General Ecology Midterm 1

adaptation

heritable characteristic that enables organism to thrive in environment

biological evolution

heritable change in a population over time

lamarck

environmental changes generate organismal needs and structures become modified through use and are passed down

natural selection

differential reproduction and survival of individuals that results in elimination of maladaptive traits from a pop

1. variation among individuals within a pop in some heritable characteristics

2. variation results in differences among individuals in their fitness

fitness

genetic contribution by an individual’s descendants to future generations; proportionate contribution of an individual to future generations

phenotypic plasticity

changing gene expression in response to changing environment conditions

-ability of a genotype to produce more than one phenotype when exposed to different environments

reaction norm

range of phenotypes produced by single genotype

developmental plasticity

a type of phenotypic plasticity —> not reversible

acclimation

phenotypic plasticity in response to current envi conditions that is eversible

ex: seasonal changes in temperature tolerance in fish

phenotypic evolution

change in mean or variance of a phenotypic trait as a result of change in allele frequencies

directional selection

when mean value of a trait is shifted toward on extreme

stabilizing selection

natural selection favors individuals near population mean value of a trait, at the expense of those at either extreme

disruptive selection

natural selection favors individuals at each extreme at the expense of mean

cline

measurable, gradual change over a geographic region in some phenotypic character or a gradient in genotypic frequency

ecotype

population adapted to its unique local environmental conditions

abrupt change from other pops of same species

geographic isolate

prevented by some intrinsic barrier from interbreeding with other sub pops

allopatric isolation

complete geographic isolation

adaptive radiation

evolution from common ancestor of divergent forms adapted to distinct ways of life

oxygenic photosynthesis

release of oxygen

light and dark reactions

light reactions

require sunlight as energy source —> split water

chlorophyll as light absorbing pigment

split water

nadp+ —> nadph

adp —> atp

dark reactions

no light required

carboxylation —> co2 combines with RuBP to form two 3-PGA

captures co2 and adds carbon to RuBP by rubisco to make 3-pga then add energy to make G3P

chloroplasts

where photosynthesis occurs

plastids, located mostly in leaves

thylacoid

chlorophyll (photosynthesis pigment) is in thylacoid membrane

C3 plants

use the C3 photosynthetic pathway

a 3 carbon molecule (3-PGA) is first molecule produced

non-oxygenic photosynthesis

energy from sunlight, but electron donor is NOT water —> oxygen NOT released

cyanobacteria

first oxygenic photoautotrophs

adaptations for staying in euphotic zone

small size

spines, colonies to increase surface/volume ratio and drag

gas pockets

lipids deposits —> oils to help them float

adaptations for surviving adverse conditions (sinking out of photic zone)

resting stage in life cycle —> if they sink they make shell to remain alive in sediments

structural adaptions for desiccation: leaves

cuticle prevents evaporation: stomata let co2 inside leaf

h20 diffuses out of leaf in transportation

plants must balance water lost in transpiration with co2 absorbed for photo

adaptation for arid condition

stomata in pits —> trap moisture

ability to reduce leaf surface by curling

trade offs for reduced leaf area

capture less light

not shading neighbors

high energy cost of producing leaves with rigid cell walls

drought deciduous

plants lose leaves before annual dry season

winter deciduous

plants lose leaves before winter

trade off: need to grow leaves again next season

more roots than leaves

allocate more resources to roots (gather water) than leaves

mesic species

adapted to moist climates

xeric species

adapted to dry climates

photorespiration

catalyzed by rubisco

reaction of RuBP with o2 that releases co2

C4 plants

two kinds of photosynthetic cells

mesophyll cells where light reaction occur and co2 is fixed as 4 carbon acid and enzyme is PEP carboxylase

4 C is pumped into vascular cell and releases as CO2 for dark reactions

C4 as adapatation

compensates for high rates of photorespiration and carbon deficiency —> better for plants because don’t have to open stomata as much

photores rates increase w temp —> beneficial to have c4 pathway when temp increases

CAM pathway

crassulacean acid metabolism

same as c4 just not separated into two kinds of cell

net co2 intake

incorporation by photosynthesis - co2 release through respiration

light saturation point

photosynthesis increases with amount of PAR until it reaches a max

light compensation point

co2 uptake into photosynthesis balances co2 released in respiration

photoinhibition

photosynthesis often decreases at light levels beyond saturation

adaptations for low-nutrient environments

low absorption rate

high efficiency of nutrient use

lower growth rate —> slow growing

high ratio of leaves to stems —> deep roots

increased leaf longevity —> don’t shed leaves

animal cell vs plant cell

animal has much more proteins than plants → lots of nitrogen

plants have lots of carbs

grazers

herbivore

leafy material, especially grass

evolved from browsers

high crowned teeth

rumen

4 chambered stomach

browsers

herbivore

woody plants and their leaves

granivores

herbivore

seeds

only seasonally available in temperate and cold climates

frugiovers

herbivore

fruit

oxygen

needed to release energy contained in food

aquatic vertebrates —> oxygen

gills

countercurrent exchange maximizes oxygrn uptake from water

terrestrial animals in arid environments

fatty acids produce a lot of metabolic water —> fat in camels humps

estivation

summer formancy

diapause

stage of arrested growth in insects to survive dry periods

poikilothermic

animals have variable body temp influenced by envi

not much energy investment to change temp

ectothermic

homeothermic

animals maintain constant internal temp regardless of envi

lots of energy invested

endothermic

heterotherms

function either as ectotherms or endotherms depending on external circumstances

surface volume ration

decreases with size

influences most biochem and physiological processes as basic metabolism requires transfer of energy and materials between the organism's internal and external environments

daily torpor

dropping of body temp to ambient temp

endemic species

geographically restricted distribution

abundance

size of population

biomass

measure of abundance

population density

number of individuals per unit area

unitary organisms

zygote grows into genetically unique organism

module organisms

zygote grows into a unit of construction that then produces further similar modules (ramets or clones)

survivorship (lx)

number of individuals surviving to a given age as a proportion of original cohort size

age specific morality (dx)

difference between number of individuals alive for any age class and the next older age class

individuals died during given time interval

age specific morality rate (qx)

number of individuals dying during give time divided by number alive at beginning of that interval

individuals died in given age class

type 1 survivorship

convex

humans

type 2 survivorship

straight

adult birds, rodents, reptiles, many perennial plants

type 3 survivorship

concave

high mortality when young

fish, invertebrates, plants

fecundity table (fertility table)

mean number of females born in each age group

net reproductive rate (Ro)

number of females left during a lifetime by a newborn female

>1 pop is increasing

exponential growth

characteristic of populations inhabiting favorable envis at low population densities

demographic stochasticity

random variations in birth and death rates

environmental stochasticity

variation in envi can influence birth and death rates

allee effect

decline of a pop of small size

density dependent effects

influence pop in proportion to its size

density independent effects

influence a pop without regard to number of individuals

reproduction vs growth

allocation to reproduction reduces allocation to growth

asexual reproduction

offspring genetically identical to parents

benefits: all identical so adapted to envi and all able to reproduce

costs: no variation

binary fission

unicellular reproduce by dividing in half

parthenogenesis

give birth to all female offspring without fertilization

sexual reproduction

genetic variation but energetically costly

simultaneous hermaphrodites

both male and female —> male organ of one mated with female of another and vice versa and the same time

sequential hermaphrodites

individual will be male during one part of female during another

handicap principle

signals for mate are costly and may attract predators

indeterminate growth

continue to grow throughout adult hood

iteroparous reproduction

multiple reproductive events with fewer offspring

semelparous reproduction

single reproductive event with many offspring

optimal reproductive effort

balance between current and future reproduction that maximizes parent fitness

r strategy

many small offspring with little or no parental care

density independent growth limitation

k strategy

few larger offspring with considerable parental care

density dependent growth limitation

altricial

helpless at birth/hatching

precocial

more independent at birth/hatching

r plants

ruderal

live in high disturbance, low stress

c plants

competitive

live in low disturbance, low stress

s plants

stress-tolerant

live in low disturbance, high streess