Evolution (Bio unit 4)

What is evolution

• the placing of the living world in its historical context 

• The change in inherited traits of a population of organisms over successive generations 

• The idea that all species are descdenats of ancient species that were different from modern day species

Whats a theory

A suggested explanation of observations which can be further tested by research or experimentation 

What can scientists use theories for

to further scientific knowledge, as well as to facilitate advances in technology or medicine.

Whats a fact

something that has really occured or is actually the case, the truth known by actual observations

Whatss the problem with observations

can be flawed, not always reliable, misleading

Whats an inference

drawing a conclusion or making a logical judgment on the basis of  circumstantial evidence rather than direct observations

What did Comte Georges Louis Leclerc de Buffon suggest

similar organisms may have a common ancestor

What did James Hutton believe

geological formation of landforms was the result of slow processes such as uprising and erosion  (these processes were ongoing and observable)

What role did Jean Bapiste Pierre Antoine de Monet play in evolution

first scientist to recognize that the environment plays à key role in the evolution of a species

And put forward the theory of inheirtance of acquired traits 

What did George Couvier

the theory of extinction

What did Sir Charles Lyell believe

the earth has been changed by the same processes in the past as can be observed occurring in the present.

what ideas from geology were important in developing the theory of evolution

providing evidence for an earth that was much older than previously thought

How did Lamerck propose that species evolve

organisms change their behavoir in response to environmental chnages

What parts of Lamarcks hypothesis have been proved wrong

organisms don't have a built in drive to become prefect, and evolution doesnt go in a predetermined order

Whats the difference between theory and hypothesis

Theory is supported by evidence, while a hypothesis is made before any research is done

How long ago was Charles Darwin born

200 years ago

What did Charles Darwin want to understand?

How you get the diversity of life on earth.

List four organisms Darwin observed on the Galapagos Islands.

Penguins (live at the equator and live in warm water), tortoises (600 lbs), iguanas (swim and dive in the sea), finches.

What did Darwin discover when it came to the embryos of snakes

you could see tiny bumps (legs), these would never develop in snakes. which could indicate that they were descents of humans

What did Darwin discover when it came to the embryos of Whales

Whales don’t have teeth but their embryos do. Whales must be descendants from animals with teeth

What did Darwin discover when it came to the embryos of humans

Tiny slits around the neck of humans (the same structure were found in fish, but in fish they became gills and in us they became the ear bone)

What helped Darwin come up with the idea for natural selection?

The idea that small changes/variations make all the difference between who gets to survive and who can’t

Explain what it means to say survival of the fittest

The creatures that survived were the best adapted to their environments (extreme climates, brilliant killers/predators, perfect to invade those who might be hunting them). 

In his book “Origin of Species”, Darwin made two main points which are significant contributions to the present day Theory of Evolution.

Darwin argued for the concept of evolutionary change.

Darwin provided a mechanism for this evolutionary  change called Natural selection

What is Descent with modifications

The Concept of Evolutionary Change

Explain the idea of descents with modifications

• Creatures are unchanging

• Change is the rule, not the exception 

• Organisms that are alive today have descended by a series of gradual changes from ancient ancestors

• Species evolve, or change, over time

What is natural selection

The mechanism of evolution

Explain the idea of natural selection

• Change is determined by natural selection

• Change is machanisitic, not designed

What three contributors play a role in the process of natural selection

• An organisms struggle for survival

• Natural variation among members of a species 

• Role of the environment

The Observations that lead to the idea of Natural Selection

• Individuals within a species vary in many ways 

• Some of the variability can be inherited 

• Every generation produces far more offspring than can survive and pass on their variations 

• Populations of species tend to remain stable in size

The Inferences of Natural Selection based on the Observations

• Members of the same species compete with each other for survival 

• Individuals with more favorable variations  are more likely to survive and pass on those traits.  

• Survival is not random 

• As the surviving individuals contribute proportionately more offspring to succeeding generations, the favourable variations will become more common.

What are 5 types of evidence that is studied

• Biogeography

• Fossil Record

• Comparative Anatomy

• Comparative development

• Molecular Biology

Whats convergent evolution

two unrelated species develop similar traits because they live in similar environments.

Whats divergent evolution

individuals in one species, or closely related species, acquire enough variations in their traits that it leads to two distinct new species.

What are the more common recognizable fossils

hard body parts as shells, bones and teeth

how many identified species are comprised on fossil records

250,000

what does fossil records shows on a geological scale

progression of life from few to many and from simpler to comple

What has fossil records been able to prove

evidence of extinction

What is homologous structures

 structures that share a common origin but may serve different functions in modern species.

What type of evolution is homologous structures

divergent evolution

What is analogous structures

structures that are anatomically different but perform the same function.  They don’t share a common ancestor

What type of evolution is analogous structures

convergent evolution

What is Vestigial structure

structures that may have had an important function in an ancestral species but have no clear function in some modern descendants.

What is comparative development

Homologous features that appear in embryonic development

What is molecular biology

Studying the genetic makeup of organisms can indicate the relatedness among species.  DNA is able to provide a record of an organism’s ancestry.

What is artificial Selection

the selective breeding of domesticated plants and animals to produce offspring with genetic traits that humans value.

Describe what Darwin meant by “descent with modification”

Organisms are not immutable. Species evolve and change over time.

What can we study today that Darwin couldn’t?

The DNA of animals

What is a gene? What do genes turn into?

Most genes contain the information needed to make functional molecules called proteins

What did the researchers find that explained the different color mice fur?

4 places where the A, T, C, and G’s were misplaced causing the same in fur colour

How many genes are in the human genome?

23,000 genes

Research on the fruit fly showed there are “switches” in DNA. What are switches

Turn genes that transform into proteins on and off

How did the lake stickleback fish lose its spikes?

DNA mutations, switch was broken and didn’t turn on the gene that made spikes

Finch beaks are all made by the same gene, so why are there different shaped beaks?

Genes turning on and off in the embryos at different times and intensities

Define transitional fossil.

Fossils that show intermediary links between groups of organisms

Why is the tiktaalik fossil so important?

• Provides clues about a key transition in the history of life

• Proved fish had legs

What do HOX genes do?

Define patterns of development in vertebrate limbs

What patterns do you see between the type of body shape a lizard has and the habitat it lives in?

Large body largo toe pads - tree crown

Large toe pads, can change colour - Upper trunk/canopy

Short body, slender legs and tail - Twig

Long forelimbs, flattened body - Mid Trunk

Stocky body, long hindlimbs - Lower trunk/ground

Slender body, very long tail -grass/bushes 

Does this pattern exist on all islands? Explain.

Yes, the pattern is the same for all islands, because all the islands have very similar environments due to them being geographically close to each other, so even though they live on different islands the patterns still exist as lizards that live in the same area adapt the same variations. 

What is evolution in genetic terms

any change in gene (and allele) frequencies in a population over time. 

Whats a gene pool

 All the alleles of an individual that make up that population

Whats microevolution

When there's a constant change of alleles from generation to generation.

What is natural selection

• The environment increases the frequency of alleles that provide a reproductive advantage

• Leads to adaptation 

What are the three patterns of natural selection

Stabilizing, Directional, Distribution

what is stabilizing selection

Selection against individuals exhibiting variations in a trait that deviate from the current population average.

An example of stabilizing selection

Babies born under the average weight are less likely to survive

What is Directional selection

Selection that favors an increase or decrease  in the value of a trait from the current population average.

Whats an example of Directional selection

 If the hummingbird population moves to a new habitat with longer flowers, individuals with bills that were best adapted to medium-length flower will no longer be ideal.

what is Distribution selection

Selection that favours two or more variations or forms of a trait that differ from the current population average.

Whats an example of Distribution selection

The African Blackbellied Seedcracker Finch (Pyrenestes ostrinus) depends on the seeds of two different types of sedge, one that produces a soft seed and the other a much harder seed.  Finches with small bills are efficient at feeding on soft seeds, while birds with larger bills are able to crack the hard seeds.

What is sexual selection

Differences in sexual success due to differences in the ability to find mates

What is artificial selection also known as

selective selection

what is artificial selection

The intentional breeding  of domestic plants and animals to produce certain traits.

what is genetic drift

Random change in allele frequencies that arise by chance 

Changes in populations are much more pronounced in populations that are much more pronounced in populations that are small 

What is the bottleneck effect

• A dramatic reduction in population size caused by server event 

• Reduces the size of the gene pool

• Decrease genetic variation  in a population 

whats the founder effect

When a few individuals from a large population leave to establish a new population

Whats the gene flow

• Genetic drift resulting from the movement of individuals between populations 

• Exchange of genes between fertile individuals or their gametes.

Whats mutations

Only source of additional genetic material and new alleles in population 

Whats are the three types of mutations

Neutral, negative, beneficial

What pattern is more likely to lead into two distinct phenotypes? explain.

disruptive selection, as it creates separation, and range  between the species in a range

Describe what can happen to a gene pool as a result of bottleneck effect?

It significantly decreases, and this leads to a lack of diversity, and affects how well the population is able to adapt to environmental change 

Explain in evolutionary terms the advantage males have when they have bright colouration and elaborate tail feathers 

Makes them more fit for the environment as they will be able to create the most offspring due to them attracting more females and this will allow them create genetic diversity and help diverive their population. 

Whats species

a population or group of populations whose members have the ability to breed with one another in nature and produce fertile offspring

What is the expedition of this definition of species

• Organisms that only reproduce asexualy 

• Organisms known only by the fossil record (extinct) 

What is speciation

 the origin of new species.  substantial between two populations arise that make mating impossible 

What is a reproductive isolating mechanism

is any behavoiral structural, or biochemical trait  that prevents individuals of different species from reproducing successfully together.

What are the two main mechanisms that prevent fertilization and maintain species isolation

pre-zygotic mechnaism, post zygotic mechanism

whats pre-zygotic mechanism

prevention  of interspecies mating and fertilization

Which Includes  ecological isolation, temporal isolation, and behavioural isolation structural differences  in the reproductive organs can prevent copulation

Whats post zygotic mechanism

Incompability of chromosomes  results in zygotic mortality

Whats Hybrid inviability

the zygote or embryo fails to develop properly

Whats Hybrid infertility

A hybrid is formed but is infertile.

whats the two types of speciation

Alopatric Speciation, sympatirc speciation 

What is alopathic speciation

• Occurs when two populations are geographically isolated  from one another

• Populations are separated either by distance or an impassable barrier

• Gene flow  is not possible between the populations

• Results in diverging species  also referred to as adaptive radiation 

What is sympatric speciation

A new species develops when members of a population develop a genetic difference (chromosome mutation) that prevents them from reproducing with members of the original species.

 List several reasons sexual reproduction is a burden to females

• only pass 50%

• time and effort to choose a mater

• birthing is dangerous for survival

• they usually are involved in rearing offspring

What is the “Red Queen” hypothesis?

• That species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species

• When a species stops evolving, it is doomed

 Sex generates variability...therefore, it is the best defense against what?

pathogens/ diseases

For songbirds, why do females risk “cheating” on their mates?

• To find a new mate to provide for her children

• Better chance of her children surviving

• for increased genetic variability

How has infanticide (killing of babies by males) affected female chimpanzee behavior?

female chimpanzees mate with all the males in the group in attempt to decrease this behavior (men were less likely to kill infants if they believed the infants might be their own)

Briefly explain what major factor is theorized to have been the force behind    the evolution of Bonobos.

female solidarity (this was allowed due to the availability of food)