Content Standard 6 Describe evidence of species variation

Content Standard 6 Describe evidence of species variation due to climate, changing landforms, interspecies interaction, and genetic mutation.

Eligible Content • Describe evidence of species variation due to climate in the cases of the snowshoe rabbit and arctic fox • Describe evidence of species variation due to gwographic isolations such as populations becoming separated by a mountain range, an island breaking off from a mainland as in the case of Australia, or when a river separates a population as in the case of the Grand Canyon squirrel populations • Describe evidence of species variation due to interspecies interaction by recognizing the roles of parasitism, mutualism, and commensalisms. • Recognize that genetic mutation leads to diversity within a species which can lead to speciation.

snowshoe rabbit & artic fox • • Climate influenced Winter – color of their coats is white Summer – color of their coats is brown Note: if either one were to live in a particular climate for many generations then their fur color would be affected • Ex. Lived in warmer climate year-round, for many generations – coat color would remain brown • Lived in cold 9 snowy climates year-round, for many generations – coat color would remain white.

Geographic Isolation • A new species may develop from geographic isolation. • Geographic isolation prevents interbreeding of the species. • Result over time = new unique species. This is called – speciation – Ex. Grand canyon squirrel populations – At least two different species of squirrels in the Grand canyon were at one time one species, they became separated by the GC river (geographic isolation) allowing for speciation to eventually occur. ( they can no longer interbreed w/each other) – Ex. Leopard frogs North America.

SPECIATION Formation of new and distinct species, whereby a single evolutionary line splits into two or more genetically independent ones. Many causes of speciation • Geographic Isolation • Isolation by emigration • Genetic isolation arising simply from the great distance separating subpopulations • Climate • Mutations • Anything that causes the species to be separated over time preventing interbreeding. • It takes many generations for speciation to occur.

SPECIATION • Evolutionary process by which new biological species arise – a population splits into two geographically isolated populations (ex. by habitat fragmentation due to geographical change such as mountain building, rivers or social change such as emigration). The isolated populations then undergo divergence and different mutations arise in the two populations. When the populations come back into contact, they have evolved such that they are reproductively isolated and are no longer capable of interbreeding.

Example- Speciation Mutation occurs Two NEW species

Species Interactions & Variations • Mutualism • Commensalism • Parasitism

MUTUALISM • Mutualism– Both organisms benefit – Neither is harmed – EX. Coral Reefs / Rooting Plants / Animals & Plants/

Mutualism The flower provides food for the bird, and the bird, by drinking from several different flowers spread pollen between flowers. The plant shelters ant colonies in hollow spaces in its limbs or leaves. The ants, in turn, protect the plant against threats from other insects or encroaching vegetation. The ants get a home; the plant gets protectioneverybody wins.

Mutualism • Relationship between the Egyptian plover and the crocodile. The crocodile lies with its mouth open. The plover flies into its mouth and feeds on bits of decaying meat stuck in the crocodile’s teeth. The crocodile does not eat the plover. Instead, he appreciates the dental work. The plover eats a meal and the crocodile gets his teeth cleaned.

Mutualism • algae give the clam extra energy and food (and make the clam look really pretty). The clam give the algae a home and benefit from the extra food production. Giant Clam & Zooxanthellae (algae)

Commensalism • symbiosis between unrelated organisms: the relationship between organisms of two different species in which one derives food or other benefits from the association while the other remains unharmed and unaffected • One organism benefits – the other organism does not benefit but is not harmed.

Commensalism anemonefish lives among the forest of tentacles of an anemone and is protected from potential predators The barnacle gains a place to live and the whale is not harmed by the presence of the barnacles. Remoras attach to Sharks as it provides them with protection, and they can feed of any food the shark leaves behind

Commensalism • Hermit crab survival depends on having and maintaining good armor. their soft abdomen is left vulnerable. However, these crustaceans seek shelter in seashells discarded by their aquatic neighbors. Hermit crabs cannot survive for long without these abandoned houses. This sort of symbiotic relationship is commensalism, since only one benefits from the arrangement while the other is unharmed.

PARASITISM • Symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. • One benefits and the other organism is harmed

Parasitism • Parasitized caterpillar, covered with wasp pupae. The parasitic wasp larvae ate most of their host. The wasp larvae spun cocoons and pupated on the outside of the caterpillar's body

Parasitism • strangler fig growing on another tree is an example of parasitism. The fig is getting support so it can grow quickly and get more sunlight. • the fig makes it harder for the tree to get water and nutrients from the soil and also blocks some of the sunlight from reaching the tree's leaves. • Strangler fig- parasite • Tree-host

Parasitism • This shows parasitism. The tick gets the blood it needs to survive, but the host is harmed by the tick transmitting disease into its blood

Parasitism Head Lice Apple worm Fungus Lamprey