genetics- genetic technology Flashcards
(36 cards)
Define: Natural Selection
the process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce, passing their traits to offspring
Natural selection can only occur if what is within a species?
genetic variation
The 6 factors that contribute to natural selection are:
variation, inheritance, competition, survival, reproduction, population change
Variation:
organisms have different traits
arise from mutations creating new alleles
Inheritance:
traits are passed down from parents to offspring
due to passing down alleles
Competition:
more offspring are produced then can survive in the environment
Survivial:
some variations affect an organisms survival
successful traits increase chance of survival
unsuccessful traits decrease chance of survival
Reproduction:
successful organisms survive to reproduce and pass their alleles to the next generation
Population Change:
the result is that over time successful alleles and traits become more common in the population
Define: Selection Pressure
is the force driving natural selection, can be anything that affects the survival and/or reproduction of organisms
ex. changes in environment, such as climate, competition for resources(food, space, mates), predators or disease
Natural selection leads to:
organisms being better suited to their environment
the three types of adaptation changes are
physiological, structural, behavioural
Physiological Adaptations:
changes to the inside workings of the cells
ex. chemicals in the blood that prevents blood from freezing in the water
Structural Adaptations:
anatomical changes to the cells or organs
ex. opposable thumbs that allow hands to grasp
Behavioural Adaptations:
changes to an organisms behaviour or response to the environment
ex. migration to warmer climates during winter
Individuals of the same species can:
interbreed to produce fertile offspring
Sometimes members of a population change so much that:
they are no longer able to produce fertile offspring with members of the original population
leads to speciation where new species are formed
Geographic barriers can:
isolate a population, resulting in new species unable to interbreed
ex. glacier, lava flow, island
Define: Adaptive Radiation
the diversification of a common ancestral species(Darwin’s common ancestor) into a variety of differently adapted species
Extinction
occurs when a species completely disappears from earth
mass extinctions result in huge decline in the number of species
Artificial selection:
is the process of humans selecting desirable traits in plants and animals by choosing which organisms breed together
also called selective breeding
Artificial selection similarities with natural selection
differences in survival and reproduction of organisms that change the alleles in the population
selected alleles will become more common in the population over time, changing the population
Artificial selection differences with natural selection
the selection pressure is created by human desires instead of by the environment
Humans breed crops to:
resist drought, disease and insect infections