The outgroup is used as a point of comparison for the ingroup and specifically allows for the phylogeny to be rooted. Because the polarity (direction) of character change can be determined only on a rooted phylogeny, the choice of outgroup is essential for
understanding the evolution of traits along a phylogeny
.
What is a good outgroup?
In general, an outgroup should be
as close as possible to the ingroup
. If there is a risk that it is really part of the ingroup, then other outgroups are needed in addition, to help resolve those relationships. Multiple outgroups give a more reliable picture.
How does an outgroup differ from a sister group?
The ingroup is the set of taxa which is hypothesized to be more closely related to each other. Thus, taxa in the ingroup are sister groups of each other. An outgroup is a group of organisms that serves as a reference group in determining
the evolutionary relationships of
the ingroup.
Where is the outgroup on a phylogenetic tree?
Many phylogenies also include an outgroup — a taxon outside the group of interest. All the members of the group of interest are more closely related to each other than they are to the outgroup. Hence, the outgroup stems
from the base of the tree
.
Why is phylogeny important?
Phylogenetics is important
because it enriches our understanding of how genes, genomes, species (and molecular sequences more generally) evolve
.
How is an outgroup chosen?
The chosen outgroup is
hypothesized to be closely related to the other groups
but less closely related than any single one of the other groups is to each other. The common approach is to select something close to the ingroup, but with no possibility of being actually within the (in)group you are studying.
What is an outgroup in psychology?
n. 1. in general,
any group to which one does not belong or with which one does not identify
.
Where does the outgroup go on a cladogram?
An outgroup may be included on
a cladogram to compare the other groups to
. In the example cladogram, the outgroup is Species E. It is related to the root organism but it is not as closely related to the other terminal nodes or species as those terminal nodes are to each other.
What are the examples of out-group?
An out-group, conversely, is a group someone doesn't belong to; often we may feel disdain or competition in relationship to an out-group.
Sports teams, unions, and sororities
are examples of in-groups and out-groups; people may belong to, or be an outsider to, any of these.
What is an outgroup definition?
:
a group that is distinct from one's own and so usually an object of hostility or dislike
— compare in-group sense 1.
Is basal taxon and outgroup the same?
No, they are not the same
. When we construct a phylogenetic tree, we branch the organisms on the basis of their evolutionary history.
What's the difference between a Cladogram and a phylogenetic tree?
A phylogenetic tree is an evolutionary tree that shows the evolutionary relationships between different groups of animals. Cladograms
give a hypothetical picture of the actual evolutionary history of the organisms
. Phylogenetic trees give an actual representation of the evolutionary history of the organisms.
What does the length of a phylogenetic tree indicate?
Branch lengths indicate
genetic change
i.e. the longer the branch, the more genetic change (or divergence) has occurred. Typically we measure the extent of genetic change by estimating the average number of nucleotide or protein substitutions per site.
What is phylogeny and why is it important?
Phylogenies are
useful for organizing knowledge of biological diversity
, for structuring classifications, and for providing insight into events that occurred during evolution.
What is phylogeny with example?
The
phylogenetic tree of animals depicting the evolution of animal organs
is a special phylogeny example. It shows animal phylogeny is terms of the evolution of animal organs. In this type of diagram, the evolutionary relationship of major animal lineages can be inferred based on the organ level of organization.
What are the benefits of using phylogenetic classification?
The advantage of a phylogenetic classification is that it
shows the underlying biological processes that are responsible for the diversity of organisms
.
