Transcript variation
EVOLUTION UNIT Adaptation & Variation Section 7.1 What are some environmental challenges that all organisms face? Reminder of terms Species: a group of organisms that can interbreed in nature and produce fertile offspring (they share similar morphological and genetic characteristics) Species diversity: the variety and abundance of species in a given area Genetic diversity: the variety of heritable characteristics in a population of interbreeding individuals Population: a group of individuals of the same species Environmental challenges that limit a population: severe weather access to food famine number of predators space competition for food ability to reproduce access to water drought number of offspring Species Diversity Diversity is the variation within the population (genetic diversity) helps the population survive some species may become extinct while others survive to produce offspring What kind of variation exists within a species? What kind of variation exists within a species? Size / weight Number of offspring Colour Birth weight Patterns Speed Adaptation A structure, behaviour or physiological process that helps an organism survive and reproduce in a particular environment What adaptations does the Polar Bear Have? What adaptations does the Polar Bear Have? - White Fur - Semi-hibernation - Thick layer of fat - Small ears - Webbed feet 3 Categories of Adaptations Structure: any physical feature that helps the organism survive Behaviour: something that an organism does... an action that helps them survive. Physiology: a body function that helps organisms survive. Structural Polar Bear Example Colouring Fat Hair Shape of beak Size Camouflage - black skin to absorb heat - hollow hair acts as insulation - fur is oily and water repellant - webbed toes for swimming - thick layer of blubber insulates Camouflage Gecko Seahorse Stick insect Frog Snake Mimicry Mimicry: a structural adaptation in which a harmless species resembles a harmful species in coloration or structure. Batesian mimicry: the mimicry by a palatable species of an unpalatable species Müllerian mimicry: when two or more poisonous species, that may or may not be closely related and share one or more common predator, have come to mimic each other's warning signals. Behavioural Behaviour Adaptation: something that an organism does... an action that helps them survive. mating times migration nocturnal activities Physiological Physiological adaptation: a body function that helps organisms survive. Hibernation Tolerance to temperature / salt / chemicals Production of venom How do Adaptations Develop? How Adaptations No twodo individuals of a species Develop? are identical Variation exists (caused by DNA and development) Not all variations become adaptations Environmental conditions determine whether a variation in an individual as a positive, negative or no effect at all Individuals with a helpful variation are more likely to survive and that variation will become more frequent