Life History
Patterns
Patterns of
Reproduction
Asexual
Processes
Sexual Proceses:
cost of contributing only half of an individual’s genome
Sexual
selection a powerful force in evolution
Plants: separate
male-female is Dioecious
Male-female
on same plant is Monoecious or hermaphroditic
Can
be in same flower or separate male-female flowers
Monogamy:
persistent pair bond formed, some for life parental care
Possibly
driven by need for parental care (precocial vs altricial)
Mamals,
parental care can be exclusively female
Most
common in birds,
Birds:
hawks, swans/geese, crows, chickadees
rare
in mammals- fox, beaver terrestrial carnivores
Cuckholdry:
Expending energy
to foster one’s own offspring: defense of mates (males):
has
no interest if genes not represented)
Balanced
with need to optimize fitness of offspring
Polygamy:
Polygyny
common (single male),
Boblinks,
pheasants, ostrich
Baboons,
seals/sealions, deer, sheep
Polandry
rare (single female): some birds
Promiscuity: no
pair bonding, individuals only meet for exchanging gametes
Chimpanzees,
small mamals, whales: sperm competition
Birds
that establish leks: grouse, bower birds
Eusocial
Structures: Haplodiploidy in Apis mellifera
Allocation of
Reproductive Energy Cost
Semelparity and
Iteroparity
Semelparous:
breed once and die: stress environments
Also
predator defense, Cicadas (fig. 19.1)
Iteroparous:
multiple breeding events in lifetime
Must
balance reproductive effort with survival for future reproduction
Reproduction
increases mortatlity
Size
reduction/growth loss: 25x in some
trout
Birds 4x basal
metabolic rate feeding young, mammals 2.5-5 x for lactation
Clutch Size:
With
increasing offspring, investment per decreases
Survial
decreases for both parents and offspring
Average
largest number parents can feed
Precocial clutch
size: adjusting egg laying to host plant size in insects
Also
plant type: adjusts size of eggs also
Minimum clutch
size = 2. protects against
infertility, “extra” offspring oftern killed
Effect of
latitude: Fig. 13.15.birds, mammals lizards:
larger
broods at higher latitudes: winter motality, food availability
other
factors unknown.
r and K
Stategists
|
|
r |
K |
Age of Maturity
|
Early
|
Late
|
|
# Offspring |
Many |
Few |
|
Size of
Offspring |
Small |
Large |
|
Lifespan |
short |
Long |
|
Parental care |
Less |
More |
|
Competive
Ability |
Less,
Exploitive |
More, Interference |
|
Plant Reproduction |
Annual |
Perennial |
Stress
Toleration important in plant ecology Fig. 13.20