are birds and insects closely related

Scientists collect information that allows them to make evolutionary connections between organisms. Similar to detective work, scientists must use evidence to uncover the facts. In the case of phylogeny, evolutionary investigations focus on two types of evidence: morphologic (form and function) and genetic.

Organisms that share similar physical features and genetic sequences tend to be more closely related than those that do not. Features that overlap both morphologically and genetically are referred to as homologous structures; the similarities stem from common evolutionary paths. For example, as shown in Figure 12.6, the bones in the wings of bats and birds, the arms of humans, and the foreleg of a horse are homologous structures. Notice the structure is not simply a single bone, but rather a grouping of several bones arranged in a similar way in each organism even though the elements of the structure may have changed shape and size.

Some organisms may be very closely related, even though a minor genetic change caused a major morphological difference to make them look quite different. For example, chimpanzees and humans, the skulls of which are shown in Figure 12.7 are very similar genetically, sharing 99 percent of their genes. However, chimpanzees and humans show considerable anatomical differences, including the degree to which the jaw protrudes in the adult and the relative lengths of our arms and legs.

However, unrelated organisms may be distantly related yet appear very much alike, usually because common adaptations to similar environmental conditions evolved in both. An example is the streamlined body shapes, the shapes of fins and appendages, and the shape of the tails in fishes and whales, which are mammals. These structures bear superficial similarity because they are adaptations to moving and maneuvering in the same environment—water. When a characteristic that is similar occurs by adaptive convergence (convergent evolution), and not because of a close evolutionary relationship, it is called an analogous structure. In another example, insects use wings to fly like bats and birds. We call them both wings because they perform the same function and have a superficially similar form, but the embryonic origin of the two wings is completely different. The difference in the development, or embryogenesis, of the wings in each case is a signal that insects and bats or birds do not share a common ancestor that had a wing. The wing structures, shown in Figure 12.8 evolved independently in the two lineages.

Similar traits can be either homologous or analogous. Homologous traits share an evolutionary path that led to the development of that trait, and analogous traits do not. Scientists must determine which type of similarity a feature exhibits to decipher the phylogeny of the organisms being studied.

Evolution is the process by which organisms undergo mutations over time that improve the fitness of some individuals and, as a result, facilitate the more efficient transmission of the trait through the gene pool. Sometimes, unrelated organisms can develop similar traits.

Concepts in Action

This website has several examples to show how appearances can be misleading in understanding the phylogenetic relationships of organisms.

The field of molecular systematics—which deals with the application of information at the molecular level, including DNA sequencing—has flourished as a result of the development of DNA technology. Not only do recent molecular character analyses validate numerous prior classifications, but they also reveal past mistakes. Variations in a gene’s single nucleotide sequence, the amino acid sequence of a protein, or the arrangement of genes are examples of molecular characters. According to phylogenies based on molecular characters, two organisms are more closely related to one another if their sequences are more similar. The rate at which genes change during evolution influences how helpful they are at establishing relationships. Sequences that are rapidly evolving can be used to infer relationships between closely related species. Sequences with slower evolutionary rates are helpful in establishing the connections between species that are distantly related. The genes utilized, such as those for ribosomal RNA, must be very old, slowly evolving genes that are present in both groups in order to establish the relationships between very different species, such as Eukarya and Archaea. Building confidence in the inferred relationships can be achieved by comparing phylogenetic trees with various sequences and determining which ones are similar.

Distantly related organisms can appear closely related when they are not because two DNA segments in these organisms can occasionally share a high percentage of bases at random locations. For instance, humans and fruit flies have 60% of the same DNA. In this case, computer-based statistical algorithms have been created to assist in identifying the true relationships; in the end, phylogeny can be determined more effectively by combining the use of both morphologic and molecular data.

Why Does Phylogenetic Analysis Matter? Phylogenetic analysis has many practical applications in addition to improving our understanding of the evolutionary history of species, including our own. Making decisions regarding conservation efforts and comprehending the evolution and transmission of disease are two of those applications. Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacteria that is resistant to antibiotics. A 2010 study examined the origin and spread of the strain over the previous 40 years. The research revealed the patterns and timing of the resistant strain’s migration from Europe, where it originated, to infection and evolution centers in South America, Asia, North America, and Australasia. According to the study, the bacteria spread from those few individuals after being introduced to new populations very infrequently—possibly just once. On the other hand, it’s possible that a large number of people spread the bacteria throughout their bodies. This finding implies that in order to stop the spread of a novel bacterial strain, public health officials should focus on promptly identifying the contacts of those who are afflicted with it.

Conservation is a second field in which phylogenetic analysis is useful. Scientists have maintained that species from all across a phylogenetic tree should be protected, not just those from a single branch. By doing this, more of the variation brought about by evolution will be preserved. Conservation efforts, for instance, should concentrate on a single species that does not have any sister species, as opposed to another species that has a group of closely related species that recently evolved. In comparison to one species in the cluster of closely related species, a disproportionate amount of variation from the tree will be lost if the single evolutionarily distinct species becomes extinct. Based on how evolutionarily distinct and extinction-prone mammal species are, a 2007 study published recommendations for their global conservation. According to the study, their recommendations were not in line with priorities that were determined solely by the degree of threat to the species’ extinction. The study suggested preserving several endangered and important large mammals, including African and Asian elephants, giant and lesser pandas, and orangutans. However, they also discovered that because of their evolutionary uniqueness, a few much less well-known species ought to be preserved. These include a number of rodents, bats, shrews and hedgehogs. Furthermore, certain critically endangered species, such as gerbil and deer mouse species, were not considered to be very important in terms of evolutionary distinctiveness. Preserving phylogenetic diversity offers an objective means of safeguarding the entire spectrum of diversity produced by evolution, even though numerous factors influence conservation decisions.

What is the current most widely used technique for creating phylogenetic trees in science? It is known as cladistics. Using this technique, organisms are grouped into clades, or groups that share the greatest degree of relatedness with one another and their common ancestor. For example, in Figure 12. 9. Every organism in the shaded area descended from a single amniotic egg-bearing ancestor. As a result, these organisms form a single clade known as a monophyletic group and share amniotic eggs. The ancestral species and every descendant from a branch point must be included in a clan.

are birds and insects closely related

Which of the following animals in this figure is a member of a clade that includes hair-bearing animals? Hair or amniotic eggs evolved first?

(Answer: Humans and rabbits are members of the clade of animals with hair.) Because the Amniota clade splits off earlier than the clade containing hair-bearing animals, the amniotic egg evolved before hair. ).

The size of a claim can change based on the branch point that it references. The fact that every organism in the clade or monophyletic group originates from a single point on the tree is crucial. Because monophyletic is derived from the words “mono,” which means one, and “phyletic,” which means evolutionary relationship, this can be remembered.

Cladistics rests on three assumptions. First, as a general premise of evolution, all living things are related by descent from a common ancestor. The second is that, basically, speciation happens when a species splits into two, never more than two at a time. Although this is a bit contentious, most biologists agree that it is a simplification. The third premise is that characteristics evolve over time to the point where they are deemed to be in a distinct state. Additionally, it is believed that one can determine a state’s true direction of change. Put another way, we believe that compared to non-amniotic eggs, amniotic eggs have a later character state. This is called the polarity of the character change. Since non-amniotic eggs are found in groups outside of clades, such as insects, we can infer that this is the more ancient or ancestral character state. Cladistics compares ingroups and outgroups. The group of taxa under study is an ingroup, in our case consisting of humans, rabbits, and lizards. An outgroup is a species or group of species that split off before the lineage that contained the group(s) of interest, in our case, the lantern, lamprey, and fish. We can identify the traits that are evolutionary modifications determining the phylogenetic branch points of the ingroup by comparing members of the ingroup to members of the outgroup and to each other.

A trait is considered shared ancestral if it is present in every member of the group and has not changed as each member of the clade descended from the trait’s ancestor. Despite the fact that these characteristics seem intriguing because they help to unite the clade, cladistics views them as being unhelpful in determining the relationships between the clade’s members because each member is the same. In contrast, consider the amniotic egg characteristic of Figure 12. 9. This trait is unique to some organisms, and for those that do, it is referred to as a shared derived character because it underwent a change during descent. This character does provide information about the relationships within the clade; it indicates that humans, lizards, and rabbits form closer social groups than do any of these organisms with fish, lampreys, or lancelets.

The relative nature of “derived” and “ancestral” characters can occasionally be confusing. The same trait may be derived or ancestral, depending on the organisms being compared and the diagram being used. When creating phylogenetic trees, scientists find these terms helpful for differentiating between clades. However, it’s crucial to keep in mind that the meaning of these terms varies depending on the context.

FAQ

What do birds and insects have in common?

There are many kinds of flying animals, including bats, birds, and various insects. All of these organisms have wings.

Do birds and insects have an evolutionary relationship?

No, evolution doesn’t work that way. Insects are invertebrates, and birds are vertebrates. The two groups are separated by around 500 million years, and there’s no way that a beetle population could turn into a population of vertebrates.

Did birds evolve from insects?

When paleontologists built evolutionary trees to study the question, they were even more convinced. The birds are simply a twig on the dinosaurs’ branch of the tree of life. As birds evolved from these theropod dinosaurs, many of their features were modified.

How closely related are birds and butterflies?

Answer and Explanation: Although both butterflies and birds both have wings, they don’t have common ancestry.