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peaks in lynx populations show time lag behind peaks i

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peaks in lynx populations show time lag behind peaks in snowshoe hare populations ... Hippopotamus Killer Whale. Human Attitudes and Predators. Human perspectives ... – PowerPoint PPT presentation

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Title: peaks in lynx populations show time lag behind peaks i


1
Population growth
Reproduction, births, natality (B)
Emigration (E)
Immigration (I)
Population
Mortality, death (D)
2
Adult survival, juvenile survival, and fecundity
are what we need to estimate ?, the intrinsic
population growth rate.
Source/ growing populations
Stable population
Sink / declining
3
From Oleyar et al. (in prep)
4
No obvious response in growth rate by landscape.
5
Declining ? outside of reserves?
6
Possible sink during development for some species
followed by recovery as subdivision ages?
7
How do these projections match up with what we
see out there?
  • Winter Wren numbers high and stable in
    reserves, low and/or declining elsewhere
  • Robin numbers stable but low in reserves,
    highest in developed residential areas
  • Are developed landscapes ecological traps for
    Robins?

8
Populations fluctuate due to
  • Density dependent factors
  • Ex Predation, competition, habitat availability
  • change population growth in predictable ways
  • N is driven by population density
  • Density independent factors
  • Random or Stochastic events
  • Ex. Weather, accidents
  • Breeding

14 aug 2007
9
Definitions
  • Population regulation the tendency of
    population sizes to stay within a certain range

of Animals (N)
time
10
Carrying capacity
Carrying capacity (k) the number of organisms
that can be supported by a given area the actual
number of organisms fluctuates near this
of Animals (N)
k
time
11
Population fluctuations
  • Carrying capacity (k)

k
N
N
time
time
Classic growth curve, unlimited resources
Classic growth curve, limited resources (k)
12
Population fluctuations
  • Example of unlimited growth
  • Australian rabbit (European hare)
  • 1859 24 hares introduced (for human food?)
  • 1865 over 20,000 hares were harvested, actual
  • population much greater.
  • Mid-1800s to mid-1900s major problem with too
  • many hares caused habitat destruction and
  • reduction in native mammals
  • 2000 still present, local problems

13
Carrying capacity
Rabbits exceeded k
No rabbits
Rabbit-proof fence
14
Population regulation food
High food addition
Low food addition
Townsends vole
No food added
Shaded area is winter
15
Population regulation food
Population cycles Ex. peaks in lynx populations
show time lag behind peaks in snowshoe hare
populations
Snowshoe hare
Population size
Lynx
Time (years)
16
Population regulation climate
17
Population regulation competition
  • Competition demand by 2 or more individuals of
    the same or different species for a common
    resource
  • Between 2 individuals of same species
    Intraspecific
  • Between 2 individuals of different species
    Interspecific
  • Limited supply of resource Exploitation
  • Not limited but interaction detrimental
    Interference

18
Inter- or Intraspecific competition?Exploitation
or Interference competition?
19
Population regulation competition
20
Niche
Niche an n-dimensional hypervolume which
includes the range of biological and physical
conditions under which an organism can exist,
including the resources that an animal must
exploit for growth and reproduction
A portion of the feeding niche of the Blue-gray
Gnatcatcher (Smith Smith 1998)
Foraging height (m)
Prey length (mm)
21
Interspecific Competition
  • Food sources (both what and where)
  • Nest or Den sites
  • Interspecific competition can lead to resource
    partitioning, and expression of a realized
    niche versus a species ecological niche.

22
Predator-Prey Relationships
23
What are predators?
  • Animals that kill and eat other animals (prey)
  • At or near the top of the trophic pyramid

24
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25
Major predators of the Arctic NWR
Wolf
Polar Bear
Grizzly Bear
Arctic fox
Ermine
Snowy Owl
26
Predation in Natural Communities
  • Almost all animals have significant predators-
    exceptions are
  • Herbivores Top predators
  • Bison Grizzly bear
  • Elephant Lions
  • Rhinoceros Polar bear
  • Hippopotamus Killer Whale

27
Human Attitudes and Predators
  • Human perspectives
  • Little Red Riding Hood
  • The Three Little Pigs
  • Human persecution

28
Why?
  • Domestication of animals
  • Protection
  • Entertainment

29
Overcoming History
  • Old attitudes die hard
  • Urban residents and predators

30
Predator-Prey RelationshipsResponse to Prey
  • Functional Response
  • Tendency of the predator to eat more of a prey
    species as the prey become more abundant

31
Predator-Prey RelationshipsFunctional Response
32
Predator-Prey RelationshipsResponse to Prey
  • Numerical Response
  • Number of predators increases with an increase in
    the density of prey animals

33
Predator-Prey RelationshipsNumerical Response
(Buckner and Turnock 1965)
34
Annual cycle of a prey population
100
Energy shortages
Energy shortages
Accidents
Disease
Accidents
Percentage of Population
Predation
Disease
Predation
J F M A M J J A S
O N D
35
Population Cycles
36
Population Cycles
Adaptations to cyclical prey cycle? Dispersal Pre
y switch Reproduction
37
Isle Royale
38
Isle Royale
  • Size 45 miles long x 9 miles wide
  • Protection National Park established in 1940
  • Wilderness designation in 1976
  • National Biosphere Reserve 1980
  • A location of a long term study of the
    relationships between the moose and gray wolf

39
Historically, two large ungulates occupied Isle
Royale Woodland Caribou Moose
40
Isle Royale
  • Settlers arrived in late 19th century
  • Responsible for fire and forest cutting
  • Moose cross ice from Minnesota and establish
    early 20th century
  • Fires change old-growth coniferous forests to
    younger deciduous forests
  • Moose outcompete woodland caribou
  • Caribou became extinct on the island
  • Wolves arrive 1950 by crossing ice

41
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42
Wolf Response to Moose
  • Functional Response lots of moose
  • Possible because wolves are cooperative hunters
  • Numerical Response lots of moose
  • wolves reproduce well
  • Immigration is unlikely since it depends on Lake
    Superior freezing (uncommon)

43
Moose Response to the Wolf
  • Most vulnerable moose are the very young and the
    old (infirm)
  • Most killed moose show signs of malnutrition and
    disease (i.e. they are more vulnerable)
  • Males most vulnerable go into winter in
    relatively poor shape because of rut

44
Wolf Population
Three major factors that control the wolf
population 1. Moose numbers 2. Linear
dominance hierarchy in wolf population 3.
Genetic diversity (inbreeding effects)
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