B4.1 Adaptation to environment

habitat

the place where an organism, population, species or a community lives

abiotic factors

non-living environmental factors e.g. pH, temperature, light intensity, water availability

biotic factors

living components of the environment and their interactions e.g. predators, competitors

sand dunes and lyme grass

• challenges of sand dunes:

  • strong winds, low water available, low mineral nutrients available, shifting sand

• adaptations of lyme grass:

  • thick waxy cuticle → reduces water loss through transpiration

  • stomata in furrows → trap humid air, reducing transpiration

  • rolled leaves → reduce water loss

  • deep roots → absorb water

  • underground stems (rhizomes) → allow growth when buried by sand

mangrove swamps and tress

• challenges of mangrove swamps:

  • waterlogged, oxygen-poor soil

  • high salinity

• adaptations of mangrove trees:

  • salt glands in leaves → secrete excess salt

  • suberin in root epidermis → reduces salt absorption

  • pneumatophores (vertical roots) → absorb oxygen from the air

  • accumulation of solutes in cells → lowers water potential, allowing water absorption

  • buoyant seeds → float for dispersal by water

how abiotic factors affect species distribution

• different species have different ranges of tolerance of abiotic factors

• species can only survive in environments that fall into their range of tolerance

range of tolerance

the range of conditions for an abiotic factor within which a species can survive

zone of tolerance curve

using transects to investigate abiotic factors

• place a transect along an environmental gradient

• use quadrats at regular intervals to record species abundance

• measure abiotic variables such as temperature, light intensity or soil ph

• compare the data to identify correlations

abiotic conditions required for coral reef formation

• shallow water → sufficient light for photosynthesis

• clear water → maximum light penetration

• warm temperatures → around 23–29°C

• slightly alkaline ph → allows calcium carbonate skeleton formation

• suitable salinity → prevents osmotic problems

biome

a group of ecosystems with similar climates and communities of organisms

climate characteristics of the six major terrestrial biomes

biome	temperature	precipitation
tropical forest	high	high
temperate forest	moderate	moderate to high
taiga (boreal forest)	low	low to moderate
hot desert	high	very low
grassland	moderate to high	low to moderate
tundra	very low	low

convergent evolution

the independent evolution of similar adaptions in distantly related species due to similar selection pressures

example of convergent evolution in biomes

• cacti in america and euphorbs in africa, both have:

  • spines → protection from herbivores

  • water storage in stems → survival during drought

  • thick waxy cuticle → reduces water loss

tropical forest named plant

• pitcher plant

• photosynthesise

• carnivorous → insects fall into the pitcher and are digested by enzymes, providing nitrates

• spines → prevent insects from escaping

• grow as epiphytes on trees rather than in soil → greater access to sunlight

tropical forest named animal

• orchid mantis

• mimics the appearance of orchids for camouflage

• young mantis is black and orange to mimic an orchid bud

• attracts insects and uses its forelimbs to capture and kill prey

hot desert named plant

• saguaro cactus

• no leaves → reduces water loss, photosynthesis occurs in the stem

• waxy cuticle → reduces water loss

• thick stem → stores water

• pleated stem → allows rapid swelling after rainfall

• spines → protect stored water

• cam metabolism → stomata open at night to reduce water loss

• shallow widespread roots → absorb rainwater

• deep roots → access deeper water

hot desert named animal

• fennec fox

• nocturnal → avoids daytime heat

• underground den → keeps the animal cooler

• large ears → radiate heat

• long fur → keeps it cool during the day and warm at night

• pale colour → reflects heat

• hairy foot pads → protect against hot sand

• panting → increases heat loss