Presentation on theme: "Changes over time Life originated from a single-celled organism."— Presentation transcript:
1 Changes over time Life originated from a single-celled organism. Finding a fossils age helps scientists to construct an evolutionary timeline.
2 Three types of Structures HomologousVestigialAnalogous
3 Homologous Structures Traits are similar in different species because they share a common ancestor.
4 The Theory of Evolution Variation, Adaptation, and Evolution
5 Evolution Learning Goals: Relate variation and adaptationDescribe how fossils are used to study ancient-lifeAnalyze Darwin’s theory of evolutionExplain how scientists reconstruct history using fossilsIdentify characteristics defining a speciesDescribe the principles of population geneticsExplain the effect of environmental change on populations
6 Variation in a SpeciesA species consists of organisms that mate with each other and that can produce healthy offspring.Differences between individuals in a population is called variation.Ex. Fur color in foxes.Two things can cause variation: mutation and recombinationMutations can be harmful, neutral or beneficial.
7 Causes of Variation*Two things can cause variation: mutation and recombinationMutations can be harmful, neutral or beneficialBeneficial mutations increase the chances of an organism’s survival.
8 AdaptationAn adaptation is an inherited trait that increases a population’s chances of survival and reproduction in an environment.Adaptations= advantages that help an organism survive.
9 BiodiversityThe many different types of organisms that make up a biologically diverse community.During times of change, populations that are better able to adapt will survive.
10 Natural Selection’s 4 points: Variation within populations- inherited through traits.Some variations are favored- improves chances of survivalNot all young survive- few live to reproduceIndividuals that survive and reproduce are those with favorable traits
11 Fossils, a peek into the past Fossils, or the remains of ancient organisms, help scientists learn about Earth’s history.
12 Changes in the PastAll life originated from a common single-celled organism.Finding the age of fossils allows scientists to construct an evolutionary timeline.
13 3 Types of structures Homologous Vestigial Analogous Similar structures in different speciesUnused structures that are reduced in sizeSimilar characteristics in different speciesShare common ancestorNo common ancestor. Independent evolution!!!
15 Causes of SpeciationGeographic isolation- members become separated from the original population due to geographic barrier.Examples: mountain range, river** Reproductive isolation- populations cannot or will not be able to produce offspring.
16 EmbryologyAnimals at the developmental stage of life look similar, but they grow up looking different.Page 385 dragonfly book picture
17 Origin of SpeciesSpeciation- is the evolution of one or more species from a single ancestor species.
18 Mechanisms of Evolution There are 3 types of evolution:Divergent evolutionConvergent evolutionCoevolution
19 Divergent Evolution Once related populations evolve independently Often happens because of geographic isolationEx. Polar Bear and Brown Bear
20 Convergent EvolutionUnrelated species have produced (analogous) similar adaptations to help these organisms live in similar environments.Ex. African Serval cat and S.American Maned wolf (pg.242)
21 CoevolutionWhen two or more populations closely interact for a long period of time, they begin to adapt together.Ex. Hummingbirds and flowers. (pg. 243)
22 Adaptive RadiationEvolution of many different, diversely adapted, species from one ancestral species.Ex. Galapagos finch (13 different species)
23 Speciation in Darwin’s Finches Founders Arrive – birds arriveSeparation of Populations- isolated one bird type onto 2 islandChanges in Gene Pool – through natural selection, mutation, etc.Reproductive Isolation – new birds don’t cross-breedEcological Competition – may lead to new birdContinued Evolution – process continues