Lecture 17/18/19/20: Biosphere/Biomes Flashcards
what is the biosphere? what does it include?
it is the global ecosystem, the sum of all the planets ecosystems. includes every place where life exists:
- entire portion of Earth inhabited by life
- ranges from the atmosphere to the deep sea and rocks underground
what is “dispersal”?
when organisms move away from crowded areas or their birthplace to new areas
how does understanding dispersal help scientists?
helps them learn about how species are spread out and how they evolve in isolation
How do scientists test dispersal?
scientists look at cases where humans have accidentally or purposely moved a species to a new area
what makes a dispersal successful? what does it mean if its successful?
the species must survive and reproduce in the new location.
- successful dispersal means that the species could live in a wider area than it currently does
why do scientists study accidental cases of dispersal instead of purposely moving species around?
moving species to new places can disrupt local ecosystems
what contributes to the distribution of organisms?
behaviour and habitat selection
sometimes animals don’t spread to all the places they could live: instead, they _____
pick specific areas
what factors affect where organisms can survive/live?
- biotic/abiotic factors
- such as the absence of other important species
- variation in water availability among habitats
what makes it harder for organisms to survive and reproduce?
negative interactions such as being hunted, getting diseases, or competing for resources
why do scientists sometimes remove predators from certain areas?
to see how it affects where prey species can live
most aquatic organisms are restricted to what environments?
freshwater or marine environments
how is temperature important in where an organism can live?
because it affects how organisms’ bodies work (biological processes).
- very few organisms can maintain an active metabolism in extreme heat/cold
terrestrial organisms face a nearly constant threat of what?
of desiccation (drying out) and have adaptations to allow them to obtain and conserve water
what does “photoperiod” mean?
the relative length of daytime and nighttime
what limits the distribution of photosynthetic organisms in aquatic environments?
light intensity
why does most photosynthesis in aquatic environments occur near the surface?
because theres more light near the surface. with every meter down, water absorbs a lot of red light and only a tiny bit of blue light
what provides the energy that drives nearly all ecosystems?
sunlight
why do some plants compete for shade?
in forests, tall trees create shade and the plants underneath have to compete for light
how does wind amplify the effects of temperature?
wind makes temps feel more extreme by speeding up heat loss through evaporation:
- For animals, wind cools them down faster by taking away body heat and moisture.
- For plants, wind causes them to lose water more quickly as it speeds up the process of water evaporating from their leaves.
in streams and rivers, what affects the water chemistry?
the substrate composition (the type of ground like sand and rocks)
what creates variety in land ecosystems?
3 examples, how does it affect the land?
- the physical structure
- acidity (pH)
- minerals in soil and rocks
affects where plants can grown and in return affects animals that rely on those plants, creating variety
what does “climate” mean?
it is the prevailing weather conditions in an area
what are the major components of climate?
- Temperature
- Water
- Sunlight
- Wind
what are the 2 scales that describe climate patterns?
- Macroclimate
- Microclimate
what levels are MACROclimate patterns on?
they are on global, regional, and local levels
what is a MICROclimate?
a small area with its own unique climate conditions, like under a tree or a rock (very fine patterns)
climate determines…
the makeup of biomes
what are biomes?
the major types of ecosystems
how are the global climate patterns determined?
by sunlight and Earth’s movement in space
What factors cause regional differences in climate? 2
- bodies of water
- topographic features (such as mountain ranges)
how do ocean currents influence climate along the coast?
by heating or cooling the air above the ocean currents which moves along the lands along the coasts
coastal areas are usually more _____ than areas inland
humid (moist)
how do oceans and big lakes help the climate?
helps keep the climate more balanced in nearby areas and makes heat less extreme
what happens to cool/dry ocean breezes in certain regions?
they are warmed when they move over land and absorb moisture. This creates a hot/rainless climate inland
in the northern hem, which facing slope receives more sunlight, north or south? what does this mean?
south-facing slopes, creates warmer and drier climates
mountains change how much ______, _____, and _____ different areas get.
sunlight; heat; rain
as you go up a mountain, it gets…
colder
what happens when warm wet air comes towards a mountain? what side does the rain fall on?
- the air is pushed upward by the mountain
- as it rises, it cools down, and the moisture in the air turns into rain
- the rain falls on the windward side (the side of the mountain facing the wind)
what happens after the rainfall on a mountain (when the air loses its moisture in rain)? what does it create?
- its moves over the top of the mountain and down the other side, becoming dry and warm
- this creates a rain shadow on the leeward side
what is a rain shadow?
a dry area on the opposite side of the mountain
where are desserts or dry regions often found (which side of mountain)?
the leeward side of mountain ranges
what do seasonal changes in wind patterns influence?
- ocean currents
- sometimes bringing cold, nutrient-rich water up from deep in the ocean
in summer and winter, many lakes form…
layers of water at different temperatures
in spring and fall, lakes go through a…
turnover where the water mixes
what happens during a “turnover” in lakes?
the water mixes, switching oxygen to the bottom and nutrients to the surface
what do scientists look at to understand today’s climate changes?
they look at what happened after the last Ice Age
what happened as it got warmer (Ice Age)?
the glaciers melted and trees spread farther north
how do scientists track where the trees spread over time?
they look at fossil pollen found in lake and pond sediments
scientists can guess how a species’ range will change with global warming by…
studying its current climate limits
How can we tell if trees will keep up with climate change?
Check if they can spread their seeds fast enough.
what are the two types of aquatic biomes?
- Freshwater: lakes, wetlands, streams, rivers
- Marine: coral reefs, open zone (pelagic zone), coastal areas (intertidal zones), ocean floor (marine benthic), and estuaries
what are estuaries?
areas where freshwater mixes with saltwater (areas of transition between river and sea)
how do scientists separate freshwater and marine biomes?
based on their salt levels. marine biomes have higher salt levels
what type of aquatic biome has more salt in it, marine or freshwater?
marine, about 3% salt
where is the majority of earth’s water?
oceans. they contain about 97% of earths water
which biomes occupy the largest part of the biosphere?
aquatic biomes
what creates most of Earth’s rainfall?
water evaporating from oceans
which organisms in marine biomes help produce much of earth’s oxygen?
algae and photosynthetic bacteria
What are freshwater biomes connected to as they flow through their environments?
the surrounding soil and living organisms
what is the photic zone?
the open water zone at the top of the water, has enough light for plants to do photosynthesis
what is the aphotic zone?
the deep water zone near the bottom, much darker, very little light
what is the benthic zone?
the substrate at the bottom of any aquatic biome
the benthic zone is home to organisms called…
benthos
what do benthos feed mostly on?
detritus (dead organic material) that falls down from the water above, the photic zone
what is the littoral zone?
the shallow, well-lit, nearshore area of a lake/pond/ocean
how are layers of temperatures in lakes created?
sunlight heats the top layer of water but deeper layers stay cold
how is community distribution determined in aquatic biomes?
What decides where communities live in aquatic biomes?
- the depth of the water
- distance from shore
- open water vs near bottom
how do oceans impact global climate and winds?
through their temperature, which influences both
why does light fade as you go deeper underwater?
because water absorbs and scatters sunlight, making less light reach the deeper layers.
what is the name of the layer that separates warmer surface water from colder deeper water?
the thermocline
where do most plankton and many fish live in marine environments?
in the photic zone (upper layer)
What’s the main difference between a lake that is oligotrophic and one that is eutrophic?
Oligotrophic lakes have clear, nutrient-poor water, while eutrophic lakes are foggy looking and nutrient-rich.
Where in a lake would you find the most plant growth?
In the shallow, sunlit area near the shore, called the littoral zone.
Why are wetlands considered highly productive?
They support a wide variety of species and have rich soil and water nutrients
What type of freshwater bodies move continuously in one direction?
Streams and rivers
Where do streams and rivers start?
In cold, clear areas called headwaters.
What is a unique feature of the intertidal zone?
It is regularly submerged and exposed by tides
where do most glowing fish live?
the aphotic zone
what are oligotrophic lakes?
they are deep, lack nutrients, lots of oxygen, good water clarity, and little life
what are eutrophic lakes?
shallow, lots of nutrients, less oxygen, less clear water, more life, highly productive
what is the limnetic zone?
the open surface water
what are mesotrophic lakes?
moderate in nutrients and oxygen, with a balanced amount of life
what does open surface water refer to?
refers to the area of a lake or ocean away from the shore, and close to the surface. well lit
what are wet lands?
areas covered with sufficient water to support aquatic plants
what do wetlands include?
marshes, bogs, and swamps
why is the water and soil of wetlands low in dissolved oxygen?
- high organic production
- still or slow-moving
- the decomposition of organic matter uses up oxygen
what are headwaters?
the beginning or source of a river/stream. they are cold, clear, turbulent and swift
What mainly determines nutrient content in headwaters?
the terrain and vegetation of the area
what is the oceanic pelagic biome?
the open, deep water in the middle of the ocean, away from the coast, where currents keep it in constant motion
the open ocean has ___ oxygen levels and ____ nutrient levels
high; low
where do coral reefs grow? which zone?
in clear, warm tropical waters with lots of sunlight. PHOTIC ZONE
what lives inside corals and helps them grow?
mutualistic algae
how are coral reefs threatened?
4 examples
- collecting
- overfishing
- pollution
- global warming
what is the marine benthic zone?
the seafloor below the surface waters. ground is covered by sand, rocks, or mud. most of it is in complete darkness
what is the abyssal zone?
deepest parts of the ocean, around 3-6,000 m below ocean surface
- high water pressure
- no sunlight
- very cold
what are the primary producers called in benthic zone communities?
chemoautotrophic prokaryotes
what are chemoautotrophic prokaryotes? how do they support other life forms
bacteria and archaea that make their own energy from chemicals rather than sunlight.
- they use chemosynthesis
- support others by providing energy
what is a climograph?
a chart that shows the average temperature and precipitation for an area throughout the year
what is stratification?
the layering of plants in an ecosystem, creating different habitats that support various species
EX:
- canopy in a forest (top layer)
- grass layer in a grassland
what is the ecotone?
the area of intergradation
- transition area between two different ecosystems/biomes
- ex: space between a forest and a grassland
what are coral reefs formed by?
the calcium carbonate skeletons of coral animals
in many biomes, the dominant plants depend on ______ ________
periodic disturbance
what is more the norm in nature, change or stability?
change
how do hurricanes help create habitats in a way?
they can clear spaces for new plants
how does snow help create new plants?
snow in forests breaks branches and lets other plants grow in gaps
why are natural events like wildfires essential in areas like grasslands, savannas, chaparral, and forests?
many plants need them to grow
the major terrestrial biomes include… (8)
- tropical forest
- desert
- savanna
- chaparral
- temperate grassland
- coniferous forest
- temperate broadleaf forest
- tundra
where are tropical forests found?
close to the equator
in which terrestrial biome is animal diversity the highest in?
tropical forests
what does the vegetation include in deserts?
sparse, includes succulents like cacti and deeply rooted shrubs
where are deserts found?
in a band near 30° N and S latitudes, and in the interior of continents
where are savanna’s found?
equatorial and subequatorial regions
do deserts have rain?
low rainfall, highly variable
does the savanna have rain?
yes, seasonally
many desert animals are ______. why?
nocturnal; so they can avoid the heat
what does the savanna vegetation consist of?
grassland with scattered trees
what element is important in maintaining savanna biomes?
fire
what animals are commonly in the savanna?
large herbivorous mammals
is there rain in chaparrals?
yes, highly seasonal precipitation
what does the vegetation look like in chaparrals?
- shrubs
- small trees
- high diversity of grasses and herbs
what makes temperate grasslands ideal for agriculture?
deep fertile soils
what have most grasslands in North America and Eurasia been converted to?
farmland
What role do natural disturbances play in maintaining biomes?
They create gaps for new species and maintain ecological balance, as seen in forests with hurricane disturbances or grasslands with wildfires.
What distinguishes temperate broadleaf forests from coniferous forests?
Temperate broadleaf forests have more diverse plant and tree species that lose leaves seasonally, while coniferous forests are dominated by evergreen trees
Why do deserts have low vegetation density?
The limited and unpredictable rainfall supports only sparse vegetation adapted to conserve water
What is the main factor that creates patchiness in biomes?
Natural disturbances, like hurricanes or wildfires, create patches with different plant and animal communities
How do chaparral plants adapt to frequent fires?
fire-resistant seeds or can quickly regrow after a fire
How does periodic flooding benefit certain biomes?
Flooding deposits nutrients and supports plant growth, especially in biomes like wetlands
Why is high water clarity important for coral reefs?
Clear water allows sunlight to reach the algae within coral, which need light for photosynthesis
what is the biggest land biome on Earth called?
the Confierous Forest, aka Taiga
what are the seasons like in the Coniferous forest?
long and cold winters
short and wet summers
what is destroying these coniferous forests quickly? what may happen?
logging.
- old trees might disappear soon
where is taiga found on Earth?
northern parts of earth. Ex: Canada, Russia, Ireland
what kind of seasons do the Temperate Broadleaf forests have?
- cold winters
- hot summers
- plenty of rain
what is a “canopy”? what does it do?
the upper layer of trees in a forest, formed by their branches and leaves.
- blocks sunlight from reaching the ground
- creates shade
what does a deciduous tree (in the Northern Hemisphere Broadleaf Forest) do in the winter? why?
drops their leaves and becomes dormant (inactive, resting state).
- this helps them save their energy
what do animals do in temperate broadleaf forests during winter months?
hibernate or migrate to warmer climates
how much does the Tundra cover of Earth’s land surface?
20%
what is the “tundra”? (location, seasons, animals, vegetation)
a cold biome that covers big parts of the arctic:
- found in arctic regions near north pole
- extremely cold, long winters and short, mild summers
- permafrost is common and restricts plant roots
- small plants, like mosses, grasses, lichens, and tiny shrubs
- inhabits musk oxen, caribou, reindeer, migratory birds
what are the differences between tundra and alpine tundra?
tundra is cold because of its location near the poles, whereas alpine is cold because of its elevation on mountains.
what is “the alpine tundra”? (location, seasons, animals, vegetation)
cold biome found at the top of mountains:
- found on high mountains all over the world
- cold temperatures but due to latitude (not longitude)
- not permafrost but soil is very thing and rocky
- small plants, like mosses, grasses, lichens, and tiny shrubs
- fewer large animals live there year round
why do birds use the tundra in summer?
for nesting
do a lot of people live in the arctic tundra?
no- sparsely settled by humans
what has the focus become in arctic tundra recently?
mineral and oil extraction (drilling)
what is “population ecology”?
the study of populations in relation to the environment, including environmental influences on the population (such as density, distribution, age structure, and size)
what is a population?
a group of individuals of a single species that live in the same general area
why do members of a population have a high likelihood of interacting with and breeding with one another?
because they use the same resources and face the same environment
how can populations change over time?
by natural selection.
- as individuals with helpful traits survive, reproduce, they pass those traits to future generations, making them more common.
what are the population characteristics? 2
size and geographical boundaries
in what ways could a population be spaced out as a group (dispersion)? 3
- uniform (penguin)
- random (flowers)
- clumped (elephant herd)
what is “population density”?
number of individuals that are in a given space (per unit area or volume)
what is the “dispersion of a population”?
how individuals are spread out in a given area
why do ecologists normally estimate population density/size?
its impractical to count every individual in a population
how do ecologists estimate population density/size?
they use sampling methods:
- like counting individuals in a random small areas and averaging the results to extrapolate the population size in the entire area
when does the sampling method work best (for ecologists when estimating population size/density)?
when the habitat is similar throughout (homogeneous habitat)
what is a homogeneous habitat?
when the habitat is similar throughout
what is the mark-recapture method?
a sampling technique
- trap and tag animals, record them, and let them go
- later on, traps are set again to see how many are tagged/untagged
- this helps estimate population size
- assumes tagged/untagged animals are equally likely to be trapped, but this may not be true always
what do the values represent in the following formula: N = [M x S]/R
N = population size estimate
M = marked individuals released
S = size of second sample
R = marked animals recaptured
how does a population grow? 2
- birth
- immigration (movement of individuals into a population)
how does a population decrease? 2
- death
- emigration (movement of individuals out of a population)
what does immigration and emigration represent? what could it create?
exchanges between populations (gene pool exchange)
- creates mutations
what causes/changes population density?
cause and change used interchangeably
the addition or removal of individuals
some populations are described by ____ _____
hint: area
geographic range
what does “geographic range” mean?
the area inhabited by a species, can vary greatly depending on species
what does “least concern” mean in relation to geographic range?
“Least concern” means a species is not at risk of extinction and has a wide or stable geographic range.
what does “vulnerable” mean in relation to geographic range?
limited area, at risk of threats
what does “critically endangered” mean in relation to geographic range?
extremely small or fragmented range, super high risk of extinction
what are important population characteristics? what does it provide? 1
- variations in local density
- provides insights into environmental and social interactions
how a population is spaced out is called population _______.
dispersion
why would a population be clumped?
b/c
- able for their growth (micro organsims)
- effectiveness of certain predators (wolves)
- mating reasons
when does dispersion “uniform” occur?
when individuals are evenly spaced
- ex. birds
- ex. some plants. secrete chemicals that disallow other competitors to grow near them
why would a population be uniformly dispersed?
- territoriality
- avoid overcrowding
- competition for resources
- ensure access to food and mates
what is random dispersion of a population?
the distribution was random/unpredictable.
- how/why they got there was random
- ex. wind blowing plant seeds
are random patterns common in nature?
no
what is demography?
the study of the vital stats of pops and how they change over time
- birth/death rates
- looks specifically at females
- looks at factors that affect the density/dispersion patterns
what is a “life table”?
CHAT: shows how a population survives at different ages
SLIDE: age specific summary of the survival pattern of a population
what is the best way to construct a life table?
to track a group of same-age individuals from birth until they pass away
what is a cohort?
a group of same-age individuals
what are people really interested in when looking at the life table?
the curves generated from that data
what are survivorship curves?
a graphic way of representing the survival data in a life
CHAT:
- graphs that show how many individuals in a population survive at different ages. They help us understand patterns of survival, like if most die young, live long lives, or die evenly over time.
what are the 3 types of survivorship curve? what do they look like? what do they mean?
- High:
- relatively flat at the start then drops steeply as age gets bigger (looks like an N)
- fewer offspring (babies) and provide significant care to ensure longer survival - Steady:
- constant mortality over time
- diagonal line downwards
- don’t have a higher risk of dying at any specific age but instead face consistent challenges throughout their lives - Low:
- drops slowly at the start, then flattens out (looks like a L)
- rely on producing large numbers of offsprings (babies) to ensure some survive in challenging environments
- little parental care
who follows the type 1 line (high survivorship)?
large mammals, primates, and humans
who follows the type 2 line (steady survivorship)?
rodents, invertebrates, annual plants, birds, reptiles
who follows the type 3 line (low survivorship)?
fishes, long-lived plants, marine invertebrates, insects, amphibians
a “stair-stepped” survivorship curve is often seen in crabs due to mortality during molts. T or F?
T
how do I create a life table?
count how many individuals die at each age and figure out
what does stair-stepped curve mean?
higher changes of dying during molting (when they shed their shell)
what determines population size when there’s no immigration or emigration?
reproductive rates
why do studies usually focus on females?
since they give birth to offspring
what does a reproductive table show?
how many offsprings females produce at different ages
what processes add individuals to a population?
birth and immigration
what type of dispersion pattern occurs when individuals are evenly spcaed?
uniform
which of the following best describes a type 1 survivorship curve: a) High death rates early in life, then stable survival
b) Constant mortality throughout life
c) Low death rates in early and middle life, then steep decline
d) Unpredictable survival patterns
C
in random dispersion, the position of individuals is influenced by:
no strong interactions among individuals
immigration and emigration have no impact on population size. T or F?
F
which dispersion is the most common pattern in nature?
clumped
Which of the following is NOT a key process in population density?
a) Immigration
b) Emigration
c) Mortality
d) Adaptation
D
Which factor can increase a population’s geographic range?
a) Increased reproduction rates
b) Habitat expansion
c) Competition for resources
d) High mortality rates
B
Population density only decreases through emigration. T or F?
F. also decreases with mortalities
what does emigration mean?
refers to individuals leaving a population or moving to another location. removing
what does immigration mean?
refers to individuals moving into a population from another location. adding
whats the diff between immigration and emigration?
IMM:
individuals move INTO a population = + size
EM:
individuals move OUT of a populations = - size
