ecology exam 2 def

Adaptive evolution

a process of evolutionary change in which traits that confer survival or reproductive advantages tend to increase in frequency in a population over time

Adaptive radiation

An event in which a group of organisms gives rise to many new species that expand into new habitats or new ecological roles in a relatively short time

allele

One of two or more forms of a gene that result in the production of different versions of the protein that the gene encodes

cline

a pattern of gradual change in a characteristic of an organism over a geographic region

directional selection

individuals at one phenotypic extreme are favored

disruptive selection

individuals at both phenotypic extremes are favored

evolution

decent with modification

evolutionary tree

a branching diagram that represents the evolutionary history of a group of organisms

fixation

with respect to the genetic composition of a population, an allele frequency of 100%

gene flow

alleles move between populations vie movement of individuals or gametes

genetic drift

a process in which chance events determine which alleles are passed from one generation to the next, thereby causing allele frequencies to fluctuate randomly over time

genotype

the genotypic makeup of an individual

mass extinction

an event in which a large proportion of Earth’s species are driven to extinction worldwide in a relatively short time

mutation

change in the DNA of a gene

natural selection

individuals with certain heritable traits survive and reproduce more successfully than other individuals

phenotype

observable characteristics that are influenced by the genotype

recombination

rearrangement of genetic material during sexual reproduction that result in the production of offspring that have combinations of alleles that differ from those in either of their parents

speciation

the process by which one species splits into two or more specie

stabilizing selection

individuals with an intermediate phenotype are favored

trade-offs

the ability to perform one function mayy reduce the ability to perform another function

allocation

 the relative amounts of energy or resources that an organism devotes to different function

alternation of generation

a complex life cycle, found in many algae and all plants, in which there is both multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte

anisogamy

gametes of different sizes

competitive plants

with superior ability to acquire light, minerals, water, and space have a selective advantage

complex life cycle

a life cycle in which there are at least 2 distinct stages that differ in their habitat, physiology, and morphology

direct development

the fertilized egg develops into a juvenile without passing through a larval stage

dispersal

the movement of organisms or propagules

fitness

the genetic contribution of an organism's descents to future generations

isogamy

gametes are equal in size

Iteroparous

species can reproduce multiple times

life history

the major events relating to an organism’s growth, development, reproduction, and survival, these events include the age, and size of first reproduction, the amount timing of reproduction, and longevity

life history strategy

the overall pattern in average timing and nature of life history events

K-selection

selection for lower growth rates in populations that are at or near carrying capacity for a population

metamorphosis

abrupt transition in form between the larval, and juvenile stages

morphs

discrete phenotypes with few or no intermediate form

Paedomorphic

resulting from a delay of a developmental event relative to sexual maturation

phenotypic plasticity

one genotype produces different phenotypes under different environmental conditions

R-selection

selection for high population growth rates; an advantage in newly distributed habitats and uncrowded conditions

Ruderals

in Grime’s triangular model, plants that are adapted to environments with high levels of disturbance and low levels of stress

Semelparous

species reproduce only once

Sequential hermaphroditism

a change or changes in the sex of an organism during the course of its life cycle

Stress-tolerant plants

 may have slow growth rates, evergreen foliage, slow rates of water and nutrient use, low palatability to herbivores, and ability to respond to temporarily favorable  environments

Absolute population size

the actual number of individuals in a population

abundance

the number of individuals of a species that are found in a given area

clone

 a genetically identical copy

clumped dispersion

a dispersion pattern in which individuals are grouped together

dispersal limitation

can prevent species from reaching areas of suitable habitat

dispersion

spatial arrangement of individuals within a population

distribution

the geographic area where individuals of a species are present

disturbance

abiotic events that kill or damage some individuals, creating opportunities for other individuals to grow or reproduce

ecological niche

abiotic and biotic conditions that a species need to grow, survive, and reproduce

genet

a genetic individual, resulting from a single fertilization event, in organisms that can reproduce asexually, and may consist of multiple genetically identical parts, each of which has the potential to function as an independent physiological unit

geographic range

the entire geographic region over which a species is found

line transect

a straight line from which an observer can count the number of individuals and estimate their abundance per unit of area

niche model

predicts a species distribution based on conditions at locations the species is known to occupy

population

group of individuals of the same species that live in a particular area and interact with one another

population density

the number of individuals per unit of area

population size

the number of individuals in a population

ramet

an actual or potential physiologically independent number of a genet that may compete with other members for resources

random dispersion

a dispersion pattern in which individuals are positioned at random

regular dispersion

a dispersion pattern in which individuals are relatively evenly spaced throughout their habitatre

relative population size

an estimate of population size based on data that are related to absolute population size, but which can be compared from one time period or place to another

age structure

proportion of the population in different age classes

carrying capacity

the maximum population size that can be supported indefinitely by the environment

cohort life table

follows the fate of a group of individuals all born at the same time

density-dependent

 birth, death, and dispersal rates change as the density of the population changes

density-independent

effects on birth and death rates are independent of the number of individuals in the population

ecological footprint

total area of productive ecosystem required to support a population

exponential growth

when individuals reproduce continuously and generations can overlap and the population changes in size by a constant proportion at each instant in time

exponential growth rate

a constant whose value is determined by per capita birth rate minus per capita death rate at each instance in time

fecundity

average number of offspring a female will have at age x

geometric growth

the change in the number of individuals within a population over time that is characterized by birth and death from one discrete time period to the next

geometric population growth rate

a constant whose value is determined by the per capita birth rate minus the per capita death rate at each discrete time period, also called the finite rate of increase

life table

a summary of how survival and reproductive rates in a population vary with the age of individuals, in species for which age is not informative, or is difficult to measure

logistic growth

 the change in the number of individuals within a population over time that is rapid at first, then decreases as the population approaches the carrying capacity of its environment

net reproductive rate

mean number of offspring produced by an individual during its lifetime

population regulation

density-dependent factors cause population to increase when density is low and decrease when density is hight

stable age distribution

if the age structure does not change

static life table

survival and reproduction of individuals of different ages during a single time period

survival rate

chance that an individual of age x will survive to age x+1

survivorship

proportion of individuals that survive from birth to age x

survivorship curve

a graph based on survivorship data that plots the number of individuals from a hypothetical cohort that will survive to reach different ages

type 1 survivorship curve

most individuals survive to old age

type 2 survivorship curve

 the chance of surviving remains constant throughout the lifetime

type 3 survivrship curve

high death rates for young, those that reach adulthood will survive

allee-effect

growth rate decreases as population density decreases

bottom-up control

increased nutrient inputs caused eutrophication and increased phytoplankton biomass, decreased oxygen, fish die-offs etc.

damped oscillation

occur at population dynamics with delayed density dependence when the product of the intrinsic growth rate, and the time lag

delayed density dependence

When a population grows very rapidly (large r), or when there is a very long time lag (large τ), population size can become much larger than carrying capacity before it starts to decline

demographic stochasticity

chance events affect survival and reproduction of individuals

environmental stochasticity

unpredictable changes in the environment that can cause extinction of small populations

eutrophication

a change in the nutrient status of an ecosystem from nutrient-poor to nutrient-rich, such changes occur naturally, but they may also be caused by nutrient inputs that result from human activities

habitat fragmentation

large tracts of habitat are converted to isolated patches, resulting in a metapopulation structure

inbreeding

mating between related individuals, tends to increase the frequency of homozygotes, including those that have 2 copies of harmful allele

isolation by distance

a metapopulation pattern in which habitat patches located far from occupied patches are less likely to be colonized than are nearby patches

jump dispersal

movement of individuals organisms across vast distances or significant geographical barriers to establish a new population in a previous unoccupied area

metapopulation

a set of spatially isolated populations linked by dispersal of individuals or gametes

natural catastrophe

an extreme environmental event such as flood, severe windstorm, or outbreak of disease that can eliminate or drastically reduce population size

outbreak

an extreme rapid increase in the number of individuals in a population

population cycles

a sudden rapid increase in a population size or abundance size or abundance over a short period of time