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Reproduction in Mammals

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Overview

• Characteristics of Mammals• Types of Mammalian Reproduction

– Monotremes– Marsupials– Placental

• Summary

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Sexual Reproduction Review

• Few offspring• Genetic variation• 2 parents produce haploid gametes• Gametes fuse to produce offspring• Offspring have characteristics of both

parents, but are not identical to each other or to parents

• Uses meiosis to produce gametes

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Characteristics of Mammals

• Warm-blooded• Have hair• Produce milk to

nourish young• High metabolic

rates• Single bone in

lower jaw• Three middle ear

bones http://www.ucmp.berkeley.edu/mammal/mammal.html

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Monotremes

• Three living monotremes– Duckbilled

platypus– 2 species of

Echidna (spiny anteater)

http://www.ucmp.berkeley.edu/mammal/monotreme.html

Echidna. Photo by Dr. Lloyd Glenn Ingles © 2001 California Academy of Sciences.

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Monotreme Reproduction

• Monotremes lay eggs incubated by parents, and nourish underdeveloped young with milk, but have no nipples.

• Special structures– Eggs, milk, but no

nipples encarta.msn.com/media_ 461534650/Platypus.html

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Marsupials• Pouched Mammals

• Some examples are: – Kangaroos, Koalas, Wombats, Red Kangaroo. Photo by Gerald and Buff

Corsi, © 2002 California Academy of Sciences.

Wombat. Photo © 2005 Sharon Chester

www.kidcyber.com.au/ IMAGES/pouch%20baby.jpeg

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Marsupial Reproduction

• Marsupials give birth to live young

• Offspring are under-developed and continue to grow in pouch, attached to nipple

• Nourished by milk

• Special structures– Nipples– Pouch

http://www.wfcr.org/OLD_WWW/opossuminfo.html

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Placental Mammals(Eutheria)

Most mammels reproduce with placenta.

A few examples are:

- Giraffe, Monkeys, Tiger, Cats, Dogs, Elephants, Humans, etc. Yellow Baboon. Photo by H. Vannoy Davis, © 2002

California Academy of Sciences.

encarta.msn.com/medias_ 761561349/Mammal.html

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Placental Reproduction

• Placental mammals give birth to live young

• Young develop in uterus and are nourished by the placenta

• Long gestation period• Nourished by milk

through nipples after birth

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Placental Special Structures

• Special structures– Uterus– Placenta– nipples

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Quick Review

• Mammals use sexual reproduction to produce offspring.