Bio Flashcards
(178 cards)
Week 8- Communities and Biomes
Community: group of species living together in a shared space at same time
6 forms of terrestrial vegetation: forest: a tree dominated assemblage with a fairly continuous canopy, ample precipitation, covers ⅓ of earth’s terrestrial surface
Woodland: a tree dominated assemblage in which individuals are widely spaced often with grassy areas or low undergrowth between them
Shrubland: a fairly continuous layer of shrubs up to several meters high Grassland: an assemblage in which grasses and forbs predominate
Scrub: mostly shrubby assemblage in which individuals are discrete or widely spaced Desert: an assemblage with very sparse plant cover in which most of the ground is bare
Deserts: have high average temperatures with low precipitation, in climogeography high temp values with short precipitation bars
High temps and high precipitation: tropical rainforests
Temperate: range of high precipitation then falls down to drier climates, seasons tell you the weather, warm + humid: summer, cold + dry: winter, loss of leaves in winter season
Arctic: low temperatures below freezing and low precipitation Marine communities:
Photic zone: uppermost layer, sunlight penetrates to allow for photosynthesis Bathyal zone: lies below photic zone, some sunlight but low light conditions occur
Abyssal zone: deepest part of ocean, temperature is very cold, and complete darkness Freshwater habitats: littoral zone: shallow nearshore area, light penetrates to bottom, supports aquatic fish and animals
Limnetic zone: open area away from shore, supports zooplankton and phytoplankton Profundal zone: deep bottom of lake, light does not penetrate, invertebrates that prefer low or no light
Benthic zone: bottom of lake, sediment and organisms live here, known for nutrient cycling and decomposition
Larger animals require more energy than small animals There are more herbivores than carnivores- true statement
Evergreen leaves advantages: photosynthesize year round, and enable plants to conserve nutrients
For what reason do temperate rainforests have few to none broadleaf deciduous trees?
There is a decrease in domination of temperate rainforests. Decidouous trees occur in the summer. There isn’t enough water for these in the temperate rainforests for them to grow.
Near-equatorial areas receive two rainy seasons in a year because of the intertropical convergence zone. Its low pressure that circles the Earth close to the equator. Its where trade winds meet, and moist air with constant rainfall.
High primary productivity in oceans: confluence of gyres near the equator, river outflows into ocean, and coastal upwelling
Near shore aquatic communities are productive because they receive nutrients from land and ocean, it filters water and buffers from oceanic storms. Near shore aquatic communities are nursing grounds for most of fish that people catch
Ecosystem: community with abiotic and biotic components and interactions Terrestrial biomes based on structure of vegetation (physiognomy)
Physiognomy: growth habitat of plants, arrangement of plants, leaf type: such as deciduous which is seasonally and evergreen is based year around, based on precipitation and temperature
Tropical rain forests- broadleaf evergreen trees, soils are nutrient poor known as latisols, light is limited here
Amazon rainforest realm: neotropic , largest rainforest , 20 ecoregions Western congolian rainforest realm: afrotropic - 1 of 6 ecoregions
- tropical rainforest in Congo basin
New Guinea lowland rainforest: 15-20,000 species of plants Most plant diverse
Major threat is deforestation: demand for resources, clearing of forests for land use loss of trees Poaching is a threat: illegal removal of plants for profit used for animal trade or resources Tropical deciduous forest: trees are deciduous (loss of leaves seasonally) in fall grows new leaves in spring
For what reason do tropical rainforests and tropical deciduous forests vary in physiognomy? They vary in physiognomy because of the difference in variation of climate and rainfall patterns Tropical rainforests: near equator warm temperatures and increased humidity- dense evergreen forests
Tropical deciduous forests: farther from equator, wet and dry seasons, lead to deciduous trees that shed leaves in dry seasons
Temperate rainforests: evergreen trees domination, needle leaves , slow growing trees Logging is a threat: deforestation and habitat loss
Why do tropical and temperate rainforests differ? Location, climate, and dominant tree species
Tropical rainforests: near equator = warm temperatures, humid, wet climates year around dominated by broadleaf evergreen trees
Temperate rainforests: has cooler areas, go through all 4 seasons, dominated by coniferous trees and high levels of precipitation
The differences are due to needles have less damage from the cold temps Why aren’t there broadleaf deciduous trees in the temperate rainforest?
Because of the climate, the temperate rainforest experiences heavy rainfall that creates humidity, deciduous trees are not able to adapt to the cold dormancy period because of their
broader leaves
Temperate deciduous forest- deciduous broadleaf trees, lots of groundcover
Boreal forest- high latitudes, cool temperatures and moist, small coniferous trees with small needle leaves
Woodlands are tree dominated with individuals that are widely spaced Tropical thorn woodland- drought deciduous thorny trees and shrubs Drier sites
Tropical thorn woodlands have deciduous trees because the trees shed their leaves during the dry season to conserve water and energy
Tropical thorn is a woodland because its less dense tree canopy and there’s a bigger space between trees not making it a forest but a woodland
Tropical savanna- less trees cover than woodlands, with perennial grasses and scattered fire resistance trees ,
Animals tend to migrate to go through seasonal grazing Abundant and diverse grazing in the world
What is the pattern of rainfall in the Serengeti, and why does it occur?
Pattern of rainfall in Serengeti is precipitation is seasonal (1 or 2 intense rainy seasons)
During the drought season, more fires, it occurs because of the Intertropical Convergence Zone, belt of low pressure around equator where trade winds occur, convergence causes the rain, and moves with seasons, where precipitation occurs the most so passes the Earth twice: twp rainy seasons
Sclerophyllous woodland- wet winters, hot dry summers, wetter regions with sandy soils (that hold less water)
Shrublands in sclerophyllous- access of water and shrubs no trees Sclerophyllous leaves- hard and evergreen
Fires happen often, plants adapted
Chaparral- sclerophyll shrublands in the Mediterranean climates, deep roots, seeds need fire for germination, fire tolerant
Grassland- between deserts and temperate forests Climate varies with seasons and years
Vegetation: grasses, tall grass in wetter locations, shorter grass in dry or the cold locations Plant growth because of fire and grazing
Deep, fertile soils many grasslands to agriculture Desert- rainfall minimal, but evaporative demand is high
Vegetation includes ephemeral with seeds that germinate with the rain and live up to weeks or months, in dry locations common w many deserts
Succulents: cactus, swell to store water, and restrict the water loss (loss of leaves) Low shrubs: have deep roots and adapt to resist water loss
Dry forest: has a period of dry season, and tropical rainforest has a period of precipitation that fluctuates
Week 9- Communities and Biomes Part 2
Aquatic communities- high specific of water, temp varies on seasonal and daily basis Classified aquatic communities: salinity, depth, and water movement and nature of substrate Body size and trophic level effect community organization
Body size- BMR (basal metabolic rate)- amount of energy needed for organism at rest Energy requirements increase w body size
Metabolic rate per unit is greater for smaller organisms
Since its accelerated it means shorter lifespans for these organisms
Storage capacity increases in linear relationship to body size
This means larger animals are able to tolerate stressful conditions
Since smaller organisms, need fewer resources for their basal energy needs: are able to use smaller areas,
Trophic levels: almost all organisms rely on sun for energy, 1st law of thermodynamics: energy is neither destroyed or created, its converted
2nd law of thermodynamics is as energy is converted, its capacity to due work is decreased Process of conversion leads to energy being released as heat
Pyramid structure of trophic levels:
Less individuals, energy, and biomass are at the higher levels 2nd law states, you cannot have more than 4-5 levels
Carrying capacity- is lower for the high trophic levels, there’s less of carnivores, larger and eat more prey species
Broad distributions
Largest animals need larger ranges
Smaller animals = support large numbers of small animals How are communities distributed?
Through spatial patterns
Transition between the communities are ecotone, can be abrupt/ gradual, more diverse then neighboring communities
Abrupt and discrete transition- intertidal zone
The distribution of tree species along a moisture gradient- is each species distribution is independent of one another
There is a typical pattern of the plant distributions
Trade offs include stress tolerance and competitive ability
Temporal patterns are development of ecosystem over space and time, then species replace one another
Disturbance removes the species, what stays is soil, seed bank, or another aspect of community remains
Species do replace each other
Temporal implications: community composition and boundaries go through change over time When structures change, species interactions do as well
NPP= net primary productivity
means how much biomass primary producers produce each year: all other organisms rely on primary producers
Open ocean and desert of tundra have similar productivity
Algal beds and coral reefs have an increased amount of productivity compared to tropical rainforests
Examples of ocean primary producers include phytoplankton, algae High productivity = nutrient availability
It will be higher at equator because of the drawing up of nutrients
High at high latitudes: allows nutrients from depth to circulate into the surface areas Marine communities are divided based on photic zone, temp, nutrients
Benthic: associated with substrate
Pelagic: live in the water column includes plankton, and swimming animals in nectonic Intertidal: is between high and low tides, goes through extreme temps and moisture
It is ecotone between marine and terrestrial Adaptations: strong shells to survive waves
Close shells to resist water loss when it’s exposed
The neritic zone is found between low tide line and the edge of continental shelf Algae beds and kelp forest: high productivity
Coral reefs: colonies of invertebrates, photic zone, low tide in tropic
Support of diversity, and under climate change threat and ocean acidification Seagrass beds- flowering plant that forms underneath meadows
Shallow and salty waters, productive systems
Deep ocean hydrothermal vents- deep ocean is dark and under pressure Includes warmth and nutrients
They have chemosynthetic (types of bacteria)
Near shore communities- salt marshes are a mixture of fresh and saltwater that go through tides Productive ecosystems (nutrients from land and ocean)
Filter water
Mangroves- trees/shrubs that grow in coastal salt waters Go through tidal changes
Excludes salt, seeds germinate branches
Freshwater swamps- forests that have deep standing water Rich soils and dominated by herbaceous plants
Flood control, water quality
Bogs and fens- wetlands that are formed on depressions in the landscapes, because of glacial ice
Bogs are high acidic
Fens are basic
Week 10: Dispersal and Immigration
Three fundamental processes of biogeography- evolution, extinction and dispersal
What impact did Alfred Wegener’s idea of continental drift (and later plate tectonic theory)
in the 20th century have on dispersal hypotheses in biogeography? The impact was a new explanation for its disjunct distribution of taxa, species were able to ride on the continents as they split and dispersed across Earth
Dispersal- studies how organisms move and spread out from one location to another, influences distribution patterns and the evolution of species
Migration-movement of species between diff geological habitats
Dispersion- spatial distribution of individual organisms within a local population
Why is it that virtually all life-forms move away from their natal sites?
-due to dispersal, moving from birthplace to new sites , like avoid competition and colonize new habitats to greater chance on fitness
Respect to dispersal, biogeographers are concerned that rariley species will shift their ranges by moving over long distance across insurmountable barriers, rare
Biogeographers study this by its hard to study use indirect evidence like
-look at dispersal as historical process + infer nature and timing of past long distance movements (distributions of living and fossil forms, and genetic similar for new isolated biotas)
For species to expand its range,
-travel to new area
-withstand the potential unfavorable conditions during the passage
-establish a viable population upon its arrival
3 dispersal events that have this result of mechanism of range expansion- jump dispersal, diffusion, and secular migration
Jump dispersal- species undergoing a long distance dispersal (movement of organisms through long distances)- happens through one or a few individuals crossing barrier through short lifespan, similarities + differences among biota , genetic isolated after dispersal
Kratatua- eruption caused removal of all existing land, study why and jump dispersal
Areas colonized through jump dispersal- Galapa and Hawaiian islands, plants and animals colonized by wind
Not all scientists believe colonization happened because of jump dispersal- other reasons is land bridges or long term history of stepping stone islands that come and go as ocean basins are developed
Long distance dispersal may have a strong selective component means special adaptations for long distance travel and successful for colonizing islands
Diffusion-slower form of range expansion involves individuals in population closer related to jump dispersal , established in new habitat = growth
Diffusion different from jump dispersal because- it can happen over generations and populations spread out from margin of species range example- cane toad, human facilitated jump dispersal
See both forms of dispersal- seen in cattle egret - large grazing herbivores , in africa
3 stages in diffusion-Invasion and range expansion occur very slowly, usually requiring repeated dispersal events and subsequent adaptations to survive in new environment
2. Once species becomes established, its geographic range expands exponentially and in a roughly symmetrical fashion
3. When the species encounters physical, climatic, or ecological barriers, range expansion slows (i.e., and distorts shape of geographic range). Ranges remain relatively stable at this point. Secular migration- In contrast to jump dispersal and diffusion (which are relatively rapid forms of range expansion), secular migration occurs so slowly that species have ample opportunity to evolve en route. Example: camels
- Very slow, occurs on the order of hundreds of generations
- There is much evidence that evolutionary divergence occurs during range expansion (i.e., species evolve en route)
- Examples: Camels and Horses originated in New World and migrated to Old World
(descendants persisted, but ancestors were extirpated from their North American homeland).
Some now extinct forms of Camels spread Southward from North America to South America; during this time, they evolved - extant products of this secu
Vagility- ability of organisms to disperse by active means ex : birds, large insects , dragonflies Pagility-ability of organisms to disperse by passive means
Passive dispersal occurs mainly in plants
- Many plants have diaspores (e.g., seeds, spores, fruits, or other plant propagules) that move away from the parent plant; Seeds that are carried by wind often have hairlike appendages or papery wings
- invertebrates, fungi, and microbes also use passive dispersal; for example, aerial plankton are small, lightweight organisms (spores, mites, spiders, insects) that are carried by wind or
sometimes enter jet streams
- Water currents and tides carry some species that are quite large (e.g., coconuts), and also disperse the pelagic larva of sedentary marine animals and coral reef fish
Exozoochory- dispersal of plants, that attach to external tissues of mobile animals Endozoochory- dispersal of plant propagules inside bodies of animals
Plausible explanation why we find same species of rodents on diff isolated mountains in American Southwest- bc glacial maximum , shift in vegetation zones
Janzen suggests elevation changes in tropics as greater barrier because tropical habitat is at low elevation and alpine habitat at high elevation
Elevation changes in temperate- lowlands deal with alpine conditions every winter and can cross over every mountain passes
Physiological barriers- Salt balance (marine vs. freshwater); the vast majority of aquatic
organisms live either in the oceans or in freshwater, and they cannot regulate their water and salt balance sufficiently to survive in the other environment., Amphibians are quite intolerant of
exposure to seawater. Likewise, many terrestrial plants are unable to withstand prolonged
exposure to seawater., Extreme temperatures can also serve as a physiological barrier (e.g., polar, temperate, tropical). For example, the Neartic family Alcidae (auks, puffins, and murres) cannot cross the tropics; another example, is that in temperate regions with seasons, some mammals can cross the ice (i.e., in the winter) to reach habitat on islands
Corridor-dispersal route permits movement of many or most species of particular taxon (one region to another)
Does not selectively discriminate against any form, and must therefore provide an environment similar to that of the two source areas
- Examples: the Tethyan Seaway (separating Africa from Eurasia) and the land bridges of Beringia, the Sunda Shelf, the Tasman Basin and Lake Erie Islands.
Filter- is a dispersal route that is more restrictive than a corridor; it selectively blocks the passage of certain forms
Filters can be identified easily since the number of species in certain taxa decreases in a regular
manner with distance from the source area
A sweepstake route- barriers that have to be crossed by such rare, interchanges EX: Hurricane Luis wind cause massive landslides
Geographic ranges of most species limited- environmental factors
Ring species- A single species becomes geographically distributed over generations in a circular (ring) pattern over a large area around a geographic barrier.
Classic example of a ring species: Ensatina salamanders
Neighboring populations in distribution vary a little but can interbreed Population at ends- cant interbreed bc genetically distinct
Past dispersal- genetic similarities
Accidental occurrence of species- outside range, migrating species (ex is jump dispersal)
Non-volant species- mammals , reptiles disperse distances by walking or swimming NOT effective: animals forced ro swim or walk through not good habitats Diaspores- seeds or fruits carried passively by wind, water, or animals
Fungi, microbes- passive dispersal Small organisms= easy passive dispersal Large organism = easily active dispersal Marine organisms disperse w current
barriers= small animals dispersing by foot
Rafting- transportation on mats of drifting vegetation, terrestrial vertebrates transport long distances Dispersal beneficial- reduced competition with relatives
What type of dispersal involves extensive evolutionary change during the migration process?
secular migration
Jump dispersal is likely to lead to which of the following mechanisms of speciation? genetic
bottleneck , founder effect
Week 11: Speciation
What chromosomal changes may lead to speciation?
