Evolution Midterm

Which example illustrates an evolutionary mutation?

An allele coding for brown eyes mutates to produce hazel eyes

Change in characteristic frequency

The increase or decrease of a characteristic’s prevalence within a population over time; this change constitutes evolution.

Evolutionary selection

The elimination or culling of characteristics that do not confer an advantage, while advantageous characteristics remain and become more prevalent.

Mutation

A change that arises during replication and can produce a different characteristic, such as an allele changing from coding for brown eyes to coding for hazel eyes.

Imperfect Repliation

The process in which organisms reproduce copies of themselves that are not always identical.

Evolution

Change in the characteristics of organisms over the course of generations; also described as descent with modification.

What happens to advantageous characteristics that remain in a population?

They become more prevalent

What generally happens to characteristics that do not confer an advantage?

They are eliminated or culled over time

What happens when organisms replicate imperfectly?

Mutations can arise that produce different characteristics

What is Evolution?

Change in the frequency of characteristics within a population over time

Fundamental principles of evolutionary biology

All life is subject to physical and chemical processes; all life contains self-encoding information in DNA or RNA; and all life has evolved.

Homology

Fundamental similarities underlying obvious physical differences among species. Vertebrate forelimbs used for different functions can have the same sequence and arrangement of bones.

Evidence of macroevolution

Includes extinction and succession, as well as transitional forms that display traits typical of ancestral populations along with novel traits later seen in descendants.

Evidence of speciation

Can be demonstrated through laboratory experiments and observations of natural populations.

What did Darwin infer after finding fossilized marine remains at the tops of mountains?

Earth and living organisms may both undergo gradual change

Vestigial structures

Features that were evolutionarily beneficial in ancestors but are no longer useful in the current generation while still being retained. Goosebumps are an example: they involve small muscle contractions that once helped ancestors appear larger when threatened and trap heat.

Evidence of microevolution

Includes selective breeding, direct observation, and retained features that were useful in ancestors but are no longer useful in present-day organisms.

Applications of evolution

This field is applied to health sciences, agriculture, natural products, conservation and environmental management, understanding ourselves, and entertainment.

Evidence that humans and apes share a common ancestor

Support includes the fossil record, DNA analysis showing that humans and chimpanzees have 98% identical DNA, similar developmental milestones, and chimpanzees’ ability to learn sophisticated cognitive skills such as counting and the concept of zero.

Evidence and stages of eye evolution

Different organisms show increasingly complex visual structures: flatworms have eyespots, nautiluses have more constricted eye openings, and humans have a rounded transparent layer over the eye opening. Human eyes also contain imperfections, including retinal tears and a small blind spot near the middle of the visual field.

Evolution in HIV/AIDS

New viral strains can arise through random mutations that allow them to resist drugs. Because viruses reproduce very quickly, evolutionary change can occur within minutes to hours.

Natural selection

A process in which random changes that improve an organism’s ability to survive are more likely to be retained and passed on through reproduction. For example, praying mantises that resemble leaves are more likely to avoid detection, survive, and reproduce.

DNA evidence for evolution

Inherited genetic information is carried by sequences of the nitrogenous bases A, T, G, and C. Mutations can produce new traits, and the universality of the genetic code supports the idea that life is connected through a single evolutionary history.

Descent with modification and the tree of life

The idea that species arise from earlier species through inherited changes, forming an ancestral chain or branching history. The variety of life can therefore be traced back to a common ancestor, while poorly adapted species fail to survive.

Adaptive specialization example

Different finch species lived on islands with similar climates and geology but had distinct beaks specialized for foods such as nuts or insects. The proposed explanation was that they descended from a common ground-finch ancestor that arrived from South America and gradually adapted to different conditions.

Geological change and Darwin’s theory of evolution

Fossilized marine remains found on mountain tops indicated that Earth had undergone gradual geological changes, including seafloor uplift that formed mountain ranges. This suggested that living organisms could also change and adapt as conditions changed.

Darwin observed that Galápagos finches on islands with similar climates and geology had different beaks. What explanation did he propose?

The finches descended from a common ground finch and adapted to different food sources

What does the phrase “tree of life” represent in Darwin’s evolutionary theory?

The idea that species may descend with modification from common ancestors

How do mutations contribute to evolution?

They can create new traits that may affect an organism’s fitness

Why can HIV/AIDS evolve into drug-resistant strains relatively quickly?

The virus reproduces rapidly, allowing random mutations to arise and spread

Which finding supports the conclusion that humans and chimpanzees share a common ancestor?

Their DNA is approximately 98% identical

Which example illustrates natural selection favoring a trait that improves survival?

Praying mantises that resemble leaves are more likely to survive and reproduce

What evolutionary sequence is illustrated by the comparison of flatworm eyespots, nautilus eye openings, and the human eye’s rounded transparent layer?

Eye structures can become more complex through evolutionary change

What is evolution?

Change in the characteristics of organisms over the course of generations

Which example demonstrates selective breeding as evidence of microevolution?

Breeding dogs for particular traits such as companionship or appearance

What are vestigial structures?

Structures that were useful in ancestors but are no longer useful while still being retained

Which observation is listed as evidence of macroevolution?

Transitional forms showing ancestral traits and novel traits found later in descendants

What does homology reveal about different species?

They share fundamental similarities despite obvious physical differences

Which statement is one of the fundamental principles of evolutionary biology?

All life has evolved