Module 5 Flashcards
(17 cards)
The geological periods from Cambrian to Querternary?
COS - DC - PT- JC - TQ
The age of the fishes?
Devonian - 1st diversification of bony fishes and the Silurian period gave rise to many species as well.
The age of the amphibians?
Permian - Tropical climate with swamp forests with ferns and horsetails
The age of the mammals?
Teritiary and quarternary - Mammals and angiosperms and is marked by global cooling, and the extinction of the dinosaurs allowed mammals to diversify and grow in size. Diversification of mammals, birds, snakes, bony fishes, angiosperms and pollinating insects.
The age of the dinosaurs?
Triasic, Jurrasic, and Cretaceous. 1st dinosaurs - Major diversification of dinosaurs - Land fauna is dominated by dinosaurs and pterosaurs. Ichthyosaurs, and plesiosaurs dominate the seas. Warm climate and high sea level
Hypothesis of how life on earth arose?
Abiogenesis is a scientific theory which states that life arose on Earth via spontaneous natural means due to conditions present at the time. In other words, life came from non-living matter:
- Emergence of organic molecules that are building blocks and abiotic synthesis of inorganic
- Joining of these building blocks to polymers
- Package inside a protective membrane -> Protocell that provided a different internal chemistry than the environment
- Origin of self-replicating molecules that eventually made inheritance possible -> Ribozymes
Arguments for life having a single common origin?
Because all life synthesizes and uses L-isomers of amino acids only and that the DNA is universal for all species, as it results in the same amino acids
Describe broadly - The history of life?
- The first traces of life come from Stromatolites - layered structures formed by microorganisms in shallow waters where sedimentary grains get trapped and cemented in biofilms. The oldest remains are 3.5 BYA. There was no oxygen in the air or the ocean, mainly dissolved iron.
- Photosynthesis and oxygen revolution (2.4-2.7 BYA): Oxygen formed (PII) by photosynthetic prokaryotes that was released to the surrounding water that reacted with iron oxide. Higher levels in the water was the released to the air, and the levels doomed many prokaryotic groups with a few surviving anaerobes and adapting to cellular respiration.
- The fist eukaryote (1.8 BYA): Nuclear envelope, mitochondria, E.R., cytoskeleton. From endosymbiosis where a prokaryotic cell engulfed a smaller cell. Serial endosymbiosis – that gave rise to the chloroplasts, a form of plastid. The similarities between the two:
Enzymes and transport system that are homologous to those found in plasma membranes of living bacteria.
Replicate by binary fission and have circular DNA molecules.
Transcription and translation machinery
Size, RNA sequences and sensitivity to antibiotics are like bacterial ribosome
- The origin of multicellularity: A diversification of single cells that gave rise to multicellular forms whose descendants include algae, plantae, fungi, and animals. The oldest one is small red algae (1.2 BYA).
- The colonization to land (500 MYA): Moved from the aquatic environments because many adaptations made it possible to reproduce on land and prevent dehydration. Plants evolved vascular system and waterproof coating and a couple of million years later the development of true roots and leaves, and mycorrhizae with fungi. Arthropods and tetrapods were the most diverse and widespread groups during the time 450-365 MYA. Tetrapods seem to have evolved from lobe finned fishes that include humans that diverged later from the other primates 6-7 MYA.
- The first photosynthesizing microorganisms arose 2.7 BYA that increased the levels of oxygen. A couple of BYA later, the first eukaryotes showed up when the air’s oxygen levels were 1-5%. More advanced multicellular organisms came 580 MYA when levels where 15% in the air. A couple of MYA later, most of the oceans were oxygenated, and the levels in the air had also increased significantly. 575 MYA the first animals appeared in the ocean and the Cambrian explosion 543-490 MYA, organisms with an exoskeleton and more advanced ecosystems
The importance of plate tectonics for evo. biologist?
Continental drift: The process of plate tectonics – where continents are part of great plates of earths crust that floats on the underlying mantle. Sliding apart – earthquakes and colliding – forming mountains. It can:
- Alter the habitats for the organisms
- The continents can shift its location
- Promote allopatric speciation
- Explain geographical distribution of extinct organisms
- Explain the current distribution of organisms – similar ecological role in distinct parts of the world
The Cambrian explosion?
Is marked by extreme radiation of organisms. Many phylum ancestors can be traced back to this period, by the appearance in fossils during the same period (535-525 MYA). Before this period, organisms were mainly soft-bodied and little sign of predation because most were grazers, filter feeders, and scavengers. During this period of 10 MYA, predators appeared with features of capturing prey and defensive adaptations: more complex tissues, organs, exoskeleton, and trophic hierarchy in the ecosystems.
Mass extinction? Describe two.
Mass extinction - a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms.
- Permian: 250 MYA 96% of marine, 8/27 orders of insects disappeared under less than 500 000 years and believed to be caused by volcanism. That raised the CO2 and T that killed many temperature-sensitive organisms. The high CO2 lead to acidification of the oceans that decreased the CaCO3 for reef-building and shell-building. Many explosions lead to higher P in the oceans that lead to microbial growth that after death became food for decomposers that use O2, resulting in lower oxygen levels. The low O2 values harmed aerobic organisms and gave anaerobes the potential to grow and produce H2S.
- Cretaceous: The suggesting is a meteor strike based on the iridium found in the proximity of the area, Chixulub crater, that dates to the time of extinction. Iridium is common in meteorites.
1st phase – Impact shocks effect the same day
2nd phase – fall-out effects that created an infrared baking oven and global forest fires 3rd phase – Impact winter the following decade since the sun was blocked
4th phase – Greenhouse warming with an impact on the ecosystems
Are birds dinosaurs and are all mammals fishes?
Birds evolved from a group of meat-eating dinosaurs called theropods. That's the same group that Tyrannosaurus rex belonged to, although birds evolved from small theropods, not huge ones like T. rex. The oldest bird fossils are about 150 million years old. These ancient birds looked quite a lot like small, feathered dinosaurs and they had much in common. Their mouths still contained sharp teeth. But over time, birds lost their teeth and evolved beaks. After more than 140 million years in charge, the reign of the dinosaurs came to an abrupt end when a huge asteroid strike and massive volcanic eruptions caused disastrous changes to the environment. Most dinosaurs went extinct. Only birds remained. Over the next 66 million years, birds evolved in many ways, which enabled them to survive in lots of different habitats. Today there are at least 11,000 bird species. In a way, yes, since we are the descendants of lobe finned fish a couple of million years ago. Sarcopterygii evolved into tetrapods, a superclass that includes amphibian, reptiles (dinosaurs and birds) and mammals. From a cladistic point of view, as both phylogenetic trees and cladograms help show the relationships between different organisms, but only phylogenetic trees have branches that represent evolutionary time and amount of change. These were formerly based on physical characteristics but are more accurately based on genetic relationships.
The first alleged ancestor of chordates?
The pikaia belonged to the group of cephalochordate and lived during the Cambrian era.
Protocell?
Or protobiont is a self-organized, endogenously ordered, spherical collection of lipids proposed as a stepping-stone toward the origin of life
Relative dating?
Uses the strata and lead fossils in sedimentary rocks. Used as the dating of extinction events from hard shells & skeletons that facilitated their fossilization. Fossils found in strata gives a sequence for the organisms but not their actual ages.
Absolute dating?
Radiometric dating uses the decay of the radioactive isotopes by using the half-life. Fossils contain isotopes that accumulated when they were alive. Direct – C14 or C12 that can be used for up to 75000 years old. If older than that, the amounts are too small. Indirect – can infer the age of fossils that are sandwiched between two layers of volcanic rocks. As the lava cools, radioisotopes from the surroundings get trapped in the newly formed rock, and some have a higher half-life that can propose the age of the volcanic rock.
The lobe-finned fishes?
Are the sister group to the ray-finned fishes. They are characterized by their paired, fleshy pectoral, and pelvic fins that are each articulated via a single bone. Ancestral records clearly show us that terrestrial vertebrates evolved from lobe-finned fishes nearly 400 million years ago.
