Evolutionary Biology Flashcards

General Patterns and Basic Information

• Understand general patterns from the previous slide (derived from the text).

• Basic understanding of chemistry and the origin of life.

Dates and Locations of Major Events

• Origin of life: Understand when and where it likely occurred.

• Origin of eukaryotes: Note the approximate time frame.

• Origin of animals: Identify when animals first appeared.

• Origin of terrestrial plants: Know when plants colonized land.

Major Changes

• Multicellularity: Understand the significance and implications, including the square-cube law.

• Animal evolution: Key developments in animal evolution.

• Life history evolution in terrestrial plants: Understand the changes in plant life cycles as they adapted to land.

Characteristics of Major Time Periods

• Precambrian: Key features and events.

• Paleozoic: Major developments and characteristics.

• Mesozoic: Dominant life forms and environmental conditions.

• Cenozoic: Rise of mammals and flowering plants.

• Pleistocene: Ice ages and the emergence of humans.

Origin of Life

• Definition: What constitutes the origin of life?

  • Transduce energy: The ability to convert energy from one form to another.

  • Replicate: The capability to create copies of itself.

  • Evolve: The capacity to undergo changes over time.

When did life originate?

• Strong fossil evidence dates back to 3 billion years ago (bya).

• Debatable evidence suggests it could be as early as 3.5 bya.

• Only one origin of life led to modern life forms.

• Use of only L amino acids.

• The presence of a code (genetic code).

How did life originate?

• Problems:

  • In modern living systems, only nucleic acids are capable of replication.

  • Proteins are essential in contemporary living organisms.

  • Simple organic molecules:

  • Found in space.

  • Can originate from abiotic reactions on Earth.

Miller-Urey Experiment

• Components

  • Atmospheric compartment: Included gases like Hydrogen (H2), Methane (CH4), Ammonia (NH3), Water (H2O), and Carbon Monoxide (CO).

  • Oceanic compartment: Liquid water to simulate the ocean.

  • Energy Input: Application of heat to the "oceanic" compartment to cause evaporation and electrical discharge in the "atmospheric" compartment to simulate lightning.

  • Condensation: Cooling system to condense the atmosphere and cycle water back to the oceanic compartment.

Assembly of Polymers

• Simple organics are relatively easy to form.

• Assembly into polymers can occur:

  • On clay surfaces.

  • Through evaporation.

• RNA can self-replicate.

• Clay, along with RNA, can catalyze the formation of a lipid envelope.

• This lipid envelope can then catalyze the assembly of amino acids into short proteins.

• Such systems are capable of evolving.

Ribozyme Example

• ACAGAACCUUAAUGC sequence illustrating stem-loop structures and substrate binding sites.

• Diagram shows a ribozyme catalyzing a reaction involving a substrate HOA-U

Key Events and Changes in the History of Life

• Origin of life

• Origin of eukaryotes

• Origin of animals

• Origin of plants

• Multicellularity (and the constraints imposed by the square-cube law).

• Animal evolution

• Life history evolution in plants

Major Time Periods

• Precambrian

• Paleozoic

• Mesozoic

• Cenozoic

• Pleistocene

Precambrian

Archean

• Early life history

• Three major lineages

• Photosynthesis in some lineages

Proterozoic

Eukaryotic Evolution

• Diagram of Common Ancestry and Divergence

  • Illustrates the common ancestor giving rise to Eucarya, Archaea, and Bacteria.

  • Eucarya further branches to include Diplomonads, Slime molds, Ciliates, Plants, Fungi, and Animals.

  • BACTERIA includes species such as Cyanobacteria. Notes the evolution of Chloroplasts from bacteria.

  • ARCHAEA includes species such as Sulfolobus, Thermoproteus, Methanogens, Thermoplasma and Halobacteria.

Timeline of Early Eukaryotes and Animals

• Early Eukaryotes appeared approximately 1.8 billion years ago (bya).

• Animals emerged around 1 billion years ago (bya).

Common Ancestry of Eukaryotes

• Depicts the relationships between various eukaryotic groups, with a focus on the transition to multicellularity and the emergence of animals.

Multicellularity and the Square-Cube Law

• Cells Rely on Diffusion: Nutrient and waste transport relies on diffusion.

• Diffusion Rate: Inversely proportional to distance.

• Being Big Requires Complexity: Due to the square-cube law, increased size necessitates specialized structures and systems.

• Cell Specialization: Requires regulation of gene expression.

• Cloning Considerations: Implications for creating large, complex organisms.

Square-Cube Law

• Cells rely on the process of diffusion.

• Diffusion rate is inversely proportional to distance.

• Larger size requires complexity due to the square-cube law.

• Cell specialization requires regulation of gene expression.

Surface Area Example

• Cube with side length 1 cm:

  • Surface Area (SA) = 1 \times 1 \times 6 = 6 \text{ cm}^2

• Cube with side length 2 cm:

  • Surface Area (SA) = 2 \times 2 \times 6 = 24 \text{ cm}^2

• Doubling the edge length quadruples the surface area.

Volume Example

• Cube with side length 1 cm:

  • Volume (V) = 1 \times 1 \times 1 = 1 \text{ cm}^3

• Cube with side length 2 cm:

  • Volume (V) = 2 \times 2 \times 2 = 8 \text{ cm}^3

• Doubling the edge length increases the volume by a factor of 8.

Surface Area to Volume Ratio

• For the smaller cube: 6:1

• For the larger cube: 24:8, which simplifies to 3:1

Animal Evolution

• Diagram of the branching relationships among different animal groups.

Deuterostomes vs. Protostomes

• Deuterostomes: The embryonic blastopore becomes the anus.

  • Includes Vertebrata, Cephalochordata, Urochordata, Hemichordata, and Echinodermata.

• Protostomes: The embryonic blastopore becomes the mouth.

  • Divided into Lophotrochozoa and Ecdysozoa.

Lophotrochozoa

• Includes Bryozoa, Brachiopoda, Platyhelminthes, Pogonophora, Rotifera, Annelida, and Mollusca.

Ecdysozoa

• Possess an external skeleton or cuticle and undergo ecdysis (molting).

• Includes Nematoda, Tardigrada, Onychophora, and Arthropoda.

Other Groups

• Ctenophora and Cnidaria: Characterized by 2 cell layers and radial symmetry.

• Porifera (Sponges): Probably NOT monophyletic.

Sponge Structure and Function

• Illustrates water flow and key cell types:

  • Incurrent pores: Water enters through these.

  • Porocytes: Doughnut-shaped cells forming channels.

  • Choanocytes: Flagellated cells lining the spongocoel that create water current and capture food particles.

  • Spongocoel: Central cavity.

  • Osculum: Outgoing water.

  • Mesohyl: Gelatinous matrix.

  • Amoebocytes: Transport nutrients and produce skeletal fibers (spicules).

Animal Evolution (Continued)

• Shows key evolutionary steps such as multicellularity, the development of two and three cell layers, radial and bilateral symmetry, and the distinction between protostomes and deuterostomes.

Paleozoic Era

Key Developments

• Diversification of major animal groups (e.g., echinoderms, other invertebrates, vertebrates).

• Origin of land plants.

• Mass extinction at the end of the period.

Cambrian Explosion

• Rapid diversification of animal life during the Cambrian period.

• 542-532 million years ago (mya), animal diversity was relatively low in the fossil record.

• Over a short period of 10-20 million years, major phyla (including chordates) and now-extinct groups appeared.

Middle Ordovician Period

• Roughly 458 million years ago.

• PANTHALASSIC OCEAN covered much of the Earth.

• Continents included LAURENTIA (North America), BALTICA, AVALONIA and Gondwana (South America, Africa, Antarctica, India and Australia).

Paleozoic Era: Continued

• Origin of jawed fishes, terrestrial vascular plants, arthropods, and insects.

• First organisms on land were plants.

• First animals on land were arthropods, NOT vertebrates.

Vertebrate Evolution

• First 4-legged vertebrates with digits.

Transition from Water to Land

Key Genera

• Eusthenopteron: A lobe-finned fish.

• Ichthyostega: An early tetrapod.

Plant Life Cycle Evolution

• Evolutionary Stages

  • Zygote Exposed: The ancestral condition.

  • Zygote Retained (Embryophytes): Zygote retained within the parent plant, providing protection and nourishment.

  • Vascular Tissue (Tracheophytes): Development of vascular tissue (xylem and phloem) for efficient transport of water and nutrients.

  • Pollen and Seeds (Seed Plants): Evolution of pollen and seeds, allowing for dispersal and protection of the embryo.

  • Flowering Plants: Double fertilization. Also less dependent on wind dispersal.

Plant Life Cycle Evolution Stages

• Zygote exposed.

• In embryophytes, zygote retained.

• In tracheophytes, vascular tissue.

• In seed plants, pollen and seeds.

• Flowering plants and diversity.

Flowering Plants

• Did not appear until the Mesozoic Era.

• Became ecologically important in the Cenozoic Era.

• Double fertilization occurs.

• Less dependent on wind dispersal for both pollen and seeds.

Plant Life Cycle Evolution Summary

• Zygote exposed.

• In embryophytes, zygote retained.

• In tracheophytes, vascular tissue.

• In seed plants, pollen and seeds.

• Flowering plants and diversity.

End of Paleozoic Era

• Occurred approximately 251 million years ago (mya).

• Continents were joined in Pangaea.

• Insects diversified.

• Origin of “reptiles,” including ancestors of mammals.

• Huge mass extinction event.

Permian Mass Extinction

• Largest known mass extinction in Earth's history.