Lecture 13 - Lecture 13: PARENTAL INVESTMENT IN ANIMALS...

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Lecture 13: PARENTAL INVESTMENT IN ANIMALS PARENTAL INVESTMENT : INVESTING ENERGY AND RESOURCES INTO THE PRODUCTION OF YOUNG AT THE RISK OF A PARENT NOT PRODUCING ANY MORE YOUNG. PARENTAL INVESTMENT CAN BE AN INVESTMENT INSIDE THE BODY ( USUALLY ONLY BY FEMALE), OUTSIDE BODY, BY ONLY FEMALE, BY BOTH MALE AND FEMALE, OR BY A LARGER GROUP (WOLF PACKS FOR EXAMPLE). WOLVES COOPERATIVELY RAISE YOUNG IN RENDEZOUS SITES . PARENTAL CARE : PARENTAL INVESTMENT THAT IS GIVEN OUTSIDE OF THE BODY SEVERAL CONSIDERATIONS FOR PRODUCING YOUNG 1 ) NEED FAVOURABLE ENVIRONMENTAL CONDITIONS FOR THE YOUNG IE. NOT TOO COLD. THIS IS THE REASON MOST YOUNG ANIMALS ARE HATCHED OR BORN IN SPRING OR SUMMER 2) THERE MUST BE SUFFICIENT FOOD AVAILABLE TO FEED THE YOUNG 3) YOUNG MUST HAVE SUFFICIENT TIME TO DEVELOP SO THAT THEY ARE ADVANCED ENOUGH TO FACE ANY MAJOR ECOLOGICAL CHALLENGES (SO THAT THEY CAN MIGRATE, STORE FOOD, WALK IN SNOW, ETC. 4) THE BIRTHING TIME MUST NOT INTERFERE WITH OTHER ESSENTIAL LIFE STRATEGIES OF THE PARENTS , SUCH AS MIGRATION, STORING FOOD, OR MATING TIMING IS NOT REALLY A PROBLEM FOR ANIMALS WITH SHORT DEVELOPMENTAL PERIODS IE. INSECTS OR SMALL MAMMALS MICE PREGNANT FEW WEEKS, YOUNG DEVELOP IN COUPLE OF WEEKS; OR BIRDS MATE SPRING, YOUNG INDEPENDENT 1 MONTH HOWEVER, AND OTHER LARGE MAMMALS – MANY HAVE LONG DEVELOPMENTAL PERIOD INCLUDING GESTATION = INTERNAL PREGNANCY PERIOD ( MOOSE = 8 MONTHS) GREAT JUGGLING ACT TO ENSURE YOUNGSTERS AND PARENTS NOT DISADVANTAGED MUST MATE AT OPTIMAL TIME FOR ADULTS & GIVE BIRTH AT OPTIMAL TIME FOR YOUNG MOOSE MATE IN FALL , CALVES BORN IN SPRING, READY BY WINTER - GOOD TIME FOR BOTH NOT ALL MAMMALS CAN DO THIS – THE BEST TIME FOR GIVING BIRTH MAY PUT MATING TIME AT A POOR TIME OF YEAR FOR ADULTS AND VICE VERSA NOVEL SOLUTION = DELAYED IMPLANTATION : DURING MATING, THE SPERM FERTILIZES THE EGGS BUT THE RESULTING EMBRYONIC BALL CALLED A BLASTOCYST DOES NOT ATTACH TO THE UTERUS WALL; IT FLOATS AROUND IN SUSPENDED ANIMATION. MONTHS LATER , WHEN IT IS A BETTER TIME FOR GESTATION, IT IMPLANTS ON UTERUS WALL AND GESTATION (PREGNANCY) CONTINUES. EXAMPLES: MANY CARNIVORES STRETCH OUT THE TIME BETWEEN MATING AND GIVING BIRTH : 1) BLACK BEARS - MATE IN JUNE / JULY PREGNANCY 2.5 MO SHOULD BIRTH IN SEPTEMBER BUT FALL STRESSFUL , THEN THEY PUT ON FAT FOR DORMANCY SO DELAYED IMPLANTATION; FOR FIVE MONTHS ALLOWS THEM TO GIVE BIRTH IN JAN OR FEB 2) FISHERS: MATE EARLY APRIL WITH A PREGNANCY OF ONE MONTH. THUS, SHOULD GIVE BIRTH IN EARLY MAY BUT A DELAYED IMPLANTATION OF 11 MONTHS ALLOWS THEM TO GIVE BIRTH ALMOST A YEAR LATER IN LATE MARCH. THIS MEANS THAT FEMALES MATE ONLY 10 DAYS AFTER GIVING BIRTH (THE LITTLE RASCALS!)
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ANIMALS MUST ALSO ENSURE THAT THEIR YOUNG GET OFF TO A GOOD START IN LIFE IN ANIMALS WITH E XTERNAL FERT– FROGS, FISH , THERE IS A SMALL INVESTMENT INTERNALLY , SMALL INVESTMENT EXTERNALLY RISK, HOWEVER, OF LITTLE SUCCESS – SO THEY PRODUCE LOTS OF EGGS FROGS = HUNDREDS
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This note was uploaded on 08/13/2008 for the course BIOL 1902 taught by Professor Runtz during the Winter '08 term at Carleton CA.

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Lecture 13 - Lecture 13: PARENTAL INVESTMENT IN ANIMALS...

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