BioDiveristy Set 6 Exam 2 -SPECIATION

Heads up the word individuals is going to be in here, a lot.

What form of genetic divergence occurs when two isolated populations come back together and attempt to breed?

PARTIAL ISOLATION –Typically, there is limited interbreeding between the two populations, resulting in LOW/NO offspring → LOW fitness

(Individual breeding within members of the same population has much higher reproductive success → resulting in HIGHER fitness)

Is partial isolation sustainable over long-term periods?

NO!!!

Since reproduction is expensive energetically, and usually the offspring from PI have low fitness, mating with individuals from the other population is wasted energy. Meaning it is not sustainable.

What is ALLOPATRIC SPEICATION

This form of speciation occurs when populations are separated geographically. Breeding/gene flow is impossible between these populations

“Different homelands”

What form of allopatric speciation occurs when a population splits from one large population, moving to a new location?

This is DISPERSAL

If these populations remain SEPARATED it will result in reproductive isolation → genetic divergence → speciation

What form of allopatric speciation occurs when the physical splitting of a habitat separates one population into two or more new populations?

This is VICARIANCE

Can occur in a multitude of ways: rivers changing flow path; volcanic action; continental drift, agriculture, ranches, or roads.

What is SYMPATRIC SPECIATION?

This speciation occurs when populations live in the same area, there are no barriers, but some factor results in NO GENE FLOW

“Together Homeland”

How does mutation contribute to sympatric speciation?

It can prevent successful breeding between individuals within populations due to specific physical differences within said individuals

Ex: The specific rotation of snail shells, right swirled shells can only mate with other right-swirled shells and vice versa

How do chromosomal events contribute to sympatric speciation?

The are changes in chromosome number between parents and offspring, resulting in no gene flow even though individuals live in the same population.

Can occur through

• Autopolyploidy

or

• Alloploidy

What is AUTOPOLYPLOIDY?

It is a form of sympatric speciation, specifically a chromosomal event in which there are errors during production of eggs/sperm. Rarely offspring survive/are fertile

What is ALLOPLOIDY?

It is a form of sympatric speciation, specifically a chromosomal event in which two very similar species interbreed and end up with offspring with a different chromosome number

What form of sympatric speciation occurs when something alters/affects the breeding habits or habitats of an individual population of a given species?

This form of sympatric speciation is defined as EXTERNAL EVENTS

Prevents breeding → no gene flow → genetic isolation → divergence → speciation

Historically, true fruit flies (Tephritidae) bred ONLY on hawthorn trees in North America until an external event around the early 1800s, possibly a windstorm, led some flies to end up on apple trees. As a result, they began to breed there. Leading to habitat isolation and no gene flow.

Because of the maintained separation → continued genetic divergence (both behavioral and temporal)

This is an example of what kind of speciation?

This displays Sympatric Speciation - specifically from External Events

What form of sympatric speciation occurs when a single species rapidly evolves into multiple new species, often times due to intense competition for resources (food, mates, optimal habitats)

This is ADAPTIVE RADIATION - For this to work, the species involved MUST have LOTS of existing variation in traits related to competition for resources