Theme B: B4 Form and Function - B4.1 Adaptation to Environment Flashcards
Habitat
a place where organisms live (or a place in which a community, species, population, or organism lives).
If more than one species have similar requirments, then a habitat can be a place where a community of multiple speces lives. Habitats provide the organisms that live there with the basic requirements to stay alive long-term.
what do organisms need from a habitat?
Organisms need: shelter, food, water, oxygen, and often light.
How can habitats be described?
Habitats can be described by their geographical or physical locationand by the type of ecosystem they exemplify.
Geographial/physical location, for example, is provided by a GPS. This may accurately show your location, but it would give a very incomplete description of your surroundings.
More useful information can be provided by describing your surroundings. This would give a better idea of the ecosystem you are visiting rtaher than just the location.
example of how organisms have adapted to harsh abiotic environments
Sand dune grass species
Sea oat, East US
The sea oat is a species of grass that creates and lives on sand dunes along the eastern seaboard of the US:
* They are drought resistant have a large shallow root system.
* They have narrow leaves to help reduce transpiration. Sea oats will close their stomata if soil/sand conditions around the roots remain dry for an extended period of time.
* The sandy “soil” they live in does not hold water for very long, so dense interweven roots are needed to maximise the take-up of water during the short period it’s available after rain.
* Sand dunes grow taller because blowing sand accumulates and is held by the root system of sea oats, preventing erosion.
* Sea oats thrive in full sun and easily tolerate salt spray; can even survive complete immersion in saltwater for a short period.
* Produce nodes and rhizomes near their base, above the sand line. When covered by blowing sand, these asexual growth shoots are stimulated and produce shoots above the newly accumulated sand. Sexual reproduction is accomplished with the production of seed heads that resemble those of a true oat plant.
example of how organisms have adapted to harsh abiotic environments
Red Mangrove Tree species
Red mangrove is a tropical and subtropical tree that grows along the saltwater tidal zone in Bermuda, Florida, the West Indies and other areas of tropical America.
* The prop roots of this tree extend above the water line, forming a “spider-like” support system.
* The roots above the water line also absorb air. The air is used to oxygenate the root tissues, which are below the water line and buried in mud.
* The roots below the water line filter salt out of the water using active transport, so that the tree has access to fresh water.
* Red mangroves are adapted to the changing water levels characteristic of saltwater tides.
* The tangled root growth under the trees provides a protective habitat for many fish and other marine animals. Marine animals often use this habitat as a nursery for their young. remember this is not considered an adaptation as it did not develop for the benefit of the mangrove.
* Produce an unusual fruit, containing a seed that germinates and begins to grow before falling from the parent plant. The young plant is called a propagule.
* The propagule eventually falls from the tree and floats in the water below. After absorbing water, it orientates itself in shallow water with its roots downwards and begins its early growth. A shoot with early leaves grows from the oppostie end. this is an adaptation for plant dispersal in a marine environment.
abiotic factors
non-living components of an ecosystem
common abiotic factors include:
- water availability
- soil composition
- temperature range
- pH range
- light intensity and duration
- salinity
limiting abiotic factors
any one of the abiotic factors can act as a limiting factor if that factor is outside the tolerance zone of an organism. organisms do not need an abiotic factor to be held at a constant level, but instead adapt to tolerate an acceptable range of values.
affects of abiotic factors
graph: environmental gradient on x-axis (one of any no. abiotic factors)
as you can see from the graph, abiotic factors can and do affect population sizes, but often the abiotic factor can be far from the optimum before an organism is excluded from an area.
organisms and their tolerance ranges within their habitat.
organism examples and what a tolerance range entails
Some organisms have developed special adaptations that extend their tolerance range within their habitat. being able to tolerate high or low values for certain abiotic factors can provide habitat opportunities for some organisms. examples of organisms that tolerate unusual habitats:
* red mangroves - high salinity shorelines
* sea oats - sandy soil along beaches
* polar bear - low air temperatures in arctic regions
* thermophilic bacteria - natural water sources at temperatures of 60-80C
they not only have a wide range of tolerance for the abiotic factors listed, but its optimum value is also relatively unusually high/low. allows the organisms to experience less compettion within a given habitat.
a limiting factor
an abiotic (or biotic) factor that limits the population size or even presence of a particular species in a habitat.
measuring limiting factors
It’s possible to work out the point at which a factor starts to limit the abundance of a species by carrying out practical experiments. The data collected needs to include a measure of the abundance of the species being studied and the level of the abiotic factor. For example, you could study the presence of a particular type of woodland plant in different light conditions.
semi natural habitat
one that may have been influences by humans but is still dominanted by wild, rather than cultivated, species.
transect
a scaled line (such as a long tape measure) that is laid along the entire length of an area you plan to investigate. to study the correlation of a limiting abiotic factor and the distribution of an animal or plant species, the organism of interest would be counted at specific intervals along the transect.
types of transects
- line transect
- belt transect
line transect
usually used to simply determine whether an organism is present or not at set intervals.
belt transect
when using a belt transect, a quadrat is placed at regular intervals along the transect and the number of individuals within each are counted.
how are corals formed?
corals are the result of a symbiotic relationship between coral polyps and a microscopic algae called zooxanthellae. both organisms in this mutualistic relationship require suitable growing conditions. the small size of the ocean surface area populated by coral reefs is an indication that the combination of all the right abiotic factors for the symbiotic species is rare.
limiting effect of following abiotic factor on coral reef growth+health
water depth
Light only penetrates to relatively shallow depths. Zooxanthellae are photosynthetic and require adequate light levels. Most of the ocean floor is too deep to allow enough light to support coral reef growth.
limiting effect of following abiotic factor on coral reef growth+health
water temperature
Corals only survive in a narrow range of water temperatures (between 20°C and 28°C). Global warming is resulting in temperatures that are too warm for corals to tolerate. When the water becomes too warm, corals become stressed, and they expel the symbiotic zooxanthellae living in their tissues. Bleached coral is the result.
limiting effect of following abiotic factor on coral reef growth+health
salinity
Corals need the correct amount of salt in the water around them. Areas with freshwater run-off may not be of the correct salinity.
limiting effect of following abiotic factor on coral reef growth+health
water clarity
Water needs to be clear for light to pass through it. If there is a lot of sediment or pollution in the water, the clarity decreases and the zooxanthellae may not receive enough light.
limiting effect of following abiotic factor on coral reef growth+health
water pH
Increased carbon dioxide from fossil fuel emissions is being absorbed into ocean water, resulting in a lowered pH that is detrimental to coral growth. A lower pH (acidification) results in less calcium carbonate compounds being available in the water for corals to use when building reefs.
what is especially limiting the growth and health of coral reefs?
Reefs have a range of tolerance for each of these factors, but human activities are resulting in the upper or lower tolerance limits for many of the factors being exceeded.
& how they are named
biome
a large geographical area that contains communities of plants and animals that are adapted to living in that environment.
they are often named after the dominant vegetation type found within in them. e.g. a grassland biome contains many different grasses. desert and tundra biomes are exceptions, but biologists can stll predict what plant and animal species will be present in those biomes.
how are biomes characterised?
biomes of any one type can be found in varuous locations on Earth, because they are characterised by specific temperatures and rainfall levels, which are not restricted to one geographic location.
e.g. deserts are found in Asutralia, Africa, Asia, and America.
variations within biomes
biomes can be subdvided based on other environmental conditions. e.g. hot deserts and cold deserts. all tropical forest biomes have plentiful rain, but some have more than three times the rainfall that other recieve.
how do biomes develop?
for any given temperature and rainfall pattern one natural ecosystem type called a biomes is likely to develop. biomes are created by varying conditions of precipitation and temperature.
give some more details
graph used to idenify biomes based on temp and precipitation
Because biomes are created by varying conditions of precipitation and temperature, they can be plotted on a graph using the two environmntal conditions as the horizontal and veterical axes. With this, biomes are identified by mean annual precipitation and mean annual temperature on the graph.
Notice that some environmental conditions lead to an overlap of biomes. also note that the avergae annual temperature starts at -20C.
the difference between an ecosystem and a biome?
an ecoystem is made up of the physical environment and the plants and animals that live there and interact with each other. biomes can contain many ecosystems, thus it’s a smaller area within a biome where organisms interact with each other and their physical envrionement.
why can’t all parts of a biome share the same interactions?
Biomes are too large and diverse for all organisms to interact in the same way. Each ecosystem within a biome has its own species, climate conditions, and ecological relationships.
e.g. In a rainforest biome, the canopy ecosystem has birds and monkeys, while the forest floor has fungi and jaguars and snakes, and the rivers have aquatic plants and river dolphins.
Why do organisms in similar biomes around the world look alike but have different genetics?
The plants and animals found in similar biomes that are geographically separated will have different genetic backgrounds.
If you visit a desert community anywhere in the world you will probably find similar organisms in each. However, while their morphology and physiology will be quite similar these organisms will usually have little genetic similarity.
this is due to convergent evolution.
convergent evolution
occurs when two or more organisms solve an environmental problem by independent (unshared) genetic adaptations. species evolve in order to adapt to challenges and can do so by different sets of “trial and error” adaptations that lead to a very similar solution. the adaptations that work best will be similar in different lovations because the abiotic conditions that are responding to are similar.
similar species that live within the same ecoystem are often genertically related to each other as often that are a result of adaptive radiation. thus, they have a fairly recent common ancestor and a very similar set of genes. in contrast, species that live in same biome but in different parts of the world may solve challenges in a similar way but have distinct genetic differences.
example of convergent evolution
carnivorous plants of different species have independently solved the challenge of living in poor soils by developing adaptations to capture and digest insects as a source of nitrogen. these different adaptations for the same purpose are examples of convergent evolution.
e.g. a sundew plant secretes a sticky digestive juice on the ends of filaments to entrap and digest a fly. the fly is then used as a source of nitrogen
pitcher plants have evolved a jug-like shaped container that holds digestive secretions in its base. the plants produce a slippery substance around the lip of their container. insects slide from the lip into the contained where they are digested, providing a ource of nitrogen.
climate conditions and typical community types of biomes
hot desert
climate conditions: very low annual rainfall (less than 300 mm per year), hot temperatures during the daytime but cold at night.
communities include: sparse vegetation, often with spines for leaves, burrowing animals only active during the cooler night time.
climate conditions and typical community types of biomes
grassland
climate conditions: semi-arid climate with somewhere between 500 mm and 950 mm rainfall per year. temps very depending on latitude. the annual range can be between -20C and 30C. grasslands can have seasons (i.e. a wet season and a dry season).
communitie include: vegetation dominated by grass species. little significant tree grwoth because of the lack of water. animal species dominated by grazers and few predators.
climate conditions and typical community types of biomes
tundra
climate conditions: Cold temperatures (between -40°C and 18°C). Low precipitation (150 mm to 250 mm per year). In the winter it is dark for long periods.
communities include: No trees because of the lack of water and short growing season. The soil is frozen for most of the year. Animals have adapted to hibernate for long periods of time or to migrate when the conditions on the tundra become too difficult.
climate conditions and typical community types of biomes
taiga or conifer forest
climate conditions: Very cold winters and relatively high precipitation in the form of snow. Temperatures can range from -40°C to 20°C. Usually between 300 and 900 mm of rain per year.
communities include: Evergreen forests dominated by conifer trees. Animals must have adaptations for a very cold climate. The largest terrestrial biome on Earth by landmass.
climate conditions and typical community types of biomes
temperate forest
climate conditions: Four seasons with no extremes of temperatures, abundant year-round precipitation (somewhere between 750 and 1500 mm of rain). Soil enriched by leaf drop each year.
communities include: Area dominated by deciduous broad-leafed trees. Rich variety of animal species.
climate conditions and typical community types of biomes
tropical forest
climate conditions: High annual rainfall (from 2,000 mm to 10,000 mm per year). Warm temperatures (around 20°C to 25°C). Nutrient-poor soil as plants are rarely deciduous.
communities include: very high plant and animal biodiversity.
hot desert biome adaptations
the saguaro cactus
The saguaro cactus is native to the Sonoran desert in southwestern United States.
* As a desert plant, most of its adaptations are related to water gathering and retention.
* The thick waxy skin is completely waterproof and is covered by bristles as a defence against grazers.
* single long taproot that it sends down to retrieve deep water when it is available, but it also has a massive shallow root system to absorb occasional rainwater.
* After a rare rain shower, the water taken up is stored in sponge-like tissue. This stored water maintains the low water needs of the plant until the next rainfall.
hot desert biome adaptations
fennec fox
The fennec fox is a small fox native to the desert areas of the Sahara in North Africa.
* It has many adaptations for desert life, the most notable being its** very large ears**. The ears are highly vascular and help dissipate heat.
* the large ears also help the animal locate small prey animals moving underground.
* Like most desert animals, fennec foxes are nocturnal hunters.
* They spend their daylight hours in large underground dens shaded from the Sun.
* They obtain their water primarily from their food, although they will drink from a water source, if available.
* Fennec foxes have kidneys adapted to reabsorb most of the water that passes through them, and they only rarely urinate.
tropical rainforest biome adaptations
the kapok tree
A tropical rainforest is characterized by high temperature and abundant rainfall. In tropical latitudes there is also** plentiful sunlight**. Collectively, those abiotic factors lead to abundant and varied plant growth. The abundant growth creates competition for available sunlight, and those species that can grow the tallest will have access to more sunlight. One of the species that can grow very tall is the kapok tree (Ceiba pentandra).
* This tree forms part of the upper canopy layer of rainforests in Costa Rica and the Amazon.
* In order to support rapid growth and a very tall trunk in a relatively shallow soil, a kapok tree makes a strong foundation from buttress roots that extend above ground.
tropical rainforest biome adaptations
poision dart frogs
Poison-dart frogs are well adapted to their tropical rainforest environments.
* As amphibians, they must reproduce by laying their eggs in water. The rainforest provides small pools of water inside the many bromeliad plants that are found in the canopy.
* Predators such as snakes and lizards are numerous, but these small frogs have developed highly toxic chemicals in their skin as a result of their diet of poisonous insects.
* They have evolved to have very bright colours and body patterns as a warning to predators. This is known as warning coloration because the predators have coevolved an instinct to avoid brightly coloured frogs.
species
organisms taht can breed to produce viable offspring
population
a group of organisms of the same species in the same place at the same time
abiotic environement
all of the non-living components of an area
ecosystem
the biotic and abiotic factors of a defined area and the interactions bewteen them.
community
an interacting group of various species in a common location
organism
a unit of life: any individual living thing.
