Population genetics! Flashcards
(26 cards)
The patrics!
Define adaptive radiation
a rapid evolutionary diversification where a single ancestral lineage gives rise to many diverse descendant species, each adapting to different ecological niches or resources
Give 2 examples of adaptive radiation
Horses
Finches
What is the earliest horse like form?
Hyracotherium
Very like a dog
Small brain case, flattened molars for herbivory
Eocene grasses
Had feet things!
What had Hyracotherium evolved into by the late Oligocene?
Miohippus
Slightly larger
Lost the little digit
Several lineages, one of which gave rise to the true horse of today
What is the true horse line that arose in Miocene?
Merychippus
Long, high crowned teeth
Coincided with extensive development of grassland
What kind of foot is more efficient for larger bodied mammals?
Spring foot
Suspensory ligaments provide lift to the limb
What came before Equus?
Pliohippus
What are Coelocanths?
A group of lobe-finned fish, also known as “living fossils,” that were thought to be extinct for millions of years. They are primitive-looking, deep-sea creatures that can live for over 60 years. Coelacanths possess unique features, including a jointed skull and limb-like fins, making them a crucial link in the evolutionary history of vertebrates
What period did Coelocanths arise in?
Devonian
What dominated the earth for the first 3.1 billion years?
Bacteria
Describe the primitive atmosphere
Nitrogen, CO2, hydrogen and water vapour
* This environment created a primordial ‘soup’ where prokaryotes developed a range of metabolic adaptations
What brought around oxygen release?
The arrival of cyanobacteria around 2.6BYA
What caused the first mass extinction?
The build up of oxygen and arrival of aerobes
What caused mitochondria to evolve during the Cambrai period?
The great oxygenation event GOE
What is the K-T event?
Extinction of the dinosaurs, pterosaurs, plesiosaurs, mosasaurs, ammonites & belemnites
* K-T Event likely due to impacts of giant meteorites, those near southeast Mexico and the Ukraine
How did K-T events cause mass extinction?
Relatively short-term acid rain and long-term atmospheric barrier to solar radiation that followed
What does the Holocene extinction describe?
The ongoing extinction events of species during the present Holocene epoch due to human activity (over harvesting, deforestation, habitat fragmentation)
What was Wegener’s continental drift hypothesis inspired by?
Partly inspired by apparently unexpected distributions of some plants and animals across the globe
* Southern beech (Nothofagus ) occurs only in patches around the Antarctic, Chile, New Zealand, Australia & New Guinea
* Fossils of Glossopteris fern occur in Antarctica, Australasia & India
What is Wallace’s line?
An imaginary line used by biogeographers to delineate faunas among islands – South East Asia & Melanesia
* West of line, the bird fauna has more in common with mainland Asia
* East of line, it has more in common with Australia
How many major ice ages have occured?
At least 5
What are the 3 effects of ice ages on faunas?
Extinction
Barriers
Population splitting
Define population
A population is defined as a “group of sexually interbreeding individuals” and has two important attributes:
i. Gene (allele) frequencies = proportion of an allele in a population
ii. Gene pool (sum of all the alleles within a population)
What does the Hardy-Weinberg principle state?
HWP states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary factors
