Transcript Chapter 53 and 54 - Madison County Schools

Chapter 53 and 54
Concept check
1. Consider two rivers:
• The constant, spring-fed stream. In more
constant physical conditions, where
populations are more stable and competition
for resources is more likely, larger well
provisioned young, which are more typical of
iteroparous species, have a better chance of
surviving.
2. One species of forest bird
• The territorial species likely has a uniform
pattern of dispersion, since the interactions
between individuals will maintain constant
space between them. The flocking species is
probably clumped, since most individuals
probably live in one of the clumps (flocks).
3. Each female
• Type III
4. Describe how population
• The mark and recapture method involves
marking a number of individuals in a natural
population, returning them to that
population, and subsequently recapturing
some of them as a basis for estimating the size
of the population at the time of marking and
release. This procedure was first used by
C.J.G. Petersen.
5. In the fish
• By preferentially investing in the eggs it lays in
the nest, the peacock wrasse increases their
probability of survival. The eggs it disperses
widely and does not provide care for are less
likely to survive, at least some of the time, but
require a lower investment by the adults. (In
this sense, the adults avoid the risk of placing
all their eggs in one basket.)
Exponential growth
• Simplest model for population growth is one with
unrestrained growth.
• No predation, parasitism, or competition.
• No immigration or emigration
• Environment with unlimited resources.
• This is characteristic of a population that has been
recently introduced into an area, such as bacteria
newly inoculated onto a petri dish.
• Usually short-lived
• Even though the human population has been in this for
over 300 years.
Carrying capacity
• Food and space
Limiting factors
• Density-dependent factors are those factors that
increase directly as the population density
increases. They include competition for food, the
buildup of wastes, predation, and disease.
• Density-independent factors are those factors
whose occurrence is unrelated to the population
density. These include earthquakes, storms, and
naturally occurring fires and floods.
Growth patterns
R-strategists
• Many young
• Little or no parenting
• Rapid maturation
• Small young
• Reproduce once
• Example: insect
K-strategies
• Few young
• Intensive parenting
• Slow maturation
• Large young
• Reproduce many times
• Example: mammals
Interactions
• Competition—G.F Gause developed the competitive
exclusion principle after studying paramecium.
• His principle states that two species cannot coexist in a
community if they share a niche, that is, if they use the
same resources.
• In nature, there are two related outcomes, besides
extinction, if two species inhabit the same niche and
therefore compete for resources. One species will evolve
through natural selection to exploit different resources.
This is called resource partitioning. Another possible
outcome is what occurred on the Galapagos islands.
Finches evolved different beak sizes to eat different of food
and avoid competition. This is called character
displacement
Interactions
• Predation
– Plants evolved spines and thorns and chemicals
– Animals evolved active defenses such as hiding,
fleeing, or defending.
– Animals also evolved passive defenses—coloration or
camouflage.
• Aposematic—very bright, often red or orange (poison)
• Batesian mimicry—copycat coloration…mimic poisonous
animals
• Mullerian mimicry—two or more poisonous species
resemble each other and gain an advantage from their
combined numbers.