Travis Ingham: Essay: Flashcards
What is Macroevolution?
Large evolutionary change, usually morphological, typically referring to the evolution of differences among populations that would warrant their placement in different genera or higher-level taxa. It occurs on large timescales and large taxonomic scales
What is the red queen hypothesis in Macroevolution?
The Red Queen hypothesis suggests that biotic factors are most important in driving macroevolutionary changes, especially coevolution with predators, competitors, and parasites/pathogens. It’s characterized by an ‘evolutionary arms race’ to stay in the same place.
What is the Court Jester hypothesis in macroevolution?
The Court Jester hypothesis proposes that abiotic factors are more important in driving macroevolutionary changes, including chaotic events such as bolide impacts and changes in the climate.
What is the Cambrian explosion (540 mya)?
The Cambrian explosion was a period of rapid diversification of animal body plans that occurred at the end of the Ediacaran and lasted about 40 million years. It saw the appearance of most modern phyla and the development of hard body parts.
What are some key innovations that appeared during the Cambrian explosion?
- Segmented bodies
- Shells and exoskeletons
- Complex eyes
- Appendages
- Notochord
- Bilateral symmetry
What is the Environmental Stimulus Hypothesis for the Cambrian explosion?
This hypothesis suggests that rising O2 levels in seawater, high enough to sustain animal diversity, sparked the Cambrian explosion. This was caused by increased photosynthesis and carbon sequestration via fossil fuel burial.
What is Piakaia and why is it significant?
Piakaia is an early chordate from the Cambrian period. Its significant because its a rare and small ancestor of modern vertebrates
What were the key characteristics of haikouichthyes?
Haikouichthyes (~535 mya) had a more defined skull, proper eye spots, and more defined fins. Its considered an early craniate (subgroup of vertebrates)
When did the first unmistakable fish fossils appear?
During the Ordovician period (495-440 mya)
When did jaws first appear?
Between 420 and 440 mya
Why were jaws considered a key innovation?
Jaws were important because they led to diversification in feeding behaviour, allowing fish to exploit different resources and niches
When was the Devonian and what major groups diversified?
The Devonian “age of fishes” occurred from 420-360 mya. The major groups that diversified were:
1. Placoderms
2. Spiny sharks
3. Cartilaginous fish
4. Ray-finned fishes
5. Lobe-finned fishes
What is Tiktaalik roseae and when did it appear?
Tiktaalik roseae is a transitional form between fish and tetrapods from the late Devonian period, ~365 million years ago. It shows characteristics of both fish and tetrapods, providing evidence for the transition of vertebrates from water to land.
When did amphibians begin to proliferate?
Early amphibians began to proliferate around 345 million years ago.
What are amniotes and when did they emerge?
Amniotes are a group of tetrapods that includes reptiles, birds, and mammals. They emerged around 310-320 million years ago during the late Carboniferous period.
Why is the amniotic egg a key innovation?
It allowed full terrestrial reproduction without the need for water (like Amphibians). This adaptation enabled amniotes to fully colonise terrestrial environments
How did amniotes diversify during the Permian period?
During the Permian (299-252 mya):
Synapsids became the dominant land vertebrates
Early reptiles diversified into various lineages
Different feeding and locomotion strategies evolved
What major event affected amniote evolution at the end of the Permian?
The end-Permian mass extinction (252 mya) greatly affected amniote evolution:
Many synapsid lineages went extinct
Created ecological opportunities for surviving groups
Led to the rise of archosaurs (including dinosaurs) in the Triassic
How did amniotes continue to evolve in the Mesozoic era?
In the Mesozoic (252-66 mya):
Archosaurs (including dinosaurs) became dominant land vertebrates
Early mammals evolved from synapsids but remained relatively small
Birds evolved from theropod dinosaurs
Various reptile groups adapted to marine environments
When did the KT (Cretaceous-Tertiary) extinction occur and what were its major effects?
The KT extinction occurred ~65 million years ago. It led to the extinction of non-avian dinosaurs, pterosaurs, plesiosaurs, and many other taxa, marking a major change in the history of life on Earth.
What was the primary trigger for the KT extinction?
The primary trigger was the Chicxulub impact on the Yucatan peninsula, with direct evidence found in the rocks.
How did mammals change after the KT extinction?
After the KT extinction, mammals diversified into many new niches due to ecological opportunity. More species started becoming active during the day, and many lineages that had diverged during the Cretaceous began to diversify rapidly.
When did primates diverge from other mammals?
Primates diverged from other mammals soon after the K-T extinction, about 65 million years ago.
When did primates diverge from other mammals?
Primates diverged from other mammals soon after the K-T extinction, about 65 million years ago.
