Transcript EVOLUTION - Somers Public Schools

EVOLUTION
By Karen Legg
for EDU 580
Evolution Happens
Lofton, Carol and Bill)
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 Selection
Stabilizing 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...
Peppered Moth
Gray moths are
well camouflaged on gray tree trunks;
black moths stand out.
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…..
Black Moths!
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)
Evidence for Evolution:
1. Fossil Evidence
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)
http://www.fmnh.org/sue/default.htm
(Field Museum Chicago)
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.
2. Homologous
Structures
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)
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
(Planet of The Apes
20th Century Fox)
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)
Human Origins Africa or Asia?
Human path from Africa.( Encarta)
Human fossils found in China. (Etler, Dennis A
Center for the Study of Chinese Prehistory)
Movies
• Evolution of
People:http://www.pbs.org/wgbh/evolution/human
s/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/mati
ng/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
Encarta
http://encarta.msn.com/find/concise.asp?ti=761554675&sid=36#s36
Encarta.96 Encyclopedia
Evolution Happens http://www.evolutionhappens.net/
Evolution The Evidence
http://www.utm.edu/~rirwin/moth.htm
Continued…….
Bibliography and Web Sites
Fossil Evidence for Human Evolution in
China
Center for Human Evolution of Chinese
Prehistory
http://www.cruzio.com/~cscp/index.html
Holt Biology Visualizing Life, Holt,
Rinehart and Winston, Inc., 1994
continued……..
Bibliography and Web Sites
Science and Creationism
http://www.nap.edu/html/creationism/evidence.html#
Sue at The Field Museum
http://www.fmnh.org/sue/default.htm
The Peppered Moth
http://www.utm.edu/~rirwin/moth.htm
Virtual Galapagos History
http://www.terraquest.com/galapagos/history/intro.html