Patterns of Evolution Chapter 17 Section 4

Macroevolution/Microevolution family large long  Macroevolution- One genus or family evolves into another….due to large scale changes that take place over long periods of time. Small species short  Microevolution- Small scale changes within a species to produce new varieties or species in a relatively short amount of time.

Macroevolution/Microevolution allele gene  Both involve changes in allele frequencies in gene pools same basic  Both work through the same basic processes differenceapproach scale  The difference is largely one of approach and scale

Macroevolution/Microevolution Macroevolution 1. L arge-scale changes in gene frequencies 2. Occurs over a l ll longer (geological) t tt time period 3. Occurs at or above the l ll level of species in separated gene pools 4. Consists of e ee extended microevolution Microevolution 1. S mall-scale changes in gene frequencies 2. Occurs over a f ff few generations 3. Occurs w ww within a species or population in s ss same gene pool 4. Refers to s ss smaller evolutionary changes

Macroevolution/Microevolution Macroevolution 5. Has n nn not been directly o oo observed 6. Evidence based on r emnants of the past 7. M M M More controversial 8. Example: Birds from reptiles Microevolution 5. O bservable 6. Evidence produced by e ee experimentation 7. Less controversial 8. Example: Bacterial resistance to antibiotics

Macroevolution/Microevolution

DDog Variability When bred for certain traits, dogs become different and distinctive. This is a common example of microevolution— changes in size, shape, and color—or minor genetic alterations. It is not macroevolution: an upward, beneficial increase in complexity. Macroevolution/Microevolution

 Macroevolution has never been observed in any breeding experiment.  Theories…?  The controversy still exists  material/Microevolution.pdf material/Microevolution.pdf  Macroevolution/Microevolution

 29+ Evidences for Macroevolution  "Evidences"?  Copyright © by Douglas Theobald, Ph.D.Douglas Theobald, Ph.D.  nces.html nces.html Patterns of Macroevolution

Much written in the support of macroevolution

A. Mass Extinctions B. Adaptive Radiation C. Convergent Evolution D. Coevolution E. Gradualism F. Punctuated Equilibrium G. Developmental Genes These are theories/models of evolution

Mass Extinctions EEvent in which m mm many types of living things became extinct a aa at the same time. PPeriod in which huge numbers of s ss species disappeared. WWhole e ee ecosystems were w ww wiped out LLeft h hh habitats/niches o oo open BBelieved to result in b bb burst of evolution of new species in new habitat DDisrupted e ee energy flow throughout the biosphere and caused f ff food webs to collapse

PPossible causes –A–A–A–Asteroids hitting earth –V–V–V–Volcanic eruptions –C–Continental d dd drift –S–S–S–Sea levels changing

 Believed to be an on-going process

Adaptive Radiation TThe evolution of an a aa ancestral species, which was a aa adapted to a particular way of life, into m mm many diverse species, each adapted to a d dd different habitat MMany new s ss species diversify from a common ancestor. TThe b bb branching out of a population through variation. TThe new species l ll live in d dd different ways than the o oo original species did.

Diversity in anoles is most striking in the Caribbean islands

Adaptive Radiation  Hawaiian honeycreepers  Variation in color and bill shape is related to their habitat and diet

Convergent Evolution OOOOpposite of d dd divergent evolution (adaptive radiation) UUUUnrelated o oo organisms independently e ee evolve similarities when adapting to s ss similar environments, or ecological n nn niches AAAAnalogous structures are a result of this process EExample: penguin limb/whale f ff flipper/fish f ff fin TThe wings of insects, birds, pterosaurs, and bats all serve the s ss same function and are s ss similar in structure, but each evolved independently AAll are believed to descend from a common ancestor…Totally theoretical!!

ocotillo (left) from the American Southwest, and in the allauidia (right) from Madagascar

Convergent Evolution Similar body shapes and structures have evolved in the North American cacti...and in the euphorbias in Southern Africa

Coevolution TThe m mm mutual evolutionary i ii influence between two species WWhen t tt two species e ee evolve in r rr response to changes in e ee each other TThey are closely connected to one another by ecological interactions (have a symbiotic relationship) including: –P–Predator/prey –P–P–P–Parasite/host –P–P–P–Plant/pollinator EEEEach party exerts selective p pp pressures on the other, thereby affecting each others' evolution TTotally theoretical

Coevolution

Coevolution Coevolution between the yucca moth and the yucca plant. (right) A female yucca moth pushing pollen into the stigma tube of the yucca flower while visiting the flower to deposit her eggs. Yucca moth larvae (left) feeding on seeds in the yucca fruit. Theoretical!!

Coevolution Clown Fish and Sea anemone

Gradualism TThe evolution of new species by gradual accumulation of s ss small genetic changes over l ll long periods of time EEmphasizing s ss slow and s ss steady change in an organism OOccurs at a slow but c cc constant rate OOver a short period of time it is h hh hard to notice

(Theoretical) Gradualism

Gradualism

Gradualism

Punctuated Equilibrium SSSStable periods of no change (genetic equilibrium) i ii interrupted by r rr rapid changes involving many different lines of descent OOpposite of g gg gradualism IIt is rare, rapid events of b bb branching speciation CCharacterized by long periods of v vv virtual standstill ("equilibrium"), " "" "punctuated" by episodes of very f ff fast development of new forms

 Horseshoe crabs have change little since their first appearance in the fossil record.  They are in a state of equilibrium

Punctuated Equilibrium

Developmental Genes DDevelopment is a p pp progressive process TThere are a variety of certain developmental genes that regulate the timing of certain events

HHox genes – are m mm master control genes SSome a aa alter the p pp position of an organ OOthers a aa alter when things happen Lamb born with seven legs

Hox Genes body plans  Determine body plans patterning  Function in patterning the body axis body regions  Provide the identity of particular body regions

Hox Genes SSSSmall changes in such powerful regulatory genes, or changes i ii in genes turned on by them, are thought to be a m mm major source of evolutionary c cc change (a) normal fruit fly (b) Antennapedia mutation Fruit fly head showing the effects of the Antennapedia gene. This fly has legs where its antennae should be.

Hox Genes  Hox Genes control development of central nervous system and are common to most organisms.  Four groups of similar Hox Genes, shown in color, appear to control related regions of the human body and the fly.  Each box represents a single Hox Gene. Illustration by Lydia Kibiuk, Copyright © 1994 Lydia Kibiuk.

Patterns of Macroevolution that are Does this equal can undergo Do they undergo inunder formin Species UnrelatedRelated Inter- relationships Similar environments Intense environmental pressure Small populations Different environments Coevolution Convergent evolution Extinction Punctuated equilibrium Adaptive radiation Flow Chart