chapter 23
species favoured by the fossil record
ones that
existed for a long period of time
were abundant and widespread
had hard bodies
eon - era -
period - epoch
the burgess shale
a fossil deposit that provides a glimpse into the diversity of life in the cambrian
contains soft bodied fossils
theory of plate tectonics
at 3 points in time land was all one super continent
there are crucial plates and where they meet is where volcanic activity happens
consequences of continental drift, formation of pangea
reduction in shallow water habitat
a colder and drier climate inland
changes in climate as continents moved toward and away from the poles
changes in ocean circulation leading to global cooling
consequences of breakup of pangea
allopatric speciation
how many mass extinctions have there been
5
permian mass extinction
planet killer
boundary between paleozoic and mesozoic eras
90% of all species and 96% of marine species went extinct
may have been caused by volcanism which led to rapid global warming, ocean acidification, and a decrease in oceanic oxygen
cretaceous mass extinction
took out the dinosaurs
boundary between the mesozoic and the cenozoic
half of marine species and most dinosaurs went extinct
caused by an asteroid
consequences of mass extinctions
takes long time to recover
can cause adaptive radiations
mammals underwent an adaptive radiation when
after the cretaceous extinction of terrestrial dinosaurs
development genes
genes that program development control the rate, timing, and spatial pattern of changes
heterochrony
an evolutionary change in the rate or timing of developmental events
paedomorphosis
the rate of reproductive development accelerates compared with comatic development
homeotic genes
determine basic features such as where wings and legs will develop
hox genes
class of homeotic genes that provide positional info during development
new morphological forms likely come from
gene duplication events that produce new developmental genes
changes in the form of organisms may be cause by
changes in regulation rather than changes in the sequence
extracting a single evolutionary progression from the fossil record can be misleading how?
because even though evolution is progressing, it is not goal orientated. each progression is still function as its own unit