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How to understand phylogenetic trees

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The Most Recent Common Ancestor (MRCA) refers to the most recent individual from which all organisms in a group are directly descended. The concept is used in various fields, including genealogy, evolutionary biology, and phylogenetics, to identify the last common point of origin shared by different species, populations, or individuals within a lineage. In human genealogy, the MRCA of all currently living humans is sometimes referred to as “Mitochondrial Eve“ for matrilineal descent (traced through mitochondrial DNA) and “Y-chromosomal Adam“ for patrilineal descent (traced through the Y chromosome). These are not thought to be the first humans, but rather the individuals whose lines of descent have not been broken by extinction or lack of offspring. Estimates suggest that “Mitochondrial Eve“ lived roughly 100,000 to 200,000 years ago, while “Y-chromosomal Adam“ is estimated to have lived around 200,000 to 300,000 years ago. However, these estimates are subject to change as new evidence emerges. In evolutionary biology, the MRCA is used to describe the most recent shared ancestor of all members of two species or other taxa. This concept helps scientists understand how species have diverged and evolved from common points in the tree of life. The search for MRCA involves analyzing genetic markers in present-day organisms to trace back through their evolutionary history. This process helps to reconstruct phylogenetic trees and understand the genetic relationships between species. The concept of MRCA highlights the interconnectedness of all life forms through shared ancestry. Problem: What inference can be made from the phylogenetic tree? A) Species A was probably much larger than any of the other organisms. B) Species G is extinct. C) Species C is the most recent common ancestor of species B and D. D) Species F and G are more closely related than species B and E.

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