[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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