Reproductive Isolation, Members of a Species Do Not Interbreed Successfully with Members

1. What does the Biological Species Concept focus on?

Reproductive Isolation, members of a species do not interbreed successfully with members of another species.

1. What are the two factors that contribute to “reproductive isolation”?

Pre-zygotic and Post-zygotic barriers

1. Define and give an example of a pre-zygotic barrier.

Barriers that act prior to formation of a zygote; barriers to mating or fertilization.

Example: Different mating songs of the Meadow Larks

1. Define and give an example of a post-zygotic barrier.

Barriers that prevent the hybrid zygote from developing into a viable, fertile adult.

Example: The cross between horse and donkey gives a mule which cannot reproduce, itself.

1. What is speciation?

Speciation requires that gene flow between populations of a species be interrupted and enough time to pass to allow accumulation of sufficient phenotypic characteristics to prevent interbreeding between the two populations.

1. What is allopatric speciation? Examples?

Development of a new species due to geographic barriers. Example: The porkfish and the isthmus of Panama

1. What is sympatric speciation? Examples?

Development of a new species in same place…due not to geographic barriers but to some other sort of reproductive isolation. Example: The Rhagoletis fly lays its eggs in the Hawthorn plant until a new host plant, the apple was introduced. Some of these flies can lay their eggs in the apple leading to reproductive isolation in the two races of Rhagoletis fly eventually leading to two closely related species. This is known as habitat differentiation.

1. What is microevolution? Macroevolution?

Microevolution – changes in allele frequencies, happens all the time and is easy to observe. Enough change may occur resulting in speciation although this is much more difficult to observe.

Macroevolution – production of distinct groups of related organisms such as families, classes, phyla etc. This is very difficult to observe because it takes a large amount of time.

1. How many different fossil species of human ancestors have been found?

20

1. How old are the oldest fossil remains of our species? Where are they from?

About 170,000 years old from Ethiopia, Africa

1. How long ago did humans reach the western hemisphere?

a)170,000 years ago

b)100,000 years ago

c)60,000 years ago

d)20,000 years ago

e)10,000 years ago

1. How many generations worth do we have recorded history of?

a)250

b)500

c)150

d)50

1. Why are fossils of primates hard to find?

Other than current day humans, primates have never had large population sizes.

1. All dogs are members of the same _____. Choose the most specific grouping that applies.

a)Phylum

b)Subphylum

c)Family

d)Species

e)Subspecies