[Babase] Ranker - rules for placing new group members
Susan Alberts
alberts at duke.edu
Wed Nov 8 10:49:51 EST 2006
When Jun and Tyler and Karl and I met last week I agreed to send a
description of how to rank individuals that do not have a rank in the
group from the previous month.
INDIVIDUALS ENTERING GROUPS.
Individuals enter the group in two ways.
1. They are born into the group. This occurs with both males and
females. When an individual enters the group by being born, s/he
should be ranked at the bottom of his/her sex (ie the youngest is the
lowest ranking until further information is provided). If several
kids are born in a month, they should be added in age order from
oldest to youngest. If two kids (AAA and BBB) of the same sex are
born on the same day, they may be ranked in either order (AAA then
BBB or BBB then AAA), there is no preference.
2. They immigrate into the group. This occurs only with males. When a
male immigrates into the group, he should be ranked at the bottom of
the adult males and above all non-adult males. Adult males are
differentiated from non-adult males by the fact that, in the
"Rankdates" table, they have an existing "ranked" date. Only adult
males have "ranked" dates in this table. [Note: A "Ranked" dates
indicates that the male in question has successfully challenged and
won a fight with at least one fully adult male in the population --
this is our criterion for adulthood. It is distinct from a "matured"
date, which is assigned when a male achieves testicular enlargement
-- i.e., puberty. Puberty occurs several years before adulthood for
males).
2a. Note that if several new males immigrate in the same month, they
should be assigned ranks in reverse age order below all adult males.
That is, the youngest new immigrant male should be placed highest
ranking among the new males, at the bottom of the adult males. The
next older male should be placed after him. Etc. Male ages are
derived by examining the "birth" column in the "biograph" table;
"birth" provides an estimated or known birthdate.
2b. If a male with no estimated or known birthdate enters the group,
he should be ranked at the bottom of all adult males, below all other
males that immigrate in that month.
NEW GROUPS COMING INTO EXISTENCE
Occasionally groups come into existence and so there are no records
of how those individuals were ranked in that group the previous
month. This is a rare event resulting either from fissions (which
occur about once every ten years) or from us starting to monitor a
new group (this has occurred three times in 35 years and probably
will not happen again).
There are two possibilities for how to deal with group fissions.
1. Force the user to provide a ranking de novo. That is, don't do any
default rankings.
2. Examine the group from which the newly fissioned group arose, and
retain the same relative rankings in the new group as in the old. It
would be nice if this were doable.
For new groups that have not been monitored before, you can only
force the user to provide a ranking de novo. However, as I noted this
is unlikely to ever happen again ( we have more than enough groups to
keep us busy for the next several decades).
Hope this helps, please let me know if you have questions.
Susan
-----------------------------------------------
Susan Alberts, Dept. Biology, Duke University, Durham NC 27708. Phone
919-660-7272, Fax 919-660-7293. alberts at duke.edu
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