BIOLOGY 1B Lecture Notes - Lecture 8: Adaptive Radiation, African Lakes, Drosophila Melanogaster
12 Jun 2018
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Lecture 8: Evolution and Ecology
9/11
• Adaptive radiation: the diversification of a group of organisms into forms filling different ecological niches
• Tarweed
o Gametes got to Hawaii from California
o Radiated into lots of forms; evolved into niches that weren’t occupied by other plants because
other plants hadn’t gotten there
o Resemble morphologically plants of other varieties
• Fruit fly- adaptive radiation
o Moved through different islands and evolved
o Haven’t changed in morphology too dramatically; changed in where they lay their eggs
• Hawaiian honeycreepers- adaptive radiation
o Different bill types to exploit different food resources
• Species flocks: faster time period than adaptive radiation
o Cichlids in African lakes
o Evolved similar strategy in different lakes; not closely related- convergence and morphology at a
community level
• Trophic guild: feeding guild
o Sympatric carnivores of Israel
▪ Mongoose, badger
o Ecomorphology: study of relationship between ecological role of an individual and its
morphological adaptations
• Stoats can prey on rabbit 10x their size
o Break skull or neck
o Measured canine diameter; feed on different prey due to different size canines
o Evolved in different regions but what we see today is a group that fits together ecologically and
has assembled into a differentiated structure
o Didn’t evolve together but assembled over evolutionary time
• Coevolution
o Direct adaptations by one organism in response to adaptations of another organism
o Ex. Sphinx and orchid
▪ Long region of flower to get to nectar; Darwin predicted moth that has a long thingy to
eat the nectar; scientists found it a year later
• Mimicry
o Batesian mimicry
▪ Butterflies coevolving; intentionally mimicking one another
▪ Model is distasteful to predators
• Another butterfly evolves to look like the model in order to scam predator
▪ A harmless species looks like a dangerous one
▪ Ex. king snake(harmless) and coral snake
o Mullerian mimicry
▪ A harmful species looks like another harmful one
▪ Unrelated populations; comodels
▪ Birds learn fast because all butterflies that look like harmful are harmful
• Newt
o One of most poisonous animals in world
o Convergently evolved with same toxin as pufferfish neutotoxin
o Toxin on skin; unken reflex- expose the really colorful part of themselves on their belly
o Aposomatism for expressing that they are dangerous
• Gartersnake develop immunity then newt develop greater toxicity- back and forth
o ARMS RACE
o This is why the newt is way more toxic than any other prey
• Mimicry
o Yellow eyed Ensatina
o Newts have yellow eyes and dark upper body and lower body
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