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BIOL > Ecology > Flashcards

Ecology Flashcards

1
Q

Ecology

A

-Ecology is the study of interactions organisms have with each other and with their environment
-Levels of Ecological Study:
Organism
Population
Community
Economy
Evolutionary

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2
Q

Organismal Ecology

A

-Physiological Ecology: normal (bodily) functions

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3
Q

Population Ecology

A
  • Population: a group of individuals of the same species living in the same area
  • Population ecology focuses primarily on factors that influence population density, growth, and dispersion
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4
Q

Community Ecology

A
  • Community: an assemblage of interacting species in the same geographic area
  • Community ecology is generally concerned with the interactions among population that affect the distribution and abundance of species within the community
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5
Q

Ecosystem Ecology

A
  • Ecosystem: a system that includes a biotic community and its abiotic environment
  • Ecosystem ecologists tend to focus on the flow of energy and matter through organisms and their environment
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6
Q

Evolutionary Ecology

A
  • Evolution: genetic changes in a population over time
  • Evolutionary ecology combines population ecology and population genetics to look at the affect of ecological interactions on the evolution of a population
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7
Q

Conservation Biology

A

Attempting to maintain biological diversity

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8
Q

Restoration Ecology

A

Restoration and management of disturbed ecosystem

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9
Q

Landscape Ecology

A

The study of spatial patterns in the landscape and how they may be impacted by human activities

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10
Q

Biosphere

A
  • The biosphere includes all living things on earth
  • The major types of ecosystems found on earth can be divided into biomes based on the types of vegetation that live there
  • The vegetation found in a particular ecosystem is largely determined by climate
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11
Q

Factors that Influence Climate

A
  • Unequal heating of Earth’s surface
  • Seasonality
  • Proximity to the ocean, and west/east coast differences
  • Orographic Effect: the effect of mountain ranges
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12
Q

Tropical Rainforests

A
  • Most occur within 20 degrees latitude of equator
  • Little temperature variation between months
  • Annual rainfall of 2000-4000 mm relatively evenly distributed
    • Quickly leaches soil nutrients
    • Mycorrhizae help gather nutrients
  • Trees and vertical dimension
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13
Q

Tropical Dry Forest

A
  • Usually located between 10-25 degrees latitude
  • Climate more seasonal than tropical rainforest
  • Soils generally richer in nutrients, but vulnerable to erosion
  • Shares many animal and plant species with tropical rainforests
  • Heavily settled by humans with extensive clearing for agriculture
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14
Q

Tropical Savanna

A
  • Most occur north and south of tropical dry forests within 10-20 degrees of the equator
  • Climate alternates between wet/dry seasons
    • Drought associated with dry season leads to lightning-caused wildfires
  • Soils have low water permeability
    - Saturated soils keeps trees out
  • Landscape is more two-dimensional with increasing pressure to produce livestock
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15
Q

Desert

A
  • Major bands at 30 degrees N and 30 degrees S latitude
    • Occupy about 20% of earth’s land surface
  • Water loss usually exceeds precipitation
  • Soil usually extremely low in organic matter
  • Plant cover ranges from spares to absent
  • Animal abundance low, but biodiversity may be high
    • Strong behavioral adaptation
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16
Q

Chaparral

A
  • Found in Mediterranean climates
  • Occur in all continents except Antarctica
  • Climate cool and moist in fall, winter, and spring, but can be hot and dry in summer
  • Fragile soils with moderate fertility
  • Trees and shrubs typically evergreen
  • Fire-resistant plants due to fire regime-plants grow back quickly after they burn
  • **The biome we live in
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17
Q

Temperate Grassland

A
  • Extremely widespread distribution
  • Annual rainfall 300-1000 mm
  • Experience periodic droughts
  • Soils tend extremely nutrient rich and deep
  • Thoroughly dominated by herbaceous vegetation
  • Large roaming ungulates
    • Bison vs. Cattle
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18
Q

Temperate Forest

A
  • Old Growth: native forests (we didn’t plant the trees)
  • Majority lie between 40 and 50 degree latitude
  • Rainfall averages 650-3000 mm
  • Fertiles soils
    • Long growing seasons dominated by deciduous plants (drops leaves)
    • Short growing seasons dominated by conifers (cone, needle like)
  • Biomass production can be very high
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19
Q

Boreal Forest (Taiga)

A
  • Confined to Northern Hemisphere
    • Covers 11% of Earth’s land area
  • Thin, acidic soils low in fertility
  • Generally dominated by evergreen conifers
  • Relatively high animal density
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20
Q

Tundra

A
  • Covers most lands north of Arctic Circle
    • Climate typically cool and dry with short summers
  • Low decomposition rates
  • Supports substantial numbers of native mammals
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21
Q

Population Ecology

A

-Population: An interacting group of individuals of the same species that use common resources and lie in the same area
-Population ecologist focus on the factors that affect the distribution and abundance of individuals in a population
-The distribution and abundance of individuals is characterized by many factors:
Density, Dispersion, Size, Growth rates, Age structure, Life History

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22
Q

Population Density

A
  • Population density is the number of a species per unit area or volume
  • Density is often related to the dispersion of individuals in a population
  • Population density can fluctuate based on habitat stability
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23
Q

Population Dispersion

A
  • Dispersion patterns refers to the way individuals are spaced in their geographic area
  • Patterns can be described in three ways:
    • Clumped distribution, Uniform distribution, Random Distribution
  • Populations can be clumped, uniform or random at small scales, but at larger cales, dispersion patterns are almost always clumped
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24
Q

Clumped Distribution

A

Individuals are attracted to each other or a resource

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25
Q

Uniform Distribution

A

Individuals are about the same distance apart from each other

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26
Q

Random Distribution

A

The distance from one individual to the next is fairly unpredictable

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27
Q

Distribution vs. Dispersion

A
  • Distribution: groups of things

- Dispersion: individuals

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28
Q

Population Size

A
  • Population size refers to the total number of individuals in a population, regardless of density or dispersion
  • How can you determine population size?
    - Direct count (census): only possible for small populations
    • Statistical estimation: ex. Mark-recapture
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29
Q

Assumption in Mark-Recapture

A
  • Markig has no effect on mortality/survivability of the individuals
  • Marking has no effect on likelihood to being captured
  • There is no immigration or emigration between sampling times
  • Equal capture probability
  • *Any method for population size has assumptions
  • **The reliability is only as good as the assumptions made
30
Q

Changes in Populations Size

A
  • Immigration adds individuals
  • Emigration subtracts individuals
  • Briths adds individuals
  • Deaths subtract individuals
31
Q

Population Growth

A
  • Modeling is a method of summarize information and processes in an informative manner (ex. caricature)
  • Two common and useful models in population ecology:
    • Exponential growth (J-curve)
    • Logistic growth (S-curve)
32
Q

Exponential Growth

A
  • The population multiplies by a constant factor during constant time intervals
  • G=rN
  • r (per capita growth rate) is assumed to be constant, meaning that population growth rate (G) depends solely on the population size (N)
  • Long periods of exponential growth are unrealistic
33
Q

Effects of Death

A

-Population will grow exponentially as long as per capita death rates are lower than per capita birth rates

34
Q

Density Dependent Factors

A
  • In nature, a population may grow exponentially for a while, but eventually one or more environmental factors will limit its growth
  • Population-limiting factors restrict population growth
35
Q

Logistic Growth Model

A
  • Modified version of exponential growth that allows population growth to be slowed by limiting factors
  • Example of limiting factors: food, space, nesting sites, waste build-up
  • G=rN[(K-N)/K]
  • K carrying capacity (number of individuals that can be supported by the environment)
36
Q

What Factors Limit Population Growth?

A

-Density-dependent factors:
-lack of food
Predation: the more prey, the more they’ll get eaten
-Competition
-Waste products
-Nesting sites
-Diseases
-Density-Independent Factors:
-Climate
-Catastrophe

37
Q

Density-Dependent Factors

A
  • Population-limiting factors whose effects intensify as the population increases in size
  • Increase a population’s death rate or decrease the birth rate
  • In many natural population, density-independent factors limit population size before density-dependent factors become important
38
Q

Complex Patterns of Population Growth

A
  • Some populations have growth patters that don’t fit well into an exponential or logistic model
  • One example of a complex pattern is the cycles that frequently occur between predator and its prey
  • Boom-and-bust cycles of the snowshoe hare and one of its predators the lynx
  • These cycles are the result of many factors, in including predation and plant defenses
39
Q

Human Population growth

A
  • Exponential so far

- Age structure differs greatly between developed and developing nations

40
Q

Life Histories and Their Evolution

A

-Life history traits are those that affect a population’s schedule of reproduction and death
-Environmental factors shape the life history of species through natural selection
Survivorship curves and life tables allow ecologists to compare life history traits among populations and species

41
Q

Life Table

A
  • Tracks age-specific patterns
  • Population is divided into age categories
  • Birth rates and mortality rists are calculated for each age category
42
Q

Survivorship Curves

A
  • Survivorship curves show the age-specific survivorship of a population
  • What do they tell us about life history?
  • life history: the timing of reproductive and other important life events
43
Q

Communities

A
  • A community consist of ll the populations of organisms living together and potentially interacting in a particular area
  • Ecologists often asses four important factors in a community:
    • Diversity, Dominant organisms, Stability, Trophic structure
44
Q

Diversity

A
  • Diversity refers to the variety of species present in the community, and is measure in two ways:
    • Species richness (the number of different species)
    • Evenness (the relative abundance of individual species)
45
Q

Dominant ORganisms

A
  • The type of organisms that dominate a community can give great insight into the processes taking place within the community or ecosystem
  • Ex. Type of vegetation can be indicative of rainfall or grazing rates; size of predominant zooplankton can suggest the type of fish around in a lake
46
Q

Stability

A

-Community stability is the ability to resist change and return to the original species composition and structure following a disturbance
-Disturbances are episodes that damage biological communities, destroy organisms, and lather the availability of resources
Ex. fire, storms, drought, hard frost

47
Q

Succession

A
  • Change in the composition of a community over time

- Succession can follow a disturbance and return a community to its former state

48
Q

Types of Succession

A
  • Primary succession: the formation of a community in a new environment where a community has never been
  • Secondary succession: the replacement of communities that were destroyed or displaced
49
Q

Pioneer Species

A
  • Species that colonize barren habitats
  • Lichens small plants with brief life cycles
  • improve conditions for other species who then replace them
50
Q

Climax Community

A
  • Stable array of species that persists relatively unchanged over time
  • Succession does not always move predictably toward a specific climax community other stable communities may persist
  • Cyclic and small-scale changes also shape community structure
  • Tree falls cause local patchiness in tropical forests
  • Fires periodically destroy underbrush in sequoia forests
51
Q

Keystone Species

A
  • A species that can dictate community structure

- Removal of a keystone species can cause drastic changes in a community; can increase or decrease diversity

52
Q

Trophic Structure

A
  • Trophic structure refers to nutritional relationships among members of the community
  • The trophic structure of a community determines how energy and nutrients pass from one link to another (trophic levels) in the food chain/web
53
Q

Food Chain

A
  • The sequence of food transfer from trophic level to trophic level
  • May have many levels
54
Q

Food Webs

A
  • The feeding relationships in an ecosystem
    • Are typically not as simple as in an unbranched food chain
    • Are usually woven into complex food webs
55
Q

Interspecific Competition

A
  • Occurs when a shared resource is limited
  • Competition inhibitts the growth of both populations and can result the competituve exclusion of one species
  • Ex. Gause’s experiemtn with paramecium
  • Competitive exclusion principle says that two species with very similar niches cannot coexist
56
Q

The Ecological Niche

A
  • A species’ ecological niche
    • IS the sum total of a specie’s use of the biotic (relating to living things) and abiotic (not derived from living things) resources in its environment
    • Is the specie’s ecological role
57
Q

Resource (Niche) Partitioning

A
  • There are two possible outcomes of competition between species with identical niches
    • Extinction of one species
    • Evolution of one species to use a different set of resources (=niche partitioning)
58
Q

Predation

A
  • Predation is when one organism consumes another
  • Predation (including herbivory) is responsible for moving energy through the community
  • Predation can play a large role in the evoltion of species, causing plants and animals to develop mechanisms to escape predation
59
Q

Ways to Escape Predation

A

-Increase size or speed
-Behavioral defneses
-Hide (camouflage or cryptic behavior)
Mimic somethin that is not good to eat
-Defensive structures (Spines, armor, etc.)
defensive chemicals

-Coevolution occurs when predator and prey evolve reciprocal adaptations to counter chagnes in the other

60
Q

Predation and Species Diversity

A
  • Predator-prey relations can actually preseve species diversity
  • The experiment of Rober Paine
    • Removed a dominant predator from a community
    • Provided evidence of the phenomenon of keystone predatore
61
Q

Keystone Predators

A

-Help maintain species diversity by preventing competitive exclusion of weaker competitors

62
Q

Symbiosis

A
  • A symbioitic relationship si when two or more species live in, on, or with each other
  • Types of Symbiosis:
    • Parasitism (+/-) ex. tapeworm
    • Commensalism (+/0) ex. eyelash mites
    • Mutualism (+/+) ex. ants and acaica
63
Q

Parasitism

A
  • IS a symbiotic relationship in which one organism benefits whil the other is harmed
  • The parasite obtains its nutrients by living in or on its host organism
64
Q

Mutualism

A

-IS a symbiosis that benefits both partners

65
Q

-Indirect Mutualism

A

-Some organisms are mutually beneficial because of the relationship with a third species

66
Q

Commensalism

A

-One species benefits, the other is unaffeected

67
Q

Ecosystem

A

An assocuation of organisms and their physical environment, inteconnected by ongoing flow of energy and a cycling of materials

68
Q

Modes of Nutrition

A
  • Autotrophs:
    • Capture sunlight or chemical energy
    • Producers
  • Heteroptrophs:
    • Extract energy from other organisms or organic wastes
    • Consumers
69
Q

Consumers

A 
Herbivores
Carnivores
Parasites
Omnivores
Decomposers
Detrivores
70
Q

Trophic Levels

A
  • All the organisms at a trophic levels re the same number of steps away from the energy input into the system
  • Producers are closest to the energy input and are the first trophic level
71
Q

Food Chain

A
  • A striaght line sequences of who eats whom

- Simple food chains are rare in nature

72
Q

Energy Losses

A
  • Energy transfers ar never 1-% efficient
  • Some energy is lost at each step
  • Limits the number of trophic levels in an ecosystem

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