Transcript Level 3 Biology - BryantNet

Level 3 Biology
Patterns of Evolution
Things to learn (in brief)
 Patterns of evolution.
 Use the process of evolution:
 speciation (sympatric, allopatric) reproductive isolating mechanisms
(geographical, temporal, ecological, behavioural, structural barriers,
polyploidy) and natural selection.
to explain/ discuss
 convergent evolution,
 divergent evolution (including adaptive radiation),
 co-evolution,
 punctuated equilibrium,
 gradualism.
Patterns – summary
 Patterns repeat – so a pattern in evolution
is simply common themes in the way
species change.
 Patterns of evolution include
 Sequential
 Divergent
 Convergent
 Coevolution
 Gradualism
 Punctuated equilibrium
These are all labels that we
give to different common
themes in the natural
world. But nature is round
not square – so in most
situations we will see a
mixture of these patterns
together.
See evolution of mammals
Convergent evolution
 In evolutionary biology, convergent evolution is the process
whereby organisms not closely related, independently evolve
similar traits as a result of having to adapt to similar
environments or ecological niches.
 It is the opposite of divergent evolution
Divergent evolution
 In evolutionary biology, convergent evolution is the process
whereby organisms not closely related, independently evolve
similar traits as a result of having to adapt to similar
environments or ecological niches.
 It is the opposite of divergent evolution
COEVOLUTION
The rough-skinned newt…
produces a toxin to deter predation from the garter snake.
The garter snake has developed resistance to this toxin, leading the
newt to produce an ever more toxic poison. The poison in a newt is
enough to kill 30 people.
COEVOLUTION
The bullhorn acacia thorns and Beltian
bodies at leaflet tips provide food for a
species of ant. The ants, in turn, live in the
hollowed out area and vigorously protect the
acacia from other insects and browsing
animals.
“Arms Race” – Animal
Battle at Kruger
National Park
Predators often coevolve with
their prey – developing
increased agility, and hunting
techniques, while the prey
evolves defence strategies and
camouflage.
Lab manual page 263/4
RATE OF EVOLUTION
At times researchers have found that species
change very little over long periods of time, then
change rapidly, or disappear suddenly.
Punctuated
Equilibrium
At other times species have been found to
gradually change.
Gradualism
Which of these
occurs seems to
depend on the
species and the
events at the time.
Lab manual page 258
HOMOLOGOUS STRUCTURES
Relationships between species is often assessed by looking at
shared physical features, called homologous structures.
Ancestors have this feature and pass it on to their descendants,
but as they evolve to different niches, the feature may be used in
different ways.
A classic example is the
pentadactyl limb passed
on to all land living
vertebrates by their
amphibian ancestor.
MAMMAL EVOLUTION
Mammals have been around for quite a while.
However, in the late Cretaceous something
happened to the dinosaurs, a host of new niches
became available, and the mammals quickly took
advantage of them.
I am here!
Lab manual page 265/6/7
RATITE EVOLUTION
It is a thought that all modern birds
evolved from Archaeopteryx.
The Ratite group split off much earlier
than other birds, then as they were
isolated by continental drift, Allopatric
speciation occurred.
Lab manual page 269-70
NZ PARROT EVOLUTION
NZ’s parrots give a
great local example of
evolution.
An Australian ancestor
came here about
100mya. Of course at
that stage there wasn’t
far to go…
Differing selection
pressures… differing
niches… no gene
flow…
The kaka and kakapo inhabited the forest, and later,
as mountain building occurred, the kea evolved.
Lab manual page 277/8
OTHER WORK…
Other bits worth looking
at… time dependent.
Extinction (pg 272)
Land snails (275/6)
Hebe (281)
Ancient NZ landscape
(273)
Wrens (279-80)
NZ Invertebrates (274)
HUMAN STUFF - INBREEDING
Pitcairn Island: Mutiny on the Bounty (1789): Population of 9
mutineers, 8-9 Tahitian females and 6 Tahitian males to
uninhabited Pitcairn Island.
Mennonites: Religious isolate; suffer from MSUD (autosomal
recessive on c'19) at high rates. Inability to metabolize 3 amino
acids, 20% die.
Afrikaners, South Africa: Fanconi anemia (autosomal recessive
on c'16); red-cell defects.
Azores: Atlantic Islands; High incidence of Machado-Joseph
disease (autosomal dominant on c'14). Late onset motor ataxia.
Yemeni Jews : PKU (amino acid processing disease) high among
them (religious isolate).
Tristan da Cunha Island, Atlantic: Retinitis Pigmentosa (eye
disorder).
Evolution of mammals