reproductive patterns life history population dynamics
TRANSCRIPT
REPRODUCTIVE PATTERNS
LIFE HISTORY
POPULATION DYNAMICS
Peromyscus
REPRODUCTION
Seasonal patterns (latitude gradient)
ASEASONAL
SEMI-SEASONAL
STRONGLY SEASONAL
Cebus capucinnus
ARGENTINA
Seasonal reproduction in the tropics
Marmosa
REPRODUCTION
Differential response to seasonal environments
Costa Rica – savannah (wet & dry seasons)
(seasonal) (aseasonal)Zygodontomys
Artibeus jamaicensis
WEANING
Seasonal reproduction
Coastal California
RAINDROUGHT
Microtus californicus (grass)
Reithrodontomys megalotis (seeds)
Seasonal reproduction
Haplonycteris fischeri (Philippine pygmy fruit bat)
births are synchronouswithin local populations
Seasonal reproduction
post-implantationdelayed development
6-9 months
Delayed developmentand
Reproductive synchrony
ovulation
birth
implantation
normal development resumes
1 litter per year
Ptenochirus jagori (Philippine fruit bat)
Seasonal reproduction
Delayed developmentand
Reproductive synchrony2 litters per year
up to6 month
delay
Initial asynchrony
Synchrony established
Synchronized births in BOTH age groups
no delay
1 litter per year
Sperm storage and delayed fertilization
Antrozous pallidus (Pallid bat)
SPERM STORAGE IN UTERUS
FERTILIZATIONBIRTH
ACTIVE (SEXES SEGREGATED)
COPULATION
HIB.HIBERNATION
SPERM PRODUCTION
SPERM STORAGE (MALE)
Seasonal delayed implantation(Mustelidae)
Delayed implantation of blastocyst (1 month)
Fertilization
Gestationand birth
Implantation
Delayed implantation of blastocyst (8+ months)
Delay of more than 9 months
Litter size and latitudePeromyscus maniculatus
Reproductive patterns
How many young? How often?
ITEROPARITY -- repeated production of offspring at intervals throughout the life cycle
Mean litter size = 8
Mean litter size = 2
Reproductive patterns
Litter size and elevation
Peromyscus maniculatus
4.0
4.4
5.0
5.6Decreasing season lengthand increasing litter sizewith increasing elevation
The increase in litter size increase with both latitude and elevation reflects the same basic life history trend:
Immediate reproductive expenditure increases with declining probability of future reproduction (in harsh environments where adult survival is low)
SEMELPARITY -- a single act of reproduction duringan organism's lifetime. Also known as:
“BIG-BANG”
Reproductive patterns
What if the likelihood of future reproductiondrops to near zero?
Semelparity is common in plants and invertebrates, but rare in vertebrates
Brown antechinusAntechinus stuartii
Gray short-tailed opossumMonodephis domestica
Didelphidae
Dasyuridae
Northern QuollDasyurus hallucatus
Semelparity in male marsupials Seasonal, promiscuous breeding
Dasyuridae
Males compete for mating opportunities during a very brief mating season
Males fast during mating, and have high levels of androgen and glucocorticoids
Extreme physiological stress
Complete male die-off following mating period
Does NOT apply to females (may live multiple years)
“PARTIAL” SEMELPARITY
26 April 2002
2-year-old male at emergence in his first breeding season
26% loss of massNumerous wounds(died ca. 23 May 2002)
Arctic ground squirrel (Spermophilus paryii)
Seasonal heterotherm (winter torpor)
Intense male-male competition for mates
Promiscuous breeding immediately following emergence
Females breed as yearlingsMales delay reproduction until 2nd spring
Same male 3 weekslater
16 May 2002
Bowhead whale (Balaena mysticetus)
Maturity: 15-25 yearsGestation: 13-14 monthsBirth interval: 3-4 years
Maximum longevity
Longest-lived mammal?
Traditional stone & ivory Inuit harpoon points (from recently killed animals)
Maximum longevity: more than 200 years?
Ornithorhynchus anatinus Duck-billed platypus 17.0
Tachyglossus aculeatus Short-nosed echidna 50.0
Antechinus stuartii (male) Brown antechinus 1.0
Antechinus stuartii (female) Brown antechinus 3.0
Macropus giganteus Eastern gray kangaroo 24.0
Suncus etruscus Savi’s pygmy shrew 2.7
Erinaceus europaeus Eurasian hedgehog 7.0
Pteropus giganteus Flying fox 31.4
Myotis lucifugus Little brown bat 30.0
Callithrix jacchus Common marmoset 16.0
Macaca mulatta Rhesus macaque 36.0
Pan troglodytes Chimpanzee 59.4
Homo sapiens Human 122.5
Gorilla gorilla Gorilla 47.0
Castor fiber European beaver 25.0
Spermophilus sp. Ground squirrel 11.0
Glaucomys sabrinus Northern flying squirrel 13.0
Perognathus longimembris Silky pocket mouse 8.3
Reithrodontomys spp. American harvest mouse 1.5
Canis lupus Gray wolf 20.0
Panthera leo Lion 25.0
Crocuta crocuta Spotted hyena 40.0
Antilocapra americana Pronghorn 12.0
Hippopotamus amphibius Hippopotamus 49.0
Tursiops truncatus Bottle-nosed dolphin 30.0
Balaena mysticetus Bowhead whale 150+
Maximum longevity
Body size & Longevity
Placentals(excluding bats)
Non-passerine birds
Passerine birds& non-hibernating
bats
Body Size and Life History Traits -- (artiodactyls)
MAXIMUM LIFE SPAN
AG
E A
T M
AT
UR
ITY
LIFESPAN AND AGE AT MATURITY
Body Size and Life History Traits -- (artiodactyls)
Body Size & Length of Gestation(Placentals)
PRECOCIAL
ALTRICIAL
ENTIRE SAMPLE
Body Size
Underlying influence of metabolic rate
Body size & Longevity
Non-passerine birds
Placentals(excluding bats)
Passerine birds& non-hibernating
bats
Hibernating bat species
Insight from heterotherms
3-fold increase
Fasting boosts longevity in animals
Thursday, March 03, 2005 Health 24.com
Fast track to longevityMouse study shows molecular connections between
caloric restriction and lifespan extension
March 7, 2005 The Scientist
THE SEARCH FOR A UNIVERSAL LONGEVITY GENE
October 2004
The Longevity GeneA gene that releases stored fat may be the key to a longer life.
Ornithorhynchus anatinus Duck-billed platypus 17.0
Tachyglossus aculeatus Short-nosed echidna 50.0
Antechinus stuartii (male) Brown antechinus 1.0
Antechinus stuartii (female) Brown antechinus 3.0
Macropus giganteus Eastern gray kangaroo 24.0
Suncus etruscus Savi’s pygmy shrew 2.7
Erinaceus europaeus Eurasian hedgehog 7.0
Pteropus giganteus Flying fox 31.4
Myotis lucifugus Little brown bat 30.0
Callithrix jacchus Common marmoset 16.0
Macaca mulatta Rhesus macaque 36.0
Pan troglodytes Chimpanzee 59.4
Homo sapiens Human 122.5
Gorilla gorilla Gorilla 47.0
Castor fiber European beaver 25.0
Spermophilus sp. Ground squirrel 11.0
Glaucomys sabrinus Northern flying squirrel 13.0
Perognathus longimembris Silky pocket mouse 8.3
Reithrodontomys spp. American harvest mouse 1.5
Canis lupus Gray wolf 20.0
Panthera leo Lion 25.0
Crocuta crocuta Spotted hyena 40.0
Antilocapra americana Pronghorn 12.0
Hippopotamus amphibius Hippopotamus 49.0
Tursiops truncatus Bottle-nosed dolphin 30.0
Balaena mysticetus Bowhead whale 150+
Maximum longevity
Logistic population growth
Population dynamics
K = carrying capacity
Exponential growth
Population dynamics – logistic growth
Growth determined by r
Growth limited by K
K-selectionSelection for traits favored in stable
environments withpopulations at or near carrying
capacity
large size
few offspring
late maturity, prolonged period of parental care
long life expectancy
individuals may reproduce many times
most individuals live to near the maximum life span
r - selectionSelection for traits favored in unstable
environments that promote rapid population growth when densities are
below carrying capacity
small size
many offspring
early maturity, shortperiod of parental care
short life expectancy
individuals have few opportunities to reproduce
most individuals die within a short time but a few live much longer
r & K selection theory
Sheep(Tasmania)
“K-selected”
Peromyscus
“r-selected”
Population dynamics
Population fluctuations
Ord’s kangaroo rat(Dipodomys ordii)
New Mexico
Multimammate mouse(Mastomys natalensis)
South Africa
Population cycles
Brown lemming(Lemmus sibiricus)
Alaska
Multi-annual “cycles”
Population cycles
Lepus americanus
Lynx canadensis
Predator – prey cycles
Canada (Hudson Bay Co.)