Chat with AIExam 16: Mechanisms of Speciation
The classical hypothesis of speciation is comprised of a three-step process.What are the three steps?
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VerifiedIsolation of populations; divergence in traits; reproductive isolation.
Speciation through hybridization may or may not involve a change in the chromosome number of the hybrids.Name and explain,using examples,how speciation events in both of these cases has been documented.
(31) 
Answered by Examlex AI CopilotSpeciation through hybridization can involve a change in the chromosome number of the hybrids, a phenomenon known as polyploid speciation, or it may not involve a change in chromosome number, known as homoploid speciation.
Polyploid speciation occurs when two different species interbreed and produce offspring with an increased number of chromosomes. This can occur through the fusion of unreduced gametes or through the hybridization of two different species. The resulting polyploid offspring are reproductively isolated from their parent species, leading to the formation of a new species. An example of polyploid speciation is the formation of the plant species Tragopogon mirus and Tragopogon miscellus through hybridization between two different species of Tragopogon.
Homoploid speciation, on the other hand, occurs when two different species interbreed and produce offspring with the same number of chromosomes as the parent species. Despite the same chromosome number, the hybrid offspring may still be reproductively isolated from their parent species, leading to the formation of a new species. An example of homoploid speciation is the formation of the monkeyflower species Mimulus peregrinus through hybridization between two different species of Mimulus.
Both polyploid and homoploid speciation events have been documented through genetic and morphological analyses, as well as through observations of reproductive isolation and ecological divergence in the newly formed species. These documented speciation events provide evidence for the role of hybridization in driving the formation of new species.
Relative to chromosome numbers,hybridization can produce speciation in two ways.What are they?
(38) Verifiedpolyploidy hybrid speciation and homoploid hybrid speciation
The model of speciation that hinges on a physical barrier preventing gene flow is ________ speciation.
(35) The species concept based on careful analysis of the anatomical details of the specimen in question is ________.
(42) There are two closely related populations of squirrels living in the Grand Canyon area―one lives on the north rim,the other lives on the south rim.Speciation in these squirrels BEST fits which model?
(25) Speciation events that occur when the geographic ranges of the populations involved overlap are termed ________.
(39) From an ecological perspective,the dispersal of fruit flies (Drosophila)on the Hawaiian islands,which has resulted in speciation,is BEST termed ________. 
(28) It now seems clear that the strongest factor in speciation events is ________.
(39) The accompanying figure most closely represents speciation by ________. 
(38) The species concept defined as a group of organisms that are capable of interbreeding to produce fertile offspring is ________.
(29) Suppose a bird population that qualifies as a single species according to the Biological Species Concept (BSC)is separated into two isolated populations by an advancing glacier during an Ice Age.What will happen when the glacier retreats,allowing the two populations to come back together (secondary contact)? Be sure to account for all possible outcomes.
(36) Factors such as behavioral,temporal,or ecological isolation mechanisms that prevent two closely related sympatric populations from interbreeding can be grouped together and classified as ________.
(28) Selection that reduces the frequency of hybridization and/or the fitness of hybrids between populations following secondary contact is termed ________.
(35) The species concept that relies most heavily on the criterion that species are evolutionarily independent units that are isolated by gene flow is ________.
(40) Species divergence due to mating behavior and sexual selection,as has been documented in the Hawaiian crickets,is termed ________.[two words]
(39) The species concept based on analysis of character states that indicate the smallest monophyletic group is ________.
(31) Geographic isolation of populations can generally come about in two ways.What are they?
(32) Research on speciation of Hawaiian crickets,shown in the accompanying figure,has led researchers to conclude that ________. 
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