1. REPRODUCTIVE
PATTERNS
LIFE HISTORY
POPULATION
DYNAMICS

2. REPRODUCTION Seasonal patterns (latitude gradient) Peromyscus
STRONGLY SEASONAL
SEMI-SEASONAL
ASEASONAL

3. Seasonal reproduction in the tropics
Cebus capucinnus
ARGENTINA

4. REPRODUCTION Differential response to seasonal environments
Costa Rica – savannah (wet & dry seasons)
Marmosa
(aseasonal)
(seasonal)
Zygodontomys

5. Seasonal reproduction
Artibeus jamaicensis
WEANING

6. Seasonal reproduction
Reithrodontomys
megalotis (seeds)
Coastal California
RAIN
DROUGHT
Microtus
californicus
(grass)

7. Reproductive synchrony
Seasonal reproduction
Delayed development
and
Reproductive synchrony
Haplonycteris fischeri
(Philippine pygmy fruit bat)
1 litter per year
births are synchronous
within local populations
ovulation
birth
normal
development
resumes
post-implantation
delayed development
6-9 months
implantation

8. Reproductive synchrony
Synchronized
births in BOTH
age groups
Seasonal reproduction
Delayed development
and
Reproductive synchrony
2 litters
per year
no delay
Ptenochirus jagori
(Philippine fruit bat)
up to
6 month
delay
Synchrony
established
1 litter per year
Initial asynchrony

9. delayed fertilization
Sperm storage and
delayed fertilization
Antrozous pallidus (Pallid bat)
SPERM STORAGE (MALE)
SPERM PRODUCTION
BIRTH
FERTILIZATION
ACTIVE (SEXES SEGREGATED)
SPERM STORAGE IN UTERUS
COPULATION
HIB.
HIBERNATION

10. Seasonal delayed implantation (Mustelidae)
Fertilization
Delayed implantation
of blastocyst (1 month)
Implantation
Gestation
and birth
Delayed implantation
of blastocyst (8+ months)
Delay of more than 9 months

11. Reproductive patterns
How many young? How often?
ITEROPARITY -- repeated production of offspring
at intervals throughout the life cycle
Litter size and latitude
Peromyscus maniculatus
Mean
litter size = 8
Mean
litter size = 2

12. Reproductive patterns Litter size and elevation
Peromyscus maniculatus
Decreasing season length
and increasing litter size
with increasing elevation
4.0
4.4
5.0
5.6
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)

13. Reproductive patterns
What if the likelihood of future reproduction
drops to near zero?
SEMELPARITY -- a single act of reproduction during an organism's lifetime. Also known as:
“BIG-BANG”
Semelparity is common in plants and invertebrates,
but rare in vertebrates

14. Semelparity in male marsupials
Seasonal, promiscuous breeding
Males compete for mating opportunities
during a very brief mating season
Males fast during mating, and have high
levels of androgen and glucocorticoids
Brown antechinus
Antechinus stuartii
Extreme physiological stress
Complete male die-off following mating period
Dasyuridae
Does NOT apply to females (may live multiple years)
Dasyuridae
Northern Quoll
Dasyurus hallucatus
Gray short-tailed opossum
Monodephis domestica
Didelphidae

15. “PARTIAL” SEMELPARITY
Seasonal heterotherm (winter torpor)
Promiscuous breeding immediately
following emergence
Intense male-male competition for mates
Females breed as yearlings
Males delay reproduction until 2nd spring
26 April 2002
2-year-old male at emergence
in his first breeding season
Arctic ground squirrel
(Spermophilus paryii)
Same male 3 weeks
later
16 May 2002
26% loss of mass
Numerous wounds
(died ca. 23 May 2002)

16. Maximum longevity Bowhead whale (Balaena mysticetus) Longest-lived
mammal?
Maturity: years
Gestation: months
Birth interval: 3-4 years
Traditional stone & ivory Inuit harpoon
points (from recently killed animals)
Maximum longevity: more than 200 years?

17. Maximum longevity Ornithorhynchus anatinus Duck-billed platypus 17.0
Tachyglossus aculeatus
Short-nosed echidna
50.0
Antechinus stuartii (male)
Brown antechinus
1.0
Antechinus stuartii (female)
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
Crocuta crocuta
Spotted hyena
40.0
Antilocapra americana
Pronghorn
12.0
Hippopotamus amphibius
Hippopotamus
49.0
Tursiops truncatus
Bottle-nosed dolphin
Balaena mysticetus
Bowhead whale
150+

18. Body size & Longevity Passerine birds & non-hibernating Non-passerine
bats
Placentals
(excluding bats)

19. Body Size and
Life History Traits -- (artiodactyls)

20. LIFESPAN AND AGE AT MATURITY
MAXIMUM LIFE SPAN
AGE AT MATURITY

21. Body Size and
Life History Traits -- (artiodactyls)

22. Body Size & Length of Gestation
(Placentals)
ENTIRE SAMPLE
PRECOCIAL
ALTRICIAL

23. Body Size
Underlying influence of metabolic rate

24. Insight from heterotherms
Body size & Longevity
Insight from heterotherms
Non-passerine
birds
Hibernating
bat species
Placentals
(excluding bats)
Passerine birds
& non-hibernating
bats
3-fold
increase

25. Fasting boosts longevity in animals
Thursday, March 03, Health 24.com
Fast track to longevity
Mouse study shows molecular connections between
caloric restriction and lifespan extension
March 7, The Scientist
October 2004
The Longevity Gene
A gene that releases stored fat
may be the key to a longer life.
THE SEARCH FOR A
UNIVERSAL LONGEVITY GENE

26. Maximum longevity Ornithorhynchus anatinus Duck-billed platypus 17.0
Tachyglossus aculeatus
Short-nosed echidna
50.0
Antechinus stuartii (male)
Brown antechinus
1.0
Antechinus stuartii (female)
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
Crocuta crocuta
Spotted hyena
40.0
Antilocapra americana
Pronghorn
12.0
Hippopotamus amphibius
Hippopotamus
49.0
Tursiops truncatus
Bottle-nosed dolphin
Balaena mysticetus
Bowhead whale
150+

27. Population dynamics Exponential growth Logistic population growth
K = carrying capacity

28. Population dynamics – logistic growth
Growth limited by K
Growth determined by r

29. r & K selection theory r - selection
Selection for traits favored in unstable environments that promote rapid population growth when densities are below carrying capacity
small size
many offspring
early maturity, short
period 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
K-selection
Selection for traits favored in stable environments with
populations 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

30. Population dynamics Sheep (Tasmania) “K-selected” Peromyscus
“r-selected”

31. (Mastomys natalensis)
Population fluctuations
Ord’s kangaroo rat
(Dipodomys ordii)
New Mexico
Multimammate mouse
(Mastomys natalensis)
South Africa

32. Population cycles Multi-annual “cycles” Brown lemming
(Lemmus sibiricus)
Alaska

33. Population cycles Predator – prey cycles Canada (Hudson Bay Co.)
Lepus americanus
Lynx canadensis
Predator – prey cycles