Natural selection can only occur if there is variation among members of the same species.
Mutation, meiosis and sexual reproduction cause variation between individuals in a species.
Adaptations are characteristics that make an individual suited to its environment and way of life.
Species tend to produce more offspring than the environment can support.
Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.
Individuals that reproduce pass on characteristics to their offspring.
Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.
Examples of Codominance. The best example, in this case, is the codominance blood type. ABO group is considered to be a codominant blood group where both father’s and mother’s blood group is expressed. It means that the properties of the blood groups exist in the ABO type.
Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.
Examples of Codominance. The best example, in this case, is the codominance blood type. ABO group is considered to be a codominant blood group where both father’s and mother’s blood group is expressed. It means that the properties of the blood groups exist in the ABO type.
Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.
Codominance is the situation when the effect of both genes are observed. This presentation describes how codominant traits work to determine human blood types and flower coloring .
#4 B1 topic 1 - continuous and discontinuous variationMr. Science
B1 Topic 1 - continuous and discontinuous variation:
Edexcell GCSE Science -> Higher -> Core Science -> B1 -> Topic 1 -> continuous and discontinuous variation
4th in the B1 Topic 1 series
- Contains everything you need to know from the specification*
- Specially designed for triple and dual science GCSE
- A good teaching tool
- A good revision tool
- Compliments the CGP revision books
*From Edexcell GCSE Science from 2011 specification, suitable for 2014 & 2015 exams
Contains detailed notes and questions that may come up in the exams.
Please comment with your views or any questions that you have
Codominance is the situation when the effect of both genes are observed. This presentation describes how codominant traits work to determine human blood types and flower coloring .
#4 B1 topic 1 - continuous and discontinuous variationMr. Science
B1 Topic 1 - continuous and discontinuous variation:
Edexcell GCSE Science -> Higher -> Core Science -> B1 -> Topic 1 -> continuous and discontinuous variation
4th in the B1 Topic 1 series
- Contains everything you need to know from the specification*
- Specially designed for triple and dual science GCSE
- A good teaching tool
- A good revision tool
- Compliments the CGP revision books
*From Edexcell GCSE Science from 2011 specification, suitable for 2014 & 2015 exams
Contains detailed notes and questions that may come up in the exams.
Please comment with your views or any questions that you have
PowerPoint presentation that highlights chapters 13 and 14 in Campbell's Essential Biology (3rd. edition). It can also be used for Miller & Levine's Biology (2006 Ed.) for chapters 15-18.
Evidence of Evolution by Natural Selection - how basic evolutionary principal...Madison Elsaadi
This PPTP is made for high school teachers wishing to introduce evolutionary concepts and exercises in regular and advance (AP) high school science courses.
The Development of Evolutionary TheoryAnthropology 1 Fall.docxarnoldmeredith47041
The Development of Evolutionary Theory
Anthropology 1: Fall 2016
Religion and science concern different aspects of
the human experience, and they are not
inherently mutually exclusive categories.
Belief in God does not exclude the possibility of
biological evolution; acknowledgement of
evolutionary processes doesn't preclude the
existence of God.
Evolutionary theories are not rejected by all
religions or by most forms of Christianity.
A substantial majority of Americans (about 7 in 10)
believe the scientific Theory of Evolution is
compatible with a belief in God – one does not
preclude the other.
◦ “Evolution and Creationism in Public Education” People For the American Way Foundation
Evolution is the most fundamental of all biological
processes, but one of the most misunderstood.
Humans evolved from a species that lived some 6-8
million years ago (mya), not monkeys or chimpanzees.
Humans do share a recent common ancestor with other
primates
Evolution takes time; hence, the appearance of a new
species is rarely witnessed
The theory has been tested and subjected to
verification through accumulated evidence (and has
not been disproved)
The theory of evolution has been supported by a
mounting body of genetic evidence.
The theory has stood the test of time.
The theory continues to grow.
Evolutionary principles were developed in
western Europe, made possible by scientific
thinking dating to the 16th century.
Western science, however, borrowed ideas from
Arab, Indian, and Chinese cultures where notions
of biological evolution had already developed.
By the 19th century, evolution wasn’t a new
concept, but Natural Selection was a new theory
The notion that species,
once created, can never
change
An idea diametrically
opposed to theories of
biological evolution.
To challenge the idea
was to challenge the
Argument from Design
(life engineered by a
purposeful God).
Came with the discovery of the New World,
introducing new ideas and challenging
fundamental views about the planet.
Exposure to new plants and animals
increased awareness of biological diversity.
Brave new thinkers began to challenge long held
church doctrine and belief
◦ Aristotle taught that the sun and planets existed in a
series of concentric spheres that revolved around the
sun.
◦ Copernicus challenged the idea that the earth was the
center of the universe.
◦ Galileo’s work supported the idea that the universe was
a place of motion.
John Ray, developed the concept of species.
Groups of plants and animals could be
differentiated from other groups by their ability
to mate with one another and produce offspring.
He placed such groups of reproductively isolated
organisms into a single category, which he called
the species.
Carolus Linnaeus, a Swedish naturalist who
developed a method of classifying plants and
animals.
In Systema Naturae, first .
Anthropogenesis is the genesis or development of the human race, especially as a subject of scientific study.
Hominization, also called anthropogenesis, refers to the process of becoming human and is used in somewhat different contexts in the fields of paleontology and paleoanthropology, archeology, philosophy, and theology.
Understandings:
Most species occupy different trophic levels in multiple food chains
A food web shows all the possible food chains in a community
The percentage of ingested energy converted to biomass is dependent upon the respiration rate
The type of stable ecosystem that will emerge in an area is predictable based on climate
In closed ecosystems energy but not matter is exchanged with the surroundings
Disturbance influxes the structure and rate of change within ecosystems
Applications:
Conversion ratio in sustainable food production practices
Consideration of one example how humans interfere with nutrient cycling
Skills:
Comparison of pyramids of energy from different ecosystems
Analysis of a climograph showing the relationship between temperature, rainfall and the type of ecosystem
Construction of Gersmehl diagrams to show the inter-relationships between nutrient stores and flows between taiga, desert, and tropical rainforest.
Analysis of data showing a primary succession
An investigation into the effect of an environmental disturbance on an ecosystem
Understandings:
The distribution of species is affected by limiting factors
Community structure can be strongly affected by keystone species
Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species
Interactions between species in a community can be classified according to their effect
Two species cannot survive indefinitely in the same habitat if their niches are identical
ATL / Approaches to teaching and learning /Mariam Ohanyan
Inquiry-based Learning includes teaching methods built on students' individual knowledge and interests and emphasizes learning how to learn and how to find out, using both traditional and contemporary media. Each teacher has the mandate that the learning within their classroom must be engaging, relevant challenging and
Այս սահիկաշարը ստեղծվել է ավագ դպրոցի սաների և ուսանողների համար, որոնք արժևորում են գիտության մեջ հետազոտական աշխատանքի կարևորությունը: Այն հնարավորություն է տալիս առավել լավ պատկերացնել ՙՙվարկած՞՞ և ՙՙփոփոխականներ՞՞ հասկացույունները և հետազոտական հարց, վարկած ձևակերպելու ուղիները:
A clade is a group of organisms that have evolved from a common ancestor.
Cladograms are tree diagrams that show the most probable sequence of divergence in clades.
Evidence for which species are part of a clade can be obtained from the base sequence of a gene or the corresponding amino acid sequence of a protein.
Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.
Traits can be analogous or homologous.
Evidence from cladistics has shown that classification of some groups based on structure did not correspond with the evolutionary origins of a group or species.
The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.
When species are discovered they are given scientific names using the binomial system.
All organisms are classified into three domains.
Taxonomists classify species using a hierarchy of taxa.
The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species.
In a natural classification, the genus and accompanying higher taxa consists of all the species that have evolved from one common ancestral species.
Topic 4.1 species, communities and ecosystemsMariam Ohanyan
Skills:
1.Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.
2.Setting up sealed mesocosms to try to establish sustainability.
3. Testing for association between two species using the chi-squared test with data obtained by quadrat sampling.
4. Recognizing and interpreting statistical significance.
This document is created for SL and HL IBDP students. It will help them better understand the content of the 3 main topics("Ecology", "Evolution", "Human physiology" ) of the core before the final exams.
This document is created for SL and HL IBDP students. It will help them better understand the content of the 3 main topics("Ecology", "Evolution", "Human physiology" ) of the core before the final exams.
Evolution occurs when heritable characteristics of a species change.
The fossil record provides evidence for evolution.
Selective breeding of domesticated animals shows that artificial selection can cause evolution.
Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
Populations of a species can gradually diverge into separate species by evolution.
Continuous variation across the geographical range of related populations matches the concept of gradual divergence.
Personal Project Guide by Mrs. Mariam OhanyanMariam Ohanyan
The Personal Project is an independent assignment that can be on any topic and take any form as long as it has a strong connection to one Area of Interaction. If you choose the right Personal Project, it will give you the opportunity to share with others something that is important to you, and it will be an exciting and rewarding experience.
It is your project that demonstrates the skills you have developed over the years in the Middle Years Program (MYP). The Personal Project holds a special place of importance in the MYP, as it is a culminating even which is completed in the final year of the program (Grade 10).
You will be working on your project over the course of many months, so be sure you pick a topic in which you have a strong interest or genuine curiosity. The project will consist of the actual project, the process journal that documents your ideas and work throughout the project, and the personal report which will be summarize your overall experience.
The Personal Project is an independent assignment that can be on any topic and take any form as long as it has a strong connection to one Area of Interaction. If you choose the right Personal Project, it will give you the opportunity to share with others something that is important to you, and it will be an exciting and rewarding experience.
It is your project that demonstrates the skills you have developed over the years in the Middle Years Program (MYP). The Personal Project holds a special place of importance in the MYP, as it is a culminating even which is completed in the final year of the program (Grade 10).
You will be working on your project over the course of many months, so be sure you pick a topic in which you have a strong interest or genuine curiosity. The project will consist of the actual project, the process journal that documents your ideas and work throughout the project, and the personal report which will be summarize your overall experience.
This article address the importance of social skills in approaches to learning. DP students must become aware how science work and how to communicate with others to achieve the best results in the learning process.
Բջիջ համարվում է բոլոր կենդանի օրգանիզմների կառուցվածքային, ֆունկցիոնալ և ժառանգական տարրական միավորը։ Բջիջը օժտված է կենդանի նյութին բնորոշ հատկություններով, որոնք պահպանվում ու փոխանցվում են հաջորդ սերունդներին։
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
2. Understandings:
Natural selection can only occur if there is variation among
members of the same species
Mutation, meiosis and sexual reproduction cause variation
between individuals in a species
Adaptations are characteristics that make an individual suited to
its environment and way of life
Species tend to produce more offspring than the environment
can support
Individuals that are better adapted tend to survive and produce
more offspring while the less well adapted tend to die or
produce fewer offspring
Individuals that reproduce pass on characteristics to their
offspring
2
02/07/18
3. Natural selection increases the frequency of characteristics
that make individuals better adapted and decreases the
frequency of other characteristics leading to changes
within the species.
By Mariam Ohanyan
3
02/07/18
Source: https://creationscience4kids.com/can-natural-selection-make-anything/
4. The process of natural selection occurs in
response to a number of conditions:
Inherited Variation – There is genetic variation within a
population which can be inherited
Competition – There is a struggle for survival (species tend to
produce more offspring than the environment can support)
Selection – Environmental pressures lead to differential
reproduction within a population
Adaptations – Individuals with beneficial traits will be more
likely to survive and pass these traits on to their offspring
Evolution – Over time, there is a change in allele frequency
within the population gene pool
By Mariam Ohanyan
4
02/07/18
6. The key components to the process of
natural selection are:
Mnemonic: ICE AGE
Inherited variation/ /ժառանգական փոփոխականություն exists within the
population
Competition/ /մրցակցություն results from an overproduction of offspring
Environmental pressures/ /միջավայրի ազդեցություն lead to differential
reproduction
Adaptations/ /հարմարողականությւոն which benefit survival are selected
for
Genotype frequency/ /գենոտիպի հաճախականություն changes across
generations
Evolution/ /զարգացում occurs within the population
By Mariam Ohanyan
6
02/07/18
7. Mechanisms of genetic
variation
Meiosis –
Via either crossing
over (prophase I)
or independent
assortment
(metaphase I)
Sexual reproduction –
The combination of
genetic material from
two distinct sources
creates new gene
combinations in
offspring
02/07/18By Mariam Ohanyan
7
Mutations –
Changing the
genetic
composition of
gametes
8. Mutations
By Mariam Ohanyan
8
02/07/18
A gene mutation is a change in the nucleotide sequence of a section
of DNA coding for a specific trait
New alleles are formed by mutation
Gene mutations can be:
beneficial,
detrimental or
neutral
9. Detrimental Mutation
Change in the base sequence of a genome that has the effect of
reducing the fitness of the so-affected organism.
Detrimental mutations simply are mutations that negatively impact
an organism's ability to survive and/or reproduce.
By Mariam Ohanyan
9
02/07/18
Source: https://raheelsbio11.wordpress.com/page/4/
10. Helpful mutations
Beneficial mutations can be found throughout the natural world.
Remember, a mutation is a change in your DNA, more specifically, a
mutation that allows your DNA to create a protein that functions
differently than it otherwise would.
Example: In humans, scientists have uncovered a recent mutation in the
receptor proteins of the cell membrane. People possessing this mutation
(though few in number) have shown a resistance to HIV. This is due to the
inability of the virus to bind correctly to the host cell.
By Mariam Ohanyan
10
02/07/18
12. Meiosis
By Mariam Ohanyan
12
02/07/18
Meiosis promotes variation by creating new gene combinations
via either crossing over or independent assortment
1. Crossing Over
2. Independent Assortment
13. Crossing over
By Mariam Ohanyan
13
02/07/18
Crossing over involves the exchange of segments of DNA between homologous
chromosomes during prophase I
The exchange of genetic material occurs between non-sister chromatids at
points called chiasmata.
14. 02/07/18By Mariam Ohanyan
14
Independent Assortment
The orientation of each bivalent occurs independently, meaning
different combinations of maternal / paternal chromosomes can be
inherited when bivalents separate in anaphase I.
15. 02/07/18By Mariam Ohanyan
15 Sexual Reproduction
The fusion of two haploid gametes results in the formation of a diploid
zygote. This zygote can then divide by mitosis and differentiate to form
a developing embryo.
16. Malthusian dilemma
In 1787 economist-philosopher Thomas
Malthus wrote an Essay on Population in
which he described how the environment
limits the size of human populations.
Malthus’s argument is simple:
“Like other animals, human populations
grow exponentially. But food production,
the factor that ultimately limits the size of
the human population, grows linearly.
By Mariam Ohanyan
16
02/07/18
18. 02/07/18By Mariam Ohanyan
18
Adaptations
•Structural: Physical differences in biological structure
(e.g. neck length of a giraffe)
•Behavioral: Differences in patterns of activity (e.g.
opossums feigning death when threatened)
•Physiological: Variations in detection and response
by vital organs (e.g. homeothermy, color perception)
•Biochemical: Differences in molecular composition of
cells and enzyme functions (e.g. blood groups, lactose
tolerance)
•Developmental: Variable changes that occur across
the life span of an organism (senescence/ֆիզիոլոգիական
/)ծերացում
22. Remember the basic
formulas:
p2
+ 2pq + q2
= 1 and p + q = 1
p = frequency of the dominant allele in the population
q = frequency of the recessive allele in the population
p2
= percentage of homozygous dominant individuals
q2
= percentage of homozygous recessive individuals
2pq = percentage of heterozygous individuals
02/07/18By Mariam Ohanyan
22
23. PROBLEM #1
You have sampled a population in which you know that the
percentage of the homozygous recessive genotype (aa) is
36%. Using that 36%, calculate the following:
02/07/18By Mariam Ohanyan
23
1. The frequency of the "aa" genotype.
Answer: 36%, as given in the problem itself.
2. The frequency of the "A" allele.
Answer: If q2
= 0.36, then q = 0.6. Since q = 0.6, and p + q = 1,
then p = 0.4; the frequency of A is by definition equal to p, so the
answer is 40%.
3. The frequencies of the genotypes "AA"
and "Aa."
Answer: The frequency of AA is equal to p2
, and the frequency of Aa is
equal to 2pq. So, using the information above, the frequency of AA is
16% (i.e. p2
is 0.4 x 0.4 = 0.16) and Aa is 48% (2pq = 2 x 0.4 x 0.6 =
0.48).
24. PROBLEM #2
02/07/18By Mariam Ohanyan
24
Within a population of butterflies, the color brown (B) is dominant over
the color white (b). And, 40% of all butterflies are white. Calculate the
following:
A. The percentage of butterflies in the population that are heterozygous.
B. The frequency of homozygous dominant individuals.
25. 02/07/18By Mariam Ohanyan
25 Answer
The first thing you'll need to do is obtain p and q.
So, since white is recessive (i.e. bb), and 40% of the butterflies are white, then
bb = q2
= 0.4.
To determine q, which is the frequency of the recessive allele in the
population, simply take the square root of q2
which works out to be 0.632 (i.e.
0.632 x 0.632 = 0.4).
So, q = 0.63.
Since p + q = 1, then p must be 1 - 0.63 = 0.37.
Now then, to answer our questions.
First, what is the percentage of butterflies in the population that are
heterozygous?
Well, that would be 2pq so the answer is 2 (0.37) (0.63) = 0.47.
Second, what is the frequency of homozygous dominant individuals? That
would be p2
or (0.37)2
= 0.14.
26. Adaptive radiation
Adaptive radiation describes the rapid evolutionary
diversification of a single ancestral line
It occurs when members of a single species occupy
a variety of distinct niches with different
environmental conditions
Consequently, members evolve different
morphological features (adaptations) in response to
the different selection pressures
An example of adaptive radiation can be seen in the
variety of beak types seen in the finches of the
Galapagos Islands
02/07/18By Mariam Ohanyan
26
29. Evolution of Darwin's finches
Peter and Rosemary Grant have seen evolution happen over
the course of just two years.
The Grants study the evolution of Darwin's finches on the
Galapagos Islands. The birds have been named for Darwin, in
part, because he later theorized that the 13 distinct species
were all descendants of a common ancestor. Each species
eats a different type of food and has unique characteristics
developed through evolution.
For example, the cactus finch has a long beak that reaches
into blossoms, the ground finch has a short beak adapted for
eating seeds buried under the soil, and the tree finch has a
parrot-shaped beak suited for stripping bark to find insects.
02/07/18By Mariam Ohanyan
29
31. The Grants have focused their research on the medium
ground finch, Geospiza fortis, on the small island of Daphne
Major.
Daphne Major serves as an ideal site for research because
the finches have few predators or competitors. (The only
other finch on the island is the cactus finch.) The major
factor influencing survival of the medium ground finch is the
weather, and thus the availability of food. The medium
ground finch has a stubby beak and eats mostly seeds.
Medium ground finches are variable in size and shape,
which makes them a good subject for a study of evolution.
02/07/18By Mariam Ohanyan
31
32. Darwin’s finches
Darwin’s finches demonstrate adaptive radiation and show
marked variation in beak size and shape according to diet
Finches that feed on seeds possess compact, powerful beaks –
with larger beaks better equipped to crack larger seed cases
In 1977, an extended drought changed the frequency of larger
beak sizes within the population by natural selection
Dry conditions result in plants producing larger seeds with
tougher seed casings
Between 1976 and 1978 there was a change in average beak
depth within the finch population
Finches with larger beaks were better equipped to feed on the
seeds and thus produced more offspring with larger beaks
02/07/18By Mariam Ohanyan
32
33. Medium ground finches with larger beaks could take
advantage of alternate food sources because they
could crack open larger seeds. The smaller-beaked birds
couldn't do this, so they died of starvation
02/07/18By Mariam Ohanyan
33
In 1978 the Grants returned to Daphne Major to document the
effect of the drought on the next generation of medium ground
finches. They measured the offspring and compared their beak size
to that of the previous (pre-drought) generations. They found the
offsprings' beaks to be 3 to 4% larger than their grandparents'. The
Grants had documented natural selection in action.
34. Antibiotic Resistance in
Bacteria
02/07/18By Mariam Ohanyan
34
An example of antibiotic resistance in bacteria can be seen in the
evolution of Staphylococcus aureus (Golden staph)
Golden staph can cause infections to the skin (lesions and boils) as
well as more serious infections (pneumonia, meningitis)
Historically, these infections were treated using the antibiotic
methicillin
Bacterial strains developed that were resistant to this antibiotic
(methicillin-resistant Staphylococcus aureus – or MRSA)
These strains proliferated while susceptible strains died out (methicillin-
sensitive Staphylococcus aureus – or MSSA)
MRSA infections are now especially present in hospitals and nursing
homes, where the use of methicillin was most common
Medical practitioners now prescribe alternate antibiotic agents to treat
infections caused by Staphylococcus aureus
35. Antibiotic Resistance in Bacteria
When treated with antibiotics, the resistant bacteria will
survive and reproduce by binary fission (asexual
reproduction)
The antibiotic resistant bacteria will flourish in the absence of
competition from other strains of bacteria (killed by
antibiotic)
Antibiotic resistant bacteria may also confer resistance to
susceptible strains by transferring plasmids via bacterial
conjugation
The introduction of antibiotic (selection pressure) has caused
the antibiotic resistance gene to become more frequent
(evolution)
02/07/18By Mariam Ohanyan
35
38. 02/07/18By Mariam Ohanyan
38
NEO DARWINISM
Neo-Darwinism is the synthesis of Darwinian
theory and modern genetics – it combines:
The works of Gregor Mendel in describing how
traits are inherited (Mendelian inheritance).
The works of James Watson and Francis Crick
in elucidating the genetic basis of inheritance
(DNA structure).
39. 02/07/18By Mariam Ohanyan
Selection pressure/ /Ընտրության ճնշում
39
Selection pressures are external agents which affect an organism’s ability
to survive in a given environment
•Selection pressures can be negative (decreases the occurrence of a
trait) or positive (increases the proportion of a trait)
•Selection pressures may not remain constant, leading to changes in
what constitutes a beneficial adaptation
Types of selection pressures include:
•Resource availability – Presence of sufficient food, habitat (shelter /
territory) and mates
•Environmental conditions – Temperature, weather conditions or
geographical access
•Biological factors – Predators and pathogens (diseases)
Selection pressures can be density-dependent (affected by population
size) or density-independent (unaffected by population)
41. Biologists sometimes define two types of
evolution based on scale:
Macroevolution, which refers to large-scale changes that occur over
extended time periods, such as the formation of new species and
groups.
Microevolution, which refers to small-scale changes that affect just
one or a few genes and happen in populations over shorter
timescales.
Microevolution and macroevolution aren’t really two different
processes. They’re the same process – evolution – occurring on
different timescales. Microevolutionary processes occurring over
thousands or millions of years can add up to large-scale changes
that define new species or groups.
By Mariam Ohanyan
41
02/07/18
43. Microevolution
By Mariam Ohanyan
43
02/07/18
Microevolution refers to varieties within a given type. Change happens
within a group, but the descendant is clearly of the same type as the
ancestor. This might better be called variation, or adaptation, but the
changes are "horizontal" in effect, not "vertical." Such changes might be
accomplished by "natural selection," in which a trait within the present
variety is selected as the best for a given set of conditions, or
accomplished by "artificial selection," such as when dog breeders
produce a new breed of dog.
44. Microevolution and Macroevolution
Microevolution describes evolutionary
changes that occur within a short
period of geological time (e.g.
between generations)
There are three main processes that
promote variation within a population
(biodiversity):
Gene mutations: A change the
genetic composition of an organism
due to alterations in the DNA base
sequence
Sexual reproduction: Introduces new
gene combinations in offspring via
random mating and meiotic divisions
Gene flow: The movement of alleles
into (or out of) a population as a result
of immigration or emigration
Macroevolution describes
evolutionary changes that occur
over relatively long geological
periods, resulting in speciation
Macroevolution involves changes
in large populations and often is
associated with significant
environmental change
Not all populations undergo
constant evolutionary
modifications, some remain
relatively unchanged (stasis)
When evolutionary changes
prevent two related populations
from interbreeding, then
speciation has occurred.
02/07/18By Mariam Ohanyan
46. Artificial Gene Transfer
The inheritance of particular
characteristics results from the
transmission of associated
genes from one generation to
the next
As this transmission requires
reproduction by the organism/s
and occurs across generations
it is called vertical gene transfer
Typically, the only way for most
organisms to develop
particular genetic traits is via
inheriting them from their
parents.
Bacteria can transfer
genes between
organisms within a
generation via the
exchange of plasmids
by bacterial
conjugation
This transmission is
called horizontal gene
transfer as it occurs
within a single
generation
02/07/18By Mariam Ohanyan
46
48. Flashcards
02/07/18By Mariam Ohanyan
48
1. provide evidence that organisms have
changed over time (evolved)
Answer: Fossils; patterns of early
development; similar body structures:
2. By examining fossils, scientists can infer…
Answer: the structures of ancient organisms.
3. Fossils show how organisms…
Answer : have changed over time
4. Organisms with similar early development
Answer : share common ancestors
Source: https://quizlet.com/86076082/52-evidence-of-evolution-
flash-cards/
Watch Videos:
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Carbon is found in several large reservoirs in the biosphere. In the atmosphere, it is found as carbon dioxide gas; in the oceans as dissolved carbon dioxide; on land in organisms, rocks, and soil; and underground as coal, petroleum, and calcium carbonate rock.