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Fish 475: Marine Mammalogy 24 May 2010 Reproduction: Cetaceans. Text reading reference: Chapter 10 Course website: http://faculty.washington.edu/glennvb/fish475

Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

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Page 1: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Fish 475: Marine Mammalogy24 May 2010

Reproduction: Cetaceans.

Text reading reference: Chapter 10

Course website:http://faculty.washington.edu/glennvb/fish475

Page 2: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Cetacean reproduction

Some general patterns:

Long gestation (typically about 1 year);

Long birth interval (at least one year, but may be much longer for some odontocetes);

Often closely linked to seasonal migratory patterns;

Parental care entirely maternal;

Delayed implantation does not occur.

Page 3: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Cetacean reproduction: Mysticetes

Breeding systems differ between the two largest families (right whales and rorquals):

Right whales:

Extreme spermcompetition, withproportionately very large testes and externalgenitalia

John Tessler

Page 4: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Cetacean reproduction

Reproduction in the mysticetes(baleen whales):

Breeding systems differbetween the two largest families(right whales and rorquals):

Rorquals:

Testes and genitaliaproportionately muchsmaller than in rightwhales. Breeding systemmore typicallycharacterized by male-male competition andpossible polygyny (morelike pinnipeds.

National Geographic Society

Page 5: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Cetacean reproduction

Reproduction in the mysticetes(baleen whales):

Calving interval is variable insome species (best known forrorquals and gray whales),Likely depending onenvironmental conditions –especially food supply:

Good conditions:

1. Conception2. Birth3. Weaning

1

Low-latitude breeding grounds

High-latitude feeding grounds

2 1

3

Page 6: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Cetacean reproduction

Reproduction in the mysticetes(baleen whales):

Calving interval is variable insome species (best known forrorquals and gray whales),Likely depending onenvironmental conditions –especially food supply:

Less favorable conditions:

1. Conception2. Birth3. Weaning

1

Low-latitude breeding grounds

High-latitude feeding grounds

2

3

1

Page 7: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction: Odontocetes

Page 8: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

“Patterns”:

1. Evidence for male-male competition in some species;

2. Diversity of life history strategies;

3. Complex relationship of social and breeding systems in many species.

Stephan Wong

1

Page 9: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Classical evidence for male-male

competition:

1. Sexual dimorphism in body size;

2. Prominent secondary sexual characteristics in males;

3. Absence of sperm competition – reduced proportionate size of testes and male genitalia.

Stephan Wong

2

Page 10: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Ecological setting for theevolution of male-malecompetition:

1. Concentration, in both time and space, of resources necessary to support lactating females and newly-weaned juveniles;

2. Limited availability of habitat appropriate for breeding activity.

3

Page 11: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Examples of odontocetespecies known to be sexuallydimorphic in size:

Sperm whalesBelugasKiller whales

4

Page 12: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Examples of odontocetespecies known to haveprominent secondary sexualcharacteristics in males:

Sperm whalesNarwhalsKiller whalesBeaked whales

5

Page 13: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Variation in life history:

Dolphins and porpoises:

Tortoises and hares?

6

Page 14: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Variation in life history:

Dolphins:

Long birth interval (2-7 yrs);

High age of first reproduction (4-17 yrs);

Long reproductive life (20 yrs or more);

Lengthy lactation (2-3 yrs).

7

Page 15: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

Variation in life history:

Porpoises (most data are from two species, harbor porpoise and Dall’s porpoise):

Annual birth interval;

Early age of first reproduction (3-4 yrs)

Short reproductive life (<10 yrs);

Short lactation (< 1 yr).

8

Terry Pyle

Page 16: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

9

Examples of linkage ofsocial and reproductive systems:

Bottlenose dolphins:

Male bands anddispersal forreproduction;

Page 17: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in odontocetes

10

Examples of linkage ofsocial and reproductive systems:

Killer whales:

Superpods and male “dispersal” for reproduction.

Page 18: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in sirenians11

Life history similar to odontoceteCetaceans:

High age of first reproduction (3-15 yrs);

Long birth interval (3-6 yrs);

Long period of lactation (2-4 yrs);

Long reproductive life (20 yrs or more).

Little evidence of sexualdimorphism or male-malecompetition.

Jeff Foote

Page 19: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in sirenians

12

Exception:

Development of tusks in adult male dugongs

Page 20: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in marine otters

13

Sea otters:

Similar to porpoises and otariids:

Annual pupping, delayed implantation capability;

Lactation 4-6 months;

First reproduction at 3-4 yrs;

Breeding life of 10-12 yrs;

Males territorial during breeding season, with slight sexual dimorphism in size (males larger)

Page 21: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in marine otters

14

Marine otters:

Poorly known:

Litter size is two (smallest litter size of any otter species, but larger litter size than any marine mammal exceptpolar bears);

Breeding system likely similar to other otters, with complex linkages to social system. Breeding activity probably occurs largely on land or in fresh water

Page 22: Reproduction: Cetaceans. - faculty.washington.edufaculty.washington.edu/glennvb/fish475/Lecture file 24 May 2010.pdf · Reproduction in marine otters. 14. Marine otters: Poorly known:

Reproduction in polar bears15

Reproductive patterns strongly influenced by annual cycles in sea ice distribution and quality.

Delayed implantation capability;gestation 8 months;

Litter size 1-3, newborn cubs altricial;

Birth interval 3-4 years;

Period of lactation about 2 yrs;

Age of first reproduction 4-8 yrs;

Breeding life span 10-12 yrs.