Chapter 25: Part two Flashcards
Stromalites
- Oldest Fossil
- rocks formed by the accumulation of sedimentary layers on bacterial mats
Photosynthesis & the Oxygen Revolution
O2 produced by oxygenic photosynthesis reacted with dissolved iron & precipitated out to form banded iron formations
O2 began accumulating in the atmosphere
& rusting iron-rich terrestrial rocks
The First Eukaryotes
Eukaryotic cells have a nuclear envelope, mitochondria,
endoplasmic reticulum & a cytoskeleton
endosymbiont theory (related to Eukaryotic cells)
proposes that mitochondria & plastids (chloroplasts & related organelles) were formerly small prokaryotes living within larger host cells
endosymbiont is a cell
that lives within a host cell
Serial endosymbiosis
supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
endosymbiotic origin of MITOCHONDRIA and PLASTIDS
Inner membranes are similar to plasma membranes of prokaryotes
- membrane bound organelles
MITOCHONDRIA
photosynthetic bacterium
Their ribosomes are more similar to prokaryotic
than
eukaryotic ribosomes
The Origin of Multicellularity
evolution of eukaryotic cells allowed for a greater range of unicellular forms
A second wave of diversification occurred
when multicellularity evolved and gave rise to algae, plants, fungi, and animals
Cambrian Explosion
efers to the sudden appearance of fossils resembling modern animal phyla
Burgess Shale
The fossils of the Burgess Shale in the Canadian Rockies preserve an intriguing glimpse of early life on Earth
The Colonization of Land
Fungi, plants, and animals began to colonize land about 500 MYA
Vascular tissue in plants transports
materials internally & appeared by about 420 MYA
Plants and fungi
likely colonized land together
Tetrapods
Mammals belong to the group of animals called
Tetrapods evolved
from lobe-finned fishes
Plate Tectonics
Earth’s crust is composed of plates floating on Earth’s mantle
Tectonic plates move slowly
rough the process of continental drift
Oceanic & continental plates can
collide, separate, or slide past each other
Pangaea
Formation of the supercontinent
- A deepening of ocean basins
- A reduction in shallow water habitat
- A colder & drier climate inland
Continental Drift
- continent’s climate changes as it moves north or south
- Separation of land masses can lead to allopatric speciation
Ex. Similarity of fossils in parts of South America and Africa is consistent
with the idea that these continents were formerly attached
mass extinction
the rate of extinction has increased dramatically and caused a
Mass extinction is the result of
disruptive global environmental changes
Permian Extinction
defines the boundary between the Paleozoic and Mesozoic eras about 250 MYA
A number of factors might have contributed to these mass extinctions
- Intense volcanism in what is now Siberia
- Global warming
- ocean acidification
Cretaceous Mass Extinction
Organisms that went extinct include
- half of all marine species
- many terrestrial plants and animals, including most dinosaurs
Adaptive Radiation
is the rapid evolution of diversely adapted species from a common ancestor
Heterochrony
is an evolutionary change in the rate or timing of developmental events…..
Major changes in body form can result from changes in
the sequences and regulation of developmental genes
Changes in Spatial Pattern
Substantial evolutionary change can also result from alterations in genes that control the placement and organization of body parts
Homeotic genes
determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged
Hox genes are a class of homeotic genes that provide positional information
during animal embryonic development
Changes in Genes
Changes in developmental genes can result in new morphological forms
Ubx gene have been identified
that can “turn off” leg development
Changes in morphology likely result from
changes in the regulation of the expression of developmental genes
