1. which of the following must occur for speciation to take place?
a. a population must be physically separated into groups
b. harsh environmental conditions must be imposed on a population
c. competition must occur between members of a populations
d. some event must occur leading to two or more groups within a population that cannot interbreed**
2. which of the following is true if species a and species b have more shared derived characteristics with eachother then they do with species c?
a. species a and b are not related to c***
b. species a,b an c do not have any common ancestor
c. species a an b are more closely related to one another than either is related to species c
d. species a and b can interbreed with one another but not with species c
3. in a cladogram a branch point represents an ________ and a branch that ends without leading to a living species represents _______?
a. common ancestor; extinction
b. mutation; puctuated equilibrium
c. extinct species; common ancestor****
d. common ancestor; speciation
plzz help
number 3 is either c or d I think
and number 2 I choosh c sorry for the mistake
1. d. some event must occur leading to two or more groups within a population that cannot interbreed
2. c. species a and b are more closely related to one another than either is related to species c
3. d. common ancestor; speciation
1. To determine which of the options must occur for speciation to take place, we need to analyze the process of speciation itself. Speciation refers to the formation of new and distinct species through the evolution of populations. One common mechanism for speciation is when a single population becomes separated into two or more distinct groups that no longer interbreed.
Therefore, the correct answer is option D: some event must occur leading to two or more groups within a population that cannot interbreed. This event can be the physical separation of a population, such as by geographic barriers like mountains or bodies of water. Once separated, the groups can undergo genetic changes independently, eventually leading to reproductive isolation and the formation of distinct species.
2. This question is asking about the relationships between three species, labeled as species A, B, and C, based on their shared derived characteristics. To determine the correct answer, we need to consider the principles of phylogenetics and the concept of a common ancestor.
Shared derived characteristics or traits are those that are present in a group of organisms but not in their common ancestor. If species A and B have more shared derived characteristics with each other than they do with species C, it indicates that they share a more recent common ancestor compared to species C.
Therefore, the correct answer is option C: species A and B are more closely related to one another than either is related to species C.
3. In a cladogram, a branch point represents an important concept in evolutionary biology. It represents a common ancestor, a hypothetical species from which two or more descendant species originate. The branch point, also known as a node, separates the lineages leading to different species.
On the other hand, a branch that ends without leading to a living species represents an extinct species. This branch represents a lineage that, at some point in its history, became extinct without giving rise to any living descendants.
Therefore, the correct answer is option C: a branch point represents a common ancestor, and a branch that ends without leading to a living species represents an extinct species.