Lesson 7 - Variation Flashcards
Adaptations:
Characteristics that increase an organism’s chance of survival and reproduction in its environment.
Three divisions of adaptations?
- Anatomical adaptations (physical features / internal and external)
- Behavioural adaptations (the way an organism acts. These can be inherited or learnt from their parents)
- Physiological adaptations (processes that take place inside the body)
Examples of Anatomical adaptations:
- Body covering
- Camouflage
- Teeth
- Mimicry
Anatomical adaptations:
Body coverings:
- Hair
- Scales
- Spines
- Feathers
- Shells
Help an organism to fly, stay warm and provide protection.
- Thick waxy layers on plants prevent water loss
- Spikes deter herbivores and protect tissues from sun damage.
Anatomical adaptations:
Camouflage:
- Outer colour of an animal allows it to blend into its environment, making it harder for predators to spot.
- Snowshoe hare is white in winter (snow) and turns brown in summer (soil/rocks)
Anatomical adaptations:
Teeth:
Shape and type of teeth present in an animals jaw is related to its diet.
- Herbivores (sheep) have continuously growing molars for chewing tough grass and plants.
- Carnivores (tigers) have sharp large canines to kill prey and tear meat.
Anatomical adaptations:
Mimicry:
Copying another animals appearance / sounds allows a harmless organism to fool predators into thinking it is poisonous or dangerous.
- Hoverfly mimic markings of a wasp.
Marram Grass adaptations to reduce the rate of transpiration:
- Curled (rolled) leaves to minimise the surface are of moist tissue exposed to the air and protect the leaves from wind.
- Hairs on the inside of surface of the leaves trap moist air close to the leaf, reducing diffusion gradient.
- Stomata sunk into pits, which make them less likely to open / lose water.
- Thick waxy cuticle on leaves and stems, reducing water lots through evaporation.
Behavioural adaptations:
- Survival behaviours
- Courtship
- Seasonal behaviours
Behavioural adaptations:
Survival behaviours:
Opossum plays dead / rabbit freezes when they think they have been seen.
Behavioural adaptations:
Courtship:
This increases the organisms’ chance of reproducing.
Behavioural adaptations:
Types of seasonal behaviours:
- Migration (animals move from one region to another, and back again when environmental conditions are more favourable. Better climate / source of food).
- Hibernation (period of inactivity in which the animal’s body temperature / heart rate / breathing rate slow down to conserve energy, reducing animal’s requirement for food.
Categories of behavioural adaptations:
- Innate (instinctive) behaviour
- Learned behaviour
Innate behaviour:
Ability to do this is inherited through genes.
- Spiders create spider webs.
- Woodlice avoid light.
- Allows organism to survive in the habitat in which it lives.
Learned behaviour:
Adaptations learned from experience or from observing other animals.
- Use of tools. Otters use stones to hammer shells off rocks.
Physiological adaptations:
- Poison production
- Antibiotic production
- Water holding
Physiological adaptations:
Poison production:
Many reptiles produce venom to kill prey and may plants produce poison on leaves to prevent themselves from being eaten.
Physiological adaptations:
Antibiotic production:
Some bacteria produce antibiotics to kill other species of bacteria in the surrounding area.
Physiological adaptations:
Water holding:
Water-holding from can store water in its body. This allows it to survive in the desert for more than a year without access to water.
Many cacti and other desert plants can hold large amounts of water in their tissues.
Anatomical adaptations provide evidence for convergent evolution:
- Analogous structures
Examples of analogous structures:
- Whale and fish tail fins perform the same role. Detail of structures are very different.
- Marsupials (Australia) and placental mammals (Americas)
What is an analogous structure:
Adapted to perform the same function but have different genetic origin
Convergent evolution:
Takes place when unrelated species begin to share similar traits. These similarities occur as organisms adapt to similar environments / other selection pressures.
Similarities between placenta mammals and marsypials:
Placental mammals: placenta connects the embryo to mother’s circulatory system in the uterus. This nourishes the embryo, allowing it to reach a high level of maturity before birth.
Marsupials also start life in uterus, but the leave and enter the marsupium (pouch) while they are still embryos. Development completed by sucking milk.
Examples within the placenta mammals and marisupials:
- Marsupial and placental mice
Small, agile climbers that live in dense ground cover and forage at night for small food items. Similar size and body shape. - Flying phalangers and flying squirrels
Gliders that eat insects and plants. Skin stretched between forelimbs and hind limbs to provide a large surface area for gliding from one tree to the next. - Marsupial and placental moles
Burrow through soft soil to find worms and grubs. Streamlined body shape and modified forelimbs for digging. Velvety fur, allows smooth movement through soil. Differ in fur colour.
Marsupial mole = white to orange
Placental mole = grey
Plant examples of convergent evolution
Aloe and agave –> desert.
