I need help with all of these. I\'m not understanding this chapter... 1.) Explai

Question

I need help with all of these. I'm not understanding this chapter...

1.) Explain what a species is and differentiate between the biological, phylogenetic, and morphospecies concepts.

2.) What are the three stages of speciation?

3.) Differentiate between allopatric and sympatric speciation, and describe the conditions under which sympatric generally occurs.

4.) Differentiate between the two types of geographic isolation.

5.) In what two ways did the results of Knowlton’s snapping shrimp study support vicariance?

6.) Describe the different types of intrinsic isolation mechanisms that can become established.

Explanation / Answer

Answer 1:-

Species can be defined as group of similar kind of living organisms that are capable of interbreeding and thus are capable of exchanging genes. Species can be classified into various concepts or better understanding. The three concepts are described below

Morphological species concept:- In this concept, species are characterized by body shape and other structural features. The structural features also include asexual and sexual organisms. This concept is useful when information on gene flow is not known. The characteristics of the body structure and the features that can be used to distinguish between species can vary.

Biological species concept:- It defines a species as member of population that can actually or potentially interbreed in nature. This concept thus is not based on similarity of appearance. Appearance is easier way to identify species, but in some cases, organisms may appear to be alike and be different species or otherwise.

Phylogenetic species concept: It defines a species as tip on a phylogeny. Species, according to this concept is the smallest set of organisms that share common ancestor.

Answer 2:-

Speciation can be defined as formation of new species. Speciation occurs through three stages viz; separation, adaptation and reproductive isolation.

Separation:- Speciation begins with separation. In separation a part of a population usually separates from the rest of their species either due to geographical barriers or other environmental factors.

Adaptation:- The separated part of the population adapts to the different geographical and environmental conditions over period of time.

Reproduction isolation- It is said to occur when the separated and adapted part of population cannot interbreed with the original population.

Answer 3:-

Allopatric speciation – It is the speciation that occurs due to presence of physical barrier. The physical barrier separated the population which then leads to speciation. Hence it is also known as geographic speciation.

Sympatric speciation - It is the speciation that occurs without presence of physical barrier. The separation of part of the population does not occur due to the physical separation.

Answer 4:-

Geographical isolation occurs when the physical barrier between the part of population and the population keep the species from mating each other. The physical barriers such as mountain ranges, rivers, canyons etc separate the population and thus create geographical isolation.

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