PCB3043 Exam 1

Ecology

The scientific study of the relationships between organisms and their environment

Ecological hierarchy

Individual, population, community, ecosystem, landscape, biome, biosphere

Abiotic

Physical and chemical conditions (abiotic factors) include;

• temperature

• moisture

• concentration of gases (O2 and CO2)

• light intensity

Biotic

Interactions with other organisms (biotic factors) include;

• mating

• predator and prey

Individual

single organism

• Smallest and simplest unit of ecology

• Sense and responds to its environment

• Reproduces -> passes on genetic information the next

generation -> contributes to future populations,

communities, ecosystems

• Birth and death are one-time events for each individual

Population

group of individuals of the same

species, found in a defined area

• Instead of discrete events, birth and death are

continuous

• measured as rates, such as births/year

Ecosystem

communities + habitats (biotic AND

abiotic components)

• emphasis shifts from species to the flows of energy and

nutrients through both biotic and abiotic components

of the ecosystem

Community

different populations of living

organisms within a specific area (interacting biotic

components)

• Focus shifts to relative abundance of species within the

community and

• How interactions among species affect birth and death

rates

Landscape

a patchwork of multiple interacting

ecosystems in which spatial patterns are

important

Biome

large scale region with similar climatic

conditions (tundra, tropical rainforest)

• focus on the distribution of different types of ecosystems

Biosphere

global zone encompassing all life on

Earth

• emphasis on the linkages between ecosystems and

other components of Earth, such as the atmosphere

• How are nutrients such as carbon exchanged between

the atmosphere and terrestrial ecosystems

Weather

can influence reproduction in plant populations, where ______ patterns are influenced by solar radiation with heat coming from shorter wavelengths- higher energy. The average net radiation = zero, half absorbed and half reflected

Insolation

Amount of solar radiation reaching surface, varies w/ latitude; shorter distance around the equator

Latitude

Short at equator, long at poles, more insolation at equator

Diurnal cycle

The hours of daylight and dark that vary with seasons except at the equator, which has 12 hrs day and 12 hrs night throughout the year

Climate

can influence succession from prairie to a forest

Bergmann's rule: Cold-climate animals are often larger than warm-climate animals, mostly applies to birds & mammals

Bergmann’s rule

Cold-climate animals are often larger than warm-climate animals, mostly applies to birds & mammals

Natural selection

differential success (survival

and reproduction) of individuals within a

population

• interactions with the environment are the

selective agents

Requirements:

1. Variation in traits must be heritable

2. Variation leads to differences in survival and

reproduction (fitness) among individuals in the

population

Changes in population leads to evolution over

time

Fitness

the proportionate contribution made by an individual to future

generations relative to other individuals in the same population

• Traits that confer higher fitness are more frequent in the next generation

Greater fitness → Higher Rates of Survival + Reproduction = More Offspring

Adaption

any heritable behavioral,

morphological, or physiological trait that

has evolved through the process of

natural selection

Phenotypic plasticity

the ability of

one genotype to give rise to different

phenotypes under different

environmental conditions, leads to increased fitness

Developmental plasticity

phenotypic changes cannot be reversed

Acclimation

phenotypic plasticity in

response to current environmental

conditions that is reversible

• fish have upper and lower limits to

temperatures they can tolerate

• these limits change as water

temperature changes with the

seasons

Subpopulations

local populations of interbreeding individuals linked by movement of individuals

Selective agent

environmental cause of

fitness differences among organisms with

different phenotypes

Directional selection

Occurs when the phenotypes

at one end of the distribution

have higher fitness than the

mean phenotype; only one extreme high/low favored

Disruptive selection

Occurs when the phenotypes

at both ends of the distribution

have higher fitness than the

mean phenotype; both high/low favored

Stabilizing selection

Occurs when the mean phenotype

has higher fitness than the

phenotypes at either end of the

distribution; average favored

Genetic drift

change in allele frequencies as a result of random chance

• Changes are random, not fitness based

Gene flow

the movement of genetic information among populations

• Reduces variation among populations by keeping allele frequencies more similar

Assortative mating

individuals in a population choose mates based on

their phenotype, which reflects their genotype

Positive assortative mating

mates are phenotypically more similar to each

other than expected by random chance

• Increases homozygosity

Negative assortative mating

mates are phenotypically less similar to each

other than expected by random chance

• Increases heterozygosity

Inbreeding

individuals mate with other

members of the population who are more

closely related to them than expected by

random chance

• This increases homozygosity at all genes

Inbreeding depression

offspring are more

likely to homozygous for harmful recessive

alleles that can lead to reductions in fertility,

vigor, fitness and even death

Cline

a measurable change in a phenotypic character or characters

over a geographic region or a gradient in genotypic frequency

Step clines

abrupt changes in local environments and in the phenotype and

genotype of the organisms

Ecotypes

population adapted to its unique local environmental conditions

Trade-off

Constrains the evolution of adaptions with the constraints being physiological, energetic, and environmental

Adaptive radiation

multiple species within a

single lineage that exploit

different features of the

environment

Light dependent photosynthesis

• Chlorophyll absorbs light

energy

• Light energy excites electrons,

splits H2O molecules

• Light energy is Invested into

ATP and NADPH

Light independent photosynthesis

• Carbon Fixation occurs during

the Calvin Cycle (C3 Cycle)

• ATP and NADPH are used with

CO2 to make glucose

Stomata

openings on the

leaf surface that allow CO2

to enter

Transpiration

when the stomata are

open, water vapor in the leaf diffuses out

Turgor pressure

the force exerted

outward on a cell wall by the water

inside the cell

C3

plants in areas without water

limitation generally use __

photosynthesis = cool moist

environments

• Stomata remains open -> inefficient in

hot, dry conditions

• CO2 is fixed in a single step within

mesophyll cells, directly forming a

three-carbon compound via the Calvin

Cycle

C4

plants typically in arid, salty, tropical or

subtropical environments

• Carbon fixation is a two-step process with spatial

separation in the leaf

1. CO₂ fixed into a four-carbon compound in

mesophyll cells

2. Released in bundle sheath cells for the Calvin

Cycle to use

• Effectively concentrates CO₂ = minimizes

photorespiration and enhance efficiency in hot

environments -> stomata opens less = less water loss

CAM

adaption to deserts, extremely low

rainfall

• Carbon fixation occurs at night- stomata stay

closed during the day to prevent water loss

1. Night- stomata is open, CO2 convert to malic

acid

• large amounts of malic acid accumulate in

mesophyll cells

2. Day- stomata is closed, malic acid converted

to CO2

• C3 pathway used to fix CO2 and produce sugars

Dry environment

Adaptions to a ____________________ include increased root production, reduction in leaf area, changes in leaf size and shape, dropping leaves before dry season

Cold environment

Adaptions to a ____________________ include frost hardening, producing compounds that allow leaves to survive freezing temperatures, and some species being winter deciduous

Aquatic environment

Adaptions to a _______________ include floating broad leaves with a waxy cuticle, reproductive parts extending out of the water, highly dissected flexible leaves and stems, reduced roots

Low nutrients

Plant adaptations to _______________ include being carnivorous, having mycorrhizal associations, nitrogen fixers

Animal

___________ adaptations to the environment include gas exchange and acquisition of energy

Herbivory

Plant adaptations to deter ________ include thorns/spines, prickles/hairs, tough leaves/bark, toxins and poisons, bitter compounds, sticky resins

Grazer

Type of herbivore that eats mainly leaves, especially grasses

Browser

Type of herbivore that eats woody material

Granivore

Type of herbivore that eats seeds

Frugivore

Type of herbivore that eats fruit

Herbivore

_____________ adaptations to the environment include having specialized mouthparts, long digestive tracks with symbiotic microorganisms to break down cellulose, and chemical receptors in the nose/mouth to discourage eating certain foods

Carnivore

______________ adaptations to the environment include having strong jaws, sharp teeth and claws, hunting strategies, keen senses, and short digestive tracts with high stomach acidity

Omnivore

___________ adaptations include having sharp front teeth and molar back teeth, foraging, medium length intestines to digest a variety of foods, acute sensory systems

Ectothermy

process of maintaining body temperature through exchange

of thermal energy with the surrounding environment

Endothermy

process of maintaining body temperature through internally

generated metabolic heat

Endothermic homeotherms

bird and mammals

• Can maintain a constant body temperature

through metabolic processes = high metabolic

rate

Ectothermic poikilotherms

typically all other

animals that aren't birds and mammals

• Body temperature varies with the environment

= low metabolic rate

Poikilotherm

________________ adaptations to changing temps include seeking out appropriate microclimates (finding sun/shade), undergo temperature acclimation, change conduction of heat, tolerance to freezing

Homeotherm

___________ adaptations to changing temps include insulation, shivering, brown fat, and decrease heat by evaporative cooling where moisture evaporates from the skin, losing heat

Temporal heterotherms

have characteristics of endotherms at some times and

characteristics of ecotherms at other times

• May be daily or seasonally or only in certain situations

Torpor

the dropping of the body temperature to approximately ambient temperature for part of a day

Metapopulations

collection of local

subpopulations linked through dispersal

or other means of genetic exchange

Abundance

Number of individuals in a population

Population density

The number of individuals per unit area of a population

Population size

Abundance is found by; population density * the area occupied

Absolute density

Complete count of individuals/area; 25 gopher tortoises/hectare

Relative density

Proportion of species relative to others in a community; 25% sunflowers/m2

Quadrat sampling

Sampling area of a given shape, count individuals in quadrats, doesn't work well on motile organisms

Transects

Sample along a line or path, record organisms that touch/are close to the line at set intervals

Mark-recapture

Capture, mark, release, recapture; good for mobile organisms

Lincoln-Petersen

Most common method for mark-recapture; N=nM/R

Two sampling periods- one for marking, one for recapturing

N = Number of animals in the population

M = Number of animals marked on the first visit

n = Number of animals captured on the second visit

R = Number of recaptured animals that were marked

Traps

live animal traps, light traps, pitfall traps, plankton nets

• number of individuals caught per unit time per trap

Catch per unit fishing effort

Catch (number or weight of fish) over the Unit of effort (time, gear, distance)

Vocalization frequency

Good for frogs/bats that may not be visible during other population surveys, calls/unit time

Natality

number of births

related to population size

• Example- number of offspring/1000

indiv./unit time

• includes hatching, germination, fission

Fecundity

number of

offspring/female/unit time

Population growth

To study this, we need to know the starting population size (N0), the net reproductive rate (R0, how many females produced by an average female), are generations discrete or overlapping, if the population is closed or open, time period of measurement or number of generations, the intrinsic rate of increase (R) per capita ate of growth of population w/ stable age distribution, environmental influences

Net reproductive rate

R0 = sum of lx * bx

lx = survivorship, the number of individuals surviving to a given age (x) as a proportion of

the original cohort size, nx/n0

bx = fecundity, the mean number of females born to each female in an age group

Life table

an age-specific account of mortality to see the patterns of mortality and survivorship within populations.

Cohort

Followed by life tables, are group of individuals in a population born in the same period of time

Geometric growth model

predicts changes in population size in discrete intervals where birth and

death are not continuous processes; unlimited resources where the growth rate isn't influenced by population size. step-wise J-shaped curve, discrete generations

Exponential growth model

continuous, unlimited growth,

overlapping generations, favorable environments with unlimited resources and no competition, smooth J-shape curve, overlapping generations

Logistic growth

found where environmental limits exist, growth

rate is influenced by population size, smooth s-shape curve, overlapping generations

Geometric

Discrete time, N(t)=N(0)*lambda^t, where lambda is the finite rate of increase

Exponential

Continuous time, N(t)=N(0)e^rt where r is the intrinsic rate of increase

Stochasticity

random, unpredictable fluctuations that influence population dynamics

Altricial

Young are born helpless, less energy before birth but more care after birth, requires parental care to survive; birds and most mammals

Precocial

Young born in advanced stage of development, can forage independently shortly after birth, requiring less parental care; ducks, geese, horses, giraffes, whales, dolphins, hares

Iteroparous

Organisms reproduce more than once in their lifetime

Semelparous

Organisms reproduce only once in their lifetime

Outcrossing

Plant mating system where cross-fertilization happens between two individuals

Autogamy

Plant mating system where self-fertilization happens