Early Animal Evolution and Biomes Overview

Mesozoic

Era of complex vascular and respiratory systems.

Dinosaurs

Dominant land vertebrates during the Mesozoic.

Triassic-Jurassic extinction event

Fourth mass extinction, affecting large amphibians.

K-Pg extinction

Fifth mass extinction; non-avian dinosaurs extinct.

Asteroid impact

Event causing K-Pg extinction in Yucatan.

Great Mammalian Radiation

Rapid increase in mammal size and behavior.

Taxonomic richness

Doubled in 100k years post-K-Pg impact.

Mammal size increase

From 0.5 kg to 50 kg over 700k years.

Coevolution

Reciprocal evolutionary changes between interacting taxa.

Plesiadapiforms

Ancestral primates diversifying after K-Pg boundary.

Purgatorious mckeeveri

Oldest genus of plesiadapiforms.

Megafauna

Large animals that existed during Pleistocene.

Glaciations

Periods of extensive ice coverage on Earth.

Wisconsinan Glaciation

Last glacial maximum in North America, ~21,000 ybp.

Beringia

Land bridge facilitating migration during glaciations.

Overkill hypothesis

Humans caused megafauna extinction via hunting.

Climate change

Altered ecosystems leading to megafauna extinction.

Glacial drift

Soil and sediments deposited by glacial movement.

Biotic communities

Organisms interacting within a specific environment.

Canadian ecosystems

Ecosystems shaped by glaciation and climate.

Climate variation

Differences in climate due to latitude and altitude.

Solar radiation

Energy from the sun affecting climate patterns.

Air pressure

Decreases with altitude, influencing climate.

Plant community

Dominant vegetation type in a biome.

Terrestrial systems

Land-based ecosystems influenced by climate.

Heat Capacity

Water cools and warms slower than land.

Climate Patterns

Influenced by oceans, wind, and topography.

Rain Shadow Effect

Mountain ranges create precipitation extremes.

Air Rising

Air cools and causes rainfall over mountains.

Desert Conditions

Dry air on the leeward side of mountains.

Moisture-laden Air

Air from Pacific Ocean brings precipitation.

Cascade Mountains

Region affected by rain shadow effects.

Rocky Mountains

Mountain range influencing regional climate.

Tundra

Treeless land located above the treeline.

Tundra Origin

Derived from Finnish and Russian languages.

Climate of Tundra

Very cold, below freezing most of the year.

Seasonal Temperature Variation

Temperature changes significantly throughout the year.

Proximity to Arctic Ocean

Moderates tundra temperatures compared to inland.

Desert-like Conditions

Tundra experiences low rainfall variability.

Sunlight Variation

Day length changes seasonally in tundra.

Permafrost

Soil remains frozen most of the year.

Short Growing Season

Limited time for plant growth in tundra.

Nutrient Poor Soil

Soil lacks nutrients, limiting productivity.

Low Productivity

Tundra supports few primary producers.

Active Layer

Top soil layer thaws during summer.

Deep Permafrost Layer

Slows biological activity and root development.

Freeze-Thaw Cycle

Creates unique growing conditions and landforms.

Polygons

Landforms resulting from freeze-thaw cycles.

Solifluction

Slow movement of water-saturated soil.

Polar grassland

Tundra ecosystem with up to 100% plant cover.

Polar desert

Tundra ecosystem with < 250 mm precipitation/year.

Active layer

Top soil layer that thaws in summer.

Musk ox

Example of tundra animal with thick fur.

Arctic hare

Example of tundra animal with reduced surface area.

Caribou

Herbivorous tundra animal consuming plants and lichen.

Polar bear

Carnivorous tundra animal consuming terrestrial animals.

Arctic fox

Cold-adapted specialist with seasonal camouflage.

Arctic woolly bear moth

Hibernates to reduce metabolism when food is scarce.

Eider ducks

Tundra animals that migrate seasonally.

Alpine tundra

High-elevation biome unable to support trees.

Treeline

Elevation beyond which trees cannot grow.

Transition Zone

Area with smaller, sparsely growing trees.

Timberline

Elevation where trees form a closed canopy.

Alpine climate

Cold, windy, and dry with snow precipitation.

Growing season

Duration of 45-90 days for alpine producers.

Soil erosion

Caused by high winds in alpine regions.

Species diversity

Higher in alpine tundra than Arctic tundra.

Endemism

High rate of species found in one location.

Alpine ecosystems

Cover ~3.5% of global land area.

Flowering plant species

Alpine ecosystems host ~4% of all species.

Alpine Habitat

Cold, dry, windy environment with limited resources.

Bighorn Sheep

Ovis canadensis, adapted for mountainous terrains.

Boreal Region

Largest terrestrial biome, covers ~14% of Earth.

Taiga

Russian term for 'untraversable forest' in boreal regions.

Boreal

Derived from Boreas, god of the north wind.

Canadian Boreal

60% of Canada's land area, 75% forests.

Boreal Climate

Cold temperatures with significant seasonal changes.

Winter Temperature

Average -20°C in winter months.

Summer Temperature

Average 18°C during summer months.

Precipitation

Average 38-50 cm/year, mostly summer rain.

Continental Climate

Wide temperature range, low humidity, low precipitation.

Primary Producers

Low productivity, high standing biomass in boreal forests.

Growth Season

50-150 days above 5°C with long sunlight.

Natural Disturbances

Fire and insect outbreaks create species diversity.

Fire Adaptations

Resin sealed cones and vegetative growth in trees.

Spruce Budworm

Insect feeding on spruce tree needles.

Black-backed Woodpecker

Prefers burnt forests for foraging insects.

Wood Bison

Bison bison athabascae, adapted to cold climates.

Spruce Grouse

Falcipennis canadensis, herbivore in boreal forests.

Ermine

Mustela erminea, has seasonal camouflage adaptations.

Canada Lynx

Lynx canadensis, has snowshoe adaptations for movement.

Wood Frog

Lithobates sylvaticus, hibernates during food scarcity.

Dark-eyed Junco

Junco hyemalis, migrates to higher latitudes seasonally.