Evolutionary trends—which may be defined broadly as identifiable patterns in which the overall evolution of a trait occurs in a given direction within a group for a prolonged period of time 1 (Fig. 1)—are both real and important.
What are evolutionary trends in animals?
Major developments that occurred within the animal kingdom include bilateral symmetry , true tissue and organ systems, a body cavity, a centralized nervous system, a complete digestive system, a segmented body plan, and a notochord.
What is an example of an evolutionary trend?
An evolutionary trend can be either directional change within a single lineage or parallel change across lineages, in other words, several lineages undergoing the same sort of change. ... For example, titanotheres (a cool, extinct clade related to modern horses and rhinos) exhibit an evolutionary trend.
What does evolutionary mean in biology?
In biology, evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection . ... Evolution relies on there being genetic variation ? in a population which affects the physical characteristics (phenotype) of an organism.
Why do trends in evolution occur?
Evolutionary change in the direction of increasing complexity was consistent and may have been caused by natural selection which favored greater shell strength. If a character causes a lineage to speciate more frequently, or go extinct less frequently, there will be a bias towards lineages that have that character.
What do evolutionary trends show?
Evolutionary trends—which may be defined broadly as identifiable patterns in which the overall evolution of a trait occurs in a given direction within a group for a prolonged period of time 1 (Fig. 1)—are both real and important.
What are the major evolutionary trends?
There are several major evolutionary trends that developed among major vertebrate groups, specifically those that allowed for the transition from aquatic to terrestrial life. These trends include improved respiration and protective and insulating body coverings .
What are the two rates of evolution?
The two generally accepted ideas for rates of evolution are called gradualism and punctuated equilibrium .
Is genetic drift evolution?
Genetic drift is a mechanism of evolution . It refers to random fluctuations in the frequencies of alleles from generation to generation due to chance events. Genetic drift can cause traits to be dominant or disappear from a population. The effects of genetic drift are most pronounced in small populations.
What are homologous features?
Homologous structures are similar physical features in organisms that share a common ancestor , but the features serve completely different functions. An example of homologous structures are the limbs of humans, cats, whales, and bats.
Who is father of evolution?
Charles Darwin : Naturalist, Revolutionary, and Father of Evolution.
What is evolutionary biology and why is it important?
Evolutionary biology provides the key to understanding the principles governing the origin and extinction of species . It provides causal explanations, based on history and on processes of genetic change and adaptation, for the full sweep of biological phenomena, ranging from the molecular to the ecological.
What was Lamarck’s theory of evolution?
Lamarckism, a theory of evolution based on the principle that physical changes in organisms during their lifetime —such as greater development of an organ or a part through increased use—could be transmitted to their offspring.
What does Darwin’s theory of evolution unifies?
Summary. Darwin’s theory of evolution by natural selection states that living things with beneficial traits produce more offspring than others do . This leads to changes in the traits of living things over time. ... He was also influenced by his knowledge of artificial selection.
Which phrase best defines evolution?
Darwin defined evolution as “ descent with modification ,” the idea that species change over time, give rise to new species, and share a common ancestor. The mechanism that Darwin proposed for evolution is natural selection.
What is the process of evolution?
Evolution is a process that results in changes in the genetic material of a population over time . Evolution reflects the adaptations of organisms to their changing environments and can result in altered genes, novel traits, and new species. ... The study of evolution can be performed on different scales.
