Evolution of Microbial Life and Macroevolution

Flashcards covering the evolution of microbial life, Earth's geological timeline, theories on the origin of life, fossil records, mass extinctions, adaptive radiations, and macroevolutionary mechanisms based on lecture notes.

Pre-RNA worlds

A hypothetical stage in the evolution of life before the RNA world, as per the timeline.

RNA world

A hypothetical stage in the evolutionary history of life where RNA stored genetic information and catalyzed chemical reactions.

RNA/protein world

A transitional stage in the evolution of life where RNA and proteins both played crucial roles.

DNA/RNA/protein world

The current stage of life where DNA stores genetic information, RNA transfers it, and proteins perform most cellular functions.

Sulfate reducers

Early microbial life forms mentioned in the timeline of Earth's history.

Anoxygenic phototrophs

Early microbial life forms capable of photosynthesis without producing oxygen.

Methanogens

Early microbial life forms mentioned in the timeline that produce methane.

LCA (Last Common Ancestor)

The most recent common ancestor of all current life forms.

Apex formation microstructures

Early microfossils mentioned in the timeline.

Stable hydrosphere

An early condition on Earth (4.2 BYA) critical for the origin of life.

Prebiotic chemistry

Chemical processes occurring before the origin of life that formed organic molecules.

Origin of life

The point at which life first emerged on Earth.

Oxygen-rich atmosphere

A later development in Earth's atmosphere (~2.8-2.5 BYA), crucial for the emergence of cellular respiration in prokaryotes.

Big Bang

The event that forged our present-day universe 13.7 billion years ago (BYA).

Earth formation

The formation of Earth, which occurred 4.5 billion years ago.

Stromatolites

Ancient microbial mats that microbes inhabited; modern ones are dominated by oxygenic phototrophic cyanobacteria.

Cyanobacteria

Oxygenic phototrophic bacteria that emerged 2.4-3.0 billion years ago and dominate modern stromatolites.

Oldest microbial fossils

Fossils around 3.5 billion years old that resemble modern photosynthetic bacteria (cyanobacteria).

First evidence of microbial life

Observed 3.7-3.8 billion years ago, identified by carbon molecules in rocks that are only made by life.

Anoxygenic phototrophic filamentous bacteria

Early microbes from 3.7-3.8 BYA, similar to modern Green non-Sulphur bacteria.

Spontaneous generation

An early scientific theory, commonly believed into the 19th Century, that life arose spontaneously from non-living matter.

Louis Pasteur (1862)

Scientist who ended the argument that modern-day organisms arise from spontaneous generation, demonstrating life comes from preexisting life.

Four stages of life emergence

Hypothesized sequence for life's emergence: abiotic synthesis of monomers, formation of polymers, packaging into protobionts, and evolution of cellular properties.

Stage 1 (Origin of Life)

Production of nucleotides and amino acids prior to the existence of cells (abiotic synthesis of monomers).

Stage 2 (Origin of Life)

Polymerization of nucleotides and amino acids to form DNA, RNA, and proteins.

Stage 3 (Origin of Life)

Polymers becoming enclosed in membranes (packaging into protobionts).

Stage 4 (Origin of Life)

Polymers enclosed in membranes evolving cellular properties like self-replication.

Earth’s early atmosphere

Possible composition was similar to gases ejected from modern volcanoes (H2O vapor, CO2, SO2, H2, H2S) and contained no oxygen.

Reducing Atmosphere Hypothesis

Proposed by Oparin and Haldane, suggested complex organic molecules arose spontaneously under pre-biotic, electron-adding conditions, forming a 'primordial soup'.

Oparin and Haldane

Scientists who proposed the reducing atmosphere hypothesis in the 1920s.

Primordial soup

A hypothetical collection of organic molecules believed to have formed in the early Earth's oceans, eventually leading to living cells.

Miller & Urey (1953)

Scientists who conducted an experiment simulating early Earth conditions, generating precursors of complex organic molecules like amino acids.

Neutral atmosphere

The current belief about Earth's early atmosphere, primarily N2 and CO2, which experiments have shown can also form organic compounds.

Deep-sea Vent Hypothesis

Suggests organic molecules may have originated in hydrothermal or alkaline deep-sea vents.

Alkaline deep-sea vents

Warm (40-90°C) vents with a pH of 9-11, possibly more suitable for the origin of organic molecules than hydrothermal vents.

Clay as substratum for polymerization

Experimental studies show that polymers can form on clay surfaces when water vaporizes and concentrates monomers.

Protobionts

A collection of abiotically created molecules within a membrane, considered a precursor to cells.

Liposomes

Certain types of lipids that spontaneously form bilayers, potentially encapsulating polymers to form protobionts.

RNA as the first macromolecule

Favored hypothesis due to RNA's ability to store information, capacity for replication, and enzymatic function (ribozymes).

Ribozymes

RNA molecules with enzymatic functions, capable of cutting/splicing other RNA molecules and attaching amino acids to proteins.

Chemical selection

A process where self-replicating RNA molecules or those with enzymatic abilities are favored and increase in amount, leading to evolutionary steps.

Fossil record

Documents the history of life on Earth, providing insights into the emergence and disappearances of organisms.

Archaean and Proterozoic eons

Early geological time periods that lasted nearly 4 billion years.

Phanerozoic eon

The last 500 million years of Earth's history, divided into the Paleozoic, Mesozoic, and Cenozoic eras.

Fossils

Recognizable remains of past life on Earth, formed when organisms are buried by sediments and their hard parts are replaced by minerals.

Paleontologists

Scientists who study fossils to gain insights into past life.

Radiometric dating

A method that measures the decay of radioactive isotopes to determine the actual ages of rocks and fossils.

Carbon-14

A radioactive isotope with a half-life of 5,730 years, used to date fossils up to 75,000 years old.

Potassium-40

A radioactive isotope with a half-life of 1.3 billion years, used to date volcanic rocks hundreds of millions of years old.

Five Large mass extinctions

Major events in Earth's history (Ordovician, Devonian, Permian, Triassic, Cretaceous) that caused 50% or more of Earth's species to go extinct and define geologic time periods.

Prokaryotes

Appeared 3.8 BYA, created Earth's atmosphere, and evolved virtually all metabolic pathways.

Atmospheric oxygen

Appeared 2.7 BYA due to prokaryotic photosynthesis.

Single celled eukaryotes

Microorganisms that emerged 2.1 BYA.

Multicellular eukaryotes

Organisms that emerged 1.5 BYA.

Animals emergence

Occurred approximately 600 MYA.

Colonization of land

Fungi, Plants, and animals moved onto land around 500 MYA.

Hominids appearance

Occurred 6 to 7 MYA.

Humans emergence

Occurred approximately 200,000 years ago.

Macroevolution

The study of evolutionary processes and patterns that occur at and above the species level, involving major changes over evolutionary time.

Continental drift

The slow, continuous movement of Earth’s crustal plates on the hot mantle, playing a major role in macroevolution.

Crustal plates

Large sections of Earth's lithosphere carrying continents and seafloors that float on the liquid mantle.

Pangaea

A supercontinent that formed 250 million years ago, altering habitats and triggering Earth’s greatest mass extinction.

Mass extinctions and adaptive radiations

Mass extinctions are characterized by loss of many species and can lead to adaptive radiations, where surviving groups diversify to fill vacant ecological niches.

Permian-Triassic extinction

Occurred 252 MYA, causing 90% of all species to disappear, triggered by extreme vulcanism in Siberia.

Cretaceous-Tertiary (K-T) extinction

Occurred 64.5 MYA, causing 76% of all species to disappear, including all dinosaurs, likely due to a large asteroid impact.

Extinction rates

The rate at which species disappear; currently 100-1,000 times the normal background rate, primarily due to habitat loss from human activity.

6th mass extinction

The current period of high extinction rates, suggesting we will be in a mass extinction within the next 300 years if current trends continue.

Cambrian explosion

An event that started about 540 MYA and lasted for about 20 MYA, characterized by a rapid increase in the diversity of marine animal life.

Ordovician radiation

An interval of intense diversification of marine animal life that lasted nearly 40 million years, following the Cambrian explosion.

Cenozoic (Age of Mammals)

The geological era from 66 MYA to today, marked by the dramatic adaptive radiation and diversification of mammals after the K-T extinction.

Adaptive radiation

A process where a group of organisms forms new species, whose adaptations allow them to fill new habitats or roles in their communities, often following mass extinctions or the evolution of novel features.

Genes that control development

Play a major role in evolution, where slight genetic changes can lead to major morphological differences between species.

Evolutionary novelties

New structures or behaviors that arise in evolution through a series of incremental modifications, each step bringing a selective advantage (e.g., the evolution of eyes).

Evolutionary trends

Patterns observed over long periods of evolution, such as the modification of vertebrate forelimbs into wings or evolutionary arms races, but do not imply evolution is goal-directed.

Evolutionary arms race

A macro-evolutionary trend where predators evolve better weaponry and prey evolve better defenses, leading to a dynamic of escalating adaptations.

Species selection

The unequal survival of species, often resulting from interactions between organisms and their environment, such as an evolutionary arms race.

Not goal directed evolution

The principle that natural selection results from interactions between organisms and their environment, and if the environment changes, apparent evolutionary trends may cease or reverse.