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1991-07-08
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CREATURE CROSS (Version 1)
==========================
Public Domain By Lance Peters
Requires 160k for Screen Memory and 32k for System sprites
A basic knowledge of inheritance, as found in most school biology text books,
is required to make proper use of this program. However for those with no
biological background I have included some basic information on the file
named "Lesson".
The program simulates breeding experiments which would normally be carried
out using organisms such as fruit flies (Drosophila). However although there
is no substitute for such real experiments they are very time consuming and
only a limited number of crosses are practical. Using a simulation you can
breed to your hearts content. By selecting the traits for investigation the
program can demonstrate aspects of inheritance from simple monohybrid
crosses up to gene mapping using triple test crosses. This version does not
include aspects such as lethal genes, multiple alleles,continuous variation,
epistasis or other effects of gene interaction. These might be possible on an
extended version.
The creatures are called Slygrons and come from the planet Eipa3. They are
useful for studying the principals of Mendelian Inheritance since they are
small (1cm tall) and easily kept. They breed very rapidly with up to 40
offspring from each mating. Their mechanism of inheritance is remarkably
similar to mammals of Earth. They have 6 chromosomes (2 pair of autosomes and
a pair of sex chromosomes). The male is the heterogametic sex (ie.XY) and he
can be recognised by the sexual spurs on his heels (used in fighting).
There are 9 easily observable traits which show discontinuous variation and
you can select the phenotype of each of the initial parents (The P1 male and
female will be homozygous for all 9 pairs of alleles).
A breeding program can be performed as far as the F3 generation and a test
cross can be performed on any individual animal in any of these generations.
A Chi-squared test can be carried out to see if an observed ratio differs
significantly from the expected ratios.
Some of the genes show complete dominance, some show partial or co-dominance,
some are sex linked (present only on the Y chromosome) and many traits will
show autosomal linkage (as there are 3 pairs of homologous chromosomes there
are 3 linkage groups). By performing appropriate crosses it should be
possible to determine the nature of the genes and if you are really dedicated
you can map the genes on each of the chromosomes. Mapping requires test
crosses to determin the % recombination in the case of linked genes (NB
unlike Drosophila crossing over occurs in both sexes). For those who wish to
'cheat' the answers are given at the end of this text.
Running the Program:
All operations except for the Chi-squared test are carried out using the
mouse. Clicking 'select' on a Buff coloured or orange box will execute the
operation. To select or count the number of individuals,'click' on the
sprite. To use the counter,'click' on 'ON' to activate it. There are 8 store
boxes for counts and the one highlighted in white is the current one. Click
on box to select another. 'C' clears the current box. 'CA' clears all the
boxes. 'OFF' returns to the main menu. Note that when the counter is
reselected it is automatically cleared.
Conditions of Use:
The program may be freely distributed provided.
1.This file is included with the program.
2.No charge is made (except for media and postage or in the case of a disc
sold for charity).
If you find the program useful for teaching purposes and would like to modify
it or have suggestions for improvement or find any bugs (other than the
Slygrons) please let me know. If you send me a S.A.E I will send you an
explanation of how it works. A desktop multitasking version would be nice
but I have not got to grips with the WIMP yet!
Address: Mr L M Peters,
4 Coatguard Cottages,
Helford Passage,
Mawnan Smith,
Falmouth,
Cornwall TR11 5LB
ANSWERS !!!!
TRAIT DOMINANT CHARACTER
Horn type Upward horn
Body colour Purple body
Antenna length Co-dominance
Antenna type Hairy
Leg size Fat legs
Leg colour Red legs
Eye colour Dark blue eyes
Eye shape Co-dominance
Proboscis length Long proboscis
Sex linked traits = Body colour and Antenna type
Autosomal linkage (Numbers indicate the map distance between the genes)
Linkage group 1
<Antenna length> 11 <Proboscis length> 4 <Eye colour> 18 <Leg size>
Linkage group 2
<Eye shape> 6 <Horn type> 14 <Leg colour>
Linkage group 3 (On the X chromosome)
<Antenna type> 23 <Body colour>