Unit 3 - Evolution

Question 1

What kinds of environmental challenges may limit the ability of an organism to survive?

Answer 1

1. extreme temperature: both high or low temps can cause dehydration or frostbite
2. limited water: water is essiential for all living organisms, leading to droughts
3. habit loss/climate change: changes in climate patterns can affect habitats, food availibity, and the timing of bilological events
4. predation/competition: leads to limited resources for survival, and increased pressure on the organism
5. disease: outbreaks can reduce populations and affect the health of organisms

Question 2

What will happen to organisms that cannot cope with these environmental challenges? example: disease, extreme temps

Answer 2

1. reduced reproduction: lower reproductive rates
2. health decline: causing weak immune systems and illness
3. population decline: if a sigmificant number of individuals in a population cannot adapt, the overall population will decline, leading to endangerment or extinction
4. behavioural changes: organisms may alter their behaviours in an attempt to survive, like migrating to new areas, changing feeding habits, however these changes may not always be successful.

———Those that can cope and survive have the
opportunity to pass along to their offspring the
genetic information that helped them survive.

This is how some species become extinct.

Question 3

What are some examples of adaptations species’ have to help them survive?

Answer 3

These adaptations, whether physical, behavioral, physiological, or ecological, help species to survive, reproduce, and thrive in their specific environments:
1. Camouflage: Many animals have developed coloration or patterns that help them blend into their surroundings to avoid predators. For example, the chameleon can change its color to match its environment, and the peppered moth has coloration that helps it blend into tree bark.

2. Mimicry: Some species have evolved to mimic other species for protection. For example, the harmless king snake has coloration similar to the venomous coral snake, deterring predators.
3. Physical Defenses: Many species have developed physical structures for defense. Porcupines have quills, armadillos have hard shells, and many plants have thorns or spines to deter herbivores.
4. Behavioral Adaptations: Animals often develop behaviors that enhance their survival. For example, birds migrate to warmer climates during winter, and bears hibernate to conserve energy during periods when food is scarce.
5. Physiological Adaptations: These are internal body processes that help organisms survive. For example, camels can survive long periods without water by storing fat in their humps, and fish have gills that allow them to extract oxygen from water.
6. Reproductive Strategies: Some species have developed unique reproductive strategies to ensure the survival of their offspring. For example, sea turtles lay a large number of eggs to ensure that some will survive to adulthood despite predation.
7. Thermoregulation: Animals have adaptations to maintain their body temperature. For example, penguins have a layer of blubber and dense feathers to insulate against the cold, while desert animals like the fennec fox have large ears to dissipate heat.
8. Water Conservation: Desert plants and animals have adaptations to conserve water. Cacti have thick, fleshy stems that store water, and many desert animals are nocturnal to avoid the heat of the day.
9. Specialized Feeding Structures: Different species have evolved unique feeding adaptations. For example, hummingbirds have long, slender beaks to access nectar from flowers, while anteaters have long tongues to extract ants and termites from nests.
10. Symbiotic Relationships: Some species form symbiotic relationships to enhance survival. For example, clownfish live among the tentacles of sea anemones, gaining protection from predators while providing the anemone with nutrients from their waste.

Question 4

Adaptation

Answer 4

a structure, behaviour or physiological process that helps an organism survive and reproduce in a particular environment.

Hibernation is an example of physiological
adaptation. For example, it allows the
ground squirrels to survive in climates with
harsh winters.

Question 5

Examples of Physiological Adaptations

Answer 5

• Barn Owls: can sneak up on prey because of fluffy feathers that make their flight slient
• Dogs: grow a thicker coat in the winter and shed more fur in the summer

Question 6

What type of adaptation is mimicry?

Answer 6

structural

Question 7

Mimicry

Answer 7

A structural adaptation in which a harmless species resembles a harmful species in colouration or structure.

Ex. The Viceroy butterfly tastes good to predators, but the monarch butterfly does not.

• As seen in the picture, the viceroy is
  similar in structure and colouration to
  the monarch. By catching and eating
  a monarch, predators learn to avoid
  both butterflies because the way the
  look warns them that the prey tastes
  bad.

Question 8

What are adaptations the result of?

Answer 8

The gradual, accumulative changes that help an
organism survive and reproduce.

• These adaptations are the result of random, heritable mutations in genetic material that accumulate over generations.

Question 9

Variations

Answer 9

Differences between individuals, which
may be structural, functional, or physiological.

Question 10

what determines whether variation in an individual has a posistive or negative effect, or no effect on the individuals ability to survive and reproduce?

Answer 10

eviornmental conditions

Question 11

Humans can also change enviornments? if so how?

Answer 11

yes they can by:
* deforestation
* land cultivation for crops

Question 12

A characteristic that may not give an individual organism a particular advantage NOW, may become critical for survival later? true or false

Answer 12

true

Question 13

The English Peppered Moth

what caused the sudden population increase in black moths?

Answer 13

The English peppered moth has two colour variations:

1. greyish white flecked with black dots (resembling pepper)
2. and black.

In the past, the black variety were extremely rare, with only 2% of the peppered moth population being this colour in 1848.

• 50 years later however, in 1898, 95% of the moths in Manchester England were of the black variety, but in rural areas, the black moths were still less frequent.

What caused the sudden increase in the number of black moths in Manchester?
* the industrial revolution caused black soot to cover the tree making white moths more easy for predators to see creating an increase in the black moths population. After the industrial revolution, the soot washed away now making the black moths easy to see on the white trees decreasing their population, and increasing the white moth population.

Question 14

Variation arises because of genes – that is why you don’t look the same as the person sitting next to you? true or false

Answer 14

true

Question 15

Mutations

and what are mutagens?

Answer 15

a permanent change in the genetic material
of an organism; the only source of new genetic variation.

• Mutations happen continuously in the DNA of any living organism. They occur spontaneously.
• You have about 175 mutations compared to your parents’ DNA because of mutations that occurred as your DNA was copied.

——–Mutagens, such as ultraviolet radiation, are
environmental agents that can also cause mutations in DNA

Question 16

Beneficial Mutations

and examples

Answer 16

Not all mutations are harmful! Some can actually be beneficial.
* Scientists have shown that
beneficial mutations do occur
to produce brand new alleles
that improve an organism’s
chance of survival in a
particular environment.
* Natural selection has been
shown to increase the
frequency of these alleles in a
population, thus increasing
the chances of survival for
that particular organism.

example: Daphnia (water flea). Normally
lives in water around 20°C, and
cannot survive in water 27°C or
warmer. However, a mutation
enables some populations to survive
in warmer temperatures and
reproduce. Without this mutation, the
Daphnia will die.

Question 17

Antibiotic Resistant Bacteria

Answer 17

organisms like bacteria and viruses reproduce quickly, since their main goal is to spread among hosts
* due to their fast reproduction rates: a new allele that resulted from a random mutation that was previously insignificant in the population may provide a selective advantage to some individuals when the environment changes.
* As a result, the organisms that have the new allele may survive long enough to reproduce and pass on the genetic information.

SUMMARY: since bacteria reproduces fast, while taking antibotics, some alleles (genes) in the bacteria will become resistant to this antibiotic, and overtime become completely resistant. this creates a problem for indivuals who are infected with the bacteria, since the bacteria is now resistant to the antibiotic it wont work and the indivual wont recover from the bacteria as fast.

Question 18

Natural Selection

how does this happen to an individual?

Answer 18

is the process that results when the characteristics of a population of organisms change over many generations.

• This change happens because individuals with certain inherited traits survive specific local environmental conditions and, through reproduction, pass on their alleles to their offspring.
• For natural selection to occur, there must be diversity within a species.
• EXAMPLE: This is what allowed the changes in proportions of the peppered moth and the resistant bacterium Staphyloccus Aureus.

Question 19

Selective Pressure

and examples

Answer 19

environmental conditions that
select for certain characteristics of
individuals and select against other
characteristics.

• EXAMPLE: A dense forest
• In a dense forest, sunlight cannot reach the ground where young trees are growing.
• Those individuals (trees) that are able to survive in the shade will reproduce and pass on their alleles to the next generation.
• In the next generation, the abundance of alleles for these conditions will increase in the population because more of the individuals will have survived and reproduced.
• Over time, the tree population will be able to survive the shady conditions.

——-Should there be a big increase in light levels, the trait for resisting these conditions will no longer be an advantage.

Question 20

NAtural selection is situational

Fitness

Answer 20

The relative contribution an individual
makes to the next generation by producing
offspring that will survive long enough to
reproduce.

• An organism with many viable offspring has high fitness, whereas an organism that has few or no viable offspring has low fitness.
• High and low reproductive rates are relative to the typical number of offspring for the species.

Question 21

Artificial Selection

and examples

Answer 21

selective pressure exerted
by humans on populations in order to improve
or modify particular desireable traits.

• Most of the foods we eat – grains, fruit, vegetables, meat and milk – comes from species that have been selectively bred.
• Ex 1: artificial selection has resulted in cows that
  produce more milk.
• Ex.2: Some varieties of chicken are bred to grow
  rapidly and have large muscles for increased
  amounts of meat. Others are bred to produce large
  eggs.
• Ex. 3: Cats and dogs are bred for their appearance.

Question 22

Biotechnology

Answer 22

the use of technology and
organisms to produce useful products.

Question 23

Artifical Selection and Food Crops

Answer 23

• We breed food crops to increase their nutritional value and harvest yield. They are also bred to be drought-resistant or pest-resistant.
• Artificial selection has limits: i.e. If plants are
  bred to grow quickly, they may not tolerate poor
  soil conditions.
• Crop breeders now understand that selective
  breeding must be balanced to maintain genetic
  variation within the crops and the ability of the
  plants to respond to conditions of environmental
  change.
• EXAMPLE: The Wild Mustard plant has been bred to make brussle sprouts, cabbage, califlower, broccoli, and kale ALL FROM ONE PLANT

Question 24

Consequences of Artifical Selection

Answer 24

Like all technologies, artificial selection has its consequences.

• Ex 1: English bulldogs are selectively bred for different traits, such as flat faces. This trait results in severe respiratory problems.
• Ex. 2: Hip Dysplasia, a type of arthritis common in German shepherds and other large dog breeds, is an unfortunate consequence of artificial selection for one trait. (size)
• Ex. 3: Monocultures – extensive plantings of the same varieties of a species over large expansions of land. (strawberry fields, rice fields, corn fields, etc.).
  ———–Both postive and negatives can be shown here: you have lots of crops which will makes alot of money when selling, but negatives from habitat loss for individuals

Question 25

Scientific contributions to evolution

Who is Jean-Baptiste Lamarck?

whats his theory

Answer 25

• 1744 -1829
• In his book, Philosophie Zoologique, Lamarck shared his ideas about changes in species over time.
• According to Lamarck, the evolution of living things came from dead matter and continues in an upward direction. It moves from simple to more complex forms until finally reaching human “perfection”.
• Lamarck stated that species never actually went extinct; they evolved.
• To support his theory, Lamarck observed what he understood to be a “line of descent” or progression, where a series of fossils led to a modern species we have today.
• He also suggested that species lose or acquire characteristic based on how much they use them in their lives.
• HIS THEORY—-Inheritance of Aquired Traits
• organisms altered their behavior in response to environmental

Question 26

Scientific contributions to evolution

The evolution of a giraffe according to Lamarck

Inheritance of Aquired Traits

Answer 26

• Giraffe ancestors had short necks, and legs
• Giraffes were required to stretch their necks and legs in order to reach the leaves that they ate in which were high up in trees
• Since giraffes continued to stretch their necks, they began to develop their long necks over time; showing the change through use and disuse theory
• The giraffes had to adapt to their environment since they struggled to get the food that they needed from their environment because of its location

this was later debunked

Question 27

Scientific contributions to evolution

Who is Charles Lyell?

and his theory

Answer 27

• 1797, Forfashire Scotland
• he first studied law and then geology
• he is reffered to as the father of modern geology
• principles of geology
• “the present is the key to the past”
• gradualism/uniformitarianism: geological changes often occur gradually over long periods, rather than through sudden, catastrophic events. This concept contrasts with catastrophism, which attributes Earth’s features to short-lived, dramatic events.
• catastrophism: natural disasters like floods, diseases, and droughts periodically wipe out local species, allowing species from nearby areas to repopulate the area.

Question 28

Scientific contributions to evolution

Darwin, Wallace, and the Theory of Evolution by Natural Selection

Answer 28

time line:
* (1831) - In 1831 after Charles Darwin’s trip on The HMS Beagle, Darwin began to answers his questions about evolution and organized his observations into a comprehensive theory to explain how species change over time.
* (1855) - Alfred Russel Wallace (1823-1913), a british naturalist did his own observations and came up with conclusions that were very similar to Darwin’s conclusions.
* Darwin and Wallace had accepted that populations changed as time passed but they did not know how populations changed.
* (1798) - Thomas Malthus (1766-1834) a economist, wrote an essay called Essay on Principles of Population. This provided Darwin and Wallace with a key idea on how populations changed over time.
* (1859) - Darwin published all his main ideas and theories of natural selection in a book called **The Origin of Species. **

Main contributions:
* Darwin, Wallace’s main major contribution to evolution was discovering that evolution was driven by natural selection
* Overtime the traits that these species have will spread to more species in the environment, and more species will survive in that environment
* Darwin, Wallace also said all life came from one unknown organism
* As descendants of the organisms spread out, different species from different environments developed adaptations that helped them survive in the environment that they lived in
* Darwin and Wallace ideas was the last evolution discovered and because of it we now know that species change over time and that new species come from preexisting species.

Main Ideas:
Survival of the fittest: the continued existence of organisms which are best adapted to their environment, with the extinction of others, as a concept in the Darwinian theory of evolution. Survival of the fittest means that organisms that are better adapted to their environment are best suited to survive and successfully reproduce

—–Animals that had favorable traits to the environment were likely to pass these traits to their offspring
* Darwin and Wallace believed that when animals with beneficial traits compete for items they require, it is because these items make it easier for them to survive.
* Also states that organisms who have adjusted the most to their environment, will be the most successful.

Descent with Modification: Darwin’s theory that natural selection does not demonstrate progress, but merely results from a species’ ability to survive local conditions at a specific time. He defined evolution as “descent with modification,” the idea that species change over time, give rise to new species, and share a common ancestor.

—-Darwin noticed that many organisms had similar structure or form but they were not the same.
* He noticed even in the same population of organisms, there was a variety between individuals.
* It is a sustained argument showing that the diversity of organisms and their characteristics can be explained as the result of natural processes

example beaks in finches changed over time due to the type of food the birds ate!!

Question 29

Scientific contributions to evolution

Who is Charles Darwin?

his theory

Answer 29

• Charles Robert Darwin was an English naturalist, geologist and biologist who was best known for his theory of evolution by natural selection.
• He was considered the Father of evolutionary theory.
• In the mid 19th century, Darwin set out to prove the theory of species adaptation
• Darwin visited remote places in Australia, South America and the Galapagos Islands, and documented the “transmutations” or abnormalities in the animals
• Darwin found evidence that proved how species in fact due change over time
• He recorded his findings in his book On the Origin of Species
• the voyage of the beagle
• the galapagos islands
• the birds and beaks

Question 30

who made the principles of geology

Answer 30

charles lyell

Question 31

fossil reconds and charles lyell

Answer 31

• Lyell stressed how the accumulation of sedimentary layers and how fossilization processes happened gradually. This made it possible for scientists to understand how fossils may be used to determine the history of the Earth.
• He demonstrated how fossils could possibly be used to provide us with insight into previous ecosystems and life forms, as well as to support the theories of evolution.

Question 32

The Voyage of the Beagle

Answer 32

• In 1831, when Darwin was just 22 years old, he set sail on a scientific
  expedition on a ship called the HMS Beagle.
• As a naturalist on the voyage, it was his job to observe and collect
  specimens of plants, animals, rocks, and fossils wherever the
  expedition went ashore.
• Darwin was fascinated by nature, so he loved his job on the Beagle.
• On this ship, he was given the opportunity to explore and observe
  the natural history of many countries and geographical locations.
• He spent more than 3 years of the 5-year trip exploring nature on
  distant continents and islands.
• While he was away, a former teacher published Darwin’s accounts of his observations.
• By the time Darwin finally returned to England, he had become famous as a naturalist.

Question 33

Who came up with the idea of naural selection

Answer 33

charles darwin and wallace

Question 34

Natural selections and “the best traits will survive”

Answer 34

• In the Pacific Islands local aboriginals showed that the tortoises had different shaped shells depending on the islands they lived.
• After seeing this, Darwin argued that all species adapt to their environment.
• The species
  that did not engage in this process, died off, more
  specifically their unsuccessful traits died off.
• Natural selection is essentially the biological survival of the fittest (the best traits will survive).

Question 35

The Galapagos Islands

Answer 35

• Darwin’s greatest observation was found on the Galapagos Islands
• Some areas of the island were rocky and dry and other areas had more
  rainfall
• He noticed that the plants and animals on different islands were different
  from each other
• He recognized that the tortoises had different shells so that they could
  survive in the habitat where there lived
• Their shells changed and they adapted based on the conditions of their
  environment

Question 36

Darwins Main Ideas/Theories

Answer 36

1. Evolution: Darwin proposed
   that species evolve and grow
   overtime. Species change
   from generation to
   generation
2. Common Descent: Darwin
   argued that all living
   organisms are connected and
   related through common
   descent. This basically means
   that all living species had a
   common ancestor at some
   point through their existence.
3. Natural Selection: Darwin’s most famous theory was about natural selection. This theory states that all organisms and species adapt to their environment. He believed that species were forced to evolve in order to survive and over centuries they passed on their survival characteristics.
4. Variation: Darwin concluded that individuals within a species show different variations in traits. These different traits are important for the process of evolution and natural selection to occur.

Question 37

darwin

The flora and fauna were different from that in England? true of false

Answer 37

true

Question 38

The fossils of extinct animals look very similar to present day
living animals? true of false

Answer 38

true

Question 39

Galapagos species looked identical at first, but they actually
varied a little between islands? true or false

Answer 39

true

Question 40

Artificial selection was possible (Darwin knew that traits
could be passed on from parents to offspring)? true or false

Answer 40

true

Question 41

Who is Georges-Louis Leclerc?

Answer 41

• Georges-Louis Leclerc was a well-known French naturalist during the 18th century.
• Throughout his life, he addressed a wide range of disciplines, including mathematics, probability theory, astronomy, physics, geology, and biology.
• However, he was most recognized for his contributions to natural history through published works in which he endeavoured to illustrate the links between natural history, geology, anthropology, and other fields of research.
• his contributions: Leclerc rejected the idea of evolution, but formulated questions that were essential to the field’s advancement.
  His most significant contribution to science was his published work of Histoire Naturelle.
  Histoire Naturelle has a total of 44 volumes.
  His first three volumes were published in 1749.
  Leclerc studied this distribution of plants and animals across different regions, contributing to the field of biogeography.
• Main ideas: Leclerc was one of the first people to oppose the idea that life forms are unchanging.
  He noticed similarities between apes and humans and proposed the idea that they shared a common ancestor, this suggested that species change over time.
  This theory of his also suggested that the Earth was much older than 6000 years old which was believed at the time.
  Leclerc was also the first paleontologist to propose the idea that the planets were created in a collision between the Sun and a comet.

Question 42

Darwins 5 points

Answer 42

1. Population has variations.
2. Some variations are favourable.
3. More offspring are produced than survive
4. Those that survive have favourable traits.
5. A population will change over time.

Question 43

Evidence for Evolution

Fossil Record

Answer 43

• The remains and traces of past life
  that are found in sedimentary rock;
  it reveals the history of life on Earth
  and the kinds of organisms that
  were alive in the past.
• When fossils are arranged
  according to their age, they show
  successive evolutionary change
• Fossils appear in chronological order in the rock layers.
• So, probable ancestors for a species are found in older rocks, which usually lie beneath the rock in which the later species is found.

Question 44

Evidence from Transitional Fossils

Transitional Fossil

Answer 44

a fossil that shows links between groups of organisms and shares characteristics common
to two now separate groups. They link the past to the present.

Example: scientists have found fossilized whales that lives 36 to 55 million years ago. These fossils link present-day whales to terrestial ancestors.

• Basilosauraus and Dorudon were ancient whales that hadtiny hind limbs but led an entirely aquatic life.
• Dorudon was about the size of a large dolphin, about 5m long. It had a tiny pelvis and legs about 10 cm long.

Question 45

Transitional Fossils

Vestigial Structures

Answer 45

A structure that is a reduced version of a
structure that was functional in the organism’s ancestors.

Example: Today humans have an appendix, tail bone, ear muscles
* The appendix may have been used to help digest raw meat. Not part of most people’s diet today, so no longer necessary.

Question 46

Ice is an excellent preservative? true or false

Answer 46

true
* Mammoth preserved
in ice for over 25,000
years
* Allows for DNA
analysis

Question 47

Evidence for evolution

Biogeoraphy

Answer 47

Study of the past and present geographical
distribution of extinct and modern species
populations.

Question 48

Biography

The pattern of distribution

Answer 48

1. pattern in time
2. pattern in space

Question 49

Evidence for Biography

Answer 49

Darwin and Wallace hypothesized that species evolve in one location and then spread out to other regions.
* Animals found on islands often closely resemble animals found on
the closest continent.

• This suggests that animals on islands have evolved from mainland
  migrants, with populations becoming adapted over time as they adjust
  to the environmental conditions of their new home.
• Ex: lizards found on the Canary Islands, off the northwest coast of Africa, are very similar to lizards found in west Africa.

1. Fossils of the same species can be found on the coastline of
   neighbouring continents.
2. Closely related species are almond never found in exactly the
   same location or habitat.

Question 50

Evidence for biogeography

Pangaea

Answer 50

• Evolution of major animal groups
  correlated with known changes in
  the distribution of land masses on
  the Earth
• Plate Tectonics or Continental
  drift helped make sense of current
  distributions

Question 51

Evidence for evolution: Anatomy

Homologous & Analogous Structures

Answer 51

Homologous Structures:
* Structures that have similar structural
elements and origin but may have a different function.
* Similar because they were inherited from a common ancestor. Same set of bones in the
limbs of modern vertebrates has undergone
evolutionary change to be
used for many different
purposes
* Homologous structures are
derived from a common
ancestor

Analogous Structures:
* Structures of organisms that do
not have a common evolutionary origin but perform similar functions.

• Ex: The wings of insects, birds and bats – are all similar in function but not in structure.

**Bones support the wings of birds, whereas a tough material called chitin (KYE-ten) make up insect wings.

Question 52

Evidence for evolution: Embryology

Embryology

Answer 52

Comparative embryology:
* Study of structures that appear during embryonic development/ early, pre-birth stages of an organism’s development

Embryology has also been used to determine evolutionary relationships between animals:

• The embryos of different organisms exhibit similar stagesof embryonic development.
• Ex: all vertebrate embryos have paired pouches, or out pocketings, of the throat. In fish and some amphibians, the pouches develop into gills. In humans, the pouches become part of the ears and throat.

——-The similarities between embryos in related groups (such as vertebrates) point to a common ancestral origin.

Question 53

Evidence for evoloution: DNA

Molecular biology:
DNA and proteins (amino acids)

Answer 53

• Since DNA carries genetic information, scientists can determine how closely related two organisms are by comparing their DNA.
• If two species have similar DNA patterns, this indicate that these
  sequences must have been inherited from a common ancestor.
• Ex: By studying gene sequences, scientists have determined that
  dogs are related to bears.

Question 54

Genetic Drift

Answer 54

produces random changes in the frequency of traits in a population.
* Evolution that arises from genetic drift is called neutral evolution.

Question 55

Darwins Journey To the Finches

Answer 55

• Studied evolutionary changes in the Galapagos Islands
• Considered the “father of Evolution”
• Started off on his journey on the HMS Beagle, and travelled to the Galapagos Islands;
  set sail from England in 1831
• He was interested in studying birds (Finches)
• Through his work and studies, Darwin was able to gain much insight into evolution,
  adaptive evolution and natural selection

Question 56

Darwins Finches

Answer 56

• Charles Darwin stepped ashore on the Galapagos Islands in September 1835
• Among other finds, he observed and collected the variety of small birds that
  inhabited the islands (Finches)
• It was not until he was back in London, puzzling over the birds, that the
  realization that they were all different, but closely related, species of finch led
  him toward formulating the principle of natural selection.
• These birds, although nearly identical in all other ways to mainland finches,
  had different beaks. Their beaks had adapted to the type of food they ate
  in order to fill different niches on the Galapagos Islands.
• Their isolation on
  the islands over long periods of time made them undergo speciation
• A few million years ago, one species of finch migrated to the rocky
  Galapagos from the mainland of Central or South America.
• From this one migrant species would come many – at least 13 species of
  finch evolving from the single ancestor.
• This process, in which one species gives rise to multiple species that exploit
  different niches is called adaptive radiation.
• The ecological niches exert the selection pressures that push the populations
  in various directions.
• On various islands, finch species have become adapted for different diets:
  seeds, insects, flowers, the blood of seabirds, and leaves.
• The ancestral finch was a ground-dwelling, seed-eating finch.
• After the
  burst of speciation in the Galapagos, a total of 14 species would exist:
  three species of ground-dwelling seed-eaters; three others living on
  cactuses and eating seeds; one living in trees and eating seeds; and 7
  species of tree-dwelling insect-eaters.
• In the Galapagos, the normal pattern of seasons is for a hot, wet season from about January
  to May to be followed by a cooler, dryer season through the rest of the year.
• But in early 1977, for some reason, the rain did not fall. The finch population of the island of
  Daphne Major collapsed from about 1200 to about 180 individuals, with smaller birds dying
  at a higher rate. The reason, again, lies in the food supply.
• At the beginning of the drought, the various types of seeds were present in their normal
  proportions.
• Species of all sizes take small seeds, and as the drought persisted, these smaller seeds
  were relatively reduced in numbers; average available seed size became larger with time.
• Now the larger finches were favored, because they eat the larger, harder seeds more
  efficiently; and the average finch size increased as the smaller birds died off.

Question 57

what forces cause populations and species to evolve?

Answer 57

• natural selection
• migration
• genetic drift
• mutation