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What is Ecology?

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What is Ecology? Scientific study of the interactions of organisms with their abiotic and biotic environments.....in order to understand the distribution – PowerPoint PPT presentation

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Title: What is Ecology?


1
What is Ecology?
Scientific study of the interactions of organisms
with their abiotic and biotic environments...
...in order to understand the distribution and
abundance of organisms in space and time.
2
Fields of Ecology
Organismal Ecology (morphology, physiology,
behavior)
Population Ecology (life history strategies,
demography, population growth)
Community Ecology (species interactions,
biodiversity)
Ecosystem Ecology (energy nutrient flow,
landscape ecology)
3
Population Ecology
  • A population is a group of individuals of the
    same species that live in a particular area and
    have the potential to interbreed.

Flock of Starlings at Dusk U.K.
4
Population ecologists are primarily interested in
  1. understanding how biotic and abiotic factors
    influence the density, distribution, size, and
    age structure of populations.
  2. the overall vitality of a population of
    organisms.
  3. how humans affect the size of wild populations of
    organisms.
  4. studying interactions among populations of
    organisms that inhabit the same area.
  5. how populations evolve as natural selection acts
    on heritable variations among individuals and
    changes in gene frequency.

5
Life History Characteristics
  • Growth
  • Change of form
  • Dispersal
  • Timing of reproduction
  • Size at birth or germination
  • Number and size of offspring
  • Age at death

6
Life History - Growth
  • Growth for at least part of their life history,
    all organisms grow by assimilating energy and
    nutrients final body size species-specific.

7
Life History Change of Form
  • Change of form - many organisms have dramatically
    different forms or stages in their life cycle.

8
Life History - Dispersal
  • At some time in their lives, most organisms go
    through dispersal enhances reproductive
    success.

Beldings Ground Squirrel
Spiders
Milkweed
9
Life History Characteristics
  • Growth
  • Change of form
  • Dispersal
  • Timing of reproduction
  • Size at birth or germination
  • Number and size of offspring
  • Age at death

10
LIFE HISTORY STRATEGIES (LHSs) Patterns of
lifespan and reproduction that characterize a
species.
LHSs are a result of natural selection, which
acts on individuals, NOT species
11
Individuals that have a life history
that maximizes fitness will be favored by natural
selection
thus, particular patterns of survival and
reproduction will eventually be shared by all
members of a population.
12
Three Main Life History Strategies
  1. Survivorship
  2. Maturity
  3. Reproductive Output

13
3) Reproductive Output
  • Parity
  • reproductive episodes in lifetime

14
Salmon
Mayfly
Agave
Semelparous species
15
Iteroparous Species
16
Your textbook says, The fundamental idea that
evolution accounts for the diversity of life is
manifest in a broad range of life histories found
in nature. Based on what you know about
evolution by natural selection, you can predict
that species that have evolved semelparity have
done so because
  • A) semelparous parents produce more offspring if
    they invest all of their resources in
    reproduction than they would if they saved enough
    resources to survive until they can reproduce
    again.
  • B) semelparous parents produce offspring that are
    more likely to survive than offspring produced by
    iteroparous parents.
  • C) iteroparous parents are less likely to provide
    parental care than semelparous parents.
  • D) semelparous parents and iteroparous parents
    are equally likely to produce offspring
    semelparity evolved for other reasons.
  • E) iteroparous parents are more likely to die
    before they can reproduce than are semelparous
    parents.

17
Two factors influence evolution of semelparity vs
iteroparity
  • Survival probability of offspring
  • Probability that adults will survive to reproduce
    again

Both probabilities are low in harsh or
unpredictable environments, so semelparity will
be favored.
18
3) Reproductive Output
  • Parity
  • Fecundity
  • offspring per reproductive episode

19
elephants
rodents
spiders
20
3) Reproductive Output
  • Parity
  • Fecundity
  • Parental Investment
  • Energetic effort put into offspring
  • Size of offspring

21
  • Some plants produce a large number of small
    seeds, ensuring that at least some of them will
    grow and eventually reproduce.
  • Other types of plants produce fewer large seeds
    that provide a large store of energy that will
    help seedlings become established.

22
General Relationship between Offspring Size and
Number of Offspring
Many
Number of Offspring
Few
Small Large
Offspring Size
23
3) Reproductive Output
  • Parity
  • Fecundity
  • Parental Investment
  • Energetic effort put into offspring
  • Size of offspring
  • Parental care

24
LHS of a hypothetical super-organism?
25
Real LHSs are compromises in the allocation of
energy!
Reproductive Trade-offs
a) Reproduction vs Future Survival
26
Reproduction vs Survival (Mortality)
27
How does caring for offspring affect parental
survival in kestrels?
100
Male
Female
80
60
Parents surviving the following winter ()
40
20
0
Reduced brood size
Normal brood size
Enlarged brood size
Fig. 53-13
28
In some bird species, the male provides no care.
If this were true for the European Kestrel, how
would the experimental results differ?
  • Females in all three groups likely would have the
    same survival values as in the graph.
  • B) Males in all three groups likely would have
    higher survival than females.
  • C) Patterns for both males and females likely
    would remain the same.
  • D) Only females with reduced brood sizes likely
    would show a reduced survival.

29
  • Reproductive Trade-offs
  • Reproduction vs Future Survival
  • Reproduction vs Future Growth
  • Current vs Future Reproduction

30
Annual Meadowgrass
Current vs Future Reproduction
Reproduction vs Future Growth
31
Particular combinations of LHSs often favored in
particular body sizes
but there are always exceptions to the rule!
32
Big Brown Bat (Eptesicus fuscus)
Baby bat
Longer lifespan (14 yrs) and lower fecundity
(1-2) than expected for a mammal of that size
(small)
33
A few, large offspring.
Parental care in carrion beetles very unusual
for an insect.
34
Octomom
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