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Population and Community Ecology > Recap Infomation (Week 1) > Flashcards

Recap Infomation (Week 1) Flashcards

1
Q

What is population dynamic

A

the pattern and processes of change in populations

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2
Q

What is a population?

A

a population consists of - individuals of a species that interact with one another within a given area at a particular time

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3
Q

What is Demography?

A

the study of population processes

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4
Q

What are Life History Strategies/ Traits?

A

A way of describing how time and energy is allocated among various activities throughout an organisms life - They vary dramatically - The variations determine how fast populations grow

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5
Q

Environmental conditions affect life history strategies. what is the simplest population model?

A

Intrinsic rate of increase (r) r = births - deaths

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6
Q

Intrinsic Rate of Increase: What happens when births exceed deaths (r>0)?

A

The population grows

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7
Q

Intrinsic Rate of Increase: What happens when deaths exceed Births (r<0)?

A

The population declines

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8
Q

Intrinsic Rate of Increase: What happens if r=0?

A

the population is stable

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9
Q

which traits are most commonly influenced by environmental changes?

A

Age at Reproduction (generation time) Number of broods per female Number of offspring per brood

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10
Q

What are iteroparous species?

A

Species which reproduce multiple time during their life - typical of organisms whose survival chances are initially low, but increase once they reach maturity. - E.g. Social insect nests are very stable environments (iteroparity is common) Examples include Northern Gannets

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11
Q

What are Semelparous species?

A

species which reproduce once - Typically produce more offspring at once - Typical of organisms with low survivorship (E.g. some fishes, many insects, all annual plants, Rusty Tussock Moth

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12
Q

Give an example where predation influences Life history strategy.

A

Guppies (Poecilia reticulata) - Trinidad - Predator fish are excludes by waterfalls and the guppies have a lower mortality rate - Lab: Compare LHS of guppies in high vs. Low predation sites High predation sites: - Mature early, produces more offspring per brood, more eggs compared with low predator guppies Conclusion: adaptation to predation due to natural selection of life history traits

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13
Q

What is expotential growth?

A

when growth rate remains constant - as population size increases, number of new individuals added per time unit increase

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14
Q

what is the mathmatical equation for Expotenial population Growth?

A

^N/^t = b-d Change in no. over time = births-deaths dN/dt=(b-d)N dN/dt defines the rate of change in potenial size over time dN/dt = rN Intrinsic rather of increase (rN is sometimes called the biotic potential of a population)

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15
Q

Is exponential populations growth unsustainable?

A

yes. for short periods of time some populations may grow at an exponential rate usually followed by a population crash. E.g. Reindeer

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16
Q

What factors limit population densities?

A

Resources become scares/depleted, birthrates drop and death rates increase

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17
Q

How are populations limited?

A

Carrying Capacity (K): - Number of individuals of a species that can be supported by an environment (Key for sustainablilty)

18
Q

What happens to a population when it nears the carrying capcity?

A

It slows down (logisitc growth) which makes an S shape on a graph E.g. sawtoothed grain beetle

19
Q

What is environmental resistance?

A

The reduction in population growth due to a known reduction in resources

20
Q

what is the formula of logistic growth when incoperating carrying capacity?

A

dN/dt= rN K-N/K r = Intrinsic growth rate N = Population size K = Carrying capacity

21
Q

what is the Allee effect?

A

Individuals have a more difficult time surviving or reproducing if the population size is too small E.g. meerkats (Suricatta suricatta)

22
Q

density-independent factors are:

A

Abiotic E.g. Deserts, Storms, cold periods of time

23
Q

Density-dependent factors are:

A

Biotic E.g. availability of food, predation, disease and migration

24
Q

What is associated with unpredictable habitats?

A

High fecundity High intrinsic rate of increase r- strategists

25
Q

What is associated with Predictable habitats?

A

Low fecundity Low intrinsic rate of increase K-strategists

26
Q

What does fecundity mean?

A

The rate at which offspring is produced.

27
Q

What are the 4 factors in favour of high density?

A
  1. Species that use abundant resources 2. Species with small body size (need less energy) 3. Complex social organization 4. Some newly introduced species
28
Q

What is a Community?

A

An assemblage of populations of various species living close enough for potential interaction E.g. carrier crabs carry sea urchins

29
Q

Classify community intereactions

A

Interspecific interactions and relationships between species in a community. May have a positive (+) or negative (-) effect, or no effect (0) at all. E.g. Predation, herbivory, symbiosis, parasitism, mutualism, commensalism and facilitation

30
Q

What sort of interaction is predation?

A

+/- interaction

31
Q

What sort of interaction is herbivory?

A

+/- interaction

32
Q

What is symbiosis?

A

A relationship where two or more species live in direct and intermate contact. E.g. Fungi and Algae to make lichen

33
Q

What sort of interaction is parasitism?

A

+/- interaction

34
Q

What sort of interaction is mutualism?

A

+/+ interaction. there are two types. - Obligatory (one species cannot live without the other - Facultative ( Both species can live alone) E.g. acacia tree and ants

35
Q

What sort of interaction is commensalism?

A

+/0 interaction - Hard to document in nature, an example is the Ox and Oxpecker

36
Q

What sort of interaction is Facilitation?

A

+/+ interaction - 1 species has a positive impact on another without direct and intermate contact E.g. Black Rush makes soil more hospitable for plants

37
Q

What is Competitive Exclusion?

A
  • Interspecific competition (-/-) when competing for resources - Strong competition can lead to competitive exclusion, local elimination of a competing species - The competitive exclusion principle states that two species competing for the same limiting resources cannot coexist in the same place
38
Q

What is an Ecological Niche?

A

The total of a species’ use of biotic and abiotic resources is called the species’ ecological niche - An ecological niche can also be thought of as an organism’s ecological role - Ecologically similar species can coexist in a community if there are one or more significant differences in their niches

39
Q

What is the fundamental niche?

A

A species’ fundamental niche is the niche potentially occupied by that species

40
Q

What is a Realized niche?

A

A species’ realized niche is the niche actually occupied by that species

41
Q

What results from having fundamental and realized niches?

A

As a result of competition, a species’ fundamental niche may differ from its realized niche – In one classic example, the presence of one barnacle species limits the realized niche of another species (Connell 1961)

42
Q

What is the trophic structure?

A
  • Trophic structure is the feeding relationships between organisms in a community - It is a key factor in community dynamics - Food chains link trophic levels from producers to top carnivores

Population and Community Ecology (1 decks)

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