POPULATION ECOLOGY

Steve  Lonhart  /  NOAA  MBNMS    

 Kathy  DeWet-­‐Oleson  /  NOAA  

Steve  Lonhart  /  NOAA  MBNMS    

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LEVELS OF ECOLOGY •  Popula=on  =  all  the  individuals  of  a  species  that  live  in  the  same  area  

M/Y/D/S  Animal  Graphics  2  

POPULATION SIZE How  does  popula=on  size  change?  •  Births  •  Deaths  •  Immigra=on  •  Emigra=on  

I

E

Steve  Choy  /  NOAA  MBNMS  

CA  Fish  &  Game  

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POPULATION SIZE

Nt+1= Nt B D I E + + - -

Steve  Choy  /  NOAA  MBNMS  

CA  Fish  &  Game  

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POPULATION SIZE Scien=sts  observed  2,813  sea  oVers  along  the  Central  Coast  in  2009.    430  oVers  died  and  328  pups  were  born.    If  there  is  no  immigra=on  or  emigra=on,  how  many  sea  oVers  were  there  in  2010?  

Informa=on  from  OVer  Project  &  USGS  

2,813  +328  –  430  +  0  -­‐  0  =  2,711  

Nt+1= Nt B D I E + + - - 5  

POPULATION SIZE If  10  sea  oVers  leave  the  Central  Coast  popula=on  and  2  enter,  what  would  the  2010  popula=on  be?  

2,711+2-­‐10=2,703  

Nt+1= Nt B D I E + + - -

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POPULATION SIZE

US  Geological  Survey  

Steve  Choy  /  NOAA  MBNMS  

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POPULATION GROWTH

Genera&on   1   2   3   4   5  

Popula=on  Size   2   4   8   16   32   8  

POPULATION GROWTH

Exponen&al  Growth  

Time  

Popu

la=o

n  Size  

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POPULATION GROWTH Why  don’t  popula=ons  

usually  grow  exponen=ally?    

•  Limited  resources  –  light,  water,  nutrients,  food,  space  

•  Disease  •  Preda=on  

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POPULATION GROWTH

Logis&c  Growth  

Exponen&al  Growth  

Carrying  Capacity  

Time  

Popu

la=o

n  Size  

K  

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POPULATION GROWTH Num

ber  o

f  pup

s  born  

Year  

Elephant Seals

hVp://www.nmfs.noaa.gov/pr/pdfs/sars/po2007sene-­‐ca.pdf  

Carrying  capacity  

Photos  by  Kris=n  McCully  12  

ACTIVITY

 Map  of  Average  Annual  Popula=on  Growth  Rate,  1980-­‐1998    

(hVp://www.worldbank.org/depweb/english/modules/social/pgr/) 13