Table of Contents
- 1 Why do organisms with different ancestry look similar?
- 2 What is it called when organisms evolve from a common ancestor but look different over time?
- 3 Why do organisms belonging to same species look similar to each other?
- 4 Why do some organisms that are not closely related look similar?
- 5 What evidence of evolution is shown when structures of unrelated species may evolve to look alike because the structure is adapted to similar function?
- 6 What term is used to describe body structures that look alike and serve a similar function but are not descended from a common ancestor?
- 7 How do scientists determine how closely related two organisms are?
- 8 What is the relationship between homologous structures and related organisms?
Why do organisms with different ancestry look similar?
are anatomical features, of different organisms, that have a similar appearance or function because they were inherited from a common ancestor that also had them. The more homologies two organisms possess, the more likely it is that they have a close genetic relationship.
What is it called when organisms evolve from a common ancestor but look different over time?
Convergent evolution is when different organisms independently evolve similar traits. Biologists call this process — when two organisms share characteristics that they didn’t jointly inherit from a common ancestor — convergent evolution.
What body structures did the common ancestor have?
Homologous structures are structures that have a common function and suggest common ancestry. For example, homologous structures include the limbs of mammals, such as bats, lions, whales, and humans, which all have a common ancestor. Different mammals may use their limbs for walking, running, swimming or flying.
What do we call structures found in different species that have shared ancestry?
homologous structures
Structures that arise in organisms that share a common ancestor, but perform different structures are called homologous structures. An example of a homologous structure is the “arm” of a mammal.
Why do organisms belonging to same species look similar to each other?
In a species, each cell consists of the same type of DNA and genes and has the same chromosome number. When the DNA passes to the next generation, the same morphology is retained in the new organism with little variations in features. So, individuals of a species look similar.
Misleading Appearances Similarly, unrelated organisms may be distantly related, but appear very similar. This usually happens because both organisms developed common adaptations that evolved within similar environmental conditions.
Why might different species evolve in similar ways?
Separate groups of organisms belonging to the same species may adapt in different ways to better exploit diverse environments or resources. They also may evolve varied characteristics for attracting mates. That is, different groups evolve in different directions.
How did some organisms end up looking similar while others are really different?
Many organisms have similar body plans. As organisms adapt and evolve, not everything about them changes. The differences, such as the zebra’s stripes, show that each species adapted to its own environment after branching off from the common ancestor.
Comparative Anatomy. Comparative anatomy is the study of the similarities and differences in the structures of different species. Similar body parts may be homologies or analogies. Both provide evidence for evolution.
What term is used to describe body structures that look alike and serve a similar function but are not descended from a common ancestor?
Such features that overlap both morphologically (in form) and genetically are referred to as homologous structures; they stem from developmental similarities that are based on evolution. For example, the bones in the wings of bats and birds have homologous structures (Figure 1).
Why do organisms look different from each other?
Mutations, the changes in the sequences of genes in DNA, are one source of genetic variation. Another source is gene flow, or the movement of genes between different groups of organisms. Organisms of even a small population can differ strikingly in terms of how well suited they are for life in a certain environment.
How can organisms look the same but yet be different?
Organisms may be very closely related, even though they look quite different, due to a minor genetic change that caused a major morphological difference. Unrelated organisms may appear very similar because both organisms developed common adaptations that evolved within similar environmental conditions.
By comparing the anatomy of these organisms, scientists have determined that they share a common evolutionary ancestor and in an evolutionary sense, they are relatively closely related. Other organisms have anatomical structures that function in very similar ways, however, morphologically and developmentally these structures are very different.
The more closely organisms are related, the more similar the homologous structures are. Many mammals, for example, have similar limb structures.
Do birds and dragonflies share a common evolutionary ancestor?
Thus, by comparing the anatomy of these organisms, scientists have determined that birds and dragonflies do not share a common evolutionary ancestor, nor that, in an evolutionary sense, they are closely related. Analogous structures are evidence that these organisms evolved along separate lines.
What is the importance of anatomical similarities and differences in evolution?
As a result of the study of evolutionary relationships, anatomical similarities and differences are important factors in determining and establishing classification of organisms. Some organisms have anatomical structures that are very similar in embryological development and form, but very different in function.