characteristics shared by a lineage irrespective of environmental factors

i.e. Marsupial mode of repro; early birth and subsequen development of young in a pouch. THINK PIPPY!!!

movements of the continents over time

have 2 important ecological consequences:

- positions of continents and ocean basins influence climate

-continental drift creates and breaks barriers to dispersal

REMEMBER PANGAEA, GONDWANA, LAURASIA, ETC.

splitting of a widely distributed ancestral population by continental drift

i.e. flightless ratite birds (ostriches, kiwis, emus, etc.) all present in the southern continents and come from a common ancestor present on Gondwana

occur in the northern hemisphere of both North America and Asia

combines molecular phylogenetic techniques with ecology and paleobotany to understand disjunction

gradual cooling of earth over last 2 million years led to violent changes in climate, and resulted in an ice age

i.e. migrations of trees in eastern NA from 18k years ago to present. Compositions of communities shifted as species migrated across the landscape

occurred at intervals of 10 to 100 million years.

-disrupt ecosystems and change course of community dev.

-may also: eliminate species thus reducing diversity; faster evolutionary responses to new conditions; create opportunities for dev. of new biological associations

process by which unrelated species living under similar ecological conditions come to resemble one another more than their ancestors did:

i.e. woodpecker-like birds fill the niche of the woodpecker in many systems that lack the woodpecker

-similar body forms of dolphins and penguins which both resemble tuna

category that groups communities by dominant life forms and environment

In general: biome=dominant life form + environment

For terrestrial systems: biome= dominant plant life + climate

temperate saltmarshes and grasslands:

-both dominated by same plant form

-two very different environments

climate!

-defines boundaries of terrestrial biomes

takes into account temp. and precip.

recognizes 9 zones

relates major biomes to annual temp. and precip.

-the "triangle"

-3 zones: equatorial and tropical climate zones: (20-30^oC) (0-400+ cm/yr)

Temperate climate zones (5-20^oC)(0-300+cm/yr)

Boreal and polar climate zones (<5^oC)(below 200cm/yr)

-located within ~20^oC of equator

-daily temp. variation exceeds monthly variation through the year

-environments are largely distinguished by differences in seasonal pattern of rainfall

-frost not a factor

Climate continually warm and moist:

-precip in excess of 200+ cm/yr

-occupies Central/S. America, W. Africa, Indo-Malayan Region

-exceedingly diverse forests dominated by evergreen or deciduous broad-leaved trees, featuring lianas and epiphytes

plant growing on another plant

-as in rainforest orchids and such.

-climate seasonally dry, but has sufficient moisture to support forests

-occur worldwide within tropics but typically found 10^oN or S of equator

-predominantly deciduous species

-grasslands with scattered trees: typical of large areas of semiarid tropics, especially high-elev. in E. Africa

-Strongly seasonal rainfall: 90-150cm/yr but driest 3-4 mos. receive less than 5 cm each.

-fire and grazing play important roles in mtnce.

Highly variable systems found under extreme aridity:

-develop at 20-30^oN and S

-rainfall sparse, often highly seasonal

-creosote bush common in subtropical American deserts along with cacti, shrubs and small trees

-typically have summer rainfall, with high species diversity, prominent annual flora

Characterized by temps between 5-20^oC at low elevs. with frost throughout the zone:

found between 30-40^oN in N. America and between 40-60^oN in Europe

-biomes differentiated by: total amts. and seasonality of precip.; length of frost-free season or growing season

develops primarily in warm temperate climates

-mild winters, heavy winter rains, summer fogs common

-found principally in the NW US, adjacent British Columbia, S. Chile, New Zealand, Tasmania

-Vegetation Dominated by tall evergreen trees, like Douglas fir and coast redwood:

-not as diverse as its tropical counterparts

Develops under moderate climates with winter freezing:

-growing season is 130-180 days

-precip exceeds evapotranspiration

-Found principally in E. N. America, Europe, and E. Asia

-Vegetation dominated by deciduous trees with understory of small trees and shrubs, often abundant herbs.

Develops in Medterranean-type climate (cool, wet winter, warm dry summer)

-fires frequent and most plants adapted as such

-Typically found at 30-40^o, west coasts, common in southern Europe, S. California

-Vegetation is dominated by sclerophyllous evergreen shrubs

Found in continental climate zones:

-summers hot and wet; winters cold

-growing season 120-300 days

-fires dominant and plants adapted as such

-extensive grasslands develop called prairies in N. America, and steppes in C. Asia.

-Vegetation dominated by grasses and forbs

-winters cold and summers hot

-precip 25-50cm/yr

-fires infrequent b/c of low fuel accumulation

-grazing can exert strong pressure on vegetation

have average temps <5^oC

-Boreal Forest (taiga) develops between temps of 5 to -5^oC

-Tundra develops at temps below -5^oC

Climate extremely cold, with temps as low as -60^oC in winter:

-avg annual temp below 5^oC; precip 40-100cm/yr

-growing season 50-100 days

-boreal forest centered on broad belt at 50-60^oN across N. America and Eurasia

-Also called taiga, vegetation of low diversity dominated by evergreen needle-leaved trees

-exceedingly cold climate, with brief, but active growing season in summer:

soils are permanently frozen, thaw to depth of 0.5-1m during brief summer growing season

-precip less than 60cm/yr but soils may be saturated because of impeded drainage

-found at high latitudes, north of boreal forest belt

-treeless expanse of dwarf, prostrate woody shrubs

-aka lotic systems: form wherever precip exceeds evaporation, draining excess water

-divided into 3 principal habitats:

-riffles

-runs

-pools

idea that streams exhibit continuous change in conditions from headwaters downstream

-streams exhibit downstream drift of organisms/material

-aka lentic systems: form in any kind of depression (typically effects of glaciation or geological activity)

-Divided into 3 principal habitats:

-littoral zone

-limnetic zone

-benthic zone

special environments at the mouths of rivers, especially where outflow is parially enclosed (such as barrier islands)

-unique because they are the interface between fresh and salt water habitats:

-typically highly productive because of influx of nutrients and their rapid exchange between sediments and surface waters

-often edged by extensive tidal marshes with emergent vegetation

enormously complex systems with conditions varying with temperature, depth, current, substrate, tides

-Classified according to depth:

-littoral zone (btwn high and low tides)

-neritic zone (beyond low tide to edge of cont. shelf, often subdivided into photic and aphotic zones, typically productive)

-oceanic zone (deeper waters, also divided into photic and aphotic zones but typically unproductive)

-benthic zone (sea floor of neritic and benthic zones)