Is convergent evolution just based off of chance? If not, what drives it?
Convergent evolution does not arise by chance. Similarities in organisms environments (abiotic and biotic factors) drives organisms to develop similar structures through natural selection.
What is convergent evolution? What does convergent evolution often result in?
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. Convergent evolution often results in analogous structures.
Which one of these represents divergent, convergent, and parallel evolution?
Left: divergent
middle: convergent
right: parallel
What is divergent evolution? What does divergent evolution oftentimes result in?
The evolution of one species into many different species by developing different traits. Divergent evolution oftentimes results in homologous structures.
True or false: since the beginning of life, there has been many extinction events.
True
Has diversity increased or decreased since life began?
increased.
Which one of these represents the theory of gradualism and which one represents the theory of punctuated equilibrium?
Top: gradualism
Bottom: punctuated equilibrium
What are the three main assertions of the theory of punctuated equilibrium?
1. many species evolve rapidly in evolutionary time
2. it occurs in small, isolated populations so a fossil record would be rare
3. After an initial burst of evolution, they are adapted to their environment so they do not change significantly for a long period of time.
Which one of these represents the theory of gradualism and which one represents the theory of punctuated equilibrium?
left: theory of gradualism
right: theory of punctuated equilibrium
Describe the theory of punctuated equilibrium.
In the theory of punctuated equilibrium, it is stated that speciation can appear abruptly (to paleontologists, 100k years is considered as abruptly) and then little change is seen over a long time. This is the theory that scientists rely on when they do not have many fossil records for the transition of a species into what it is today.
How do we get evidence of the theory of gradualism?
By seeing that there is a series of fossil records, showing the gradual change of an organism over millions of years. The fossils that show how an organism transitioned into what it is today are called "transition fossils"
Describe the theory of gradualism.
In the theory of gradualism, it is said that speciation takes place slowly, at a steady pace. Throughout the process, there are many "transition" species.
Describe the three steps that will allow allopatric speciation to occur.
1. A physical barrier separates a single population (these barriers can be human caused)
2. Natural selection works on the separated groups independently
3. Over time the changes in each individual group become so great that if you were to reunite the separate populations, they would no longer be sexually compatible.
What is allopatric speciation?
Allopatric speciation is when a new species is formed by reproductive isolation.