Adaptations to environment Flashcards
Define habitat.
A habitat is the place where an organism lives.
What does a single habitat typically contain?
Any one habitat will contain many species which together form a community.
What are the two main ways to describe habitats?
Habitats can be described in terms of:
- Geographical location
- Type of ecosystem
Give an example of a habitat described by geographical location.
A polar habitat is located at the North and South Poles.
Give an example of a habitat described by ecosystem type.
A grassland habitat occurs in many locations, including prairies in North America and Savannahs in Africa.
List four different types of habitats shown in the images.
- North American grassland
- Arctic polar habitat
- Sahara desert
- UK wetland
How can the description of a species’ habitat include both geographical and physical locations?
A habitat description can include the specific geographical area (e.g., North America) as well as the physical features of the location (e.g., prairie grassland).
How does the concept of ecosystem relate to habitat in this context?
The type of ecosystem (e.g., grassland, desert, wetland) is used to describe and categorize different habitats, even when they occur in different geographical locations.
What are abiotic factors?
Abiotic factors are non-living factors that affect organisms within their habitat.
List 8 examples of abiotic factors.
- Light intensity and wavelength
- Temperature
- Turbidity (cloudiness) of water
- Humidity
- Soil or water pH
- Soil or water salinity
- Soil composition
- Oxygen or carbon dioxide concentration
What are three abiotic factors in sand dune habitats?
- Low water availability
- High salinity
- Low nutrient levels
What is a xerophyte?
A xerophyte is a plant adapted to survive in dry conditions.
What challenges do xerophytes face in dry conditions?
- Steep concentration gradient between leaf interior and surrounding air, causing rapid water evaporation
- Low soil water availability, making it difficult to replace lost water
How do marram grass leaf adaptations help reduce water loss?
They raise the humidity of the air surrounding the leaf, reducing the steep concentration gradient and thus reducing water loss by evaporation.
List four adaptations of marram grass leaves to reduce water loss.
- Leaves are rolled up to reduce surface exposure to wind
- Stomata are sunken in pits to trap water vapor
- Inner surface of the leaf is covered in tiny hairs to trap water vapor
- Thick waxy cuticle on outer surface to reduce evaporation
What are three abiotic factors in mangrove swamps?
- High salinity
- Low fresh water availability
- Low oxygen availability (due to being underwater)
List three challenges mangrove trees face with roots submerged in sea water.
- Underwater root cells unable to take in oxygen for respiration
- Low availability of fresh water due to surrounding salt water
- Risk of losing water from submerged roots by osmosis due to higher solute concentration in sea water
How do mangroves adapt to low oxygen levels?
Mangroves have some form of aerial root system; the parts of the roots above water take in oxygen for respiration.
What are prop roots in red mangroves?
Prop roots are partially underwater root networks that:
- Provide stability in unstable soil
- Take in oxygen for respiration
- Provide crucial shelter for marine animals
What are pneumatophores in black mangroves?
Pneumatophores are structures that grow vertically upwards out of the water-logged soil to take in oxygen.
How do red mangroves deal with low fresh water and high salinity levels?
Red mangroves have cells that:
- Do not allow the entry of salt into their water-transport systems
- Allow the trees to take up fresh water
- Prevent the outward movement of water, avoiding water loss by osmosis
How do black mangroves manage salt levels?
Black mangroves:
- Take salt water into their cells
- Excrete excess salt through salt glands in their leaves
What are the challenges mangrove trees face with their roots submerged in sea water?
Mangrove trees grow with their roots submerged in sea water, so they face challenges such as:
- The cells of the roots that are underwater are unable to take in oxygen for respiration
- The surrounding salty water means that the availability of fresh water is low
- The surrounding sea water has a higher solute concentration than the contents oft he
mangrove root cells, so there is a risk of the mangrove roots losing water from its
submerged roots by osmosis
Define abiotic factors and their influence on species distribution.
Abiotic factors are non-living factors in the environment that can influence the distribution of species.
List 7 abiotic factors and their effects on living organisms.
- Light intensity: Required by plants for photosynthesis
- Temperature: Affects rate of enzyme-controlled reactions
- Water availability: Required by all living organisms for survival
- Soil pH and mineral content: Different plant species require different pH levels and nutrient concentrations
- Wind speed: High winds can increase water loss by evaporation from plant leaves
- Carbon dioxide concentration: Needed by plants for photosynthesis
- Oxygen concentration: Needed by organisms for aerobic respiration
How can abiotic factors act in a habitat?
Abiotic factors in a habitat can act as limiting factors for species distribution.
Define “range of tolerance” for species.
The range of tolerance is the range within which environmental conditions are tolerable for a species. Certain conditions are ideal (optimum), but some variation from these ideal levels can be tolerated.
Give an example of a species’ range of tolerance.
Mangrove trees grow best in a salinity range between 3-27 parts per thousand (ppt), but they can survive in fresh water and in salt concentrations of up to 75 ppt.
What happens when abiotic conditions are outside a species’ range of tolerance?
Species will not be found in areas with abiotic conditions that are outside their range of tolerance.
How do species adapted to extreme conditions differ in their range of tolerance?
Species adapted to extreme conditions may have an especially wide range of tolerance, allowing them to live in areas where other species cannot survive.
How does the environmental optimum of extreme species compare to average species?
Extreme species will often have an environmental optimum that is higher or lower than average. For example, marram grass has a lower optimum level for water availability than other plant species.
How do extreme species perform in extreme environments?
These extreme species will do well in extreme environments where competition from other species is low.
How might extreme species perform in moderate environments?
Such extreme species may do less well in more moderate environments due to competition from species with an average environmental optimum.
What will species have a range of tolerance for?
Species will have a range of tolerance for all abiotic factors, and while some factors may have a
more significant effect than others, the abiotic factors interact to determine the distribution
of a species
What is a limiting factor in ecology?
Any biotic/abiotic factor that restricts organism growth and determines species distribution (e.g., soil water levels, temperature, light intensity).
Define range of tolerance.
The environmental conditions (e.g., salinity, temperature) a species can survive within, bounded by critical minimum/maximum thresholds.
How do limiting factors affect species distribution?
Species cannot survive outside their range of tolerance for a limiting factor (e.g., plants die if soil water is too low).
What is a transect?
A linear sampling method to measure species abundance/distribution along an environmental gradient (e.g., from wet to dry soil).
Name the 4 types of transect studies.
- Continuous line transect
- Interrupted line transect
- Continuous belt transect
- Interrupted belt transect
How does a continuous belt transect work?
Quadrats are placed end-to-end along a tape measure to sample all species within them across a habitat.
What is the purpose of interrupted belt transects?
Quadrats are placed at regular intervals (e.g., every meter) to sample species distribution efficiently.
Why is sampling used in transect studies?
It saves time by representing large areas with small measurements, avoiding counting every organism.
What abiotic variables can sensors measure in transect studies?
Temperature, light intensity, soil pH, humidity, or salinity (per syllabus).
What is a semi-natural habitat?
Human-influenced areas dominated by wild species (e.g., hedgerows, unmanaged grasslands).
How to investigate soil water’s effect on plant distribution?
Set a transect along a water gradient, measure abundance at intervals, and correlate with soil moisture data.
Why must samples be representative?
To ensure data reflects the whole habitat (avoids bias; requires large sample size).
What does a kite graph show?
Species abundance changes along a transect; width = abundance at each point (e.g., rocky shore zonation).
What is an environmental gradient?
Gradual change in an abiotic factor (e.g., elevation on a shore, soil pH across a field).
How do zones of stress differ from zones of intolerance?
- Stress: Species survive but with reduced reproduction.
- Intolerance: Species cannot survive.
Example of a species’ range of tolerance.
Mangroves tolerate 3–27 ppt salinity (optimal) but survive 0–75 ppt (full range).
How does gene flow affect range limits?
Introduces maladaptive traits at edges, reducing survival (soft limit per search result).
What role do quadrats play in transects?
Rectangular frames to quantify species density at set intervals (e.g., every 5m).
Why use interrupted line transects?
Record species touching the tape at intervals (e.g., every meter) for efficiency.
What does Shelford’s Law of Tolerance state?
Species have optimal survival conditions between critical min/max thresholds (supports range of tolerance concept).
What instrument is used to measure humidity?
A hydrometer, an electronic device that measures water vapor content of air.
How is water turbidity measured?
Using a turbidity meter to measure scattered light, or a Secchi disc lowered until no longer visible.
What is a kite diagram used for in ecological studies?
To visually represent both distribution and abundance of species along an environmental gradient.
How is soil water content determined?
By calculating the difference in mass between a wet soil sample and the same sample after drying.
How is species abundance shown in a kite diagram
By the width of the ‘kite’ around the central horizontal line.
What additional information can be added to kite diagrams?
Changes in abiotic factors at different points along a transect, e.g., height above sea level or soil pH.
What is a coral reef?
A coral reef is formed by the calcium carbonate secretions of thousands of individual coral polyps over time.
Describe the symbiotic relationship in corals.
Corals result from a symbiosis between:
- Coral polyp (animal): provides shelter and protection
- Zooxanthellae algae: carries out photosynthesis and produces carbon compounds like carbohydrates
Where are reef-building corals primarily distributed?
Reef-building corals are limited to the tropics and subtropics.
List five abiotic factors that limit coral reef formation.
- Water depth
- pH
- Salinity (salt concentration)
- Water clarity
- Temperature
How does coral’s range of tolerance affect its distribution?
Coral has a narrow range of tolerance for all these abiotic factors, resulting in its limited distribution.
Why is water depth important for coral reef formation?
Corals need shallow water for light penetration, as their symbiotic algae require light for photosynthesis.
How does pH affect coral reef formation?
Corals require slightly alkaline water (pH around 8.0-8.3) to form their calcium carbonate structures effectively.
What salinity range do most coral reefs require?
Most coral reefs require a salinity range of 32-42 parts per thousand.
Why is water clarity important for coral reefs?
Clear water allows sunlight to penetrate, which is crucial for the photosynthetic activity of the zooxanthellae algae.
What temperature range do most coral reefs require?
Most coral reefs require water temperatures between 20-28°C for optimal growth.
How does water depth affect coral reef formation?
Corals can only grow at shallow depths where light can penetrate the water at high enough levels for the zooxanthellae to photosynthesise.
How does pH affect coral reef formation?
The hard outer layer secreted by coral polyps is made from calcium carbonate, which dissolves when the pH is too low.
- Corals need carbonate ions to build calcium carbonate. The H+ ions that are present at lower pH levels combine with carbonate ions to form hydrogen carbonate ions, reducing the availability of carbonate ions for reef-building.
- Increased carbon dioxide released from the burning of fossil fuels dissolves in the oceans and lowers the pH of the water, reducing coral growth.
How does salinity affect coral reef formation?
- Since corals are marine animals they need salty water, within a 32-42% range, to survive.
- Freshwater run-off from land can reduce salt concentrations and limit coral growth.
How does water clarity affect coral reef formation?
- Water clarity must be good for light to penetrate through the water.
- Sediment from land run-off, and water pollution, can reduce water clarity and limit coral growth.
How does temperature affect coral reef formation?
- Corals have a range of tolerance of roughly 20-28 °C, though they grow best in water temperatures above 23 °C.
- While they can withstand short periods of higher temperatures, rising sea temperatures causes the polyps to expel their algae symbionts, leading to coral bleaching.
Define biome.
A large community of plants and animals that has occurred as a result of environmental factors. Biomes occur over large geographical areas and are usually named after their dominant vegetation type.
List 7 examples of biomes.
- Temperate rainforest
- Tropical rainforest
- Temperate deciduous forest
- Boreal/coniferous forest (taiga)
- Grassland (temperate or savanna)
- Tundra
- Desert (hot or cold)
What are the two main abiotic factors affecting biome distribution?
Average temperatures and rainfall patterns.
What is a climograph?
A graph showing biome development plotted against mean annual rainfall and temperature on its axes.
What biome will likely develop at a mean average rainfall of 200 cm and mean average temperature of 25°C?
Tropical seasonal forest.
What are two limitations of climographs?
- They show distinct boundaries between biome types, but in reality there’s a gradual shift.
- They don’t account for other variables like soil type and animal grazing that may play important roles.
Why might the allocation of temperature and rainfall to graph axes vary in climographs?
Neither rainfall nor temperature can be described as being an independent or dependent variable, so their placement on x or y axes may vary.
What should you be careful about when interpreting climographs?
Be sure to read the axis labels and values carefully before drawing conclusions, as the orientation and direction of axes may vary between graphs.
What biome will likely develop at a mean average rainfall of 300 cm and mean average temperatures of 15°C?
Temperate rainforest.
What biome will likely develop at a mean average rainfall of 100 cm and mean average temperatures of 0°C?
Taiga, or boreal forest
How are dotted lines used in some climographs?
They show situations where other variables, such as soil type and animal grazing, may play an important role in biome development.
How might the temperature axis be plotted differently on climographs?
The temperature can be plotted from high to low or from low to high on the y-axis.
What does a climograph illustrate about the relationship between temperature, rainfall, and biome type?
For any given combination of temperature and rainfall factors, a specific biome will result.
What are the key characteristics of a Tropical Rainforest biome?
- Located around the equator
- Warm temperatures year-round (10-20°C average)
- High rainfall (over 200 cm annually)
- Dense vegetation with tall trees forming canopies
- Extremely high biodiversity
Describe the main features of a Desert biome.
- Covers over 1/5 of Earth’s land
- Less than 25 cm of rain annually
- Can be hot or cold
- Sparse vegetation (cacti, small shrubs)
- Animals often nocturnal to avoid extreme temperatures
What defines the Taiga (Boreal Forest) biome?
- World’s largest land biome
- Located below the tundra
- Long, cold winters and short summers
- Dominated by coniferous trees (fir, pine, cedar)
- Home to migratory birds and mammals with thick winter coats
What are the characteristics of a Temperate Deciduous Forest biome?
- Found in eastern North America, Europe, parts of Asia
- Four distinct seasons
- Trees lose leaves in winter
- Fertile soil
- Moderate temperatures and rainfall
How would you describe a Temperate Grassland biome?
- Large areas of mainly grass with few trees
- Found in North and South America, Europe, Asia
- Hot summers and cold winters
- Moderate rainfall
- Fertile soil suitable for agriculture
What are the key features of a Savanna biome?
- Mix of grassland and scattered trees/shrubs
- Warm temperatures year-round
- Distinct wet and dry seasons
- Found in Africa, South America, Australia
- Home to large grazing animals and predators
What defines the Tundra biome?
- Coldest biome (-40°C to 18°C)
- Low precipitation (150-250 mm annually)
- Located in Arctic regions and high mountains
- Permafrost underground
- Vegetation includes mosses, lichens, small shrubs
- Few trees due to short growing season
What determines which biome develops in a particular location?
Abiotic environmental factors, such as rainfall and temperature patterns.
Why do different parts of the world contain the same biome?
Regions of the world that experience similar abiotic factors will contain the same biome, e.g. desert occurs in parts of Africa, North and South America, and Australia.
Why do ecosystems in equivalent biomes in different parts of the world contain similar communities?
These similarities exist due to shared abiotic factors and resultant convergent evolution.
Explain convergent evolution in the context of biomes.
Species face similar selection pressures, so similar features provide a survival advantage. These advantageous features become more common in the population due to natural selection.
Why are communities in similar biomes similar despite not evolving from a recent common ancestor?
They have independently adapted to have similar features due to similar environmental pressures.
How are species in similar biomes on different continents related?
Species adapted to survive in similar biomes (e.g. deserts) on different continents are not close genetic relatives, though they may have similar morphology due to convergent evolution.
What are the climate conditions and community features of Tropical forest biomes?
Climate conditions:
- Annual rainfall 2000 - 10,000 mm
- Temperatures consistently between 20 - 25°C
Community features:
- Layers of vegetation, e.g. canopy and undercanopy
- Nutrient poor soil due to lack of seasonal leaf fall
- Highly productive, i.e. high levels of photosynthesis
- Very high levels of biodiversity
What are the climate conditions and community features of Temperate forest biomes?
Climate conditions:
- Annual rainfall 750 - 1500 mm
- Seasonal, but no extremes temperatures
- Fertile soil due to leaf fall each autumn
Community features:
- Dominant deciduous trees
- Productive during part of the year
- High levels of biodiversity
What are the climate conditions and community features of Taiga (conifer forest) biomes?
Climate conditions:
- Annual rainfall 300 - 900 mm but high snow fall
- Very short summer growing period
- Temperatures between -40 - 20°C
Community features:
- Dominant coniferous (evergreen) trees
- Low productivity
- A small number of well-adapted species
What are the climate conditions and community features of Grassland biomes?
Climate conditions:
- Annual rainfall 500-950 mm
- Dry and wet seasons
- Temperatures between -20 - 30°C (differs depending on region)
Community features:
- Dominant grasses
- Not enough water for significant tree growth; low productivity
- Grazing animals and a small number of top predators
What are the climate conditions and community features of Tundra biomes?
Climate conditions:
- Annual rainfall 150-250 mm
- Dark winter periods and frozen soil
- Temperatures between -50 - 18°C
Community features:
- Not enough water, light, or warmth for tree growth; low productivity
- Hibernating or migrating animal species
What are the climate conditions and community features of Hot desert biomes?
Climate conditions:
- Annual rainfall less than 250 mm
- Hot days (up to 49°C) and cold nights (down to 0°C)
Community features:
- Productivity very low due to lack of water
- A small number of well-adapted species
How do the cacti of South American deserts and euphorbias of African deserts demonstrate convergent evolution?
The cacti of the South American deserts and the euphorbias of the African deserts share spines and succulent stems as adaptations to their desert biome environments, but the two plant groups are not closely related. This demonstrates convergent evolution in response to similar environmental pressures.
Define adaptations and explain how they come about.
“Adaptations are traits, or characteristics, that increase survival chances in a specific environment. Adaptations come about by the process of natural selection.”
How are species adapted to their biomes?
“Species are adapted to the abiotic and biotic features of the biome in which they live, e.g.
- Species living in hot desert biomes have adaptations to hot, dry conditions
- Species living in tropic rainforests are adapted to deal with competition and predation”
Describe the adaptations of the Saguaro cactus (Carnegia gigantea) to hot desert conditions.
“The saguaro cactus (Carnegia gigantea) is native to the hot deserts of North America, and is adapted for survival in dry conditions:
- Its stem has a thick waxy cuticle to reduce water loss by evaporation
- It has spines instead of leaves; this reduces the surface area from which water can be lost by adaptation, and reduces grazing
- Cells in the stem can expand to take on and store water
- A deep tap root enables access to water deep under the ground, and shallow surface roots allow fast absorption of any water from rainfall”
Explain the adaptations of the Kangaroo rat (Dipodomys sp.) to hot desert conditions.
- “Kangaroo rats (Dipodomys sp.) are small rodents found in the hot deserts of North America
- They spend daylight hours in underground burrows, a behavioural adaptation that allows them to avoid the high daytime temperatures
- Kangaroo rats are able to extract enough water to survive from their diet, and can produce highly concentrated urine, so can go without drinking water for extended periods”
Describe the adaptations of the Kapok tree (Ceiba pentandra) to tropical rainforest conditions.
- Kapok trees (Ceiba pentandra) form parts of the upper canopy in the tropical rainforests of Central and South America
- Rapid growth allows Kapok trees to outcompete other species by growing tall very quickly; this height allows them to absorb enough sunlight in a densely forested habitat
- Wide buttress roots provide a sturdy base to support the trees during their rapid growth”
Explain the adaptations of the female Orchid mantis (Hymenopus coronatus) to tropical rainforest conditions.
- “The orchid mantis (Hymenopus coronatus) is an insect found in the tropical rainforests of southeast Asia
- The adult female mantis looks very similar to an orchid flower, enabling it to attract insect pollinators which then become its prey; this is an example of mimicry
- Scientists believe that orchid mantis are ‘aggressive mimics’, meaning that they are more attractive to insects than the surrounding orchid flowers”
How does the male Orchid mantis differ in its adaptation from the female?
“The male orchid mantis is much smaller and plainer in appearance, allowing it to camouflage in amongst the stems and branches of plants”
