EVOLUTIONARY PROCESSES AND PATTERNS Theory of Special Creation –Species unchanged through time & independent of one another

EVOLUTIONARY PROCESSES AND PATTERNS Theory of Spontaneous Generation –New organisms (species) suddenly appear

EVOLUTIONARY PROCESSES AND PATTERNS Prior to Darwin and Wallace - Lamarck

EVOLUTIONARY PROCESSES AND PATTERNS Theories of Evolution Darwin and Wallace –Species are related to one another, and they change over time, thus species existing today have descended, with modifications, from other preexisting species

Evolution What is evolution? Microevolution: Macroevolution:

Population Characteristics Species –A group of organisms capable of interbreeding

Population Characteristics Species –A group of organisms capable of interbreeding and producing fertile offspring. –Isolated gene pools Isolation –Temporal –Spatial –Mechanical –Behavioral Genes go in but they don’t Come out!

Evolution Allopatric Speciation

Evolution Sympatric Speciation ?

Evolution Parapatric Speciation ?

Darwinian Selection All natural selection results in evolution, but not all evolution is the product of natural selection. What is evolution? What is natural selection? What is an adaptation?

Darwinian Selection All natural selection results in evolution, but not all evolution is the product of natural selection. What is evolution?

Darwinian Selection All natural selection results in evolution, but not all evolution is the product of natural selection. What is evolution? –Evolution is the change in allele frequencies (or traits) over time. What is natural selection? What is an adaptation?

Darwinian Selection All natural selection results in evolution, but not all evolution is the product of natural selection. What is evolution? –Evolution is the change in allele frequencies (or traits) over time. What is natural selection? –Natural selection is the differential reproductive success resulting from an adaptation. What is an adaptation?

Insects, spiders, nectar Tools use to get insects Leaves and fruit Ticks off of iguanas etc. Seeds

Darwinian Selection Is there variation about a trait?

Darwinian Selection Is there an excess of individuals so that only some animals live to reproduce? Are resources limited?

Darwinian Selection - Drought of 1977 eliminated seed set by most of the plants producing small soft seeds. -Large and hard seeds became dominant food item. -Only large birds with deep beaks could defend resources and access the resources

Darwinian Selection Did evolution occur? El Niño produced 1359 mm of rain and lavish seed set by the small soft seeded plants. -Birds with shallow beaks harvest these seeds more efficiently and thus reproduced better than birds with deep beaks, undoing the selection shown here. - Fluctuating environmental conditions maintained both phenotypes.

Types of Selection Directional Selection Stabilizing Selection Disruptive selection

Directional Selection Phenotype at one extreme of population distribution has selective advantage. Leave more offspring

Types of Selection Directional Selection Stabilizing Selection Disruptive selection

Stabilizing Selection Intermediate phenotypes have selective advantage.

Types of Selection Directional Selection Stabilizing Selection Disruptive selection

Disruptive Selection Intermediate phenotypes selected against

Darwinian Selection The consequences of natural selection are expressed at the population level.

Genetic drift Genetic drift results in a gradual loss of genetic diversity Over time an individual locus and gene frequency will drift until one allele becomes fixed

Convergent Evolution

ISOLATION AND CONVERGENT EVOLUTION Convergence – Myrmecophages anteaters, aardvark, aardwolf, numbat, pangolins

ISOLATION AND CONVERGENT EVOLUTION Convergence – Cursorial herbivores pronghorn, capybara, guanaco, kangaroos digestive tract, dentition, elongated limbs

Convergent Evolution Batesian Mimcry –Benign species resembles a noxious or dangerous species

Convergent Evolution Mullerian Mimicry –Noxious species resemble each other

Convergent Evolution Mullerian Mimicry –Noxious species resemble each other –Pitohui birds in New Guinea

Convergent Evolution Aggressive Mimicry –Noxious or dangerous species resembles a benign one

Coevolution AssociationEffect on Species A Effect on Species B ParasitismPositiveNegative CommensalismPositiveNone MutualismPositive PredationPositiveNegative CompetitionNegative