Adaptation and Environment Notes

Habitat

Habitat means 'he lives' or 'she lives.'
In biology, it refers to where an organism lives geographically and its physical environment.

Adaptations to Abiotic Environment

Environment = everything around.
- Biotic: Other organisms.
- Abiotic: Non-living materials like air, water, and rocks.
Dominance of biotic or abiotic factors varies.

Adaptations of Grasses to Sand Dunes

Sand dunes are formed from wind-blown sand in deserts and at the top of beaches.
Conditions in sand dunes:
- Sand retains little water after rainfall, and the environment contains little organic matter.
- At the beach, sand may contain high salt concentrations, hindering osmosis. Therefore special adaptations are needed.

Lyme Grass and Its Adaptations

Thick waxy cuticle on leaves to reduce transpiration.
Stomata in indentations (furrows) where humid air can remain even in windy conditions.
Leaves can roll up during droughts, creating a humid chamber and reducing the surface area exposed to wind.
Tough sclerenchyma to prevent wilting during droughts.
Rhizomes (underground stems) that grow upwards as sand accumulates and extend deep into the dune to obtain water.
Accumulation of carbohydrates known as fructans in root and leaf cells to increase osmotic potential and thus water uptake.

Mangrove Trees Adaptations

Secretion of excess salt from the salt glands in the leaf.
Root epidermis coated in suberin (cork), which reduces permeability to salt and prevents excessive absorption.
Cable roots growing close to the soil surface where there is the most oxygen.
Pneumatophores, which are vertical root branches that grow up into the air and can absorb oxygen for usage in roots.
Stilt roots that grow out in a downward arch from the central trunk to buttress the tree in the soft mud.
Large buoyant seeds that can be carried by the ocean to distant muddy shores.
Accumulation of mineral ions (in roots and leaves) and carbon compounds as mannitol, which increases the osmotic potential of root and leaf cells, allowing water absorption from the very saline environment.

Mangrove Swamps

Develop on the coast in the tropics; these swamps are flooded with seawater at high tide.
Dominant species are trees.
Conditions: waterlogged anaerobic soils and high salt concentrations.

Abiotic Variables Affecting Distribution

Distribution can be shown on a map.
Plant distribution can be affected by: temperature, water availability, light intensity, soil pH, soil salinity, availability of minerals.
Every plant species has a range of tolerance.
Plants in northern regions have chemicals in their cells that act as antifreeze to prevent damage by the formation of ice crystals. No adaptations for growing in the tropics.

Animal Distribution

Animal distribution is also affected by temperature and water availability.
Elephants: large ears with a dense blood vessel network.
Salmon: Require fast-flowing freshwater streams no more than 3 m deep for spawning; particle sizes 10 - 100 mm, pH 5.5 to 8.0
Also have a range of tolerance for each abiotic factor, based on their adaptations.

Transect

Can be investigated experimentally by finding correlations between distributions of a species and an abiotic factor.
Transects: should span different levels - taken down a slope from woodland to peat bog.
Several methods:
- Line intercept sampling: a tape is laid along the ground between two poles, and all organisms that touch the line are recorded.
- Belt transects: the abundance of species is estimated in the area between two lines separated by a fixed distance (0.5 - 1 m) - assessed by using quadrants.
- Observational intersects: The observer walks along a defined route at a defined pace and records sightings of target species- monitor changes in population sizes, investigate ranges of tolerance.

Making Observations with Sensors

LabQuest: A device that records the level of a parameter.
Data logging is a digital storage of measurements.
Advantages:
- Less expensive than some older designs
- Compact and portable
- Many parameters measured
- Fast repeated measurements
- Transferred easily into a PC

Conditions Required for Coral Reef Formation

Hard corals contain mutualistic zooxanthellae, which need light for photosynthesis.
Conditions required:
- Depth less than 50m
- pH - above 7.8 - allows the deposition of calcium carbonate in the skeleton
- Salinity - 32-42 parts per thousand of dissolved ions to avoid osmotic problems
- Clarity - turbidity would prevent penetration of light, so the water must be clear
- Temperature - 23-29 degrees Celsius so both the coral and the zooxanthellae remain healthy

Abiotic Factors as the Determinants of Terrestrial Biome Distribution

Combination of factors = one particular type of ecosystem
All ecosystems of a specific type = Biome
Principal determinants - temperature and rainfall.

Biomes

Groups of ecosystems that resemble each other due to similar abiotic conditions - plants and animals with adaptations to fit in there = Convergent Evolution.
Types of Biomes:
- Tropical Rainforest
- Temperate Forest
- Taiga
- Hot Desert
- Grassland
- Tundra
Biome Characteristics:
- Tropical Rainforest: High temperature, high precipitation, high light intensity, high seasonal variation.
- Temperate Forest: Medium temperature, high/medium precipitation, medium light intensity, high/medium seasonal variation.
- Taiga: Low temperature, medium precipitation, medium/low light intensity, warm summers, short dry season or cold season.
- Hot Desert: High temperature, very low precipitation, high light intensity, minimal seasonal variation.
- Grassland: Medium temperature, high/medium precipitation, medium light intensity, warm summers, long cold winters.
- Tundra: Low temperature, low precipitation, medium light intensity, very short summer, very cold winters.

Adaptation in Deserts and Rainforests

Desert: Low precipitation, high temperatures, but cold nights, soil development limited.
Adaptations of Cactus:
- A wide-spread root system to collect water up to $30m$ from the stem.
- Deep tap roots that collect water from up to $1m$ down in the subsoil.
- Fat stems with storage tissue to conserve water after infrequent rains.
- Pleated stems that allow shrinkage in droughts and swelling after rains.
- Vertical orientation of stems to reduce interception of sunlight at midday and maximize at cooler times of day.
- A thick waxy cuticle on the stem epidermis to reduce transpiration.
- Leaves reduced to spines: reduce surface area and prevent slow-growing cactus from being eaten by herbivores.
- CAM metabolism allowing stomata to open at night and close during the day - again reducing transpiration.

The Fennec Fox - adapted for this environment as well.

Adaptations:
- Nocturnal to avoid highest temperatures.
- Builds an underground den - cool during the day.
- Long thick hair to provide heat insulation during the nights and days.
- Hairs covering the pads - insulation on hot sand.
- A pale-colored coat - reflects sunlight (darker coat would absorb it).
- Large ears - radiate heat and keep the body cool.
- A variable ventilation rate that can be increased to more than 600 breaths per minute to cause heat loss by evaporation.

Tropical Rainforest

Tropical Rainforest: High temperatures, high precipitation, high light intensity.
The Meranti has adaptations for this environment:
- Grows over $100m$ high, overtopping other trees - more light, more food.
- Trunk of hard dense wood to provide support, especially against wind stress.
- The trunk is buttressed at the base to provide increased support because the rainforest soils are shallow.
- Smooth trunk to shed rainwater rapidly.
- Broad oval leaves with pointed tips to shed water.
- Evergreen leaves which take advantage of ideal conditions for photosynthesis.
- Enzymes of photosynthesis adapted to tolerate temperatures of $35$ degrees Celsius.
- Flowers and seeds produced in large amounts about one year in five, with none in the other years to deter species that eat the seeds.

Spider Monkey - adaptations:

Long arms and legs for climbing and reaching food.
Flexible shoulders allowing swinging from tree to tree.
Large hook-like hands without thumbs that can grasp branches and lianas and pick fruit.
Feet that can act like extra hands.
Long tail that can grip onto branches and act like a fifth hand.
Highly developed larynx allowing a wide range of sounds to be made to communicate in the dense rainforest canopy.
Sleeping at night and active in the daytime when vision is most acute and distances can be judged between branches.
Breeding at any time of year, as there is a constant supply of fruit, nuts, seeds, buds, insects, and eggs.

Ecological Niche

The role of an organism in an ecosystem.
Has both biotic and abiotic elements.
Zones of tolerance for abiotic variables determine the habitat of a species.
Food is obtained either by photosynthesis or by taking it from other organisms - to limit competition, the species must specialize.
Other species are utilized for a range of services - pollination, recycling matter.
The ecological niche is multidimensional - all of its dimensions must be fulfilled for a species to survive, grow, and reproduce.

Anaerobic Organisms

Do not require oxygen.
Some microorganisms (bacteria, archaea, protozoa) can only live in the total absence of $O<em>2$ . Anoxic organisms (lack of $O</em>2$ ) occur in swamps, water-logged areas, intestinal tracts, and deep in lakes.
Categories:
- Obligate aerobes: Require a continuous oxygen supply, so only live in oxic environments. Ex: All animals, plants, micrococcus luteus - skin bacteria
- Obligate anaerobes: Inhibited or killed by oxygen - anoxic conditions. Ex: Clostridium tetani (tetanus bacterium), methanogenic archaea
- Facultative anaerobes: Use oxygen if available, so these live in oxic and anoxic environments. Ex: Escherichia coli (a gut bacterium), Saccharomyces (yeast)

Photosynthetic Organisms

Photosynthesis: Energy from the sunlight is used for fixing carbon dioxide and using carbon from it to produce sugars, amino acids, and many other carbon molecules.
Three groups of photosynthesizers:
- Plants - including mosses, ferns, and flowering plants
- Eukaryotic algae - seaweeds and unicellular algae
- Bacteria - including cyanobacteria (blue-green bacteria) and purple bacteria
Only in two domains (EUKARYA and PROKARYOTA) of life, not archaea.

Holozoic Nutrition

Animals obtain nutrients by consuming food = Heterotrophic.
Macromolecules - digested before they can be absorbed internally = Holozoic Nutrition
Sequence of Stages:
- Ingestion - taking the food into the gut.
- Digestion - breaking large food molecules into smaller.
- Absorption - transport of digested food across the plasma membrane of epidermis cells, into the blood and tissues.
- Assimilation - using digested foods to synthesize proteins and other macromolecules and thus making them part of the body's tissues.
- Egestion - voiding undigested material from the end of the gut. (SPIDERS digest externally, not holozoic).

Mixotrophic Nutrition in Some Protists

Some protists used both heterotrophic and autotrophic nutrition = Mixotrophic.
Euglena gracilis has chloroplasts (when there is enough light), but it can also feed on detritus or smaller organisms - Facultative Mixotroph.
Obligate Mixotroph cannot grow until they utilize both autotrophic and heterotrophic modes of nutrition. The food that they consume supplies them with carbon compounds -consume algae - use their chloroplasts until they degrade and have to be replaced.
Ochromonas - has chloroplasts, can uptake intact cells.

Saprotrophs

Secrete digestive enzymes into the dead organic matter and digest it externally, then absorb the products of digestion.
Many types of bacteria and fungi are also known as decomposers. They break down carbon compounds in dead organic matter and release elements such as nitrogen into the ecosystem, allowing them to be used again.

Nutrition in Archaea

One of the domains - unicellular, no nucleus. Some are adapted to extreme environments - hot springs, salt lakes, volcanoes…
Modes of obtaining ATP:
- Phototrophic - using other pigments, but similar to photosynthesis
- Chemotrophic - oxidation of inorganic chemicals $(Fe^{3+})$
- Heterotrophic - oxidation of carbon compounds obtained from other organisms.

Hominidae Nutrition

Hominidae includes all genera that contain Humans (Homo), Orang-utans (Pongo), gorillas (Gorilla) and chimpanzees (Pan).
Some are exclusively herbivorous diet, some omnivorous.
Show relationship between diet and dentition - studied with observation of skulls or digital collections eSkeletons (online).
Herbivores - large teeth and flat to grind down fibrous plant tissues
Omnivores - mix of different types of teeth to break down both.

Herbivores vs Plants

Herbivores have structural features that adapt them to their diet.
Insects that feed on plants can be divided into:
- Beetles: jaw-like mouthparts for biting off, chewing, and ingesting plants.
- Aphids: tubular mouthparts for piercing leaves or stems to reach phloem sieve tubes and feed on the sap.
Plants show adaptations to deter herbivores: tough sharp-pointed spines, stings to cause pain, synthesize substances that are toxic (some herbivores are able to detoxify) - only a few species of herbivore adapted to feeding on them.

Adaptations

Behavioral adaptations can change relatively quickly. In the 1920s, blue tits started feeding on cream from milk bottles delivered to doorsteps - spread across Europe but disappeared once the deliveries ended.
Structural adaptations take longer to develop - genetic change. Galapagos Finches changes in beak shape.
Chemical adaptations are the slowest because new enzymes are needed - may take millions of years.

Plants Harvesting Light

Plants compete for light.
The leading shoot grows rapidly to a great height to reach the forest canopy - unshared by other trees.
Lianas climb through the trees, using them as support.
Epiphytes grow on the trunks and branches of trees - with minimal soil.
- Strangled epiphyte - grows above the tree branch and shades it. The tree dies, leaving only the epiphyte.
Shade-tolerant shrubs and herbs absorb light reaching the forest floor.