Concept explainers
Name the two types of
To name: Two types of speciation represented in the diagram and also to describe for each type in what way the reproductive barriers might have developed between the new species.
Concept introduction:
The speciation is an evolutionary process by which new species are formed. It can occur due to geographic, behavioral, anatomical and physiological factors.
The new species formed differ from their ancestors and cannot interbreed with their ancestral species to produce viable offspring.
Explanation of Solution
The type of speciation represented in the diagram (a) is allopatric speciation and in (b) is sympatric speciation.
The allopatric speciation occurs when two populations of a species are separated by a physical barrier such as a mountain or a hill. The gene flow between the two populations is stopped and over the time they become reproductively isolated due to natural selection, mutation or genetic drift.
In sympatric speciation, a new species arise from an ancestral species, while occupying the same geographical region. The two populations become reproductively isolated due to polyploidy, habitat differentiation and sexual selection.
Pictorial representation: Fig. 1 shows two types of speciation: (a) Allopatric speciation (b) Sympatric speciation.
Fig.1: (a) Allopatric speciation (b) Sympatric speciation.
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Chapter 14 Solutions
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- Define two modes of speciation and give examples of each.arrow_forwardIndicate the order in which the following steps would take place to result in Sympatric Speciation [enter 1 for the first step, 2 for the second, etc; write only the number -- no words, no spaces] As they adapt to their specific environments, the fitness of any hybrid formed is reduced. Reproductive isolating mechanisms are selected for so that less fit hybrids are not formed. Two species now exist. Interbreeding populations connected via gene flow occur across a range. The populations in the new environment adapt to their particular circumstances while the remainder stay as they were. Something happens so that some members of the populations/species change their environment (shift hosts; have a genetic change like polyploidy or inversions), so that they are separated from the others even thought hey are living in the same area.arrow_forwardthe choices are homogenization and speciation for all threearrow_forward
- Indicate the order in which the following steps would take place to result in Parapatric Speciation [enter 1 for the first step, 2 for the second, etc; write only the number -- no words, no spaces] Something happens so that the environment is different in one part of the range relative to the other, even though the populations are still contiguous. As they adapt to their specific environments, the fitness of any hybrid formed is reduced. The populations adapt to their environment in the part of the range where they live. Interbreeding populations connected via gene flow occur across a range. Reproductive isolating mechanisms are selected for so that less fit hybrids are not formed. Two species now exist.arrow_forwardScientists studying reproduction compared three closely related species of bagworm moths. The reproductive methods for these species are given in the table. Which of the following research questions would provide additional information about the population level impacts of meiosis and sexual reproduction? A - How do the number of D. charlottae offspring compare with the number of S. rupicolella offspring? B - Do D. charlottae and S. rupicolella populations express greater genetic diversity than D. fennicella populations? C - Are the offspring of D. fennicella genetically unique compared to the offspring of D. charlottae and S. rupicolella? D - Does crossing-over in D. fennicella result in increased genetic variation compared to D. charlottae and S. rupicolella?arrow_forwardWhat is speciation? List any two events that lead to speciation?arrow_forward
- Which of the following statements about sympatric speciation is correct? It is a process through which two populations can diverge and develop reproductive isolation while in two different geographic area. It is the most common mechanism for populations to form independent species. Postzygotic isolation is the main form of reproductive isolation for the sympatric speciation process. Genetic isolation through large scale chromosomal mutations, such as chromosome inversion or polyploidy, are more likely contributing to sympatric speciation. None of the abovearrow_forwardTwo hundred years ago, the fly species Rhagoletis pomonella only laid its eggs on fruit of the hawthorn tree. Today, different "host races" of R. pomonella lay their eggs on hawthorns OR apples. Apples occur within the range of hawthorns, so divergence between apple flies and hawthorn flies could be the first step in sympatric speciation. Choose the evidence that would suggest that R. pomonella is currently undergoing sympatric speciation. Check ALL answers that apply. A. Apple flies and hawthorn flies are able to form fertile hybrids. B. Apple flies and hawthorn flies are physically indistinguishable from each other. C. Apple flies typically mate with apple flies, and hawthorn flies typically mate with hawthorn flies. D. Apple flies and hawthorn flies emerge from their hosts at different times of the year.arrow_forwardExplain the type of speciation (allopatric, parapatric, or sympatric) most likely to occur under each of the following conditions: A. A pregnant female rat is transported by an ocean liner to a new continent. B. A meadow containing several species of grasses is exposed to a pesticide that promotes nondisjunction. C. In a very large lake containing several species of fish, the water level gradually falls over the course of several years. Eventually, the large lake becomes subdivided into smaller lakes, some of which are connected by narrow streams.arrow_forward
- Indicate the order in which the following steps would take place to result in Allopatric Speciation [enter 1 for the first step, 2 for the second, etc; write only the number -- no words, no spaces] The two groups develop reproductive isolating mechanisms so that they no longer interbreed. Interbreeding populations connected via gene flow occur across a range. The two separate groups adapt to their new environments. Some sort of physical barrier develops to split the once contiguous population(s) into two separate groups If they come back together, any hybrids formed are less fit.arrow_forwardObserve the three species of fruit fly and their evolutionary relationships in the tree below: Fly species 1 MRCA of fly species 1 & 2 Fly species 2 Note that the three fly species have the following characteristics: Fly species 1: white eyes, lots of leg bristles, striped wings Fly species 2: red eyes, lots of leg bristles, striped wings Distant relative: white eyes, lots of leg bristles, plain wings Distant relative Q3. What are the most likely characteristics of the most recent common ancestor (MRCA) of fly species 1 and fly species 2, labeled in the diagram above? Lots of leg bristles; can't tell on the other two traits Lots of leg bristles, striped wings; can't tell on eye color Lots of leg bristles, striped wings, red eyes Lots of leg bristles, striped wings, white eyesarrow_forwardTwo morphological variants in a population of medium ground finch on the Galapagos Islands have been found to exist. Individuals of each variant respond more strongly to songs produced by the same variant, and prefer to mate with individuals of their own morphological variant. What type of speciation could be in progress, and what measurements could inform the extent of prezygotic reproductive barriers that have developed? A. Sympatric speciation by sexual selection; survival and reproductive success of hybrids of the two morphological variants. B. Allopatric speciation by habitat differentiation; survival and reproductive success of hybrids of the two morphological variants. C. Sympatric speciation by sexual selection; frequencies of mating and numbers of viable offspring of the two morphological variants. D. Allopatric speciation by habitat differentiation; frequencies of mating and numbers of viable offspring of the two morphological variants.arrow_forward
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