Download population time

Big Idea
• As the biotic potential of a population
increases, the population will incur more
environmental resistance as the carrying
capacity is reached
interbreeding assemblages of
a single species in an area
can be expressed by 2
different curves
J curve
S curve
Population growth at
slow rate which
increases quickly,
because total # of
potentially
reproducing
organisms increases
[exponential].
TIME
Population
size does have
a limit (food,
space, etc).
After species
have a large
growth in
population, it
will level off
TIME
the maximum rate at which
any individual can reproduce
factors in the environment
that impede population growth
maximum population that an
ecosystem can support
Populations approaching
their biotic potential begin
to encounter
environmental resistance,
whereupon growth slows
as the carrying capacity is
reached.
Rapidly growing
populations can
overshoot, or quickly rise
above the environment’s
carry capacity.
This can bring harsh
pressures on their own
numbers and a population
crash, rapid decline or
can result.
Rate of natural increase can be
positive, negative, or zero.
Density Dependent Controls
•
•
•
•
Competition for resources
Predation
Parasitism
disease
Density Independent Controls
• Effect a population regardless of
size:
- floods
- hurricanes
- severe drought
- fire
- habitat destruction
- pesticide spraying
R-Strategist Species
• Have a capacity for a high rate of
population growth
• Tend to be opportunists; reproducing and
dispersing rapidly when conditions are
favorable
• Offspring mature quickly
K-Strategist Species
• Reproduce late and have few offspring with
long generation times
• Offspring mature slowly
• Tend to live longer
human
hydra
dandilion
the populations living and
interacting together in an area
Sexual Dimorphism
•differences between males and females of
the same species
•clearest dimorphism
is between
gamete size
(leads to
behavioral
differences)
Females gametes: large, nutrient-filled,
expensive to produce, limited in
number and produced infrequently.
Male gametes: small, no nutrients,
cheap to produce, constantly made
Sexual Selection
•trait that gives an advantage in acquiring
mates and producing offspring
•occurs in two forms:
1. out-compete members of the same sex
for access to mates i.e. Madagascar Tortoise
2. evolve preferences for desirable qualities
in potential mates i.e. Blue Footed Booby
Female Reproductive Strategy
•seek quality not quantity
•look for certain criteria
Physical Features: size and strength
which confer dominance and thus
preferential access to resources.
Behavioral Features:
most desirable (alpha) males.
Male Reproductive Strategy
•less choosy
•seek quantity
•will take any sexual
opportunity
•compete with other
males for access to females
•small number of males will achieve the
most matings, while many males will
never mate.
Parental Investment(PI)
Any investment in an offspring that
increases the offspring’s chances of
surviving (and hence reproducing)
In most species, females invest
heavily in their offspring while
males do not.
WOMEN POWER!
•female is always 100% certain that an
offspring is hers …. male cannot be
sure
•to avoid ‘cuckoldry’ male must
continually provide resources, PI, and
protection so the female won’t be
tempted to cheat
Blue Footed Booby
•mating dance
Penguins
•life partner
Green Winged Teal
•gang rape
females many
times killing her in
the process
Sea Lions
•harem
•non alpha males= rape
Lions
•harem
•take over other
harems
Chimpanzees
•Promiscuous
female
•children stay with
mom until teens
Peacocks
•sexual
dimorphism
African
Elephants
•taste female’s
urine to test for
estrous
•larger more alpha
male preferred
•after copulation,
male and female
may remain
connected for up
to a half hour