BIO 1001 Exam 3

UMN Willis

symbiosis

-2 different species live together in direct contact
-ex: lichen and mycorrhizae
-fundamental to the health of multicellular organisms

mutualism

any relationship in which both parties gain immediate benefits

endosymbiosis

-where one species lives inside the cells/body of another species
-ex: mitochondria, chloroplasts, gut sumbionts

examples of struggle of survival

origins of the Eukaryotes, origins of multicellularity, and symbiosis.
competition means being faster, stronger, and sexier (for mating)

eukaryotic cells

-animals: contain mitochondrion and nucleus
-plants: contain nucleus, chloroplasts, and mitochondrion

where can the mitochondrion and chloroplasts be transmitted

in the cytoplasm of the egg or ovule; never in the sperm or pollen

mitochondria

-primary site of cell metabolism
-aerobic
-contains own DNA
-circular chromosome
-reproduces by binary fission
-ancestors: aerobic eubacteria
-allowed cells to survive in oxygen-rich environments

heterotrophic eukaryotes arose when

anaerobic bacteria engulfed aerobic bacteria

protists

-single-celled eukaryotes
-10x larger than prokaryotes
-eukaryotes with mitochondria

multicellularity advantages

-larger size
-division of labor between specialized cells
-greater potential for complexity

colonial bacteria

can move as a unit...motility depends on how well cells stick together

slime molds

-single-celled eukaryotes that can merge to form colonies of less than 20,000 cells
-first eukaryotes to live on land

heterotrophs

organisms that obtain nutrients from other organisms (ex: fungus and all animals)

fungus

-first multicellular land organism
-largest organism in the world

mycelium of fungus

turns dirt to humus (organic component of soil)

earliest ancestor of the animals

choanoflagellate (grow via cell adhesion)

autotrophs

organism that can produce their own organic nutrients (ex: plants and algae)

3 crucial components needed for multicellular organisms to evolve from single-celled organisms

1. ability for cells to stick together
2. selection for larger size
3. selection for greater complexity

autotrophic eukaryotes arose when

heterotrophic protists engulfed cyanobacteria

chloroplasts

-structure within the cells of plants and green algae that is the site of photosynthesis
-ancestor: cyanobacteria
-important: allowed cells to produce their own food from sunlight

conjugation

direct transfer

transformation

uptake of naked DNA

transduction

viruses move DNA between hosts

lateral gene transfer

-antibiotic resistance can transfer from 1 hospital pathogen to another
-resistance in animal pathogens can transfer to human pathogens

prokaryote

-has neither a distinct nucleus with a membrane nor other specialized organelles
-ex: bacteria and cyanobacteria

nucleus

the central and most important part of an object, movement, or group, forming the basis for its activity and growth

colonial protists

individual protists that form a colony and act as a larger, multicellular organism

mycorrhizae and lichen

-lichen: fungus and green algae
-mycorrhizae: provide soil nutrients to plants and receive carbohydrates from the plant (photosynthesis)

How do our endosymbionts keep us healthy?

They help us to digest food, good gut bacteria prevent infection by harmful bacteria, bacteria in birth canal protect infants against asthma and allergies.

How does lateral gene transfer between bacteria cause problems for human health?

-Antibiotic resistance can transfer from one hospital pathogen to another (ex. erythromycin resistance from strep to staph)
-Resistance in animal pathogens can transfer to human pathogens (ex. antibiotic use in farm animals leads to resistant strain of E.coli that infect humans)
-Bacteria have existed for \>3 billion years: LGT must have been common in history of life

How does overuse of antibiotics in humans and livestock risk human health?

Antibiotics can cause disease by creating opportunities for the most resistant bacteria to survive and reproduce.

heterotrophic animals need

-digestive system
-sense organs

mobile animals need

-circulatory system
-muscolo-skeletal system

diversification of animals

-retention of ancestral trait (homology)
-parallel evolution (analogy)

paedomorphosis

where adults retain the juvenile traits of their ancestors

coelom

body cavity; allows greater mobility without getting your guts in a twist

hydrostatic

skeletal system

homologies of animals due to common ancestry

-type of symmetry (radial vs. bilateral)
-paedomorphosis (ancestral larvae--\>adult descendants)
-open/closed gut; coelom
-developmental pathways
-segmentation

analogies of animals due to similar responses to similar problems

-limbs, fins
-circulatory system
-vision, hearing, brain

radial symmetry

-symmetry around a central axis
-ex: sponge, starfish or a tulip

bilateral symmetry

-being divisible into symmetrical halves on either side of a unique plane
-ex: worms

coelomate

ex: mollusks, arthropods

evolutionary innovation for acquisition of lungs in bony fishes

moving from the oceans to fresh water

evolutionary innovation for paired appendages in amphibia

moving from water to land

evolutionary innovation for better lungs, waterproof skin, and eggshells in reptiles

moving further onto dry land

evolutionary innovation for mammals

becoming active at night

evolutionary innovation for primates

-living in a 3-d habitat
-relying more on learning than instinct?

monotremes

-cloaca (single opening for urination, defecation, and egg laying like reptiles)
-covered in hair
-females secrete milk

3 defining traits of animals

1. mammary glands
2. hair
3. endothermy

marsupials

-live birth-embryonic young
-after birth, babies are carried in the mother's pouch

placentals

live birth-fully developed young

endothermy

physiological generation and regulation of body temperature by metabolic means : the property or state of being warm-blooded.

open digestions

tube; there is a mouth and an anus

closed digestion

sac; one hole

what enabled the transition from water to land

lungs and limbs

Live birth is NOT a \______ trait shared by all mammals

homologous

mitochondria and chloroplasts originate from

prokaryotes

transitional fossil

any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group

bipedal

ability to walk on two feet (open gait)

culture

the ability to pass on behavior through social learning

Adaptions in the modern human lineage arising after our last common ancestor with chimps

-Tool making, larger brain size, complex habitat, reliance on memory, culture, changes in regulatory genes, language-need to coordinate group

Lucy (Australopithecus afarensis)- characteristics of

-walked mostly, bipedal-we can tell by her pelvis bone
-she used tools, tool-using meat eater

Proximal mechanism for rapid evolution of "human-ness"

Regulatory genes control how much RNA is transcribed and thus the extent of protein synthesis

Ecological factors associated with large brain size

Complex environment
-Habitat: arboreal species \> burrowing species (squirrel vs. gopher)
-Food distribution: fruit-eaters larger brained than leaf-eaters

Reliance on memory
-Food-storing bird species are relatively large-brained
-Chickadees have more memory neurons in harsh climates (MN\>KS)

Social learning

Relying more on learning than on instinct-
Culture-ability to pass on behavior through social learning (young chimps watching mother gather termites)

Characteristic behaviors that define the genus Homo (the hominids)

-Defined by ability to make tools
-Homo erectus- first hominid with modern gait: landed on heel, pushed off forefoot
-Adaption for running and long distance travel

Movement of hominids out of Africa

Homo erectus- first hominid to leave Africa

Homo neanderthalensis (neanderthals)- left Africa ~300,000 BP- second hominid to leave Africa. In Europe from 300,000-25,000 BP

Homo sapiens (modern humans)-third hominid to reach Europe ~45,000 BP- co-existed with Neanderthals for 20,000 years.

Interbreeding between modern humans and Neanderthals

4% of genes in Europeans and Asains come from Neanderthals, no interbreeding with Africans. Absence of Neanderthal mitochondria in modern humans suggest "their" males mated with "our" females.

"ginger genes" from Neanderthals causes:
-red hair
-fair skin and freckles
-originated 100,000 years ago, only found in Europeans

Characteristics unique to modern humans

-sophisticated tool kits
-art, sculpture, music, religion
-spread from Africa to Europe, Asia and Austrailia and New World

Diversification of languages following human migrations

-modern languages reveal common ancestry
-human variant of FOXP2 gene originated

New selection pressure: UV light exposure from the sun

Skin color + sunshine
-chimpanzees have white skin (but thick body hair)
-without thick hair, too much sunshine penetrates light skin, breaking down vitamin B complex, causing birth defects and male sterility
-dark skin is necessary in strong sunlight
-dark skin blocks sunlight, inhibiting vitamin D production causing skeletal deformities
-light skin is necessary in low sunlight

new selection pressure: animal domestication

-9,000-13,000 ya
-continuous close contact with other species (rinderpest--\>measles)
-change in diet: dairy products--\> lactase enzyme appeared 3,000-10,000 ya --\> evolved 4 separate times

new selection: high altitudes

-Tibetans live at high altitudes of 13,000 feet, breathing only 60% as much oxygen as at sea level, yet rarely suffer from moutain sickness
-compated to Han Chinese, Tibetans show evolutionary change \> (or equal to) 30 genes as adaption to life on the high plateau.
-Tibetans and Han Chinese split apart 3,000 years ago

new selection pressure: plant domestication

-High human population density near water:
-standing water --\> mosquitos --\> malaria
-genetic resistance to malaria: new alleles at 4 diferent loci appeared 3,300-9,300 ya

new selection pressure: exercise

-hair & sweat
Fewer hair follicles allows:
-more sweat glands
-more rapid evaporation of sweat
Humans are hairless so as to be able to sweat during bursts of physical activity.

behavioral ecology

the adaptive significance of behavior

evolutionary psychology

is a theoretical approach to psychology that attempts to explain useful mental and psychological traits—such as memory, perception, or language—as adaptations, i.e., as the functional products of natural selection

dilution effect

reduces individual risk of being attacked

selfish herd

reduces own risk of being chosen for attack

confusion effect

reduces chances that attack will succeed

Group selection

a type of natural selection that acts collectively on all members of a given group. Individuals reduce their risks from predation by living in groups. Group living confers advantages to predatorys and prey. In some circumstances, group selection can become as important as individual selection

Group living as a behavioral adaption against predation

dilution effect, selfish heard, confusion effect

Benefit of similarity within group

less likely of being picked out by predator (confusion effect)

Group living as a behavioral adaptation for improved access to resources

Food- a single cape hunting dog is unable to catch a wildebeest... but a pack is almost always successful.

Territory- improves access to resources through group territory (ions response to trespassors)

Heritability of homosexuality

- (heritability can only be measured in populations, not individuals) Homosexuality has a heredibility of ~60% in men, ~25% in women, ~3-6% of people in every human society are gay. Possibly maintained by pleiotropy

Heritability of religiosity

- (Duggars quote pslams, "each child is a gift from God"
-Neurological basis of religious feelings and attitudes associated with different seratonin receptors- skeptical people \= more receptors

Benefits of religiosity

-High degree of religiosity significantly increases cooperativeness in adults (especially men) by providing group identity
-High levels of religiosity significantly reduce the risks of depression in adolescent girls through a sense of connectedness

Human sense of fairness

Reputation/ memory
- we know who you are, and we saw what you did...
-language

Group membership
-Hunter-gatherer bands are equalitarian- resources are shared
-Cooperation within the same group, but hostility to neighboring groups (as in chimps and lions)
-Within a vast society, religious institutions restrict mebership to a subset of well-behaved individuals and monitor their behavior

When does group selection work?

When cooperation helps win competitions among groups

exponential growth

-unlimited population growth of organisms
-assumes that r (intrinsic growth rate of a population) will remain constant

density dependence

growth slows as population density increases

carrying capacity \= K

represents an upper limit on growth

logistic (density-dependent) growth rate:
dN/dt \= Nr (K-N) / K

tells us what the population size will be over time. dN/dt is the growth rate (change in population size per change in time). r\= intrinsic growth rate. k\= carrying capacity. (K-N)/K\= proportion of total resources that are unused

r-selected species

-always below carrying capacity- can have exponential growth rate
-competition low

k-selected species

-up against carrying capactiy all the time, you will be always coping with high population-density
-limited food and space
-competition high

population momentum

-Refers to population growth at the national level that would occur even if levels of childbearing immediately declined to replacement level. For countries with above-replacement fertility (greater than 2.1 children per woman), population momentum represents natural increase to the population
-People in India are starting to have smaller families, but the population will continue to grow as younger generation reach reproductive age

Intrinsic growth rate of a population
r \= (b + i) - (d + e)

b\= birth rate, i\= immigration rate, d\= death rate,
e\= emigration rate
(r \= intrinsic growth rate of a population)

Density dependent

-food limitation
-limitation of space
-territory/habitat
-parasites thrive at high host densities (disease)

Density independent

-pertubations that affect population size regardless of density
(fire, storm, drought, flood, avalanche, ect.)

logistic growth

when r is small, population eases towards k