Lecture 8 - Adaptive Radiations In Relation To Food Acquisition Flashcards
How did ‘Darwin’s finches’ evolve?
It is believed that granivorous grassquit finches strayed onto the galapogas islands. They had no competition here and evolved into a variety of different insectivores due to the diversity of insects on the islands. In some granivory re-evolved
Give the definition of an adaptive radiation
The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage
OR
The rapid evolution from a common ancestor of several species that occupy different ecological niches
What were the two lineages of eutherian mammals present at the end of the Cretaceous period?
Protoeutheria - an insectivore like group
Condylarthra - a hoofed group
What are the three major mammalian groups?
Monotremes
Marsupials
Placental mammals
Give an example of a monotreme
The echidna which is an insectivore living in Australasia
Give an example of a marsupial
Red kangaroo
Give an example of a placental mammal
Ursus maritimus
How are placental mammals classified again?
By feeding type:
Herbivores -gnawing, grazers and browzers
Omnivory
Carnivory
Give an example of a gnawing herbivore
Naked mole rat
Give an example of a grazer
Cattle
Give an example of a browser
Deerw
How are walruses specialised?
They are mollusc specialists which have adapted with elongated canines for making holes in the ice
Name a plankton specialist
Baleen whales
Give an example of an extreme insectivore specialist
Giant ant eater which only eats termites
Why did the saber toothed cat die out?
It became overspecialised leading to an evolutionary dead end. Due to it’s tendency to prey upon slow moving megafauna it adapted two dagger like canines with a gape up to 180 degrees leading to small bite pressure meaning that as the herbivorous megafauna died out they were unable to feed on smaller mammals
What is the definition of a niche?
The part of the environment thaf is used by organisms
What are the different environment niches?
Fossorial Semi-fossorial Aquatic Semi-aquatic Volant Scansoria Arboreal
What is gumivory?
Where an animal feeds on gum or tree sap
What is a myrmecophage?
An organism specialised for eating ants and termites
What is a frugivore?
A fruit eater
What is a sanguivore?
A blood feeder
What are the feeding adaptations of the spotted hyena?
Great strength per unit area
Muscle wraps underneath the jaw
Enormous bite strength
Huge canines
What is the feeding specialisation of a giraffe?
No canines mostly molars
What is type of teeth do horses have?
Hypsodonts
What teeth do hippos have?
Brachydonts
In how many fish species have at least 2 trophic morphs been found?
About 100
How does colouration evolve?
It can evolve rapidly in response to sexual selection
How is lake surface area tied to the number of species?
It has an exponential relationship with the number of species present
What is the relationship between the age of an adaptive radiation and the number of species present?
Negative relationship between residual number of species and age of adaptive radiation
How does an adaptive radiation develop?
It explodes then slows down
What is special about the Arctic Char?
It has a variety of different genetically true trophs within the same lake, pescivorous large benthic, planktivorous and dwarf
What is special about the threespine stickleback?
There are many different morphs for it across the world
Where do benthic limnetic pairs of three spine sticklebacks occur and why?
In the Canadian great lakes due to allopatric speciation
What are the main features of the limnetic morph of three spine stickleback?
Large eyes
Narrow body
Gill rakers are long and numerous
What are the features of a benthic threespine stickleback?
They have small eyes, wide mouths and gill rakers which are short and few
What is sympatric speciation?
Speciation through competition for limited food
What is allopatric speciation?
Speciation by way of double invasion
What happened in Lake Washington with three spine sticklebacks?
In the 1950s it mainly had low plated three spine sticklebacks common with freshwater lakes. However later they found that they seemed to have reverted back to their marine fully plated form and increased on size. This is believed to be due to the Lake being cleaned up in the early 70s leading to an improvement in water clarity therefore they needed more protection from cutthroat trouts.
