I. Biological Evolution:• A change in a population from one generation to the next
BUT ITS NOT THAT SIMPLE – all things can change but if they do not involve descent through genetic inheritance, it cannot be described as an example of biological evolution
Changes are due to GENE FREQUENCY in populations
Changes involve DESCENT of a different species from a COMMON ANCESTOR over generations
Leaves on trees change colorand fall over several weeks.
Mountain rangeserode over millions ofyears.
A genealogy illustrateschange with inheritanceover a small number ofyears.
Over a large number ofyears, evolution producestremendous diversity in forms oflife.
II. Evidence of Evolutiona. Fossil Records: RELICS or IMPRESSIONS of organism from the past preserved in ROCK showing the succession of organisms
• Each layer is a boundary of CATACLYSMIC CHANGES that destroyed many species at that time in an area Floods Eruptions Meteor Impacts
• The DIVERSITY of species increased the chance of some species surviving these events due to adaptation over time
b. Homology: different organisms share similarcharacteristics from a COMMON ANCESTOR
• Structures may look similar, BUT HAVE A DIFFERENT FUNCTION• Altered version of ancestors
• Ex: All MAMMALS have same number of bones in forelimb, but the position, shape, and function are differentWhat are thefunctions of each ofthese limbs?We call thesehomologousstructures…similarstructure, differentfunction
c. Analogy: different organisms share similarcharacteristics despite DIFFERENT ANCESTORS
• Structures look similar, AND HAVE THE SAME FUNCTION• Changes due to response to ENVIRONMENT, nature shaped ADAPTATIONS
• Ex. Winged animals: insects, birds, and bats
d. Embryonic Development:• Adult homology MAY NOT be apparent• During mitotic divisions, stages of offspring DEVELOPMENT of different species may have similar appearances (morphologies)• Similar structures may develop different functions
Ex. All vertebrates have PHARYNGEAL POUCHES– which develop into gills in fish, or tubes in earsthat connect to throat in humans
e. Biochemistry:similar species sharenearly the samegenetic machinery• Similar DNA and RNA sequences• Similar AMINO ACID sequencing• Ex. Hemoglobin and digestive enzymes
Learning CheckAnswer the following questions based on theinformation covered in your notes.Example:1. Humans, chimpanzees, whales, and bats all have the same bonesin their arms, fins, or wings.a. What type of evidence is this? homologous structuresb. Why is this evidence of evolution?This is evidence of evolution because if all these animals havethe same bones, they probably all evolved from one creaturethat had those bones a very long time ago. Some of itschildren evolved (or changed) into humans, and other evolvedinto whales or bats or chimpanzees.
2. Scientists find fossilized bones of a hugeanimal that doesn’t exist today.a. What type of evidence is this?b. Why is this evidence of evolution?
3. The human gene for your muscle protein isdifferent from monkey muscle protein in 4places and different from a chicken’s gene in 25places.a. What type of evidence is this?b. Why is this evidence of evolution?
4. Honey possums lick nectar from flowers usinga long tongue made of soft muscle. Butterflieslick nectar from flowers using a long tonguemade of hard protein.a. What type of evidence is this?b. Why is this evidence of evolution?
5. Humans, rabbits, and zebras all have anappendix, an extra piece in their digestivesystem, although in humans it’s much smaller.a. What type of evidence is this?b. Why is this evidence of evolution?
Let’s get this straight…• Misconceptions about humans…The phylogeny of living species most closely related to us looks like thisIt is important to remember that:• Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human.• Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split, humans and chimpanzees have each evolved traits unique to their own lineages.From http://evolution.berkeley.edu