Darwin discovered that the traits of the birds and tortoises varied among the different islands in Galapágos.

C. Charles Darwin

Darwin came across fossils that serve as clues to what the Earth was in the past. Fossils are from the remains of ancient living things that are formed and buried under the sediments.

A. fossils

Lamarck proposed that *acquired characteristics can be inherited*. If an organism had altered its body structure during its lifetime, this characteristic can be passed onto its offspring.

To illustrate, if a person spent his lifetime lifting weights to build big muscles, then their offspring would also inherit large muscles. This inheritance idea was later found to be incorrect.

A

In biology, the term variation refers to the differences among cells, organisms, or groups of species.

A. natural variation

Artificial selection is the process in which the breeding of animals and plants are done to produce an offspring with a desirable trait. In this case, to produce cows that give more milk, an animal breeder uses artificial selection.

D. artificial selection

In biology, the term adaptation refers to the process in which individuals undergo a genetic or structural change to become better suited to its new environment.

B. adaptation

When natural selection is involved in identifying the traits that are passed from the parent to its offspring, there are chances that the organism will have changes in its genetic makeup and structure. The living species that descended and underwent changes over time have experienced changes in their structures, habitat, and niches. This event is referred to as the principle of descent with modification.

A. descent with modification

In biology, the term fitness represents an individual’s ability to adapt and survive life. If an individual is able to live longer and reproduce more offspring in a given situation, it has a high fitness; hence, it can adapt to its current environment.

A. adaptation

Homologous structures usually have the same embryonic tissues during its development stage. However, when these tissues mature, their structures appear differently.

C. homologous structures

Malthus proposed the relationship between population and resources. He suggested that a high population growth may lead to overpopulation and it would negatively affect the supply of food and living space.

C. Malthus

The theory of evolution explains how different species have evolved from ancient organisms. One example that shows an evolution in a species is the colorful peacock feathers. A few thousand years ago, not all male peacocks have brightly colored feathers. However, since female peacocks always choose a male which has the fanciest or the brightest colored feathers, the genes responsible for the colorful feathers started to get passed on to the next generation. As a result, males peacocks have fancier feathers now than the ones that existed a thousand years ago.

During his trip to South America and the Galapagos Islands, Darwin observed different types of animals that led to the development of the theory of evolution. Some examples of animals he observed include finches and tortoises.

With regards to the finches, Darwin observed that the finches exhibit variations in beak size and shape. He noticed that the beak structure of a finch is related to the preferred diet of the finch. This would suggest that finches adapt to their environment.

With regards to tortoises, Darwin also observed variations in shell size and shape. He also realized that the shape of the tortoise’s shell is related to the available food in an area, which explains why variations often appear between different types of habitats.

Aside from finches and tortoises, Darwin had also observed variations among many other species of plants and animals. He noticed that variations also occur not only between species but also within species. This also provided evidence to the process of evolution.

Darwin’s observations in the Galapagos Islands had led him to realize that organisms exhibit variations, and that certain variations appear more frequently in certain environments.

This observation led him to the development of the theory of natural selection. In this theory, he explained that species with beneficial traits (known as adaptations) survive better in certain environments and thus are “naturally selected” by nature.

On the other hand, organisms that do not exhibit beneficial traits are less likely to survive in their local habitat. In summary, variations in species are acted upon by natural selection, which ultimately leads to the “survival of the fittest”.

In the past, people used to believe that the Earth was only a few thousand years old. However, James Hutton proposed that the Earth is much more older than that. He suggested that the Earth is actually more than millions of years old.

Furthermore, people also used to have various theories regarding the processes that shaped the Earth in the past. However, Charles Lyell proposed that scientists should explain past events in terms of geological processes that can be observed.

Lyell suggested that the geological forces that shape the Earth in the present must have also shaped the Earth in the past. This means that processes such as volcanic eruptions and erosion have shaped the Earth in the past, present, and most likely in the future.

Additionally, these geological processes are believed to operate at an extremely slow rate, meaning that it would take millions of years for them to shape the Earth as it is today. This supports Hutton’s idea that the Earth is more than millions of years old.

Lamarck explained that due to the involvement of natural selection in the way animals use or misuse their organs or body parts, organisms have altered, acquired and lost particular traits in their entire lifetime. Those traits that are well-adapted to the environment are passed down to the next generation. As a result, evolution in the species occurs.

In biology, the term natural variation refers to the differences among cells, organisms, or groups of species. Due to the differences or variation among individuals, it allows the process of natural selection to take place. Variation among species can help individuals to adapt to certain conditions. As a result, those organisms which are not able to adapt will eventually die, whereas organisms which can survive will be able to reproduce. This event causes evolution to occur.

Artificial selection is the process by which the breeding of animals and plants are done to produce an offspring with a desirable trait. This concept, together with Darwin’s observation, has influenced Darwin to understand the concept of heritable variation, which is now known as genetic variation.

In biology, fitness and adaptation are relative to each other. The term fitness represents an individual’s ability to adapt and survive life. If an individual is able to live longer and reproduce more offspring in a given environment or condition, it has a high fitness. An adaptation of an organism depends on its fitness. If an organism can adapt to changes, it increases its fitness. For example, polar bears have a thick fur which helps them survive an environment with a cold temperature. Compared to a dog, a polar bear has a better chance of surviving when they are both placed in the same cold environment. Because polar bears are better adapted to live in this environment than dogs, they have a greater fitness than dogs.

The process of “survival of the fittest” is associated with the process of natural selection. In this process, organisms that are well-suited to their environment survive better than others.

Therefore, an organism’s “fitness” or the chances of survival and reproduction would depend on how they adapt to their habitat. Thus, the environment plays a role in natural selection.

If an organism is not able to adapt to its environment (not well-suited), then the organism is said to be “selected against” by nature. This might cause the organism to eventually die off.

The living species that descended and underwent changes over time have experienced changes in their structures, habitats, and niches. This event is referred to as the principle of descent with modification. This principle explains how the species in the present have gone through multiple series of changes in their genetic and structural form. An example of this is when parents pass their genes to their offspring. However, the offspring do not get the exact same copy of the parents’ genes but instead, they are combined. When the combinations of genes are made, there might be changes or mutations which may occur along the way. As a result, genetic variation and evolution take place.

The fossil record shows us how organisms are evolutionarily related to each other based on similarities in body structure. One example of a similarity is shown by *homologous* structures.

Homologous structures are those found in different organisms that are derived from a common ancestor. These structures suggest that organisms are descendants of a common ancestor.

The fossil record may also provide us with other information about the life of organisms in the past. They might tell us about their food preferences, mode of locomotion, and much more.

Darwin discovered that the traits of the tortoises varied among the different islands in Galapágos. For instance, the structure of the tortoise indicates their adaptation to different habitats and its present condition. Since Hood Island has sparse vegetation, the tortoise inhabiting the island has a longer neck in order to reach the vegetation. On the other hand, the tortoise living in the Isabela island, which has lush vegetation, has a shorter neck.

A vestigial organ is a rudimentary structure found in an organism that serves no purpose, but was retained in the organism due to its function in ancestral organisms during evolution.

Vestigial organs often appear as residual structures, which means that they usually have a small or reduced form. One example of a vestigial organ is the *appendix*, found in humans.

The appendix is considered as a vestigial organ because it served no apparent function in humans. However, a theory suggests that the appendix acts as a storage for “good bacteria”.

Embryology serves as evidence for evolution as related organisms often show similarities in their development patterns. This suggests that they are descendants of a common ancestor.

Scientists may look for similar structures that develop during the embryonic stages of development in different organisms. These similar structures suggest that they are related.

For instance, the presence of a structure called the *notochord* can be found in the embryos of a group of organisms. These organisms are thus related and are known as “chordates”.

Darwin’s theory explains that living organisms are related through the process of evolution. Some organisms exhibit similarities that suggest they are descendants of a common ancestor.

Additionally, Darwin’s theory also explains that the variations among organisms is influenced by the environment. These characteristics are acted upon by the process of natural selection.

Darwin discovered that the traits of the birds and tortoises varied among the different islands in Galapágos. Due to the differences or variation among these animals, it allowed them to adapt to certain conditions. As a result, those organisms which can survive will be able to reproduce and pass their genes to their offspring. This concept, together with his own observation, has influenced Darwin to understand the concept of heritable variation, which is now known as genetic variation.

Nature selected those giraffes with the longest necks because they were the ones who could reach the tree leaves more easily; they survived longer and reproduced more than the giraffes who couldn’t find food as easily. Since “longer neck” is determined genetically, the longer-surviving giraffes passed this trait on more frequently.

Over time the mosquitoes gained adaptations that would reject the DDT and the mosquitoes without the adaptations died off and the adaption continued to develop more complex and evolved into a resistance.

The genetic makeup changed over years to become resistant to the DDT

The non-flight turkeys may not be able to survive in the new open environment because of natural predators they may encounter. Given that they cant fly, means that are less likely to escape from predators.

see explanation for solution

If a person tries to protect endangered species who are about to go into extinction due to irresponsible human activities, then it is not upsetting the process of natural selection but an act of conserving biodiversity. However, if a person tries to save species which are barely adapting to a new environment, then it is upsetting the process of natural selection.

Darwin’s theory was that these separate species would have evolved from an original South American ancestor species after becoming isolated from one another. The Hood Island Tortoise and Isabela Island Tortoise share same ancestors. As they dispersed into different regions of the Earth, they adapted to their new environment and through natural selection, they experienced descent with modification.

Nest-building behavior in birds and other animals such as the beaver would be an adaptation that ensures reproductive fitness because they are protecting their offspring, thereby giving them a better chance of survival, and giving the overall species a better chance of survival. for now!

33. Yes, because the homologous human arm and whale flipper indicate a similar descent, so they should have similar anatomies. The whale may have these structures because of their common ancestor with humans had them, but provide no functions. This is similar to the human tail bone.

It means that they descended from a common ancestor because of similar features.