Principles of Evolution in General Biology - Lecture Slides | BIOL 1001, Study notes of Biology

Download Principles of Evolution in General Biology - Lecture Slides | BIOL 1001 and more Study notes Biology in PDF only on Docsity!

Chapter 14

Principles of Evolution

Biol 1001 Spring 2012

Evolution  Change over time in the characteristics of a population  More specifically: 

Change in genetic makeup of a population over

time due to natural selection

 Natural selection is driving force

 Allows a species to

 Adapt  (^) Survive  Reproduce  Essential for species survival

How Was Evolution Discovered?  1700s  “Naturalists” observed the variety of life  Each area had its own distinct set of species  Some species closely resemble others, but differ in certain characteristics  Speculation that species changed over time  Life originated with a small number of species  These species changed over time into larger number of species  Discovery of fossils

Fossils  Known about since 15 th century

 Originally thought to be rocks shaped/carved into

animal/plant forms

 Preserved remains of living organisms

 Bones, shells, wood, body impressions

 Petrified or preserved in stone

Archaeopteryx  Important fossil discovery (1861)  Link between dinosaurs & modern birds  (^) Reptile like: teeth, claws, long bony tail  (^) Bird like: feathers, wings, reduced “fingers” http://www.anyonefortee.com/Scoring/Birds.html http://www.ucmp.berkeley.edu/diapsids/birds/archaeopteryx.html

Fossils  Distributed within layers of rock  Similar fossils always found within same layers  Noticeable progression of fossils  Fossils in older rock layers different than species currently on Earth  Older fossils often of extinct organisms  Evidence that different organisms lived at different times

(a) Trilobite (b) Seed ferns (c) Allosaurus Youngest Oldest Fig 14-

Jean Baptiste Lamarck  First to propose a mechanism of evolution  Observed that  Older fossils were simpler than younger fossils  (^) Younger fossils were more like current species  Hypothesis:  Organisms evolved by inheriting acquired characteristics through the use or disuse of body parts  (^) Organisms possess a drive for perfection (Note: Mendel hasn’t run his experiments yet!)

http://www.bio.miami.edu/ecosummer/lectures/lec_evolution.html

Charles Darwin -  1831 – survey expedition along S. America

 Served as official “naturalist”

 Observed and collected geological & biological

specimens

 The Galapagos Islands

 Noticed a great diversity of life on each island

 (^) Did diversity develop after species became isolated on separate islands?

 Recognized that competition & variation  survival

 1859 – On the Origin of Species

Postulates of Evolution  Postulate 1:

 Individual members of a population differ from

one another (variation)

 Variation in nature arises by chance

 Due to random DNA mutations  (^) Genotypes vary  phenotypes vary  Each individual’s DNA is unique  (^) Individuals differ in physical traits (color, height, size…)  Postulate 2: 

Traits are passed from parent to offspring

 Offspring tend to resemble parents  Supported much later by Mendel’s work

Postulates of Evolution  Postulate 3:  Some individuals fail to survive & reproduce  Keeps population sizes to a manageable number  More individuals are born than survive  Not all individuals reproduce  Postulate 4:  Survival & reproduction are not determined by chance  Depends on characteristic of individual  Natural selection- those that survived to reproduce are considered the “fittest”

Natural Selection  “Survival of the fittest”  Fitness  Likelihood of passing on genes

 Reproductive success of an organism

 Acts on individuals within population

 Fate of individual affects population



Individuals with favorable traits eventually

outnumber others

 Evolution occurs within population over time  Not individuals

Evidence For Evolution  Fossils

 Ancestral species  modern species



Progressive series of fossils showing changes



New species eventually replaced previous ones

 Ex: whales evolved from land-dwelling ancestors

Modern whale 0 40 45 50 Basilosaurus Dorudon Rhodocetus Ambulocetus Pakicetus Millions of years ago Fig 14-

Evidence for Evolution  Comparative anatomy  Similarities due to shared ancestors/origins  (^) Differences due to evolutionary changes  (^) Homologous structures  Structures with similar anatomy  Modified to serve different purposes  (^) Ex: forelimb of vertebrates

Pterodactyl Bird Bat Dolphin Seal Dog Sheep Shrew humerus ulna metacarpals phalanges radius carpals Human FLYING SWIMMING RUNNING GRASPING Homologous Forelimbs Fig 14-

Evidence for Evolution  Comparative Anatomy  Vestigial structures  Homologous to functional structures  Serve no apparent purpose/function  Ex: hind limb bones human appendix molar teeth in bats http://www.ecology.com/2011/09/10/gut-ecology-human-appendix/

Vestigial Hind Limbs Fig 14- Vestigial bones similar in structure to salamander but serve no function; all 3 inherited bones from common ancestor Bones of salamander’s hindlimb function in support & locomotion Boa constrictor Baleen whale Salamander

Evidence for Evolution  Comparative Anatomy  Analogous structures  Structures similar in appearance & function  Different internal anatomy  Ex: Wings of birds & insects  Convergent Evolution  Independent evolution of similar structures among unrelated organisms due to similar environmental pressures

Analogous Wings

Evidence for Evolution  Comparative Embryology  (^) Related organisms undergo similar embryonic development  (^) All vertebrae embryos look similar early in development  (^) Ex: all vertebrates have embryonic tails & gills

http://www.geology.ohio-state.edu/~vonfrese/gs100/lect32/index.html

Evidence for Evolution  Molecular Biology  DNA sequencing  (^) All organismal cells:  Have DNA as genetic material  Use RNA & ribosomes for protein synthesis  Use most of the same 20 amino acids  Use ATP as cellular energy  (^) Presence of any protein encoded for by same gene & that performs same function  Species may have slight differences in sequence  Ex: cytochrome c

human mouse human mouse human mouse human mouse human mouse human mouse human mouse human mouse Cytochrome c Gene Sequence

350 nucleotide gene 

Fig 14-12

Evolution By Natural Selection  Artificial Selection  (^) Breeding of organisms to produce desirable features  modified species  (^) Ex: Domestic dogs  (^) Descended from wolves  Same species, different breeds  (^) Humans selectively bred for individual traits