BIO 1M03 Final Exam + Test 2 content

What is adaptive radiation?

The rapid production of many descendant species from a single lineage

What are the three hallmarks of adaptive radiation?

1. They are a monophyletic group

2. They speciated rapidly

3. They diversified ecologically into many niches

What are extrinsic factors?

Favorable new conditions in the environment

What are intrinsic factors?

Evolution of key morphological, physiological or behavioral traits

What is ecological opportunity?

The availability of more or new types of resources

What is the example of adaptive radiation from lecture?

The anolis lizards

What is the escape-and-radiate coevolution hypothesis?

proposes that species diversify through an evolutionary "arms race" between consumers and producers

What is the Cambrian explosion?

Sudden diversification of new species and evolutionary change

What is a fauna?

A collection of animal species

What triggered the Cambrian explosion?

Higher oxygen levels

Evolution of predation

New niches beget more new niches

New genes, new bodies

What is the Burgess Shale?

The Burgess Shale is a 508-million-year-old fossil deposit in Canada, preserving diverse Cambrian organisms with exceptional detail, offering key insights into early animal evolution and biodiversity.

What are hominids?

Large bodied animals with long arms, short legs and no tail

What are the different ways hominids walk?

Different types of primates (gorillas, chimps, bonobos) fist-walk when on the ground

Humans are bipedal and walk upright on two legs

When did human evolution begin?

7 million years ago

How many "human species" are estimated to have evolved?

20 early human species

What are the three major hominin groups?

Early hominins, australopithecines, homo genus

When did early hominins evolve? What were their key traits?

4.4-7 million years ago. small cranial capacity, small canines, many ape like traits but some human like traits

When did australopithecines evolve? What were their key traits?

1.4-4.4 million years ago. Some ape like traits. Had shifts in the spine, hip and legs towards human like features

When did homo genus evolve? What were their key traits?

2.4 - 1.4 million years ago. Higher cranial capacity, used tools, first to control fire,

What synapomorphy defines the hominins?

Bipedalism

What animals are humans most related to according to DNA sequence data?

Chimpanzees, bonobos and gorillas

What four groups did researchers organize hominins into?

Gracile australopithecines

Robust australopithecines

Early Homo

Recent Homo

What traits were present in the hominin evolution timeline between 4.5-1 mya?

Small bipeds with small teeth

What traits were present in the hominin evolution timeline between 2.7 - 1mya?

small bipeds with big teeth (probably ate plants)

What traits were present in the hominin evolution timeline at 2.3 mya?

Larger braincase, reduced cheek teeth

What traits were present in the hominin evolution timeline at 1.8 mya?

Even larger braincases, used fire to cook food, stone tools

What traits were present in the hominin evolution timeline at 400-24 kya?

Last hominin species to live with our species

Heavily built, large brains, low foreheads, powerful haws, large brow ridges, small chins

What traits were present in the hominin evolution timeline at 195 kya?

Reduced brow ridges, flat faces, largest braincases

How was natural selection involved in the evolution of hominins?

Thought that natural selection was responsible for the ability to reason and communicate, triggered by increased tool and language use

What is the out-of-Africa hypothesis?

Homo sapiens evolved traits in Africa then dispersed throughout the world, and Homo sapiens evolved independently of earlier European and Asian species of Homo

Where did Homo Neanderthalensis reside?

Europe and the Middle East

Where did Homo Erectus reside?

Asia

Where did the first wave of Homo Sapiens migrate to?

East and South towards Australia

Where did the second wave of Homo Sapiens migrate to?

Europe and mainland Asia

Did Homo Sapiens interbreed with other species as they migrated? What evidence supports this?

Yes they did

1-4 % of genomes of indigenous Europeans and Asians is derived from Neanderthals

Why did hominins evolve to become bipedal?

1. Lower surface area exposed to sun (less heat stress)

2. Hands free to carry food or tools and forage better

3. Long-distance migration, follow migrating prey

Describe the position of foramen magnum

Enters skull from below in fully bipedal hominins

What were the major modifications in the shape of the hominin pelvis?

Bowl-shaped to support upper body and provide better balance for upright posture

What were the major modifications in the feet of hominins?

Lost opposable great toe

Large heel, arched foot, ridged lever vs grasping

Propel forward, absorb forces of bipedal walking

What were some of the advantages of increased brain size?

Sophisticated tool manufacture and use

Foraging and hunting techniques more complex and effective

Cooperative social skills, social learning

What was a cost associated with larger brains?

Energy expensive

What occurred when brain size increased regarding brain development?

Took much longer than our descendants

Dependent on parental care for much longer

What were the sexual dimorphisms and differences in parental care in homo sapiens?

Males are 15% larger

There is greater parental care:

- More food sharing

- Division of labor

- Pair-bond mating

What is the FOXP2 gene? Why is it important?

It is the language gene. Essential for human speech

What evolved in homo sapiens to allow for better speech?

Hyoid bone positioned to allow tongue movements in speech

What is altruism? How might this affect evolution?

Benefiting another individual at one's own expense

Reciprocation: benefitting others feeds back to benefit you

Cheaters (take and not reciprocate) are punished

What are some pieces of evidence for cooperative hunting?

Injuries due to hunting

Healing from wounds that would have required care from others in the social group

What are some examples of how humans are still evolving today?

- Coevolution with pathogens

- Effects of C-section on evolution of head size

- Spread of lactose tolerance mutation

- Human skin pigmentation

- Resistance to malaria

Describe the evolution of human skin pigmentation?

Over 350 genes associated with skin color (MC1R gene has allele for lighter and darker pigmentations)

Where is UV radiation most intense?

Equator

Where does natural selection favor darker skin pigmentation?

Near the Equator

What are some selective agents of skin pigmentation?

Skin cancer

Folate

Vitamin D

What are the two main types of skin cancer?

Melanoma and Non-melanoma

Which type of skin cancer is more common? Which is more fatal?

Non-melanoma is more common

Melanoma is more fatal

What is folate? Why is it important?

An essential nutrient, cannot be synthesized and must be obtained from diet

Necessary for DNA repair and synthesis

Deficiencies decrease reproductive success in women (chance of improper fetus development) and men (chance sperm do not develop and mature properly)

How does UV radiation effect folate?

Causes breakdown in blood folate

How is vitamin D obtained? Is it synthesized in the human body? What is required?

Vitamin D is obtained through diet

Can be synthesized in our bodies, pathway requires UV light

What is vitamin D important?

Necessary for calcium absorption

Regulates immune function

Correlations between Vitamin D deficiencies and cancer

Describe the fitness trade-off regarding human skin pigmentation?

Darker skin pigmentation means more protection from UV damage, but reduces vitamin D synthesis

Who is usually affected by malaria?

young children and pregnant women

How is malaria transmitted to humans? What occurs when in the body?

mosquitos. Replicates within RBCs and causing them to burst open and release more

How has selection affected the resistance to malaria?

Favored modifications of RBCs that reduce the success of malaria. (sickled cell shape due to HbS mutation).

What happens if an individual is homozygous for HbS?

Develop sickle cell anemia

What happens if an individual is heterozygous (HbS/HbA)?

Strongly protected against malaria

What is balanced polymorphism?

A steady state when both alleles persist in the population

When is lactase production halted?

After weaning

What is pastoralism?

the domestication of animals around 5-10 kya

How did selection affect pastoralist populations?

Lactase production continued after the age of 2 due to dominant mutations that kept the lactase gene active

What are mismatches to modernity?

Biology cannot keep pace with cultural and rapid environmental change

What is the hygiene/old friends hypothesis?

Gut-associated microbes are essential for normal development and improved health

What happened when modern medicine and hygiene practices were introduced?

Removed some coevolved microbes, leading to immune system dysregulation. Worms evolved to dampen inflammatory responses. Without them, immune responses can be over-reactive

What is the relationship between contraception and breast cancer?

Women who delay having children through contraception are more susceptible to breast cancer because they have more menstrual cycles. Each menstrual cycle, breast tissue goes through many rounds of mitosis, which means more room for replication error

What is degenerative disease?

Disease caused by a deterioration of the body

What affect does age have on selection intensity?

Decreases as we age

What is antagonistic pleiotropy regarding reproduction and lifespan?

It is the genetic coupling of traits, and increased reproduction reduces lifespan

What is the evidence behind the cost of reproduction in humans?

Alleles associated with increase reproductive performance raise the risk of cancer later in life

How did cancer evolve?

Through mutation and clonal competition.

What do successful clones of cancer lead to?

Metastasis and drug resistance

What happens when less malignant clones are removed through chemotherapy?

Removes competition, allows aggressive clones to expand

What do lower chemotherapy doses do?

Maintains competition and slower malignancy

Why is AMR significant?

Leading cause of death

Why is AMR a problem?

Pathogens evolve resistance quickly, and Horizontal gene transfer spreads the resistance genes rapidly, accelerating AMR evolution

What does overuse of antibiotics cause in AMR?

causes selection for multidrug-resistant pathogens

How can resistance development be slowed in AMR?

Using lower effective antibiotic doses

What is a biotic factor?

A living organism

What is an abiotic factor?

Nonliving aspects

What is a population?

Individuals of the same species in the same place at the same time

What is the size feature of a population?

total number of individuals present in the same area at the same time

What is the range feature of a population? What drives the range feature?

Area over which a population is spread (driven by abiotic and biotic factors)

What is the density feature of a population?

Size divided by range

What is the random spatial distribution?

Individuals in the population are placed random with no clear pattern. Equal chance of occupying any position

What is the clustered spatial distribution? What causes it?

When individuals are grouped together in various locations.

Caused by clustering of resources or if proximity enhances fitness

What is the uniform spatial distribution?

Individuals are distributed evenly , due to territories, limited resources or predation

What is the lime swallowtail butterfly?

Native to Asia, a butterfly that spread around South America. Eat the leaves of citrus trees

What is sessile?

adult forms stay attached to one place; generally don't move

What is the formula for the mark-recapture method?

N = (C/R) M

N = population size

C = total caught on day 2

R = # of M recaptured

M = marked on day one

What is the Asian vulture crisis? Why did it occur?

The rapid decline of 3 species of Gyps vultures.

Caused by traces of veterinary drug diclofenac found in the kidneys. Caused visceral gout in vultures, leading to renal failure then death

What are the four factors that determine population size?

Birth, Death, Immigration, Emigration

What is the equation for the change in population?

Change = (B-D) +(I-E)

What is the equation for change in population over time?

Delta N / Delta t