Adaptive radiation in mammals

This presentation describes the general basis of adaptive radiation and how adaptive radiation has occured in mammals.

1. ADAPTIVE RADIATION IN MAMMALS SAMBIT KUMAR DWIBEDY ROLL NO-8 PG 1 ST YEAR

2. CONTENTS Introduction What is Adaptive Radiation? Causes Types Characteristics Mechanism The rise of Mammals Examples of adaptive radiation in Class-Mammalia Significance Conclusion

3. INTRODUCTION “Where do new species come from?” This is the key question that biology have been asking for more than 200 years. Charles Darwin Gave us part of the answer in his explanation of natural selection. Now we know that new species are formed by evolution .Evolution occur in 2 different patterns. Successive Speciation Adaptive Radiation

4. WHAT IS ADAPTIVE RADIATION? First use of term Adaptive Radiation-Osborn It is the evolutionary divergence of members of a single phyletic line into a series of different niches. ( Mayer,1931) Adaptive radiation is a process in which organism diversify rapidly from an ancestral species into a multitude of new forms. (Smith, 1976)

5. LAW OF ADAPTIVE RADIATION A n isolated region, if large and sufficiently varied in its topography , soil, climate and vegetation, will give rise to a diversified fauna from primitive types . Branches will spring off in all directions to take advantage of every possible opportunity of securing food.” Osborn(1902)

6. CAUSES OF ADAPTIVE RADIATION Entry into an adaptive zone by :- Evolution of a key innovation Invasion into a new habitat Extinction of competition (Simpson) Ecological Opportunity ( Dolph Schlutler,2002) Mass extinction

7. THE AMNIOTIC EGG: Perhaps one of the greatest key innovations of all time

8. ANOTHER KEY INNOVATION: WINGS

9. TYPES 3 types General Adaptive Radiation Adaptive radiation by environmental change Adaptive radiation in Archipelagos

10. CHARACTERISTICS Common ancestry Phenotype –Environment correlation Trait utility Rapid speciation

11. MECHANISMS

12. THE RISE OF MAMMALS Mammals are amniotes that have hair and mammary glands. 5300 species in class Mammalia Mammals evolved from synapsids . Mammals originated in the Mesozoic era. They were mouse like with quadrupedal locomotion. Mesozoic Mammals remained small till Cretaceous due to the presence of Dinosaurs. 65 million years ago , after the extinction of Dinosaurs ,in the early Coenozoic era the number and diversity of mammals exploded.

13. SMALL SIZED MAMMALS IN THE MESOZOIC ERA IN THE PRESENCE OF DINOSAURS

14. ADAPTIVE RADIATION IN MAMMALS

15. ADAPTIVE RADIATION IN PLACENTAL MAMMAL BASED ON LOCOMOTION The limb structure (mode of locomotion) of placental mammal provides an classical example of adaptive radiation. The ancestor of the present day placental mammal was a five-toed short legged terrestrial insectivore. From such stem mammals, various modern types of mammals have evolved by the modification of limbs Flying placental mammal Climbing placental mammal Swimming placental mammal Cursorial placental mammal Fussorial placental mammal

16. AUSTRALIAN MARSUPIALS DEMONSTRATE AN ADAPTIVE RADIATION IN THE ABSENSE OF COMPETITIVE INTERACTIONS WITH PLACENTAL MAMMALS KANGAROO WOMBAT

17. ADAPTIVE RADIATION IN MARSUPIALS

18. GRAZING WALLABIES INSECTIVOROUS BANDICOOT CARNIVORUS NATIVE CAT BANDED ANT-EATER

19. ARBOREAL KOAALA CURSORIAL TASMANIAN WOLF FLYING PHALANGER FOSSORIAL MARSUPIAL MOLE

20. FUTURE ASPECTS There is a single living species of genus Homo . Adaptive radiation in humans has not occurred yet but there is a chance of occurrence of adaptive radiation in humans when the homo species will be diverged into different lineages. CHINA CARRIBEAN INDIAN AFRICAN AUSTRALIA

21. SIGNIFICANCE 1.Diversification of organisms 2.Origin of new species 3.Acquisition of novel adaptive traits 4.Less competition 5.Less chance of extinction

22. CONCLUSION The highly advanced mammals are the result of adaptive radiation. Much research has been done on adaptive radiation of Mammals due to its dramatic effects on mammalian diversity. However more research is needed especially to fully understand the many factors affecting adaptive radiation.

23. REFERENCE 1.Rastogi , V. B. “Evolutionary biology”, Kedar Nath Ram Nath Publication,(U.P) India, pp. 333-347. 2. Dobzhansky , T. (1973) “Evolution”, Surjeet Publication, Delhi, India, pp.150-170. 3 .Chattopadhyay S.,(2008).’Evolution Adaptation & Ethology’ pp.332-338. 4. Schluter , D. (1996) “Ecological causes of adaptive radiation.” American Naturalist 148:540-564. . 5..Simpson , G. G. (1953). The Major Features of Evolution. New York : Columbia University Press . 6..Meyer J. R., Schoustra S., Lachapelle J.and Kassen R. (2011). Overshooting dynamics in a model adaptive radiation. Proceedings of the Royal Society PP.392–398 . 7.. Losos , J. B. (2010) “Adaptive radiation, ecological opportunity and evolutionary Determinism” American Naturalist 175(6):623-39