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Life History Analyses

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Agave vegetative growth up to 25 yrs. Also clones. ... Agave a semelparous plant that also produces clones. Life History Continua ... – PowerPoint PPT presentation

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Title: Life History Analyses


1
Life History Analyses
2
7 Life History Analyses
  • Case Study Nemo Grows Up
  • Life History Diversity
  • Life History Continua
  • Trade-Offs
  • Life Cycle Evolution
  • Case Study Revisited

3
Case Study Nemo Grows Up
  • Nemo the clownfish is depicted as having a very
    human-like family in the movie Finding Nemo.

Figure 7.2 Life in a Sea Anemone
4
Life History Diversity
Concept 7.1 Life history patterns vary within
and among species.
  • Individuals within a species show variation in
    life history traits.
  • The differences may be due to genetic variation
    or environmental conditions.
  • Generalizations about life history traits of a
    species can still be made.

5
Figure 7.3 Life History Strategy
6
Figure 7.4 Plasticity of Growth Form in
Ponderosa Pines
7
Life History Diversity
  • Phenotypic plasticity may produce a continuous
    range of growth rates or discrete typesmorphs.

8
Figure 7.5 Polyphenism in Spadefoot Toad Tadpoles
9
Figure 7.6 Life Cycle of a Coral
10
Figure 7.7 The Cost of Sex (Part 1)
11
Figure 7.7 The Cost of Sex (Part 2)
12
Figure 7.8 Isogamy and Anisogamy
13
Figure 7.9 The Pervasiveness of Complex Life
Cycles
14
Figure 1.3 The Life Cycle of Ribeiroia A
complex life cycle
15
Figure 7.10 Alternation of Generations in a Fern
(Part 1)
16
Figure 7.10 Alternation of Generations in a Fern
(Part 2)
17
Life History Continua
Concept 7.2 Reproductive patterns can be
categorized along several continua.
  • Several classification schemes.
  • The schemes place patterns on continua

18
Life History Continua
  • How many reproductive bouts occur during the
    organisms lifetime?
  • Semelparous species reproduce only once.
  • Iteroparous species can reproduce multiple times.

19
Life History Continua
  • Semelparous species include
  • Annual plants.
  • Agavevegetative growth up to 25 yrs. Also
    clones.
  • Giant Pacific octopussingle clutch of eggs and
    broods them for 6 months, dying after they hatch.

20
Agave a semelparous plant that also produces
clones
21
Life History Continua
  • Iteroparous species include
  • Trees such as pines and spruces
  • Most large mammals, like humans

22
Life History Continua
  • r-selection and K-selection describe two ends of
    a continuum of reproductive patterns.
  • r is the intrinsic rate of increase of a
    population.
  • r-selection - high population growth rates
    uncrowded environments, newly disturbed habitats,
    etc.

23
Life History Continua
  • K is the carrying capacity for a population.
  • K-selection - slower growth rates in populations
    that are at or near K crowded conditions,
    efficient reproduction is favored.

24
Life History Continua
  • A classification scheme for plant life histories
    is based on stress and disturbance (Grime 1977).
  • Stressany factor that reduces vegetative growth.
  • Disturbanceany process that destroys plant
    biomass.
  • Competition superior ability to survive

25
Figure 7.12 Grimes Triangular Model
26
Trade-Offs
Concept 7.3 There are trade-offs between life
history traits.
  • Trade-offs Organisms allocate limited energy or
    resources to one structure or function at the
    expense of another.
  • Trade-offs shape and constrain life history
    evolution.

27
Figure 7.14 Clutch Size and Survival
28
Figure 7.15 Seed SizeSeed Number Trade-Offs in
Plants
29
Trade-Offs
  • Trade-offs between current and future
    reproduction
  • Iteroparous - the earlier it reproduces, the more
    times it can reproduce over its lifetime.
  • But not all reproductive events are equally
    successful.
  • Often the number of offspring produced increases
    with size and age of the organism.
  • Example is Atlantic Cod

30
Trade-Offs
31
Life Cycle Evolution
Concept 7.4 Organisms face different selection
pressures at different life cycle stages.
  • Different morphologies and behaviors are adaptive
    at different life cycle stages.
  • Differences in selection pressures over the
    course of the life cycle are responsible for some
    of the distinctive patterns of life histories.

32
Figure 7.18 Parental Investment in the Kiwi
33
Life Cycle Evolution
  • Dispersal and diapause
  • Small offspring are well-suited for dispersal.
  • Dispersal can reduce competition among close
    relatives, and allow colonization of new areas.
  • Dispersal can allow escape from areas with
    diseases or high predation.

34
Life Cycle Evolution
  • Diapause State of suspended animation or
    dormancyorganisms can survive unfavorable
    conditions.
  • Many seeds can survive long dormancy periods.
  • Many animals can also enter diapause.

35
Case Study Revisited Nemo Grows Up
  • Change in sex during the course of the life cycle
    is called sequential hemaphroditism.
  • These sex changes should be timed to take
    advantage of the high reproductive potential of
    different sexes at different sizes.

36
Figure 7.22 Sequential Hermaphroditism
37
Figure 7.23 Clownfish Size Hierarchies
38
Connections in Nature Territoriality,
Competition, and Life History
  • Why do the clownfish maintain the hierarchy?
  • They are completely dependent on protection by
    the sea anemone. They are easy prey outside the
    anemone.
  • Conflicts result in expulsion and death, probably
    without having reproduced.

39
Connections in Nature Territoriality,
Competition, and Life History
  • Sea anemones are a scarce resource for clownfish.
  • This controls ontogenetic niche shifts. Juveniles
    returning to the reef must find an anemone that
    has space, where it will be allowed to stay and
    enter the hierarchy.

40
Connections in Nature Territoriality,
Competition, and Life History
  • Complex life histories appear to be one way to
    maximize reproductive success in such highly
    competitive environments.
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