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Genetics > Lecture 31 > Flashcards

Lecture 31 Flashcards

1
Q

What is ecology?

A
  • the way in which organisms interact with their environment (including other organisms)
  • also the name for the study of these interactions
  • these processes drive evolution by natural selection
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2
Q

What is evolution?

A
  • the change over time of inherited traits found in populations of individuals
  • evolution is genetic change
  • not design, or predetermine by the organism- eg. the snail did not decide to make a shell to avoid predation
  • rather natural selection favours individuals that have traits that give them an advantage, meaning they are more likely to survive and reproduce
  • these adaptations are inherited by their offspring
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3
Q

What are examples of how interactions with other animals can drive evolutionary change:

A
  • males are often very colourful
  • the most colourful males females and predators
  • stream with high numbers of predators have dull males
  • dull male population introduced into predator-less stream, become brightly coloured within two generations
  • how ecology can drive evolutionary change
  • when lot of predators= not as colourful (the advantage of attracting more females is outweight by the attraction of predators)
  • no predators= lot mor ecolourful males over time
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4
Q

What are the 4 levels at which ecology can be studied?

A
  1. Ecosystem
  2. Community
  3. Population
  4. Individuals
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5
Q

What is an ecosystem?

A

An entire environment, its physical properties and all the organisms and communities found there.

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6
Q

What is a community?

A
  • any group of species that live in the same place and potentially (or actually) interact with each other
  • can refer to a collection of related species in an area (eg. Darwin’s finches in the Galapagos)
  • communities can describe interactions between just a few (even two) species in the same area
  • eg. Ragwort= aphids feed on ragwort, ants feed on the aphid honeydew
  • cinnabar moth caterpillars feed on ragwort but damage it
  • damaged= ragwort= bad for aphids= bad for ants
  • ants attack cinnabar moth caterpillars and remove them from the ragwort
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7
Q

What is a population?

A
  • a group of individuals of the same species

- population ecology involves understanding why species numbers vary and the causes of variation within species

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8
Q

What is symbiosis?

A

-when two species interact closely together in a way which is beneficial to one or both
-interaction can be either essential to existence of one or both species (OBLIGATE) or not (FACULTATIVE)
-three types of symbiosis
=Mutualism
=Commensalism
=Parasitism

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9
Q

What is mutualism?

A
  • both species benefit from the association
  • Obligate= corals have symbiotic algae(zooxanthellae)
  • Facultative=oxpecker feed off ticks and fly maggots on the skin of buffalo
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10
Q

What is commensalism?

A
  • one species benefits; the other appears unharmed

- barnacles on whales=barnacle= gets to areas with more food while whale not harmed, but no positive effect either

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11
Q

What is parasitism?

A
  • one species in the relationship benefits, the other harmed
  • Ectoparasites
  • lampreys on fish
  • parasitic isopod (crustacean)

Endoparasites
-cestode tapeworms in vertebrates

brood parasites
=cuckoos on other birds

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12
Q

What are parasitoids?

A
  • some animals(mostly insects) are parasites in the larval form, but not as adults= Parasitoids
  • parasitoids flies and wasps lay eggs inside other animals (hosts), their larvae then eat hosts from within
  • only parasites at some of their life
  • usually larvae stage is parasitic
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13
Q

Do parasitoids display manipulating behaviour?

A
  • when infected it protects the unhatched wasps larvae= they change her behaviour somehow, when they hatch she dies
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14
Q

What is predation?

A

-another form of interaction where one species benefits at the expense of the other
-prey evolve traits to avoid being caught by predators
=run faster
=develop defences (e.g. shells, toxins)
=become better at hiding (e.g. camouflage)
=deception (eg. mimicry)

these are adaptations- characteristics of an organism that has evolved because it provides a survival benefit to that organism

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15
Q

How about parasites and evolution?

A

-species evolve means to avoid parasites
-improved immune system or means of removing parasites
-behavioural adaptations (such as avoiding possible areas of infections)
=eg. kangaroos avoid grazing on grass with kangaroo faeces present= so the don’t get parasites in their gut
=blue tits line their nests with aromatic herbs to deter parasites

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16
Q

What is a counter adaptation?

A
  • the predator or parasite will evolve means to overcome the prey defences
  • cuckoos have evolved egg mimicry to fool their hosts
  • fox runs faster
  • both species have to continue evolving in response to each others’ counter adaptations =have to keep running to stay in the same place= Evolutionary arms race!
17
Q

What is the evidence of arms races from the fossil record?

A
  • size of herbivore (ungulates) and carnivore brains in the fossil record
  • both herbivore and carnivore brain sizes increase over time
  • carnivore brain size is always relatively larger and “ahead”
18
Q

How do evolutionary arms races end?

A

-One side wins= can drive the other to extinction (smallpox virus) the other side for whom winning is less important drops behind
-Both sides reach a stable optimum= they evolve the optimum strategy they can afford
-They don’t= the arms just keep on changing
-The Ultimate Red Queen scenario
third scenario= most readily observed in nature

19
Q

What is co-evolution?

A

-evolutionary arms races are an example of coevolutuion
-evolutionary change in one species influences evolutionary change in another species
eg. orchids that mimic female wasps(visual and chemical)
= orchid phylogeny mirrors wasp phylogeny
=as a wasp species evolve, it’s orchid mimic has evolved with it
-not all coevolution is an arms race eg. Fig wasps pollinate figs, they develop in fig fruit, when females emerge they pick up pollen, females move to a new fig tree with pollen, fertilise new fruits and lay eggs
-fig phylogeny mirrors wasp phylogeny

20
Q

What is competition?

A
  • if there is a limited supply of a biologically important resource (eg. food, habitat, mates), there will be competition
  • competition results in the evolution of characters which make individuals better at competing (eg. enormous body size in male elephant seals)
  • competition may take place between individuals of the same species= intraspecific competition
21
Q

What is Interspecific competition?

A

-competition between two or more species
eg.
-coal tits feed on outer branches, willow tits inside
-on trees without yellow tits, coal tits feed inside as well
-removal of willow tits has the same effect
-willow tits competitively exclude coal tits
= result is niche separation=differentiation

22
Q

What is a niche?

A

-describes the position a species has in a community (the way it makes its living in a community)

23
Q

What are the evolutionary consequences of interspecific competition?

A
  • if two species with the same niche overlap (exist in sympatry) then there will be competition
  • result may be a behavioural change so that there is niche separation
  • alternatively there may be a change in physical characteristics (character displacement) so that there is niche separation
24
Q

What happened with Darwin’s finches?

A
  • character displacement
  • medium ground finch (Geospiza fortis) had range of beak sizes
  • In 1982 a new species with a big beak (Geospiza magnirostris) invaded the island
  • after a drought in 2003, G. fortis evolved much smaller beaks, to avoid interspecific competition with G. magnirostris

Genetics (40 decks)

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