Life Over Time and Mass Extinctions Flashcards
Why are plants and animals in India different than Southeast Asia?
India was its own continent until 45 million years ago
Angiosperm
flowering plant
Gondwana
Ancient supercontinent that consists of Africa, South America, Australia, Antartica, India, and the Arabian Peninsula
How do lizard species on mainland California compare in diversity to those found on islands?
Due to greater ecological opportunities on islands, there is greater differences between island species
What is exceptional about the early animal faunas from the Ediacaran period just before the Cambrian?
soft-bodied animals are well represented by these fossils
soft bodied fossils are rare
Key innovation (evolutionary innovation)
a novel phenotypic trait that allows subsequent success of a taxonomic group
Does genetic drift directly cause adaptive radiation?
No
Can an unusual event splitting a habitat, such as a hurricane led to adaptive radiation?
No
When did Pangea occur?
Late Paleozoic and early Mesozoic era
What major evolutionary episode corresponded the closest with the formation of Pangea?
Permian extinctions
How do fossils start to form?
Start with burial in sediment
Intact fossil
forms when decomposition does not occur and the organic remains are preserved intact
Compression fossil
forms when sediments accumulate on top of the organism and become cemented into rocks such as mudstone or shale
the sediments weight compresses the organic material below into a thin, carbonaceous film
Cast fossil
forms when organisms decompose after they are buried
the hole that remains fills with dissolved minerals, which creates an accurate cast of the remains
Permineralized fossil
forms when organisms decompose extremely slowly
Trace fossil
forms when sedimentation and mineralization preserve indirect evidence of an organism in the environment
ex: footprints, tracks, feces
Conditions for fossils to occur
- buried rapidly
2. decompose slowly
Habitat bias
Organisms that live in areas where sediments are actively being depositing (beaches, swamps) are much more likely to form fossils than are organisms that live in other habitats
Taxonomic and Tissue Bias
Organisms with hard parts, such as bones or shells, are most likely to leave fossil evidence
similar idea applies with tissues
Temporal bias
Recent fossils are much more common than ancient fossils
The older a fossil is, the longer it has been exposed to destructive forces
Abundance bias
fossil record is weighted towards common species
Paleontologists
scientists who study fossils
Why is it hard to estimate when species first appeared in the fossil record?
A particular species or lineage can exist for millions of years before leaving fossil evidence
Precambrian
Interval between the formation of the earth and the appearance of most animals (541 bya)
Unicellular
Oxygen was virtually absent until photosynthetic bacteria
Phanerozoic Eon Eras
Paleozoic, Mesozoic, and Cenozoic
Paleozoic Era
starts with appearance of most major animal lineages
ends with the obliteration of almost all multicellular life-forms (end-permian extinction)
initial diversification of the animals, land plants, and fungi, as well as the appearance of land animals
Mesozoic Era
begins with end-permian extinction and ends with the extinction of the dinosaurs
gymnosperms were dominant plants
dinosaurs were dominant vertebrates
Cenozoic Era
angiosperms were dominant plants
mammals were dominant vertebrates
What era are we currently in?
Cenozoic era
Adaptive radiation
the sudden appearance of related, diverse species in the fossil record
3 Hallmarks of Adaptive radiation
1) monophyletic group
2) speciated rapidly
3) diversified ecologically (occupy many niches)
Niche
range of conditions that a species can tolerate and the range of resources that it can use
Ecological opportunity
Can trigger adaptive radiation
marked by the availability of more resources
When did most modern animal phyla evolve?
Paleozoic
When did animals first appear?
Precambrian
Flowering plants first appeared during?
Mesozoic era
How to determine if two species are an example of adaptive radiation?
Ask yourself if they came from a single lineage
Stromatolites
fossilized mats of billions of bacteria cells
oldest found 3.5 bya
What era was the Cambrian explosion?
Paleozoic
What conditions allowed for the Cambrian explosion?
1) oxygen levels rose rapidly
2) evolution of predation
3) new niches beget more new niches
4) new genes, new bodies
What new genes were developed during the Cambrian explosion?
Hox genes
determine where things are placed in the body developmentally
3 domains of life
Bacteria, archaea, eucarya
Intrinsic factors of adaptive radiation
Evolution of key morphological, physiological, or behavioral traits
These traits are called synapamorphies
Extrinsic factors of adaptive radiation
ex: favorable new conditions in the environment
