BIOL1130 Lecture Notes - Lecture 13: Jarrah Forest, Monomorphism, Sodium Fluoroacetate
7 Jun 2018
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Course
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Coevolution
• Species Interactions
o Species interactions lead to evolutionary changes in the interacting
species (coevolution)
o Two types:
▪ Mutualistic interactions – evolutionary changes benefit
each species
▪ Antagonistic coevolution – evolutionary changes decrease
fitness of the other species
o Physical Plant defences against herbivores
▪ E.g. growing tall, small leaves, spines, hairs etc.
o Plant Secondary Compounds
▪ Chemicals that plants synthesise to make them poisonous
or unpalatable e.g. caffeine, morphine, nicotine.
▪ Selection for tolerance to the chemicals in these plants
▪ E.g. 1080 poison (monofluroacetate) is used widely as fox
bait in Australia
• High toxic to vertebrates but WA native mammals
are resistant
• 1080 is derived from the Gastrolobium genus
(poison peas), 18 species of which occur naturally in
WA
• WA native mammals are resistant to the poison due
to coevolution
▪ The evolution of resistance to plant toxins allows
herbivores to use the resource
• Additional pressure on plants to produce more
toxins
• Relative brain sizes in prey and predators
o Coevolutionary arms race → larger brain sizes
▪ As prey gets bigger (bigger brain size) to defend
themselves, predator does too to combat this
• Warning Colouration
o Common characteristic of noxious or dangerous animals
o Advertises noxious state to prevent would be predators from
attacking
o Palatable species can fool predators by having the same bright
colouration as noxious species (mimicry)
o Batesian mimicry – noxious model species, palatable mimic species
▪ E.g. The monarch butterfly
• Native to North America
• Larvae feed on milkweed (poisonous to most
animals) which accumulate in its body and make it
poisonous
• Brightly coloured – but this does not prove that they
function as a warning
o Predators will attack a warning colouration but will learn to avoid
it
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