The development of understanding of genetics and evolution

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Darwin and Wallace: Developing the Theory of Evolution

Charles Darwin spent five years on a voyage around the world on HMS Beagle, studying plants and animals at every location the ship visited.
Darwin noticed variation between members of the same species and that individuals with characteristics best suited to their environment were more likely to survive and reproduce.
From these observations, Darwin developed the theory of evolution by natural selection, published in his book×On the Origin of Species×in 1859.
Alfred Russel Wallace independently developed a theory of evolution by natural selection after his own travels and evidence gathering.
Darwin and Wallace published scientific papers together on the theory in 1858, which prompted Darwin to publish his book the following year.
Wallace is best known for his work on warning colouration in animals (especially butterflies) and for his pioneering work on speciation.

Evolution of the horse: changes in molar teeth, whole-animal size, and forefeet from Hyracotherium to the modern horse.

Evolution by Natural Selection

Evolution is the change in the inherited characteristics of a population over many generations.
Individuals in a species show a wide range of variation caused by differences in their genes.
Individuals with characteristics most suited to their environment have a higher chance of survival and more opportunities to reproduce.
The alleles that code for advantageous characteristics are passed to offspring more often than those for less suited characteristics.
Over many generations, beneficial characteristics become more common in the population and the species changes — this is natural selection, often called 'survival of the fittest'.
An example is the peppered moth, where a mutation producing a different colour became advantageous as the environment changed.

Natural selection in peppered moths

Why Evolution Was Gradually Accepted

The theory of evolution by natural selection was only gradually accepted because it was controversial and challenged the idea that God made all living things.
At the time it was published, there was insufficient evidence to convince many scientists.
The mechanism of inheritance and variation was not known until about 50 years after the theory was published.
The theory developed over time from information gathered by many scientists.
Jean-Baptiste Lamarck proposed an earlier theory that changes occurring during an organism's lifetime can be inherited — we now know this type of inheritance cannot occur in the vast majority of cases.
Lamarck suggested giraffes stretched their necks to reach high leaves and passed on the elongated neck, but this is incorrect.

Speciation

Speciation is the process by which new species form.
A new species is formed when populations become so different that they can no longer interbreed to produce fertile offspring.
Speciation occurs through a combination of isolation and natural selection.
Geographic isolation happens when a physical barrier (such as a new river or mountain range) separates populations of the same species.
The environments on either side of the barrier differ, creating different selection pressures.
Natural selection causes different characteristics to become more common in each isolated population.
Over many generations, the populations become so distinct that they can no longer interbreed — they are now separate species.

Mendel and the Understanding of Genetics

Gregor Mendel was an Austrian monk who carried out breeding experiments on pea plants in the mid-19th century.
Mendel discovered that inheritance of each characteristic is determined by 'units' that are passed to descendants unchanged.
He showed that some characteristics are dominant (e.g. tall pea plants) and others recessive (e.g. short pea plants).
Mendel's work provided the foundation for modern genetics but was not recognised until after his death.
His studies were totally new to science and there was no knowledge of the mechanisms behind his findings (DNA, genes and chromosomes had not been discovered).
In the late 19th and early 20th centuries, scientists observed that chromosomes behaved like Mendel's 'units', leading to the idea that the units (now called genes) were located on chromosomes.
In 1953, the structure of DNA was determined and the mechanism of gene function was worked out, leading to the development of gene theory.

Evidence for Evolution: Fossils

Fossils are the remains of organisms from millions of years ago, found in rocks.
Fossils can form from parts of organisms that have not decayed because conditions needed for decay were absent.
Fossils can also form when parts of the organism are replaced by minerals as they decay.
Fossils can be preserved traces of organisms, such as footprints, burrows and rootlet traces.
The fossil record is incomplete because many early life forms were soft-bodied and left few traces, and geological activity (such as tectonic plate movements) destroyed many traces.
This is why scientists cannot be certain about how life began on Earth.
Fossils show how much or how little different organisms have changed as life developed on Earth.

Evidence for Evolution: Resistant Bacteria

Antibiotics are chemicals that kill or inhibit the growth and reproduction of bacteria.
Bacteria reproduce rapidly (on average every 20 minutes), so evolution occurs in a much shorter time span.
Random mutations in bacterial DNA can cause some bacteria to become resistant to an antibiotic.
When the population is treated with the antibiotic, resistant bacteria survive and reproduce with less competition from non-resistant bacteria.
The genes for antibiotic resistance are passed on with much greater frequency to the next generation.
Over time, the whole population becomes antibiotic-resistant — this is natural selection.
MRSA is a dangerous strain of×Staphylococcus aureus×that is resistant to most antibiotics and is difficult to treat.

Reducing the Development of Antibiotic Resistance

Doctors should avoid prescribing antibiotics inappropriately, such as for viral infections or mild infections that the immune system will clear up.
Patients should complete their full course of antibiotics so all bacteria are killed and none survive to mutate into resistant strains.
The agricultural use of antibiotics should be restricted to reduce the spread of resistance.
Good hygiene practices such as handwashing and hand sanitisers reduce the spread of resistant strains like MRSA in hospitals.
Isolation of infected patients helps prevent the spread of resistant strains, especially in surgical wards.
Developing new antibiotics is costly and slow, making it difficult to keep up with the emergence of new resistant strains.

Development of antibiotic resistance

Extinction

Extinction occurs when there are no remaining individuals of a species still alive.
Species that are poorly adapted to their environment are less likely to survive and reproduce.
If a species cannot survive and reproduce sufficiently to maintain its population numbers, it will eventually go extinct.
Factors that may contribute to extinction include environmental changes, new predators, new diseases, and competition for resources.
Human activities have massively increased extinction rates in recent history — humans have hunted many species to extinction (e.g. the dodo) and compete for resources such as space, food and water.

Evidence for Evolution: The Pentadactyl Limb

A pentadactyl limb is any limb with five digits (fingers or toes).
Pentadactyl limbs are found in many species across mammals, reptiles and amphibians.
In different species, the pentadactyl limb has a similar bone structure but may fulfil quite different functions (e.g. human hand for handling tools, bat wing for flight).
Although the individual bones differ in shape and size, their layout is almost exactly the same.
This similarity provides strong evidence that these groups all evolved from a common ancestor — their limbs would have very different structures if they had evolved from different ancestors.

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1.Which scientist independently developed the theory of evolution by natural selection after travelling the world and gathering evidence?
Easy
- AGregor Mendel
- BAlfred Russel Wallace
- CCarl Woese
- DJean-Baptiste Lamarck
2.Which of the following best defines evolution?
Easy
- AA change in an individual organism during its lifetime
- BA change in the frequency of a phenotype in a population over many generations
- CThe extinction of a species that is poorly adapted to its environment
- DThe formation of a new species from two existing species
3.The theory of evolution by natural selection was immediately and widely accepted by scientists when Darwin published it.
Easy
True or false?
4.Which of the following statements about Darwin's theory of evolution by natural selection are correct? (select all that apply)
Medium
- AIndividuals in a species show a wide range of variation caused by differences in genes.
- BIndividuals with characteristics most suited to the environment have a higher chance of survival and more chances to reproduce.
- CCharacteristics acquired during an organism's lifetime are always passed on to offspring.
- DOver many generations, beneficial characteristics become more common in the population.
- EOnly the strongest individuals survive, regardless of whether their characteristics suit the environment.
5.Which scientist proposed a theory of evolution based on the idea that changes occurring in an organism during its lifetime can be inherited?
Medium
- ACharles Darwin
- BAlfred Russel Wallace
- CJean-Baptiste Lamarck
- DGregor Mendel
6.What is speciation?
Medium
- AThe extinction of a species due to environmental change
- BThe process by which a new species is formed
- CThe movement of individuals from one population to another
- DThe change in an individual organism over its lifetime
7.Place the steps of speciation in the correct order.
Medium
- Populations become isolated by a physical barrier
- Different selection pressures act on each population
- Natural selection causes different characteristics to become more common in each population
- Populations become unable to interbreed and produce fertile offspring
8.What causes bacteria to become resistant to antibiotics?
Easy
- ABacteria learn to avoid the antibiotic after exposure
- BRandom mutations in bacterial DNA produce resistance
- CAntibiotics cause bacteria to mutate deliberately
- DBacteria inherit resistance from human cells

Plus de questions

9.Which of the following actions would help to reduce the development of antibiotic-resistant bacteria? (select all that apply)
Medium
- ADoctors prescribe antibiotics only when necessary
- BPatients stop taking antibiotics as soon as they feel better
- CPatients complete the whole course of antibiotics
- DAntibiotics are used routinely to treat viral infections
- EThe use of antibiotics in agriculture is restricted
10.Antibiotics are effective against viruses.
Easy
True or false?
11.Which of the following is the correct definition of a fossil?
Medium
- AAny dead organism found in soil
- BThe remains of organisms from millions of years ago, found in rocks
- CA mineral crystal formed in sedimentary rock
- DThe preserved DNA of an extinct species
12.Match each hominid fossil to its correct description.
Medium
- Ardi
- Lucy
- Turkana Boy
- 4.4 million years old; ape-like big toe for climbing; walked upright
- 3.2 million years old; arched feet; brain slightly larger than Ardi's
- 1.6 million years old; brain similar in size to a human brain
13.What is a pentadactyl limb?
Easy
- AA limb with five digits (fingers or toes)
- BA limb adapted only for flight
- CA limb found only in mammals
- DA limb with no bone structure
14.The similar bone structure of the pentadactyl limb in humans, bats and whales provides evidence that these groups evolved from a common ancestor.
Easy
True or false?
15.Which scientist developed the three-domain system of classification?
Medium
- ACarl Linnaeus
- BCarl Woese
- CCharles Darwin
- DGregor Mendel
16.Which of the following are domains in the three-domain system of classification? (select all that apply)
Medium
- AArchaea
- BBacteria
- CEukaryota
- DFungi
- EProtists
17.Match each scientist to the correct description of their work.
Medium
- Charles Darwin
- Alfred Russel Wallace
- Gregor Mendel
- Carl Woese
- Proposed the theory of evolution by natural selection after a voyage on HMS Beagle
- Independently developed the theory of evolution by natural selection and studied warning colouration in butterflies
- Carried out breeding experiments on pea plants and showed that characteristics are determined by 'units' passed on unchanged
- Developed the three-domain system of classification in 1990
18.Which of the following are reasons why the theory of evolution by natural selection was only gradually accepted? (select all that apply)
Medium
- AIt challenged the idea that God made all the animals and plants that live on Earth
- BThere was insufficient evidence at the time the theory was published to convince many scientists
- CThe mechanism of inheritance and variation was not known until 50 years after the theory was published
- DDarwin had never travelled outside England to gather evidence
- EWallace refused to publish any of his findings
19.Which statement best explains why bacteria can evolve rapidly?
Medium
- AThey reproduce quickly, so mutations that give an advantage spread through the population in a short time
- BThey deliberately mutate their DNA when they come into contact with an antibiotic
- CThey are able to inherit characteristics acquired during their lifetime
- DThey reproduce sexually, which produces a lot of genetic variation
20.Which of the following statements about the pentadactyl limb are correct? (select all that apply)
Medium
- AThe pentadactyl limb has a similar bone structure in mammals, reptiles and amphibians
- BThe pentadactyl limb provides evidence that these groups evolved from a common ancestor
- CThe pentadactyl limb is used for the same function in all species that have it
- DThe pentadactyl limb is found only in humans and bats
- EThe pentadactyl limb of a bat is highly adapted for flight
21.A population of beetles lives on a small island. A river changes course and splits the population into two groups that can no longer meet. Over many generations, the two groups become so different that they can no longer interbreed to produce fertile offspring. What is this process called?
Medium
- ASpeciation
- BExtinction
- CNatural selection
- DClassification
22.In a population of mice, some have thick fur and some have thin fur. A sudden cold period kills most of the thin-furred mice. The surviving thick-furred mice reproduce. Which statement best explains why the population now has mostly thick fur?
Medium
- AThick fur is an acquired characteristic that the mice developed during their lifetime and passed on
- BThick-furred mice had a survival advantage, so they reproduced more and passed on the alleles for thick fur
- CThe cold caused a mutation for thick fur in every surviving mouse
- DThe thin-furred mice chose to grow thicker fur to survive
23.A patient is prescribed a course of antibiotics for a bacterial infection. After 3 days they feel better and stop taking the antibiotics. A week later the infection returns and the antibiotic no longer works. Which statement best explains this?
Hard
- AThe patient's immune system became resistant to the antibiotic
- BThe bacteria learned to avoid the antibiotic during the 3 days
- CSome bacteria had a mutation giving resistance; they survived the incomplete course and reproduced, so the resistant population increased
- DThe antibiotic changed the patient's DNA, making them resistant
24.The diagram shows the pentadactyl limbs of a human, a bat, a whale and a cat. Although they have different functions, the bones have a very similar layout. What is the best explanation for this?
Medium
- AThe limbs have evolved to be similar because the animals live in similar environments
- BThe animals all use their limbs in the same way, so the bones have become identical
- CThe similar layout is evidence that these animals evolved from a common ancestor
- DThe similarity is a coincidence and provides no evidence for evolution
25.Which of the following are reasons why the fossil record is incomplete? (select all that apply)
Medium
- AMany early life forms were soft-bodied and left few traces
- BFossils are only found in sedimentary rock
- CGeological activity such as tectonic plate movement has destroyed many fossils
- DSoft tissues often decay completely before they can fossilise
- EAll organisms that ever lived have been fossilised
26.Which of the following statements about antibiotic resistance are correct? (select all that apply)
Hard
- AAntibiotics should not be prescribed for viral infections
- BPatients should stop taking antibiotics as soon as they feel better
- CBacteria can evolve rapidly because they reproduce quickly
- DOveruse of antibiotics in agriculture can increase resistance
- EAntibiotics kill viruses as well as bacteria
27.Mendel's work on inheritance was widely recognised and celebrated during his lifetime.
Easy
True or false?
28.The three-domain system classifies organisms into Archaea, Bacteria and Eukaryota.
Medium
True or false?
29.Match each scientist to their contribution to the understanding of genetics and evolution.
Medium
- Darwin
- Wallace
- Mendel
- Woese
- Proposed the theory of evolution by natural selection after a voyage on HMS Beagle
- Independently developed the theory of evolution by natural selection and studied warning colouration
- Carried out breeding experiments on pea plants and proposed 'units' of inheritance
- Developed the three-domain system of classification
30.Which of the following is the best definition of a fossil?
Medium
- AThe remains of organisms from millions of years ago found in rocks
- BAny dead organism preserved in ice
- CThe bones of any animal that has died
- DA rock that looks like an organism
31.A scientist finds a fossil in a deep rock layer and another in a shallower rock layer above it. Which statement is most likely correct?
Medium
- AThe fossil in the deeper layer is older
- BThe fossil in the shallower layer is older
- CBoth fossils are the same age
- DThe age of the fossils cannot be compared using rock layers
32.A student compares the bone structure of a human arm and a bat wing. They find the same set of bones arranged in a similar way, but the bones are different sizes and shapes. What conclusion can the student draw?
Hard
- AThe human and bat evolved from different ancestors
- BThe human and bat evolved from a common ancestor
- CThe human arm is more advanced than the bat wing
- DThe bat wing is a modified human arm
33.Which of the following is an example of an acquired characteristic that Lamarck believed could be inherited?
Medium
- AA giraffe's long neck stretching to reach high branches
- BA mutation in a gene that causes white fur
- CA random change in a DNA base sequence
- DThe inheritance of alleles from parents
34.A population of insects is exposed to a new pesticide. Most insects die, but a few survive and reproduce. After several generations, most insects are resistant to the pesticide. Which statement best explains this?
Medium
- AThe pesticide caused mutations that made the insects resistant
- BSome insects already had a mutation giving resistance; they survived and passed it on
- CThe insects learned to resist the pesticide during their lifetime
- DThe pesticide became less effective over time
35.Bacteria can evolve rapidly because they reproduce quickly and acquire random mutations.
Medium
True or false?
36.Which of the following are evidence for Darwin's theory of evolution by natural selection? (select all that apply)
Hard
- AThe fossil record shows how organisms have changed over time
- BAntibiotic resistance in bacteria shows natural selection in action
- CCharacteristics are passed on to offspring in genes
- DAll organisms were created at the same time and have not changed
- EThe pentadactyl limb has a similar bone structure in different species
37.The diagram shows an evolutionary tree. Species A and B share a recent common ancestor. Species C shares a more distant common ancestor with A and B. Which statement is correct?
Medium
- ASpecies A and B are more closely related to each other than either is to species C
- BSpecies A and C are more closely related than A and B
- CSpecies B and C are more closely related than A and B
- DAll three species are equally closely related
38.A scientist discovers a new organism in a hot spring. It is single-celled, has no nucleus, and its DNA sequence is very different from known bacteria. Which domain is it most likely to belong to?
Hard
- AArchaea
- BBacteria
- CEukaryota
- DFungi
39.Which of the following is the correct sequence of classification from largest to smallest group?
Medium
- AKingdom, Phylum, Class, Order, Family, Genus, Species
- BSpecies, Genus, Family, Order, Class, Phylum, Kingdom
- CKingdom, Class, Phylum, Order, Family, Genus, Species
- DDomain, Kingdom, Phylum, Class, Order, Family, Genus, Species
40.A patient is infected with a strain of bacteria that is resistant to penicillin. The doctor prescribes a different antibiotic, but the infection does not improve. Which statement best explains why?
Hard
- AThe bacteria have become resistant to all antibiotics
- BThe bacteria may also be resistant to the second antibiotic
- CThe patient's immune system is not working
- DThe second antibiotic was not taken with food
41.Complete the sentences about evolution using the correct terms.
Easy
Evolution is a change in the inherited ____ of a population over time. Evolution occurs through a process of ____ .
42.Complete the sentence about speciation.
Medium
When populations of the same species become separated by a physical barrier such as a river or mountain range, this is known as ____ isolation.
43.Complete the sentence about classification.
Medium
In the three-domain system, organisms are divided into three large groups called ____ , which are then subdivided into smaller groups such as kingdom, phylum, class, order, family, genus and species.
44.The number of death certificates mentioning MRSA in England and Wales was 713 in 2001 and 1652 in 2006. Calculate the percentage increase between 2001 and 2006. Give your answer to the nearest whole number.
Medium
45.A population of bacteria doubles every 20 minutes. If there are 100 bacteria initially, how many bacteria will there be after 1 hour?
Medium
46.The number of MRSA cases in a hospital was 400 in 2015 and 500 in 2020. Calculate the percentage increase in MRSA cases between 2015 and 2020.
Hard
47.Name the scientist who independently developed the theory of evolution by natural selection after travelling the world and gathering evidence.
Medium
48.What is the name of the process by which a new species is formed?
Medium
49.Complete the sentence about evolution.
Medium
Evolution is a change in the inherited ____ of a population over time.
50.A fossil is found in a rock layer that is 3.2 million years old. Another fossil is found in a layer that is 4.4 million years old. How many million years older is the second fossil?
Medium
51.Name the scientist who developed the three-domain system of classification.
Medium
52.What is the name of the process by which organisms with characteristics best suited to their environment survive and reproduce?
Medium
53.Give two reasons why the theory of evolution by natural selection was not widely accepted when it was first published.
Medium
54.Suggest two reasons why there are gaps in the fossil record.
Hard
55.Explain how a population of bacteria can become resistant to an antibiotic through natural selection.
Hard
56.Explain how the emergence of antibiotic resistance in bacteria can be used as evidence for Darwin's theory of evolution by natural selection.
Hard
57.Describe the main events in the late 19th and early-to-mid 20th century that gave evidence in support of Mendel's work.
Hard
58.The number of death certificates mentioning MRSA in England and Wales was 713 in 2001 and 1652 in 2006. Calculate the percentage increase between 2001 and 2006. Give your answer to the nearest whole number.
Medium
- A158 %
- B145 %
- C132 %
- D119 %
59.A population of bacteria doubles every 20 minutes. If there are 100 bacteria initially, how many bacteria will there be after 1 hour?
Medium
- A720 bacteria
- B800 bacteria
- C960 bacteria
- D880 bacteria
60.The number of MRSA cases in a hospital was 400 in 2015 and 500 in 2020. Calculate the percentage increase in MRSA cases between 2015 and 2020.
Hard
- A22 %
- B31 %
- C25 %
- D28 %
61.A fossil is found in a rock layer that is 3.2 million years old. Another fossil is found in a layer that is 4.4 million years old. How many million years older is the second fossil?
Medium
- A1.2 million years
- B3.2 million years
- C2.2 million years
- D0.2 million years

Cartes mémo

What is evolution?

A change in the inherited characteristics of a population over time, through the process of natural selection.

Who proposed the theory of evolution by natural selection, and in which book?

Charles Darwin proposed the theory and published it in his book 'On the Origin of Species' in 1859.

What are the key steps of natural selection according to Darwin?

Individuals in a species show variation; those with characteristics best suited to the environment are more likely to survive and reproduce; they pass on their advantageous alleles to offspring; over many generations, these characteristics become more common in the population.

Why was Darwin's theory of evolution by natural selection only gradually accepted?

It challenged the idea that God created all life; there was insufficient evidence at the time; and the mechanism of inheritance and variation was not known until 50 years later.

Who was Alfred Russel Wallace and what is he known for?

A scientist who independently developed a theory of evolution by natural selection. He is known for his work on warning colouration and his pioneering work on speciation.

What is speciation?

The process by which new species form. It occurs when populations of the same species become so different that they can no longer interbreed to produce fertile offspring.

How does geographic isolation lead to speciation?

A physical barrier (e.g., a river or mountain) separates populations. Different environments on each side create different selection pressures, so natural selection causes different characteristics to become more common. Over many generations, the populations become so different that they cannot interbreed.

What was Lamarck's theory of evolution?

Lamarck proposed that changes acquired during an organism's lifetime can be inherited. For example, he suggested that giraffes stretched their necks to reach food, and this longer neck was passed to offspring. We now know this type of inheritance cannot occur.

What did Gregor Mendel discover through his breeding experiments on pea plants?

Mendel found that inheritance of each characteristic is determined by 'units' (now called genes) that are passed on to descendants unchanged. He showed that some units are dominant and others recessive.

Why was Mendel's work not recognised until after his death?

His studies were totally new to science in the 19th century, and there was no knowledge of the mechanisms behind his findings (DNA, genes and chromosomes had not been discovered yet).

How did the understanding of chromosomes support Mendel's work?

In the late 19th and early 20th centuries, scientists observed that chromosomes behaved in a similar way to Mendel's 'units'. This led to the idea that the 'units', now called genes, were located on chromosomes.

What is the evidence for evolution from fossils?

Fossils are the remains of organisms from millions of years ago found in rocks. They show how much or how little different organisms have changed as life developed on Earth, and provide evidence for evolution.

Why is the fossil record incomplete?

Many early forms of life were soft-bodied and left few traces; what traces existed have been mainly destroyed by geological activity such as tectonic plate movements.

What is extinction?

Extinction occurs when there are no remaining individuals of a species still alive.

Give three factors that may contribute to the extinction of a species.

Factors include: environmental changes (e.g., climate change), new predators, new diseases, competition for resources, and human activities such as hunting or habitat destruction.

How do bacteria become resistant to antibiotics?

Random mutations in bacterial DNA can cause some bacteria to become resistant to an antibiotic. When the population is treated with the antibiotic, resistant bacteria survive and reproduce, passing on the resistance genes. Over time, the whole population becomes resistant.

Why can bacteria evolve rapidly?

Bacteria reproduce quickly (on average every 20 minutes), so mutations that give a survival advantage can spread through the population in a short time.

What is MRSA and why is it difficult to treat?

MRSA is a strain of Staphylococcus aureus that is resistant to methicillin and many other antibiotics. It is difficult to treat because few antibiotics are effective against it.

How can the development of antibiotic-resistant bacteria be slowed down?

Doctors should avoid unnecessary prescriptions (e.g., for viral infections); patients should complete their full course of antibiotics; and agricultural use of antibiotics should be restricted.

How does antibiotic resistance provide evidence for Darwin's theory of evolution?

It shows natural selection in action: bacteria with random mutations that give resistance survive and reproduce when exposed to antibiotics, passing on the advantageous genes. Over time, the population evolves.

What is the pentadactyl limb and what does it show about evolution?

A pentadactyl limb is a limb with five digits. Many mammals, reptiles and amphibians have pentadactyl limbs with a similar bone structure but different functions. This similarity suggests they evolved from a common ancestor.

What are the three domains of classification?

Archaea, Bacteria, and Eukaryota. This system was developed by Carl Woese in 1990 based on genetic analysis.

What is an evolutionary tree?

A diagram that shows the relationship between species over evolutionary time. A new branch shows where speciation has occurred.

What is the role of genes in evolution?

Genes are passed from parents to offspring and determine characteristics. Variation in genes leads to variation in characteristics, which is the basis for natural selection.

Why is it important to conserve genetic diversity?

Genetic diversity helps species adapt to changing environments, so conserving it is important for protecting endangered species from extinction.

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