AD Adaptation Flashcards
What does the almost constant rate of molecular evolution suggest?
It is mostly governed by the accumulation of nearly neutral mutations over time rather then by natural selection
What is genetic drift?
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
What is a gene?
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
What is fitness?
Survival, mate-finding and reproduction. Ability to leave offspring in the next generation?
What is sexual selection?
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
What is Batesian Mimicry?
An edible mimic deceives predators by resembling a toxic model
What is pre-adaptation?
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
How do we recognise adaptions?
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
How do we study adaptions?
Develop a hypothesis/model of the structure’s function
Test predictions made from hypothesis
What does ecological development, or eco-devo mean?
The influence of environmental factors on
the expression of phenotypic traits, including morphology, behaviour, life history of organisms
Describe Eco-devo: African cichlids
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
What is an ecological niche?
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)
Coping with the cold is an example of an adaptation
Describe hibernation
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
Describe chemical defense as an adaptation
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
Describe animals that synthesise toxins
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
Describe animals that accumulate toxins
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
What are some Mechanisms by which a population can adapt when its local environment changes?
- Dispersal (move) to track its preferred environment
- Adapt to the new local conditions
- No adaptation – dire consequences
What’s changing in the Anthropocene?
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
Coral reef bleaching is very serious. What species have adapted to overcome this?
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.
Describe the Tragedy of the commons – Atlantic cod
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
Describe the Tragedy of the commons – passenger pigeon
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
What is an island?
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
What is special about islands?
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
What is island colonisation?
• 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
