Flashcards in Evolution Deck (43):
What is the consequence of evolution?
How can biodiversity be described?
Species diversity and genetic diversity
What is species diversity?
Number of different species within an ecosystem
What is genetic diversity?
Range of genetic characteristics within a single species
How can genetic variation occur?
Variation in offspring and mutations
What is when there is a variation in offspring?
When genetic material from both parents combine and the offspring have genes of a random mix.
What is when there is a mutation?
When there’s an incorrect code within the gene, thus coding for something different
What is the Lamarckian theory of evolution?
-Theory of acquired characteristics
-Organisms can develop characteristics during its lifetime in order to adapt to its environment
-Those characteristics will be passed onto its offspring
-E.g. giraffes have stretched their necks to reach their food. This trait has been passed through several generations resulting in the giraffes today with long necks
What is Darwin's and Wallace's theory of evolution?
-All organism come from a common ancestor and over time they begin to change and diverge away from this ancestor
What are Darwin's finches?
-Exemplary example of Darwin’s theory of natural selection
-Found on Galapagos Islands
-There were 13 finches in total with different characteristics representing a different species
Cute beak: only ate fruits and seeds from trees or on the ground
Mid beak: Ate both fruits and larger insects on trees or the surface
Long beak: Ate insects within the soil e.g. worms
What are Darwin’s tortoises?
-Two types of tortoises: dry island tortoises and dense vegetation tortoises
-Hence both tortoise’s shells differ representing a new species
Dry land island where vegetation are shrubs and small trees: Shells has a higher border to allow for head mobility to access food
Dense vegetation island: Shell has lower border because there is no need for head mobility and is tougher to push through its habitat
What is Wallace known for?
-Discovery of the Wallace line
-Imaginary line dividing the fauna of Australia and Asia
-Where there was drastic difference between organism on either side of the line
-There is nothing close to a kangaroo in Asia
What are the 4 steps of natural selection?
1.Variation in a population
-Due to genetic differences from mutations and random reproduction
2.Selective pressures e.g. predation, environment
-Change in environment
E.g. Prior to Ice Age, Species of mammoth had no fur
In the population, variation occurred, few mammoths grew fur
During the Ice Age, weather changed (selective pressure) and those without fur could not survive
Those with fur survived and passed on their favourable trait to offspring
3.Individuals with favourable characteristics will survive and pass their trait to their offspring
4.Over many generations, majority of population now has the favourable characteristic
What are examples of biotic selective pressures?
Predators, access to food
What are examples of abiotic selective pressures?
Case study: The peppered moth evolution
Before the Industrial Revolution: variation of English peppered moths: black moths and white moths
Selective pressure: Industrial Revolution
1.Increased production of CO2, CO and C in the atmosphere
2.Carbon/ soot pollute trees and stain them black
3.Black moths camouflage whilst white moths stood out
4.Black moths avoided predation and passed down their characteristics
5.Eventually the population of peppered moths become black
How is evolution phyletic?
The process of forming a new species is a slow, gradual and uniform
What is speciation?
Formation of a new species
What defines a new species?
When a species can no longer interbreed
What is divergent evolution?
-When a new species evolves from a common ancestor
-Through different selective pressures acting on a species aka adaptive radiation
-Gradually the population will show favourable characteristics to the selective pressure and speciation would occur
E.g. Koalas, who came from a common possum- like ancestor but was divided and subjugated to different selective pressures
What is convergent evolution?
-Is when species are subjugated to the same or similar selective pressures
-2 species are still separate but show similar phenotypes
-Does not form one species
-E.g. dolphins and sharks: have a different common ancestor but both shows fins and streamline body
How is convergent evolution evidence to natural selection?
-Selective pressures will choose organisms with favourable characteristics
-Hence under same or similar selective pressures, they must have similar characteristics as those are favourable characteristics
What is co- evolution?
-When 2 species influence each other’s evolution
-Is a biotic selective pressure?
-E.g. birds and flowers
-Birds: different shaped beaks to better suit the shape of the flower they get their nectar from
-Flower: to become more vibrant to attract birds
What is adaptive radiation?
Selective pressures that causes divergent evolution
What is extinction?
The loss of a species from earth which may affect the evolution of another
-Consequence of the inability to successfully reproduce under changed environmental conditions
Label each of the following as a result of convergence or divergence
a) bats and birds
b) emu and ostrich
a) convergent (mammal and bird)
b) divergent (bird and bird)
List evidence of evolution?
What is biogeography?
-Refers to the graphical distribution of species
-Reveals: species originate from one area with a common ancestor. Dispersed outwards, subjugated by different selective pressures and evolve (divergent evolution)
-Unrelated species living in the same or similar environment will evolve analogous structures (convergent evolution)
What are analogous structures?
-Structures that perform the same role but are structurally different
e.g. bats and butterfly
What are fossils?
-Parts of organisms that provide evidence of their existence
-E.g. bone, feather, teeth
What is relative dating?
-Techniques of observing of fossil’s position in the strata to determine the relative age of a fossil
-As fossil in layers are older as they go down which will give relative time when the organisms lived
Why must you consider the movement of tectonic plates in relative dating?
Folds and faults would have shifted the fossil upwards or sideways giving a false impression of their relative age.
What is absolute dating?
Is the use of radiometric technologies to measure half- life of isotopes within the fossil to get the age of the fossil
What is a half- life?
Is the amount of time taken for half the radioactive substance to decay and become stable
How are fossils formed?
1)Organisms dies and are covered by sediments to prevent decomposition
2)Overtime, sediments turn into rock and remains or organism turn into fossil
3)Fossil is compressed and flattered by layers of rocks preserving the fossil
4)Overtime, fossils could resurface through erosion or evacuation
What does dating fossils and having a fossil record do?
Allows palaeontologists to observe how fossils change overtime
How does fossils contribute to the theory of evolution: archaeopteryx
Features similar to birds: feather, wings
Features similar to dinosaurs: claws, teeth, jointed bony tail
This suggests birds evolve from dinosaurs
Horse species change over in terms of:
Since forest was replaced with open plains, allows horses with longer legs to survive (natural selection) since they can escape from predators. Thus taller horses
Not a lot of fruit and leaves, but a lot of grass, (from forests to plains) made teeth for grazing more advantageous
Hooves was more advantageous than multiple spread out toes because of their strength and speed
What are the types of fossils?
-Whole organisms trapped inside amber or petrified
What are moulds?
-Rocks that have the impressions if the organism
-The physical appearance is hallowed out
-E.g. a footprint in mud
What are casts?
Opposite to a mould, they have the shape of the organism protruding out
What are imprints?
Carbon imprints are dark prints of an organism on a rock