BIO115 Exam #2 (Genetic Drift Up to Homology)

genetic drift

random fluctuations in allele frequency

True

T or F: Genetic drift is always occuring in finite populations, both large ones and small ones.

False - it is felt more in smaller populations

T or F: The impact of genetic drift is felt less in smaller populations.

decreases; increases

WITHIN a population, genetic drift _________ variation. BETWEEN populations, genetic drift __________ variation.

bottleneck event

an extreme form of genetic drift; most of the population is killed in a catastrophic event, but a few survive; the population has decreased exponentially

gene flow

migration of individuals among populations that may bring in new alleles and change frequencies

maintains/increases; decrease

WITHIN a population, gene flow ___________ variation. BETWEEN populations, gene flow __________ variation.

negative, positive, or neutral

What kinds of effects on fitness can gene flow have?

True, it requires variation.

T or F: Natural selection requires variation

decreases

Natural selection ___________ genetic variation.

balancing selection

this process maintains variation in a population; frequency-dependent selection where the fitness of the trait changes based on how common it is in the population

heterozygote advantage

when heterozygotes have greater fitness than either homozygote; more likely to reproduce; hypothesized to be the reason many disease-causing alleles persist in human populations (cystic fibrosis, sickle cell anemia)

False - females invest a lot more energy

T or F: Females and males invest the same amount of energy in reproduction.

sexual selection

selection for traits associated with obtaining mates; these traits differ in males and females

False - they do not

T or F: Male traits improve fitness in females

sexual dimorphism

the systematic difference in form/appearance between individuals of different sex in the same species (ex. male cardinals are red, female cardinals are brown)

intrasexual selection

males compete for mates; traits that are better for size and combat and fighting other males are favored; antlers, pinchers

intersexual selection

females choose mates based on traits in males; showy, ornamental traits that attract female attention are favored; colorful patterns, large wings or feathers

speciation

a process in which one species develops into two

1.) Populations able to interbreed

2.) Produce fertile offspring

3.) Reproductively isolated from other groups

three tenets of biological species concepts

species producing asexually

a potential challenge for the tenets of biological species concepts

habitat isolation

a form of reproductive isolation where two species are living in different places; prezygotic barrier

temporal isolation

a form of reproductive isolation where the organisms mate at different times or seasons; prezyogtic barrier

behavioral isolation

a form of reproductive isolation where courtship dances and displays are different; prezygotic barrier

mechanical isolation

a form of reproductive isolation where genitalia doesn’t fit correctly and sperm can’t be delivered; prezygotic barrier

gametic isolation

a form of reproductive isolation where sperm are unable to fertilize; makes it to the egg cell, but the egg cell won’t let the sperm in; prezygotic barrier

prezygotic barrier

a form of reproductive isolation where formation of a zygote is prevented

postzygotic barrier

a form of reproductive isolation where we have a zygote, but it doesn’t work

reduced hybrid viability

a form of reproductive isolation where the zygote dies during development or at a young age; no bearing on fitness; postzygotic barrier

reduced hybrid fertility

a form of reproductive isolation where the animal lives but cannot reproduce; postzygotic barrier

hybrid breakdown

a form of reproductive isolation where hybrid zygotes do not mature as normal; postzygotic barrier

allopatric speciation

development of a new species based on geographical isolation; 1.) begins with habitat isolation, 2.) environmental differences in locations lead to different selection pressures, 3.) then differences in selection pressures lead to evolution of additional isolating mechanisms, and 4.) these additional isolating mechanisms keep new species separated even if contact is restored

sympatric speciation

evolution of a new species, but the cause is not related to geographical isolation; apple flies; no physical barrier, must be another form of reproductive isolation (temporal, etc.)

increase, increase

WITHIN populations, mutations ________ variation. BETWEEN populations, mutations ________ variation.

ecology

study of how organisms interact with other organisms and with the environment; where organisms live and why

population

reproductively compatible; a pool of mating options living together at a time; a single species; group of individuals of the same species living in the same place at the same time

community

all the populations/species living in a particular habitat at a time; can break down into the tree community, bird community, etc.; group of populations living close enough to interact

ecosystem

all biotic or abiotic factors in the environment; sum of all living organisms in an area and the abiotic factors which interact

population ecology

study of how and why population size changes over time

birth rate, immigration rate

ways to increase the population

death rate, emigration rate

ways to decrease the population

exponential model

this simplest model of population growth assumes optimal conditions and unlimited resources; not realistic in most situations

logistic model

this population model is more realistic than exponential growth; it takes into account the limitations of resources and carrying capacity

True

T or F: Carrying capacity is not a firm ceiling.

lifespan, age at first reproduction, frequency of reproduction, number of offspring per reproductive event, degree of paternal care

traits that affect the “schedule” of reproduction and survival

there is a fitness trade-off; not enough energy to have both be high

the reason we can’t have a high survivorship, high reproduction life history pattern

r-selection

selection associated with rapid population growth; many offspring per event with one reproduction event in a lifetime (semeiparous); limited parental care with a short lifespan and a high early mortality rate; survivorship curve 3

k-selection

selection associated with stable population growth; few offspring per reproduction event with multiple reproduction events in a lifetime (iteroparaus); high level of parental care, with low early mortality rate and a long lifespan; survivorship curve 1

frogs, cicadas, flies

examples of r-selection

humans, elephants

examples of k-selection

abiotic factors

non-living factors that usually affect populations equally, regardless of size (density independent); temperature, precipitation, etc.

biotic factors

living factors involving other organisms; stronger effect in larger populations; density dependent; competition, predation, disease, etc.

False - carrying capacity varies based on the size of the population

T or F: Carrying capacity is determined by density-independent factors.

community ecology

study of how species interact with each other and how communities are structured

mutualism

a positive-positive interaction between species (both are benefitting)

commensalism

a species interaction where one species gets a positive effect and one has no effect

exploitation/ parasitism

a species interaction where one species benefits and the other is harmed

competition

a species interaction where both species are affected negatively

vicariance event

a geographic barrier such as water isolates a population

dispersal event

a subset of a population migrates to a different habitat

Gause’s Experiment

used P.aurelia and P. caudatum to show the principle of competition, and that the two species could not coexist

competitive exclusion principle

two species using the same limiting resources cannot co-exist indefinitely; the situation must be resolved, like with the death of one of the species

character displacement

species diverge morphologically; this allows for shifting of traits, less competition, and coexistence of two species

competition avoidance

When it comes to selection, what kind of avoidance is favored?

camouflage; cryptic coloration

coloration that allows a species to blend in with its environment as a way to avoid predators and deter physical attacks

aposematic coloration

bright coloring that can scare off predators; a defensive, aggressive method; bright yellow belly of a newt, bright colors of a poison dart frog

tetrodotoxin

a chemical used by newts for chemical defense; if a predator tries to eat the newt, they will taste the bitterness

defensive; consumer

Selection favors _________ strategies in prey/host. Selection also favors the ability of the ________ to overcome defenses. (coevolutionary arms race)

coevolutionary arms race

both species want a limited resource; predator and prey act as selective agents on each other

primary producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers

order of food chain trophic levels

ecosystem ecology

the study of how energy flows and chemicals cycle in an environment

conservation of energy

energy cannot be created or destroyed, it can only be converted into other forms

inefficient

Energy transfers are _________ since energy is lost as heat.

detritus

dead organic matter

lower

________ trophic levels have more energy available. Thus, the productivity pyramid is always wider at the bottom.

biomass

weight of living material

10; 90

About ____% of energy goes to the next trophic level. Thus, there is a _____% loss of energy.

50%

Of the plant material eaten by a caterpillar, what percent goes to feces/waste (is not assimilated)?

16.5%

Of the plant material eaten by a caterpillar, what percent goes to growth and new biomass? (one part of being assimilated?)

33.5%

Of the plant material eaten by a caterpillar, what percent goes to cellular respiration for energy production? (One part of being assimilated)

lower

Carnivores have a _______ population density than primary producers.

short

Food webs are typically _____.

net primary productivity

energy stored in organic molecules by primary producers’ a measurement; increase in biomass of primary producers; the foundation of food webs and trophic pyramids

regions along the equator

areas with the highest NPP; lots of biodiversity here because of this

water, carbon, nitrogen, phosphorous cycle

the four most important chemical cycles

provisional services

areas that provide resources for services; ex. is a spawning ground for commercial fisheries

regulating services

areas that help with absorption of water and regulation of floods and environmental concerns; buffer flooding regions, wetlands, prevention of erosion, and clean water

cultural service

these services enhance the quality of life; recreation, home for migrating birds, canoeing, kayaking, etc.

1.) Higher productivity (more biomass)

2.) Greater resistance to stress

3.) Difficulty for invasive species to invade

Higher diversity in an ecosystem leads to…

habitat loss

loss of land; when nature of a habitat is destroyed

fragmentation

a forest still exists, but it exists in in pieces that are isolated

edge effects

boundaries between habitats are not sharp; edgy forest is what’s left, and that’s not as good; environmental conditions near boundary different than “core” habitat conditions

genetic variation

raw material for natural selection

1.) changing environment

2.) new disease

3.) new food source

Lack of variation limits ability to adapt to:

extinction vortex

positive feedback loop where a small population leads to inbreeding and increased genetic drift, a loss of genetic variability, lower individual fitness and population adaptability, low reproduction and higher mortality, and an even smaller population

introduce new communities of the same species to the population that was declining; helps with genetic variation and artificially createst gene flow

Best way to pull a species out of an extinction vortex, and why?

fragments can recolonize each other; gene flow is more likely; increases genetic diversity or maintains it

Why is it important to have fragments close to each other?

larger size; fragments closer together; connected fragments (movement corridors)

traits that are larger for nature preservations

movement corridors

spaces and paths that connect species, help with movement between environments, and help with crossing inhospitable environments; good for gene flow.

invasive species

native to one part of the world, but have moved to another part to where they are not native and are typically causing negative effects; many agricultural pests