EEMB 120 Midterm 2 Terms

UCSB

age distribution

calculated difference in proportion of individuals in each age class; assumes difference in mortality

birthrate

number of young produced per female in period of time

clutch size

amount of offspring per reproductive cycle

cohort

group of animals of the same species, identified by a common characteristic

cohort life table

identify individuals born of same time & keep records from birth

colonization cycle

dynamic interplay between dispersal of two or more locations within an environment, inclusive of reproductive trends that may affect populations

drift

active or passive downstream movement of stream organisms

fecundity schedule

tabulation of birth rates for females in different ages in a population

geometric rate of increase (λ)

the ratio of the population size at two points in time; λ = N_t+1/N_t

metapopulation

group of subpopulations connected by exchange of individuals

net reproductive rate (R₀)

the average number of female offspring produced by an individual female in a population during her lifetime

per capita rate of increase (r)

equals per capita birth rate minus per capita death rate; r = lnR₀/T or r = b-d

population dynamics

concerned with factors influencing expansion, decline, and maintenance of populations

stable age distribution

birth rate and death rate are equal

static life table

record age at death of individuals

subpopulation

portion of a larger population, with which it sustains a connection through immigration and emigration

survivorship curve

summarizes pattern of survival in population; patterns vary between species

type I survivorship curve

convex curve; late loss, high surivorship throughout life, majority reaches maturity, typical of k-selected species (i.e. elephants, humans, annual plants)

type II survivorship curve

diagonal curve; constant loss, independent of age (i.e. birds, rodents, Hydra, perennial plants)

type III survivorship curve

concave curve; early loss, low mortality rate after maturity, typical of r-selected species (i.e. oysters, small fishes, trees)

carrying capacity (K)

maximum number of individuals area is able to support

density-dependent factor

affected by population density, often biotic factors

density-independent factor

not affected by population density, often abiotic factors

exponential population growth

population growth that produces a J-shaped pattern of population increase; the change in numbers with time is the product of the per capita rate of increase, r, and population size, N

geometric population growth

population growth in which generations do not overlap and in which successive generations differ in size by a constant ratio

intrinsic rate of increase

per capita rate of increase attained when birthrates, death rates, and age structures are stable; r_max

logistic equation

equation for sigmoidal population growth; dN/dt = r_maxN (K − N|K)

logistic population growth

pattern of growth that produces a sigmoidal, or S-shaped, population growth curve; population size levels off at carrying capacity

sigmoidal population growth curve

an S-shaped pattern of population growth, with population size leveling off at the carrying capacity of the environment

allopatric

two species occur apart from each other

amensalism

one organism harmed with no impact on other (-/0); rare because usually energetic cost of borth organisms

character displacement

two species differing more in areas where they co-occur than in areas where their distributions do not overlap

competition coefficients

coefficient expressing the magnitude of the negative effect of individuals of one species on individuals of a second species

commensalism

one species benefits from association, other neither benefits nor harmed (+/0)

competitive exclusion principle

proposes that two species with identical niches cannot coexist indefinitely, which leads to the prediction that coexisting species will have different niches

granivore

rodents that feed chiefly on seeds

interference competition

direct interactions between individuals; can occur in cases of resource limitation (i.e. aggressive territory defense, production of chemical toxcins, reducing access to recources, etc)

interspecific competition

competition between individuals of two species; reduces fitness of both

intraspecific competition

competition with members of own species

isoclines of zero population growth (ZPG)

curves that show all combinations of two species’ population sizes where one species’ population does not change (growth = 0)

-2/3 thinning rule

a rule resulting from the observation that plotting the average weight of individual plants in a stand against density often produces a line with an average slope of approximately −3/2

mutualism

association between organisms of two different species in which each benefits (+/+)

niche partitioning

an evolutionary process whereby organisms decrease direct competition by differentiating in their use of resources by altering which, how, or when resources are used

parasitism

symbiotic association in which one species benefits at expense of other

resource competition

individuals compete through their dependence on the same limiting resources

resource limitation

limitation of population growth by resource availability

self-thinning

reduction in population density as a stand of plant increases in biomass, due to intraspecific competition

sympatric

describes the condition in which populations or species have overlapping geographic ranges

combined response

combined effect of functional and numerical responses by consumers on prey populations; determined by multiplying the number of prey eaten per predator times the number of predators per unit area, giving the number of prey eaten per unit area; generally expressed as percentage of total number of prey

exploitation

interaction that enhances fitness of one individual while reducing fitness of exploited individual

negative phototaxis

movement of an organism away from light

parasite

organism that lives in or on another organism (host) deriving benefits from it; reduces host fitness, generally does not kill

parasitoid

an insect whose larva consumes its host and kills it in the process; functionally equivalent to predators

pathogen

any organism that induces disease (debilitating condition) in their hosts (i.e. viruses, bacteria, protozoans)

positive phototaxis

organism moves towards the light

predator

organism that consumes another organism

predator satiation

defensive tactic in which prey reduce individual probability of being eaten by occurring at very high densities; can only eat so many prey

prey-dependent functional response

functional response in which rate of feeding by a predator is a function of prey population size only

ratio-dependent functional response

functional response in which the rate of feeding by a predator is a function of the ratio of prey population size to predator population size, that is, the number of prey per predator

arbuscular mycorrhizal fungi

fungus inside the plant

arbuscule

exchange site of fungus

balanced growth

cell growth in which all cell constituents, such as nitrogen, carbon, and DNA, increase at approximately the same rate

commensalism

interaction between two species in which one species is benefited and other is neither benefited nor harmed (+/0)

ectomycorrhizae

outside of the plant/roots

extrafloral nectar

sugar-rich liquid from nectaries

facultative mutualism

species can live without its mutualistic partner

mutualism

interactions between individuals of different species that benefit both partners

hyphae

fungal filaments

mycorrhizae

mutualistic association between fungi and the roots of plants

obligate mutualism

species dependent on mutualistic relationship

selection coefficient

relative selective costs associated with being a successful mutualist, or an unsuccessful mutualist, or a nonmutualist

vesicle

energy storage organs in fungi

community

association of interacting species inhabiting some defined area

community structure

attributes such as the number of species, the relative abundance of species, and the kinds of species comprising a community

DNA barcoding

genetic analysis tool that involves sequencing the same small region of DNA across many individuals

equilibrium

when environmental conditions remain relatively stable

guild

group of organisms that all make their living in similar way

intermediate disturbance hypothesis

predicts that intermediate levels of disturbance foster higher levels of diversity

life-form

combination of structure and growth dynamics of plant (similar to guild)

lognormal distribution

distribution of relative abundances of species produced by plotting the abundance of species as a frequency distribution in which each abundance interval is twice the preceding one, 1, 2, 4, 8, etc.; the result follows an approximately normal distribution

rank-abundance curve

portray relative abundance and species diversity within community by plotting relative abundance of species against their rank in abundance

species diversity

measure of diversity that increases with species evenness and species richness

species evenness

relative abundance of species

species richness

number of species in a community

species rarefaction

type of model that defines the number of samples likely needed to record all or almost all species at a location of interest