Biology Exam 4

behavior

the internally coordinated response of an organism to internal or external stimuli; the way an organism changes its activity to interact w/environment; has genetic basis → acted upon by selection

tinbergen’s 4 questions

1. mechanism of behavior (genes, alleles, hormones)

2. development/ontogeny of behavior (how does behavior change; critical pts)

3. function/adaptive value of behavior (behavior helps fitness)

4. evolution/phylogeny of behavior (how older gens contributed to development of behavior)

genetics of behavior

many behaviors are complex traits, thus dependent on many genes—some can be influenced by one gene

development of behavior

some behaviors only expressed at certain times due to changes in gene expression that are mediated by hormones

critical period

sensitive developmental state when learning must take place (ex. imprinting)

how does selection choose individuals to favor?

it favors those with higher fitness benefits than costs and behavioral plasticity

benefits: more food, mates, offspring survival

costs: energetic, risk, opportunity (time)

ecology

study of the interaction between organisms and their environment (biotic and abiotic)

hierarchy of ecological systems

individual, population, community, ecosystem, landscape

difference between weather and climate?

scale; weather is short-term meteorological conditions

climate

large scale w/conditions that occur over long periods of time. shapes environments in which populations evolve and diversify. tropical, arid, temperate, continental, polar

solar radiation’s role

radiation interacts w/atmosphere, oceans, geography to create diverse environmental conditions

greenhouse effect

results from absorption of solar radiation by the Earth and its atmosphere; warms surface and solar radiation turns into infrared radiation that rises and is emitted back down to surface

solar radiation and temp near equator

sunlight travels thru less atmosphere and is spread over a small area

solar radiation and temp at high latitudes

sunlight experiences more atmospheric absorption and is spread over a large area

circulation cells

driven by unequal solar heating, linking temp to precip patterns since warm air holds more water vapor; warm air at equator rises and dry air created at 30 latitude

ocean gyres

caused by earth’s rotation and unequal heating; redistribute heat and shape regional climates

topography

physical features like mountains and plains

rain shadow

caused by mountain ranges that alter elevation and produce distinct climate zones on each side

upwellings

areas of ocean where cold, nutrient-rich water rises to surface along continental coasts

how does proximity to water affect climate patterns?

large bodies of water absorb and release heat slowly, reducing seasonal temperature extremes

how does vegetation affect climate patterns?

forests have low albedo (reflectiveness) because they absorb solar radiation → greater evapotranspiration → precip

how do human activities affect climate patterns?

deforestation increases local temperatures; urban areas create heat islands where buildings and pavement absorb and retain heat

biogeography

scientific study of distribution and diversity of life on earth; species distribution reflects evolutionary history and isolations

why is species diversity is highest in tropics and declines moving north or south away from it?

1. high speciation and low extinction rates due to less variability in temp and precip, more solar radiation, constant natural selection rates, higher metabolism

2. tropics had more time to diversify w/o ice ages

3. higher environmental energy in tropics (supports diversity w/more resources)

population

group of individuals of the same species in a particular area that have potential to interbreed

population dynamics

changes in spatial structure (distribution and density), and changes in growth and size

metapopulations

groups of populations connected by dispersal; species consist of multiple; interconnected subunits of populations

dispersion patterns

1. uniform — establishing territories

2. clumped — safety living in group

3. random — rare, resources are evenly distributed and individuals don’t mind being next to others

what controls population dynamics?

physical environment, biological interactions (competition), dispersal

intraspecific competition

competition for resources by individuals of same species

interspecific interactions

interactions among individuals of different species (predation, competition, mutualism, etc)

dispersal

movement of individuals affects colonization and gene flow; active (animals move), passive (plants use wind to move seeds), facilitated (reliance on another organism to move seeds)

demography

study of changes in population size over time

what contributes to calculating population growth?

births, deaths, immigration, emigration, and population size (N)

simple eqn for closed population size

change in N= rN_o where r=(b-d)

what is r?

intrinsic growth rate; large pos values indicate faster population growth

all populations have the potential for ____

exponential growth —when not limited by resources

density-independent factors

factors independent of population size, like natural disasters

density-dependent factors

effects change w/population size, like

limiting resources (intraspecific competition increases w/population size)

predation (higher densities of prey attract more predators)

pathogens (higher densities of hosts = faster pathogen spread)

carrying capacity

K — maximum population size that can be supported by the environment

logistic growth eqn

change in N = rN_o(1-N/K) where is N is large, (1-N/K) stops growth

life history

describes the lifetime pattern of growth, reproduction, and survival; strategies evolve thru natural selection on how individuals allocate limited resources and shapes traits of populations

type I survivorship

in many large mammals; high survival rates at most ages that has a steep drop off at old age

type II survivorship

in many birds, fish, plants; steady decrease in survivorship across age groups; impacted by a biotic factor (predator) that impacts them regardless of age

type III

in most insects and annual plants; rapid loss of survivorship that levels off for middle age groups before survivors die

trade offs

when investments in one component of fitness decreases another component of fitness

r specialists

where natural selection favors high growth rates → exponential growth; early reproduction, many small offspring, type III survivorship, fast population growth, high tolerance for environmental variability

k specialists

where natural selection favors carrying capacity → logistic growth; late reproduction, few large offspring, type I survivorship curve, slow population growth, low tolerance for environmental variability

species interactions

affect individuals and populations, can lead to (co)evolutionary change, and vary in direction and strength

coevolution

2+ species affect each other’s evolution (ex. predator-prey); usually result of strong interactions/relationships

predation

predators evolve strategies to capture and consume prey; prey evolve strategies to minimize likelihood of being captured/consumed

carnivory

prey is usually killed; active pursuit, ambush, subdue

prey use structural, behavioral, chemical, and crypsis defenses

herbivory

prey are rarely killed; may drive evolution of structural and chemical defenses in plants

parasitism

hosts are not typically killed; parasites evolve close associations w/specific host species

microparasites

bacteria, viruses, protists — pathogens that cause disease

macroparasites

worms and insects

competition

occurs when two or more species use the same limiting resource

interference competition

direct; active interference w/other species access to resource

exploitative competition

indirect; both species depress each other through shared resource

competitive exclusion

when one species outcompetes another for limiting resources, leading to the local loss of the inferior competitor

competitive coexistence

occurs when species reduce or avoid direct competition, allowing them to persist in the same area

resource partitioning

occurs when species use different parts of the same resource, reducing competition and enabling coexistence

can lead to coevolution over time

character displacement

facilitates coexistence when competing species evolve differences in shared traits where they occur together

increase their differences to reduce competition for resource

mutualism

positive interaction where two or more species benefit from interacting; can be necessary (obligate) or optional (facultative)

how do positive interactions help populations?

they increase population abundance and promote greater community diversity

community

group of species living together at the same place and time; complex networks of interacting species

what are the subsets of species used to define different types of communities?

taxonomic affinity, guild, functional group

food webs

used to represent the trophic or energetic connections among species in a community

species diversity

measure that combines # of species (richness) and their relative abundances (evenness)

community membership

depends on the regional species pool, dispersal ability, abiotic conditions, and species interactions

keystone species

have strong community-wide effects despite to their small size and abundance; may impact abiotic components, in addition to biotic components

foundation species

strong community-wide effects due to their large size and abundance; often habitats/food for other species

ecosystem engineers

create or modify aspects of the physical environment for themselves and thus other species

trophic cascades

occur when strong feeding interactions at one trophic level trigger indirect effects that ripple through the rest of the community

why do more complex habitats support higher diversity?

there are more unique environments, more shelter, and more ways for species to coexist

what type of disturbance shapes community diversity?

communities w/intermediate levels of disturbance support the highest diversity

what happens in communities with high species diversity?

they tend to be more productive, more stable, more resilient (less mortality)

ecosystem

communities of organisms interacting w/their physical and chemical environment, focusing on how energy and nutrients move within environment

primary production

photosynthesis and chemosynthesis; sun is ultimate source of energy

secondary production

consumers biomass (tissue) accumulation

how do nutrients move thru living and non-living environment?

thru soil, water, atmosphere

process by which nutrients are recycled?

consumers eat producers → die → nutrients back into environment → grows producers

how do we measure primary productivity?

using the rate at which light is captured and converted into chemical bonds

gross primary production (GPP)

rate energy is captured and assimilated by products

net primary production (NPP)

rate producer biomass is gained from assimilating energy; supports all life in an ecosystem via production of organic matter

NPP = GPP- respiration

how is NPP affected by climate?

NPP increases w/temp, and increases then declines w/precipitation

net secondary productivity

rate of consumer biomass accumulation; result of consuming primary producers

what limits how long food webs can be?

the fact that most energy is lost from primary to secondary production

how do ocean primary producers differ from terrestrial primary producers?

ocean producers are more r-selected and terrestrial producers are more k-selected

what types of areas tend to have longer, more complex food webs?

areas w/high primary productivity

how long do nutrients cycle?

indefinitely; elements trapped on earth cycling

biodiversity

diversity of life on earth

how do human activities impact biodiversity?

genetic, species, and ecological diversity are declining as a result of human impacts

ecosystem services

instrumental and intrinsic value of ecosystems to humans