EVOLUTION

 

2)Explain which type of reproductive isolating mechanism is at work in each of the following situations:

a)Zebroids, the hybrid offspring of matings between horses and zebras, are sterile.

Hybrid Infertility because the offspring is sterile and can't reproduce

b) Asian lions were once common and lived in open grasslands, while Asian tigers preferred forests.

Ecological isolation because the lion and tigers were isolated. They both lived in different environments.

c) Female fireflies identify males by the pattern of light flashes they produce. Each species has a unique pattern of flashes.

Behavioural isolation because the fireflies use a matting call which is flashing light to attract a male.

d)Male geese have a penis, while male herons do not. Male herons are unable to fertilize female geese.

Mechanical Isolation because the two animals don’t have the right parts to reproduce.

 

5) How can the separation of two populations lead to:

a) The formation of a new species?

Separation leads to isolation and the species in their new isolated areas may be exposed to a different environment. For example, a species that is usually found on land is separated and finds itself in water. This will force the animals near the water of that species to adapt to the change in environment and eventually an offspring with webbed feet will be born and become the fittest of that species. Eventually that offspring will give birth and when the individual of that area attempts to breed with the individuals from the original area and the two animals aren't able to conceive a child or have a sterile child, then a new species is created.

 

b) A reduction in genetic diversity of the populations and a possible threat to their survival?

Reduction in genetic diversity means the animals are too similar. That means if one individual is affected, most of them will be affected. That makes them prone to diseases and if there is a disease that can target that species, the entire species will go extinct. 

 

6) An unusual and endangered Tasmanian plant, Lomatia tasmanica, is a triploid plant (3n=33 chromosomes) and is completely sterile. It can reproduce only asexually, and all known individuals are genetically identical clones of one other. Fossil evidence suggests this clone existed for more than 43 000 years.

 

a) How many chromosomes do you think would be found in the plant species from which it evolved?

33 chromosomes because it is possible that when it evolved it may have retained the same amount of chromosomes. 

 

b)Do you think this species arose by allopatric or sympatric speciation? Explain.

I believe it arose by sympatric speciation because the species may not have experienced isolation. Separate species may have been created and just this one out of chance became sterile.

 

 

c) In what way does this plant not fit a typical definition of a species?

This is not a definition of a species because to be considered a species it must breed with other individuals within the same species. This plant just duplicates itself.