EVOLUTION

Evolution HappensLofton, Carol and Bill)

By Karen Leggfor EDU 580

Evolution - Genetic change in a species over time.

Theory - An assumption based on limited knowledge.

Fact - Something that has been objectively verified.

DARWIN

Galapagos

Islands:

13 major (above 14 square kilometers, 5 square miles);

8 smaller islands above .12 square kilometers. (.5 square miles);

40 named islets.

Climate:

Seasons: warm and wet from January to June, cool and dry

(garúa) from July to December. Land Temperatures: High daily

temperatures on land are usually in March at about 30° C,

and lows come in September at about 19° C. Sea temperatures:

Range from 16° C to 28° C, following high/low pattern of

air temperatures. Rainfall: High rainfall comes February-April,

over 70 mm per month; these are also the sunniest and

warmest months,with the drier months being coolest and overcast. Education Workbook

Darwin’s Finches

Evolution to Survive

The birds beaks largely characterizes them in

the different species.

The variety that has a neat, sharp bill eats small insects.

The variety that eats larger insects, has a broader bill,

but still pointed back.

Birds with heavier beaks eat small seeds,

but still the beak is less blunt that the finch

that eats the large seeds.

http://www.horizon.fr/Galapagos/pinsonan.html

Natural Selection•DDDDirDirectional Selection

de Shifts in environmental conditions, such as climate change or the presence of a new disease or predator, can push a population toward one trait. In periods of prolonged cold temperatures, for example, natural selection may favor larger animals because they are better able to withstand extreme temperatures.

recessional SelectionStabilizing Selection

Sometimes natural selection acts to maintain traits by favoring the intermediate version of a characteristic instead of one of two extremes. An example of this type of selection, known as stabilizing selection, was evident in a study of the birth weight of human babies published in the middle of the 20th century. It showed that babies of intermediate weight, about 3.5 kg (8 LB), were more likely to survive. Babies with a heftier birth weight had lower chances for survival because they were more likely to cause complications during the delivery process, and lightweight babies were often born premature or with other health problems. Babies of intermediate birth weight, then, were more likely to survive to reproductive age.

( Encarta)

coital Selection Continued…..

Natural Selection

Disruptive Selection

Sometimes natural selection favors two extremes, causing alleles for intermediate forms of a trait to become less common in the gene pool. The African Mocker swallowtail butterfly has undergone this form of selection, known as disruptive selection. The Mocker swallowtail evades its predators by resembling poisonous butterflies in its ecosystem.

Sexual Selection

Sexual selection operates on factors that contribute to an organism's mating success. In many animals, sexual attractiveness is an important component of selection because it increases the likelihood of mating. Sexual selection rarely affects females, because the duration of pregnancy and infant care limits the number of babies they can have. Males, on the other hand, have few limitations on the number of offspring they can father, and a male who produces many offspring has a high level of evolutionary fitness. Males of many species, then, must compete with other males to mate with females. Some males win females' attention more often than others and, as a result, pass their genes to more offspring.

( Encarta)

Peppered Moth ( Natural Selection)

In pre-industrial England, the peppered moth was located.

Almost all peppered moths were gray with dark flecks, but very rarely a black moth was seen.

The different colors of moths belong to the same species; they reproduce with

each other, and the color difference depends mostly on alternate alleles for a single gene.

The black moths were presumably produced by a

mutation: biochemical change in DNA that makes up the genes for a trait.

( The University of Tennessee at Martin, Biology 391)

Continued...

Gray moths are

well camouflaged on gray tree trunks;

black moths stand out.

Peppered Moth

It has been shown experimentally (by Kettlewell)

that in areas with gray tree trunks,

black moths are much more likely to be eaten by

birds than are gray moths (presumably because

black moths are much easier for the birds to see.)

When industry developed in England, pollution

from factories turned tree trunks in forests

in industrial areas black. As illustrated here,

on black tree trunks, black moths are well camouflaged; gray moths stand out.

( University of Tennessee at Martin, Biology 391)

Continued…..

In industrial areas, because black moths avoided being

eaten by birds, they survived better and therefore reproduced

more (had higher fitness.) As a result, each generation,

more and more of the offspring born came from

black parents and inherited the black coloration,

since the color differences between moths (gray versus black)

are genetic. After many moth generations,almost all the moths

in industrial areas were black. Black coloration is an

adaptation to an environment with black tree trunks;

that is, it has evolved through natural selection

because black individuals have higher fitness in

forests with black tree trunks than do gray moths.

( University of Tennessee at Martin, Biology 391)

Black Moths!

Evidence for Evolution:1. Fossil Evidence

http://www.fmnh.org/sue/default.htm(Field Museum Chicago)

In 1799 an engineer named William Smith reported that, in undisrupted layers of rock,

fossils occurred in a definite sequential order, with more modern-appearing ones closer to the top.

Because bottom layers of rock logically were laid down earlier and thus are older than top layers,

the sequence of fossils also could be given a chronology from oldest to youngest.

His findings were confirmed and extended in the 1830s by the paleontologist William Lonsdale,

who recognized that fossil remains of organisms from lower strata were more primitive

than the ones above. Today, many thousands of ancient rock deposits have been identified that

show corresponding successions of fossil organisms. ( Science and Creationism)

When comparisons are made of the anatomy

of structures which seem to have

evolved very different functions,

it can be seen that the process of natural

selection has led to these differences.

Homologous structures such as the

forelimbs of a variety of mammals

(eg human, cat, whale and bat) can be shown

to possess the same skeletal elements,

suggesting that a common ancestral

forelimb has beenmodified for many different

functions. Homologous structures

such as those described above should

not be confused with analogous structures

(eg bat wing and insect wing),

where evolution has given rise to anatomically very

different structures which have similar function

(aid in flying) where this function provides

a survival advantage in a particular environment.

( VCE Biology Web Site)( Science and Creationism)

2. Homologous Structures

3. Analogous Structures

• Structures that evolve separately to perform a similar function are analogous. The wings of birds, bats, and insects, for example, have different embryological origins but are all designed for flight.

4. Vestigial Structures

• These are homologous characters of organisms which have lost all or most of their original function in a species through evolution.

• These may take various forms such as anatomical structures, behaviors and biochemical pathways. Some of these disappear early in embryonic development, but others are retained in adulthood.

• All such characters can, be traced to the genes which code for such characters. Some genes no longer code for anything, and can be called vestigial themselves, or junk DNA.

Vestigial Structures Examples

• http://www.livescience.com/animals/top10_vestigial_organs-1.html

5. Embryology

• Embryological development in many species is similar if not identical.

6. DNA

• Despite the great diversity of life on our planet, the simple language of the DNA code is the same for all living things.

• Many of the same genes exist between different species

7.Geographical Distribution

• Major isolated land areas and island groups often evolved their own distinct plant and animal communities.

• Unique biotic environments is that the life forms in these areas have been evolving in isolation from the rest of the world for millions of years.

Human Evolution

Human evolution, a long process of change where people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people over a period of at least 5 million years. ( Encarta)

(Planet of The Apes20th Century Fox)

Human Origins Africa or Asia?

Human fossils found in China. (Etler, Dennis ACenter for the Study of Chinese Prehistory)

Human path from Africa.( Encarta)

Movies• Evolution of People:http://www.pbs.org/wgbh/evo

lution/humans/humankind/index.html• Evolution of the

eye:http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.html

• The Dating Gamehttp://www.pbs.org/wgbh/evolution/sex/mating/index.html

• Microbial clockhttp://www.pbs.org/wgbh/evolution/survival/clock/index.html

Bibliography and Web Sites

Darwin’s Finches http://www.horizon.fr/galapagos/pinsonan.html

Darwin’s Finches http://www.terraquest.com/galapagos/wildlife/island/finch.html

Encartahttp://encarta.msn.com/find/concise.asp?ti=761554675&sid=36#s36

Encarta.96 Encyclopedia

Evolution Happens http://www.evolutionhappens.net/

Evolution The Evidencehttp://www.utm.edu/~rirwin/moth.htm Continued…….

Fossil Evidence for Human Evolution in ChinaCenter for Human Evolution of Chinese Prehistoryhttp://www.cruzio.com/~cscp/index.html

Holt Biology Visualizing Life, Holt, Rinehart and Winston, Inc., 1994

continued……..

Bibliography and Web Sites

Science and Creationismhttp://www.nap.edu/html/creationism/evidence.html#

Sue at The Field Museumhttp://www.fmnh.org/sue/default.htm

The Peppered Mothhttp://www.utm.edu/~rirwin/moth.htm

Virtual Galapagos Historyhttp://www.terraquest.com/galapagos/history/intro.html

Bibliography and Web Sites