Understanding Diversity and Evolutionary History in Biology

Monophyletic group

Group that includes an ancestral species AND ALL its descendants. Example: All birds and dinosaurs together.

Paraphyletic group

Group that includes an ancestral species and SOME, but NOT ALL descendants. Example: Reptiles (when birds are excluded).

Polyphyletic group

Group containing species from DIFFERENT ancestral lineages. Example: Flying animals (birds, bats, insects).

Synapomorphy

SHARED DERIVED character passed from ancestor to descendants. Example: Feathers in birds.

Plesiomorphy

ANCESTRAL character that appeared in a group's ancestor. Example: Backbone in all vertebrates.

Autapomorphy

UNIQUE derived character in just one species. Example: Giraffe's long neck.

Systematics

Study of EVOLUTIONARY RELATIONSHIPS and biological diversity. Example: Using DNA to classify organisms.

Taxonomy

NAMING and CLASSIFYING organisms. Example: Placing a newly discovered beetle into its family.

Binomial nomenclature

Two-part scientific name: GENUS (capitalized) + species (lowercase). Example: Homo sapiens.

Community

Association of DIFFERENT SPECIES populations living and interacting in same place and time. Example: All organisms in a forest.

Ecosystem

Biological community + ABIOTIC environment. Example: A lake with its fish, plants, water, minerals.

Biome

Large TERRESTRIAL region with similar climate, soil, plants, animals. Example: Tropical rainforest, desert.

Ecotone

TRANSITION ZONE where communities/biomes meet. Example: Where forest meets grassland.

Biogeographic realm

Large spatial regions with DISTINCTIVE BIOTA. Example: Nearctic (North America).

Six biogeographic realms

Nearctic (N.America), Neotropical (S.America), Palearctic (Eurasia), Oriental (S.Asia), Ethiopian (Africa), Australian. Remember: 'NEPONA’

These are regions defined by distinct flora and fauna that reflect evolutionary history across the globe. '.

Laurasia and Gondwana

Two landmasses 200 MYA during TRIASSIC period that later formed today's continents.

Three levels of biodiversity

ECOSYSTEMS, SPECIES, GENES. Example: Forest ecosystem, wolf species, genetic variation in wolves.

Properties of community structure

1) Species present 2) Relative abundance 3) Species interactions 4) Resilience 5) Energy flow 6) Productivity.

Early Earth conditions

No oxygen, volcanic activity, lightning storms, UV radiation. Led to formation of organic molecules.

RNA World hypothesis

RNA was FIRST self-replicating molecule, acting as both genetic material AND enzyme before DNA/proteins.

Oparin-Haldane model

Suggested early Earth conditions led to formation of AMINO ACIDS.

Miller-Urey experiment

Simulated early Earth conditions, created AMINO ACIDS within a week. 40 different amino acids found in 2008 reexamination.

LUCA

Last Universal Common Ancestor. NOT a living organism but a PHYLOGENETIC EVENT HORIZON at 3.6 BYA.

Earth timeline

Formation (4.5 BYA) → First life (3.7 BYA) → LUCA (3.6 BYA) → Eukaryotes (1.8 BYA).

Multicellularity theories

1) Cells STAY TOGETHER after division 2) Different cells COME TOGETHER.

Cambrian Explosion

Rapid DIVERSIFICATION of animal body plans. Most modern animal phyla appeared.

Extinction

When ALL INDIVIDUALS in a species have died out.

Background extinction

SLOW, GRADUAL, COMMON with diverse direct causes (predation, competition, disease, climate change).

Mass extinction

FAST, CATASTROPHIC, RARE with indirect causes (volcanoes, asteroids).

'Big Five' mass extinctions

Ordovician, Devonian, Permian, Triassic, Cretaceous. Remember 'Old Dinosaurs Prefer Tasty Chicken'.

Permian extinction

MOST SEVERE. 252 MYA. 96% of marine species extinct. Caused by massive volcanic eruptions (Siberian Traps).

K-T extinction

Ended age of dinosaurs. ASTEROID IMPACT evidence: iridium in rocks, crater in Yucatan peninsula.

10 major evolutionary transitions

1) Self-replicating molecules 2) RNA→DNA 3) First cells 4) Eukaryotic cells 5) Sexual reproduction 6) Developmental complexity 7) Individuality 8) Groups 9) Eusocial societies 10) Terrestrialization.

Origin of animals

Started during CRYOGENIAN period with sponge-like organisms. Hard to distinguish from colonial single-celled organisms.

Ediacaran fauna

EARLIEST FOSSILS of large animals, found in Australia.

Evolution of dinosaurs

Bigger dinosaurs in JURASSIC, T-rex during CRETACEOUS period.

Human origins

Humans originated 200,000 YEARS AGO.