The document discusses various species concepts in biology, emphasizing their definitions and classifications such as typological, nominalistic, biological species concepts, as well as taxonomic ranks like variety and subspecies. It explains that species are groups capable of interbreeding, while varieties and subspecies represent specific classifications within species. Additionally, it addresses the concept of sibling species that resemble each other but do not interbreed.

1. SPECIES CONCEPT
Varieties, Subspecies, Sibling Species, Race
Mr. Akash Bagade
M.Sc. Zoology, NET, GATE
LECTURER IN ZOOLOGY
Post Graduate Department of Zoology,
Prof. Ramkrishna More ACS College Akurdi,
Pune-44

2. Species:-
 In biology, a species is one of the basic units of
biological classification.
 It most commonly refers to a group of physically
similar organisms that can exchange genetic
information and produce fertile offspring.

3. Human Taxonomy:-

4. Species Concepts:-
• 1. Typological Species Concept:
• According to this concept, there are a number of
diversities on the surface of the earth that exist as a
limited number of types.
• These types do not bear any relationship to each other.
These types are called species.
• This concept, was in the philosophies of Plato and
Aristotle and was the species concept of Linnaeus and
his followers. Cain (1954, 1956) regarded the above
concept as the morpho-species concept. Another group
of scientists refer to this as essentialist species concept
because the members of a taxon or the species can be
recognised by their essential characters.

5. Species Concepts:-
• 2. Nominalistic Species Concept:
Occan, the proponent of this concept and his
followers (Buffon, Bessey, Lamarck, etc.) believed
that only individuals exist but do not believe in the
existence of species.
Species are man’s own creations and have no actual
existence in nature. Therefore, such concept (i.e.,
species) of man has no value. This concept was
popular in France in 18th century and still now is
used among some botanists.

6. Species Concepts:-
3. Biological Species Concept:-
Due to some incompleteness in the above mentioned
concepts a new concept the biological species
concept emerged in the middle of 18 century. The
concept took a number of years to get its foot in the
soil of biology.
K. Jordan (1905) first gave the definition of
biological species concept. Later Mayr proposed the
biological species concept. According to this
concept, “a species is a group of interbreeding
natural population that is reproductively isolated
from other such groups”.

7. VARIETY
In botanical nomenclature, variety is a taxonomic rank
below that of species and subspecies but above that of
form. As such, it gets a three-part infra-specific name.
A variety will have an appearance distinct from other
varieties, but will hybridize freely with those other
varieties (if brought into contact).
A Variety is a plant that is only slightly different from
the species plant, but the differences are not so
insignificant as the differences in a form. The Latin is
varietas, which is usually abbreviated to var.
The name follows the Genus and species name,
with var. before the individual variety name.
Ex. (Ranunculus flammula subsp. flammula) var.
tenuifolius

8. VARIETY
Varieties of Lupines

9. SUBSPECIES
A taxonomic category that ranks below species,
usually a fairly permanent geographically isolated
race. Subspecies are designated by a Latin trinomial.
A subspecies cannot be recognized independently. A
species will either be recognized as having no
subspecies at all or at least two (including any that
are extinct).

10. SUBSPECIES
Panthera tigris altaica Panthera tigris tigris

11. SIBLING SPECIES
Sibling species are species which look alike, but
cannot breed with each other.
The classic case is Drosophila pseudoobscura and
D. persimilis. They are almost identical, but they do
not interbreed.
Another example was the European mosquito
known as Anopheles maculipennis. This turned out
to be a cluster of six different species, some of
which transmit malaria, and some do not.

12. SIBLING SPECIES
Drosophila pseudoobscura and D. persimilis are structurally
similar except minor differences in wing size, genitalia and sex
comb, gene arrangement.

13. RACE
The biological definition of race is a geographically
isolated breeding population that shares certain
characteristics in higher frequencies than other
populations of that species, but has not become
reproductively isolated from other populations of the
same species.

14. Thank You