AD Adaptation

Question 1

What does the almost constant rate of molecular evolution suggest?

Answer 1

It is mostly governed by the accumulation of nearly neutral mutations over time rather then by natural selection

Question 2

What is genetic drift?

Answer 2

Frequencies of alleles with similar fitness in a population may change at random from generation to generation
Smaller populations can show larger rates of genetic drift

Question 3

What is a gene?

Answer 3

A sequence of nucleotides that codes for an RNA or a protein product
It is a unit of hereditary
Due to mutations, the sequence of a gene usually shows variation within a population: different alleles

Question 4

What is fitness?

Answer 4

Survival, mate-finding and reproduction. Ability to leave offspring in the next generation?

Question 5

What is sexual selection?

Answer 5

Natural selection that acts on mate-finding and reproductive behaviour
Acts on an animal’s ability to obtain and copulate with a mate
Often powerful enough to produce adaptations that are harmful to the individual’s survival.
Eg male competition and female choice

Question 6

What is Batesian Mimicry?

Answer 6

An edible mimic deceives predators by resembling a toxic model

Question 7

What is pre-adaptation?

Answer 7

A structure’s function changes completely without much change in the structure itself
The structure was pre-adapted to its new function
eg feathers of birds may first have evolved as heat insulation and they are preadapted now to form the aerofoil used in flight

Question 8

How do we recognise adaptions?

Answer 8

The character appears to fit too well to its environment to have arisen by chance
There is an appearance of complex design
The character helps the animal’s survival and reproduction

Question 9

How do we study adaptions?

Answer 9

Develop a hypothesis/model of the structure’s function

Test predictions made from hypothesis

Question 10

What does ecological development, or eco-devo mean?

Answer 10

The influence of environmental factors on

the expression of phenotypic traits, including morphology, behaviour, life history of organisms

Question 11

Describe Eco-devo: African cichlids

Answer 11

A change a males’ social status, - a perceived
opportunity to rise in rank – initiates rapid proliferation
of neurons in regions of the brain that control complex
behaviours

Question 12

What is an ecological niche?

Answer 12

The place or function of a given organism within its ecosystem

Organisms can construct/alter niches by
1. Modifications of the external environment
Tenebrionid beetles dig trenches in the Namib
desert to harvest water
2. Modification of the environmental experience
Bicyclus anynana: Larvae that are poorly
nourished emerge form the pupae with
more strongly developed thoracic muscles
so they are strong fliers and can reach new
(favourable habitats)

Question 13

Coping with the cold is an example of an adaptation

Describe hibernation

Answer 13

An adaptive strategy used when periods of reduced food availability coincide with low winter temperatures and result in increased demand for metabolic energy to maintain body temperature
80% of stored energy used
Animals will wake up throughout hibernation though to raise body temperature to avoid infections

Question 14

Describe chemical defense as an adaptation

Answer 14

There are two main ways animals can use chemicals to
defend themselves
Animals can synthesize toxin using their own metabolic
processes, or they can accumulate toxin from the
food they eat

Question 15

Describe animals that synthesise toxins

Answer 15

Animals which synthesize their own toxin are able
to convert chemical compounds in their body to a
poison

The fire salamander makes a nerve poison, which it can
squirt from glands on its back
The poison dart frog has poison glands scattered
all over its body

Question 16

Describe animals that accumulate toxins

Answer 16

Larvae of Monarch butterflies accumulate toxins from plants
Birds that eat the Monarchs vomit and learn to avoid them in the future. Their bright coloration allows birds to remember and avoid them
Aposematic colouration

Question 17

What are some Mechanisms by which a population can adapt when its local environment changes?

Answer 17

1. Dispersal (move) to track its preferred environment
2. Adapt to the new local conditions
3. No adaptation – dire consequences

Question 18

What’s changing in the Anthropocene?

Answer 18

Global climate change, overexploitation, and habitat
alteration are causing sustained and consistent pressures on wild populations

The unusual rate and extent of change may exceed the capacity of developmental, genetic, and demographic mechanisms that populations have evolved to
deal with change

Question 19

Coral reef bleaching is very serious. What species have adapted to overcome this?

Answer 19

American Samoa, A. hyacinthus lives naturally in both hot and cool pools
20% of corals from the hot pools
bleached
55% of corals from the cool pools
bleached
Corals can adapt and survive heat, and heat-tolerant corals might gain a reproductive advantage over
time.

Question 20

Describe the Tragedy of the commons – Atlantic cod

Answer 20

Better fishing vessels, devices and navigation led to massive over-exploitation in the 1970’s

1980’s – still plenty of fish, but hyper-aggregation was
occurring

In 1992 Canadian government
issued a ban on cod fishing after
population collapse

Question 21

Describe the Tragedy of the commons – passenger pigeon

Answer 21

1490’s – Columbus arrives. Passenger pigeon
population estimated at 3-5 billion

1813: Audubon encounters a
flight along the Ohio River that
darkens the sky for three days

1895: The last nest and egg to be found in the
wild are collected near Minneapolis

Passenger pigeons were an extremely gregarious
species. Once their numbers dwindled (due to
hunting and clearcutting) their social systems
broke down, and they could no longer effectively
reproduce or avoid predators

The Allee effect: Warder Allee (1885 -1955) observed
that under-crowding and NOT competition limited
population growth for some species

Question 22

What is an island?

Answer 22

a patch of suitable habitat surrounded by unfavorable
environment that limits the dispersal of individuals

Area that is biologically isolated such that species
cannot mix with any other population of the same
species
• Geographic island
• Mountain top
• Ponds

Question 23

What is special about islands?

Answer 23

Islands comprise 5% of Earth’s land area but 30% of the
world’s biodiversity hotspots, 50% of marine tropical diversity

they provide clear examples of evolution in action. They show interesting patterns of colonisation, adaptation, and
speciation

Question 24

What is island colonisation?

Answer 24

• Colonisation - arrival
• float
• fly
• swim
• be carried (by other
animals)
• wind (ballooning spiders)
• Anthropogenic (humans)

In surtsey 1964 a new animal arrived and in 1993 the first earthworm arrived. It was a blank slate for colonisation

Question 25

What is speciation?

Answer 25

evolutionary process by which populations evolve to
become distinct species
eg Darwin’s finches
Because the mainland was so distant the finches must have arrived in the past and adapted over time

Question 26

What is adaptive radiation?

Answer 26

Organisms diversify rapidly from an ancestral species into a multitude of new forms to exploit empty niches

Question 27

Describe the Speciation of drosophila in Hawai’i

Answer 27

A single introduction of Drosophila to an island west of Kauai - now spectacular fruit fly diversity (500
spp.)

Question 28

What is an endemic species?

Answer 28

• Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type

Question 29

hawaiian islands have a high degree of endemicity - because of the relatively small area involved, many
Hawaiian species are considered threatened even when at their normal population levels.
How are the honeycreepers here doing?

Answer 29

12 species critically endangered
4 endangered

At least 56 species of Hawaiian honeycreepers are known to have existed, all but 17 of them are now extinct

Question 30

Why are endemic species vulnerable to extinction?

Answer 30

they are adapted to a unique niche and are found nowhere else in the world.
Humans and the species they bring with them are a huge threat
eg Dodo became extinct in 1660’s

Question 31

What is the island rule?

Answer 31

The island rule is a hypothesis whereby small animals evolve larger size on islands while large insular animals dwarf

Question 32

Gigantism of invaders- What are the consequences for native species?

Answer 32

House mice are the only introduced species on
Gough island and have evolved to be MASSIVE – 3
times larger than house mice in the UK

Question 33

True or false?

50% of all animal species are parasitic

Answer 33

true

Question 34

What are the morphological adaptations for parasites?

Answer 34

structures for penetration and attachment to hosts
Needle like mouth parts
Barbed mouth parts

Dorso-ventrally flattened to prevent host removal

Question 35

What are the physiological adaptations for parasites?

Answer 35

Strong, impermeable cuticle (nematodes) or Tegument (cestodes)

To protect from the harmful effects of digestive
enzymes, the helminth stimulates the host gut to
secrete huge amount of mucous that surrounds the
parasite and protect it from the digestive juice of the
host

Most helminths produce antienzymes which protect
them from the gastric juice and digestive enzymes of
the host

• Reduction in “unnecessary” structures
• Reduced sense organs, nervous system, locomotion and digestive system
• High fecundity (offspring)- Tapeworm produces proglottids
• Resistant stage in life cycle – human hookworm exhibits cryptobiosis

Question 36

What are the immunological adaptations for parasites?

Answer 36

Before S. mansoni can infect humans, it uses snails as an intermediate host. In order to survive, S. mansoni must use the power of molecular mimicry

The immune system of a snail is
comprised of molecules called lectins,
which seek out foreign particles and
stimulate an immune response.

S. mansoni possess sugars that are
already present in snails, making it very
difficult for the lectins to recognize
parasite as ‘foreign’

Question 37

What are the behavioural adaptations for parasites?

Answer 37

• 1 – Host finding behaviours
• 2 - Periodic behaviours
• 3 – Host modifying behaviours

Question 38

Describe host finding behaviours

Answer 38

Ticks do not jump or fly, but wait on vegetation for a
host to brush against their extended front legs
Carbon dioxide, heat and movement serve as stimuli
for questing behaviour

Question 39

Describe periodic behaviours

Answer 39

Filarial worms - live in blood and transmitted by mosquito

or flies. Microfilariae move to peripheral blood on periodic basis corresponds to “biting hours” of vector

Question 40

Describe host modifying behaviour

Answer 40

Carpenter ants turn into ‘Zombies’ when
infected with a fungus, O. unilateralis

Manipulated by a fungal parasite, an infected ant will
leave the trees and head to the forest floor—an area more suitable for fungal growth.

Here, it becomes a zombified ant. The fungus grows inside the ant’s body, eventually piercing through the ant’s head and releasing its fungal spores

Some parasites have an intermediate host and
a definitive host The intermediate and/or
definitive host often have their behaviour manipulated by the parasite to aid its own transmission