This document discusses sympatric speciation, which is the evolution of reproductive isolation between populations of the same species living in the same geographic area. It provides examples of sympatric speciation occurring in apple maggot flies, bacteria, Midas cichlid fish, and orca whales. Polyploidy, a process where organisms contain more than two sets of chromosomes, is also discussed as a mechanism for instant sympatric speciation, especially in plants. The document outlines criteria for determining if speciation occurred sympatrically and mechanisms that can drive the process, such as changes in habitat or food preference.

1. SYMPATRIC SPECIATION
RANGANAYAGI.S
II – BBT
21BT0048

2. INTRODUCTION
 Sympatric speciation, The evolution of reproduction
isolation without geographic barriers, remains highly
contentious
 Speciation process when two groups of identical
species lived in identical geographical area, They
evolve in such a way that they could no longer
interbreed, They are considered to be a different
species.

3. Sympatric speciation
 This is unique because it taked place with 2
subpopulation of same species are occupying the
same range. Eventhough the territory that organisms
live in same, They are able to split into 2 different
groups that become genetically different from one
another that they can no longer breed with each
other. When one group van no longer breed with
another, it is separate species

4.  Sympatric speciation (sym – together, patric – nature
land) Sympatric speciation is controversial. Some
scientists don’t believe it exist.
 Sympatric speciation occurs when there are no
physical barriers preventing any members of a
species from mating with another and all members
are in close proximity to one another.
 The reproduction isolation brings about sympatric
speciation.

5. Sympatric speciation

6.  The change in host preference, food preference or
habital preference.
 The partitioning of an essential but limiting resource.
 Instant speciation as a result of polyploidy
(particularly among plants, as in evolution of wheat)
 Most of sympatric speciation occurs due to
chromosomal change and non random mating

7. This can happen in variety of way.
They are
1. Due to mutation
2. Change in alleb frequency
3. Behaviour changes
4. Reproduction isolation
5. Preference changes
6. Seasonal reproduction

8.  Jerry coyne and H.Allen Qrr have developed 4 criteria
for inferring whether species have arisen
sympatrically, They are
1. Species ranges must overlap significantly
2. There must be complete speciation (i.e. The 2 species
cannot interbreed)
3. The species must be sister species (Most closely
related to each other) or monophyletie group, all
descendent species have to be included if there are
more than 2, not just some of them.
4. The history of species geography range and evolution
must make alloparty sum very unlikely, as allopatric
speciation is much more common than sympatric
speciation.

9. EXAMPLE:
 In Apple Maggot Files:
Sympatric speciation maybe occuring in the apple
maggot fly. Some maggot flies began to lay their eggs
on apple instead. Now there are 2 groups of apple
maggot flies. One that lays eggs on hawthorns and one
that lays egg on apples. Male look for mates on the
same type of fruit that they grew on and female lay
their eggs on same type of fruit that they grew up on.
Flies that are up on hawthorns will raise offspring on
hawthrons and flies that grew up on apples will raise
offspring on apples. This shows how speciation can
occur even when different subgroups of the same
species have the same geographic range.


10. IN BACTERIA
 Sympatric speciation is through to occur move often in nature
in bacteria, because bacteria can exchange genes with other
individuals that aren’t parent and offspring in a proters known
as horizontals gene transfer. Sympatric speciation has been
observed in bacteria and synechoccus species in bacteria in
bacterioplankton vibrio splendidus, among others. Subgroups
of species that are undergoing sympatric speciation will show
few difference. If some members are specialized for living in
certain environments evolve into a new species over time.

11. IN CICHLIDS
 Another example of sympatric speciation is found in 2
species of Midas cichlid fish (Amphilosphus species)
which live in lake Apoyo. Researches analyzed the
DNA appearance and biology of there 2 closely
related species. The 2 species, though overall very
similar, do have slight difference in appearance and
they cannot interbreed. The newer species evolved
relatively relently, but in terms, this means that it is
thought to have evolved less than 10,000 years ago.

12. OREA
 The divergence of “ resident “ and “ transient “ orea
form in the northeast pacific is an uncommon egs. Of
sympatric speciation living in the same water, oreas
avoid each other and do not interested. They are
different diets, voacal behavior and social structure.
They also attack different prey. A reduction in the
population occurs almost 200,000 years back which
not only reduces the size of population but also
affects gene variation. After that numerous ecotype
emerged.

13. EXAMPLE:
PAINTED FROGS
 The rosy perches
 Collared Inca Finch
 Common cuckoo Finch
 Aylesbury Duck
 Kangaroo Rats
 Sqapberry bugs
 Fire lilies
 Garden orchid
AMPHIBIANS
 Fish
 Bird
 Bird
 Birds
 Rodent
 Insect
 Plants

14. INFECTIOUS SPECIATION:
1. The bacterium wolbachia can cause
cytoplasmic incompatibility.
2. When infected male hosts (w+)
male with uninfected females (w-)
no viable offspring are produced.
3. Different strains of wolbachia are
incompatible.

15. POLYPOIDY
1. Polyploidy refers to instant
speciation which occurs in most often
in plants.
2. Polyploidy cells and organisms are
those containing more than 2 paired
(homologous) sets of chromosome.
3. Polyploidy may occurs due to
abnormal use division, either during
mitosis, or commonly during
metaphase in meiosis.

16.  The normal primore is diploid with 14 chromosomes.
2N=14
 In this species there was a total nondisjunction event
resulting in primroses that are tetraploid. 4N=28
 These primroses cannot successfully mate with the
diploid species
 There are 2 types of polploidy. They are
1. Autopolyploidy
2. Allopolyploidy

17. AUTOPOLYPLOIDY
1. This is the mechanism for
autopolyploidy. A diploid
plant becomes a tetraploid
plant. The offspring look very
much like the diploid plant
but may be a little larger and
more vigorous
2. An individual where
chromosome complement
consist of more than 2
complete copies of the
genome of a single ancestral
species.

18. ALLOPOLYPLOIDY
1. Allopolyploidy are
polyploidys with
chromosome derived
from different species.
2. Precisely, it is present
result of multiplying the
chromosome number in
an F1 hybrid.