The document discusses cytotaxonomy, a branch of taxonomy that utilizes chromosomal characteristics to classify organisms and examine their relationships. It covers the definition, history, chromosome number, shape, and evolution, particularly in primates, highlighting the comparative study of chromosomes in understanding species relationships. Key findings include the chromosomal similarities between humans and chimpanzees and the implications of these findings for evolutionary biology.

1. Topic Assigned: Cytotaxonomy
Presented by: Ishtiyaq Mir
MSc Zoology (1st Semester)
Batch: 2021
Supervisor: Prof. Farooq Ahmad

2. CONTENTS
 INTRODUCTION
 DEFINITION
 HISTORY
 CHROMOSOME NUMBER
 CHROMOSOME SHAPE
 CHROMOSOME BANDS
 CHROMOSOME EVOLUTION IN PRIMATES
 BIBLIOGRAPHY

3. Introduction to Cytotaxonomy
 Cytotaxonomy is a branch of taxonomy that uses the
characteristics of cellular structures (especially
chromosomes) to classify organisms.The Term
Cytotaxonomy was proposed by Levan et al.
 In Cytotaxonomy, the chromosomal configuration is
widely used parameter to study relationships
between organisms.
 The number, structure and behaviour of
chromosomes is of great value in taxonomy.

4. Definition and History
 Cytotaxonomy is a branch of taxonomy dealing with the
classification of organisms using comparative study of
chromosomes during cell division in the elucidation of
taxonomical problems.
The species relationships is based on the assumption that
closely related species share similar chromosomal setup
(karyotype)
Cytology has contributed to track the evolutionary history of
many organisms especially primates.

5. Chromosome Number
All individuals within a species possess the same
chromosome number.
Variation in chromosome number is a taxonomic tool.
Its number is usually constant within a genus.
It helps in controversies in identifying the genus.
Example, Homo sapiens(23 pairs).
Pan troglodytes (24 pairs).

6. Chromosome Shape
On the basis of position of centromere
a. Metacentric:- centromere central in position ( p and q arms equal in length)
b. Sub-metacentric:- one chromosome arm slightly shorter than other
c. Acrocentric:- one arm very long and another very short.
d. Telocentric:- centromere terminal in position showing only one arm.

7. BANDED CHROMOSOMES AND
PHYLOGENY
 Chromosome Banding refers to alternate dark and
light regions along the length of chromosome,
produced after staining with a dye(G-banding, R-
banding).
 Chromosome evolve by
a) Deletion of DNA segments
b) Duplication of DNA segments
c) Inversion of DNA segments
d) Translocation of DNA segments

8. Chromosome Evolution in Primates
Apes and Men
Chromosome banding techniques have now been
applied to non human organisms.
The karyotypes are more than 60 species of primates
have been studied and compared, with the use of
almost all banding techniques.
Relations among different breeding populations can
be estimated by comparing chromosomal
characteristics of different taxonomical groups.

9. Man( Homo sapiens) and Chimpanzee(Pan troglodytes)
are placed in different genera Homo and Pan
respectively. But these species are much alike in almost
all features(DNA, Protein composition)
Comparisons of chromosomes show basic similarity with
a few super imposed structural re-arrangements.
The overall number of chromosomes is (46 for Homo,
48 for Pan)
Two acrocentrics in Pan(2A and 2B) have the same bands
as one sub-metacentric to make the equivalent of 46 in
both species.

10. Courtesy of A.D. Stock, Genetics, Gardner

11. A.D Stock, Dr. K. Miller, Wienberg compared the
banded chromosomes of these two species and
concluded:
o Chromosome 2 in H. sapiens is long and sub-
metacentric but is comparable with two acrocentric
chromosomes in P. troglodytes.
o When these two chromosomes of Pan are fused together
near the centromere of one chromosome and telomere of
another chromosome, a chromosome similar to H.
sapiens chromosome 2 is produced
o Thus shows that H. sapiens have been evolved from
Chimpanzees.

12. References/Bibliography
 Principles of Genetics by Gardener et-al., John Wiley.
 Principles of Systematics by Ernst Mayr, Tata McGraw Company
 Organic Evolution by N Arumugam, Saras publication.
 https://www.slideshare.net/gkumarimahesh/cytotaxonomy
 https://www.scribd.com/presentation479985036/INTERDICIPLIN
ARY-APPROACH-IN-TAXONOMY-CYTOTAXONOMY
 https://Youtube.com