common function, but not structure, are called analogous structures. The wing of a bee and the wing of a bird are analogous structures.

Vestigial structures are inherited from ancestors, but have lost much or all of their original function due to different selection pressures acting on the descendant.The hipbones of bottlenose dolphins are vestigial structures. In their ancestors, hipbones played a role in terrestrial locomotion. However, as the dolphin lineage adapted to life at sea, this function was lost.

Geologists were studying the structure and history of the Earth, and suggesting that Earth had changed over time.

Naturalists were investigating connections between organisms and their environment.

Biologists also were suggesting that life on Earth had changed.

Hutton and 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 introduced the concept of deep time — the idea that our planet’s history stretches back over a period of time so long that it is difficult for the human mind to imagine.

Lyell believed that the geological processes we see in action today must be the same ones that shaped Earth millions of years ago.

The rock layers in the Grand Canyon were laid down over millions of years and were then slowly washed away by the river forming a channel.

No. Jean-Baptist Lamarck, a French naturalist, proposed two hypotheses on the subject during the 18th century.

First, that organisms could change during their lifetimes by selectively using or not using various parts of their bodies.

Second, that individuals could pass these acquired traits on to their offspring, enabling species to change over time.

Traits altered by an individual organisms during its life.
For example, a black-necked stilt could have acquired long legs because it began to wade in deeper water looking for food. As the bird tried to stay above the water’s surface, its legs would grow a little longer.

He believed that all organisms have an inborn urge to become more complex and perfect.

As a result, organisms change and acquire features that help them live more successfully in their environment, and then pass the acquired traits to their offspring.

First, organisms do not have an inborn drive to become perfect.
Evolution does not mean that over time the species becomes better.

Second, traits acquired by individuals during their lifetime cannot be passed on to offspring.

He recognized that there was a link between an organism’s environment and its body structures.

An hypothesis is a possible explanation for a set of observations or possible answer to a scientific question.

A theory is a well-tested explanation that unifies a broad range of observations and hypotheses.

Malthus noted that humans were being born faster than people were dying. He reasoned that if the human population wasn’t balanced, there would not be enough living space and food for everyone.

Malthus noted that humans were being born faster than people were dying. He reasoned that if the human population wasn’t balanced, there would not be enough living space and food for everyone.

In artificial selection, nature provides variations and humans select those they find useful.

He studied changes produced by plant and animal breeders. He concluded that some of the variations could be passed from parents to offspring and used to improve the species.

Before Darwin, scientists thought variations among individuals in nature were simply minor defects.

Because it provided the raw material evolution, even though had no idea how heredity worked or what caused heritable variation.

The Origin of Species. In it, he combined his own thoughts with ideas from Malthus and Lamarck.

Darwin’s view that if more individuals are produced than can survive, members of a population must compete for food, shelter and other limited necessities of life.

Darwin hypothesized that some traits are better suited to life in their environments than others. Thus, only the stronger/faster survive.

Any heritable characteristic that increases an organism’s ability to survive and reproduce in is environment.

Survival of the fittest means the organism’s ability to stay alive as well as to reproduce and pass adaptations on to the next generation.

The individual’s characteristics are not well suited to their environment, so they die without reproducing or they leave few offspring.

Mimicry is an adaptation in which an organism copies or mimics a more dangerous organism, such as the scarlet king snake that mimics the poisonous eastern coral snake.

Camouflage is an adaptation that allows an organism to blend into the background and avoid predators (for example, a grasshopper’s green coloring).

Because of its similarities to artificial selection. It is the process by which organisms with variations most suited to their local environment survive and leave more offspring.

In natural selection the environment, rather than a farmer or animal breeder, influences fitness.

Because those are the only characteristics that parents can pass on to their offspring.

If local environmental conditions change faster than a species can adapt to those changes, then the species may become extinct.

Darwin proposed that living species are descended from common ancestors. He drew a tree, we call “the single tree of life” to illustrate this point.

The sound that the cricket makes is intended to advertise their presence and reproductive quality to their potential mates. The study of the Bush cricket shows that crickets had developed this adaptation over 100 million years ago, which is consistent with Hutton and Lyell’s contribution to Darwin’s theory: Deep time gave enough time for natural selection to act. The fact that the Bush cricket is extinct, however, probably means that as the environment changed the Bush cricket did not adapt to other factors that would have allowed it to survive and reproduce, including that its sounds may have been too weak in a habitat that had more, larger and louder animals. It went from a higher fitness level to a low fitness level.

If you can, go on to Moodle and review the slide presentation, Darwin_Theory_Evidence_evolution, but specifically slides 8 -12, and slides 28 – 31. Ask yourself, “What principle is this showing?” Also, Google Darwin’s “tree of life” so that you remember what it looks like.