SIO Marine Mammal Behavior, and Social Systems: Ma;ng. John Hildebrand, Scripps Inst. Oceanography, UCSD

Transcription

1 SIO Marine Mammal Behavior, and Social Systems: Ma;ng John Hildebrand, Scripps Inst. Oceanography, UCSD

2 Ma;ng Strategies Individuals behave to maximize reproduc;ve success Male and female reproduc;ve strategies together make up the "ma;ng system Female (mammals) invest more heavily in rearing offspring Males in maximizing the number of mates These strategies generate structures and physiological adapta;ons ~ e.g. sexual dimorphism The sexes do not necessarily agree and may some;mes be in conflict.

3 Cetacean Reproduc;ve PaVerns Odontocetes Calf every 2-8 years Weaning yrs Feeds during lacta;on Mys;cetes Calf every 1-2 years Weaning 5-12 months Fasts during lacta;on Ma;ng over extended season Fixed season for ma;ng/calving Both: Rela;vely high level of investment in young

4 Prolonged Development

5 Odontocete Social Groups Low adult mortality Stolen and Barlow 2003 High juvenile mortality must protect offspring to increase reproduc;ve success

6 Odontocete Parental Care Females responsible for care Alloparental care taking care of offspring other than your own Tizzi et al. ALLOPARENTAL CARE IN TURSIOPS TRUNCATUS: A CASE REPORT

7 Senescent Females in KW and PW Killer Pilot Human Female life history paverns Primates reproduc;ve period is conserved in pilot whales and Killer whales extended post- reproduc;ve life span Infancy is defined as the period of nursing. Juvenile period includes post- weaning to age at first birth Whitehead and Mann 2000 Matriarch as repository of ecological knowledge?

8 Female Reproduc;ve Strategies Females maximize their reproduc;ve success by being good mothers and may benefit from choosing males with good genes (males that are dominant, older, immunologically Incompa;ble, etc.) given the energe;cs and other constraints of searching for mates. LiVle is known about female choice. Do females have Preferred companions? Exert cryp;c female choice?

9 Male Reproduc;ve Strategies Males maximize their reproduc;ve success by ma;ng with as many females as possible and most devote the bulk of their energies to this pursuit No known male parental care in marine mammals The poten;al for males to mate with many females depends on temporal & spa;al distribu;on and mobility of females Males compete with other males for access to females both pre- and post- ma;ng

10 Pre- ma;ng Compe;;on Contest Compe22on aggressive interac;ons to limit access of other males to females (size and weaponry) Scramble Compe22on compe;;on to disperse and find sexually recep;ve females (agility and speed) Mate Choice Compe22on compe;;on in courtship to be chosen by the female (display)

11 Weaponry Beaked Whales: based on scarring paverns, Males appear to use their teeth as weapons In aggressive encounters with other males (females lack teeth)

12 Display Display may take several forms Male Spinner dolphin Modified appendages Pigment paverns Acous;c display (song, sperm whale clang) Sperm Whale Clang Minke Whale Boing

13 Odontocete Ma;ng Systems Resident Killer Whale ma;ng during mul;pod gree;ng ceremonies between subpopula;ons - Bigg, BarreV- Lennard and others Sperm Whale Extreme polygyny with roving males Whitehead et al. BoVlenose Dolphins sequen;al female defense polygyny with male alliances sexual coersion and polyestrous females Conner, Mann and others

14 Sperm whale groups - Female Matrilineal groups (~10) Interact with other groups for short period Female bond based on cooperative care of young - Leave calves at surface during feeding dives Emerging understanding of complexity

15 Sperm whale groups - Male Males disperse (> 6 yrs) Increasingly solitary Form loose breeding associations Roam between female groups Sexual Dimorphism: Males > Females

16 Fusion - Fission System Fusion - Groups join for reproduction or feeding Fission - Groups split to stable sub-units

17 Male Bottlenose Dolphin Grouping - Strong, stable alliances (2-3 members) - Pairs join larger groups for mating - Super alliances = short term grouping - Aggressively separate females from groups Connor et al Synchrony, social behaviour and alliance affilia;on in Indian Ocean bovlenose dolphins, Tursiops aduncus

18 Female Bottlenose Dolphin Grouping Not as strong as male alliances Vary by location Reproductive Status Typically 4-7 Individuals Mothers with most recent offspring

19 Mys;cete Ma;ng Solitary Promiscuous Body size: Females > Males presumed for fetal and calf development Breeding discrete phase of each year Migrate between produc;ve feeding grounds and lower la;tude breeding grounds Best data on humpback, gray, and right whales More data on males than females

20 Pinnipeds Amphibious: Solitary forager at sea Return to land or ice for parturi;on Aggrega;on of Females on Land Avoid harassment by males Protect pups Ice breeding seal dispersed

21 Pinniped Ma;ng Systems Characteristic Otariids Most phocids H. grypus and Mirounga spp. No. of species Female density 15 Gregarious 15 Solitary to Moderately Gregarious 3 Gregarious Mating system Male parental care Sexual dimorphism Breeding substrate Mating substrate Lactation Polygyny No High Land Land Long Slight polygyny No Low Ice or land Water Short Polygyny No High Land Land Short Cassini 1999 Behavioral Ecology

22 Sea OVers Live close to coastal forage areas Females claim year- round territories Females aggregate in small groups raps Males aggregate outside reproduc;ve ;mes Adult males establish territories that overlap with one or more female