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Environmental Systems > Species and Populations > Flashcards

Species and Populations Flashcards

1
Q

What is a species?

A

A species is a group of organisms (living things) sharing common characteristics that interbreed and produce fertile offspring

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2
Q

What is a population?

A

A population is a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding

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3
Q

What is a habitat?

A

A habitat is the environment in which a species normally lives

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4
Q

Three factors affect population size:

A
  • Natality (birth rate)
  • Mortality (death rate)
  • Migration (immigration and emigration)
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5
Q

What are abiotic factors?

A

Abiotic factors are the non-living, physical factors that influence the organisms and ecosystem

e.g. temperature, sunlight, pH, salinity and pollutants

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6
Q

What are biotic factors?

A

Biotic factors are the living components of an ecosystem - organisms, their interactions or their waste - that directly or indirectly affect another organism

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7
Q

What is a niche

A

A niche describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds

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8
Q

What is a fundamental niche?

A

Fundamental niche describes the full range of conditions and resources in which a species could survive + reproduce

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9
Q

What is a realised niche?

A

Realised niche described the actual conditions and resources in which a species exists due to biotic interactions

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10
Q

Name 4 biotic factors in a niche

A
  • every relationship that organism may have
  • where it lives
  • how it responds to resources available, to predators, to competition
  • how it alters these biotic factors
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11
Q

Name 2 abiotic factors in a niche

A
  • how much space there is

- availability of light, water etc..

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12
Q

Can two species inhabit the same ecological niche in the same place at the same time?

A

No two species can inhabit the same ecological niche in the same place at the same time.

If many species live together they must have slightly different needs and responses so are not in the same niche

e.g. Lions and cheetahs live in same area of African savannah but lions hunt bigger herbivores e.g. zebras whereas cheetahs hunt smaller herbivores e.g. impalas

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13
Q

What are limiting factors?

A

Limiting factors are factors which slow down growth of a population as it reaches its carrying capacity

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14
Q

Give 2 examples of limiting factors that restrict the growth of populations in nature

A
  • Phosphate being in limited supply in most aquatic systems

- Low temperature in tundra which freezes the soil + limits water availability to plants

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15
Q

What is the carrying capacity?

A

Carrying capacity is the maximum number of species or ‘load’ that can be sustainably supported by a given area

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16
Q

What is population dynamics?

A

Population dynamics is the study of factors that cause changes to population sizes

17
Q

When does competition take place?

A

All organisms in any ecosystem have some effect on every other organism in that ecosystem

Any resource in any ecosystem exists only in a limited supply

When these 2 conditions apply jointly, competition takes place

18
Q

What is intraspecific competition?

A
  • Intraspecific competition is between members of the same species.
  • When the numbers of a population are small, there is little competition between individuals for resources
  • Provided individuals can find mates, population growth will be high
19
Q

Give an example of intraspecific competition (negative feedback mechanism)

A
  1. POPULATION FALLS (leads to)
  2. Decrease comp. for good nesting sites
  3. Increased no. eggs hatch successfully
  4. Birth rate increases
  5. POPULATION GROWS
  6. Increased comp. for good nesting sites
  7. Decreased no. eggs hatch successfully
  8. Birth rate decreases
  9. POPULATION FALLS
20
Q

What does intraspecific competition tend to do?

A

Intraspecific competition tends to stabilise population numbers . It produces an S-shaped curve

21
Q

Name 1 way species deal with intraspecific competition

A

By being territorial e.g. deer

Individual / pair holds an area + fends off rivals

Individuals that are most successful reproductively will hold biggest territories + hence have access to more resources so will be more successful at breeding

22
Q

What is interspecific competition?

A
  • Individuals of different species competing for same resource
  • May result in a balance, in which both species share resource
  • One-species may totally out-compete the other (COMPETITIVE EXCLUSION)
23
Q

Give an example of both interspecific competition + competitive exclusion

A

A garden has become overrun by weeds. A number of weeds coexist together, but often the original domestic plants have been totally excluded

24
Q

Why does competition reduce the carrying capacity for each of the competing species?

A

Competition reduces the carrying capacity for each of the competing species, as both species use the same resource(s)

25
Q

What is predation?

A

Predation is the consumption of one organism by another.

It may be when one animal eats another animal, but also includes herbivory and parasitism

26
Q

What is parasitism?

A
  • Parasitism is a relationship between 2 species in which the parasite lives in or on a host, gaining its food from it.
  • Form of symbiosis (living together)
  • Normally parasites dont kill the host
  • But high parasite pop. densities can lead to host’s death
27
Q

Give two examples of parasites

A

Vampire bats

Intestinal worms

28
Q

What is mutualism?

A
  • Mutualism is a relationship between 2+ species in which all benefit + none suffer
  • Form of symbiosis
29
Q

What is commensalism ?

A
  • When one partner is helped and the other is not significantly harmed
  • Form of symbiosis

e.g. A fern growing half-way up a tree trunk

30
Q

Give an example of mutualism on land

A
  • Lichen // fungus underneath, green alga on top
  • Fungus benefits by obtaining sugars from the photosynthetic alga
  • Alga benefits from minerals + water fungus absorbs + passes on to the alga
31
Q

Give an example of mutualism in the sea

A
  • Sea anemones and clownfish are mutualist
  • The clownfish provide food for the sea anemone in the form of their faeces
  • The anemone’s stinging tentacles protect the clownfish from predators, but do not affect the clownfish
32
Q

What do S and J population curves describe?

A

S and J population curves described a generalised response of populations to a particular set of conditions (abiotic and biotic factors)

33
Q

What are S-curves?

A
  • Start with exponential growth
  • No limiting factors at first
  • Above certain pop. size, growth rate slows down gradually
  • Finally resulting in pop. of constant size at carrying capacity
34
Q

What is the area between the exponential growth curve and the S-curve called?

A

Environmental resistance

35
Q

What are J-curves?

A
  • J-curves show ‘boom and bust’ pattern
  • Population grows exponentially at first + then suddenly collapses (diebacks)
  • Often pop. exceeds carrying capacity before collapse occurs (overshoot)
36
Q

What is a J-shaped population growth curve typical of?

A

Microbes
Invertebrates
Fish
Small mammals

Environmental Systems (30 decks)

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