bio HL - ecology & evolution dp2 tw1

population

groups of individual organisms of the same species living in an area

individuals of the same species can … to produce … …

reproduce, fertile offspring

the … the sampling value, the … the sampling error

greater, lower

standard deviation

degree of variability

population size using lincoln (capture recapture) index

• M x N / R

• M = marked initially

• N = number of recaptured

• R = marked in recaptured

assumptions of lincoln index

• no deaths/births

• no migration

• marked and unmarked have the same chance of survival

• marks do not affect survival

• marks remain visible

carrying capactiy

the maximum population size an environment can support, most likely due to limited resources

density independent factor

factor causing a population to change no matter its size, eg fire

density dependent factor

factor causing a population to change that is affected by the population’s size specifically when it is larger, eg. competition, predation, disease

sigmoid curve

exponential phase followed by a plateau phase

community

several populations living and interacting with each other

intraspecific relationship

relationship between individuals of the SAME species

example of intraspecific competition

• competing for food

• competing for mates

• competing for territory

example of intraspecific cooperation

• huddling together for warmth

• hunting in groups

interspecific relationship

relationship between individuals of different species

types of interspecific relationships (6)

1. herbivory (primary eats primary)

2. predation (one kills another)

3. interspecific competition

4. mutualism (both benefit)

5. parasitism (parasite on host)

6. pathogenicity (pathogen in host)

example(s) of mutualism

1. root nodules in legumes

2. mycorrhizae in orchids

3. zooxanthellae algae in hard corals

   • corals provide CO2 and protected environment close to surface for algae to photosynthesize (light), the algae then provides the coral with carbohydrates and oxygen

endemic species

species native to the area

alien species

species introduced to an area where they are not native by humans

invasive species

alien species that spread rapidly due to lack of density-dependent factors and outcompete endemic species

ecosystem

• all of the organisms and abiotic factors in an area

• open systems

saptrotrophs

decomposers that digest things externally

detritivores

decomposers that digest things internally

autotrophs

• producers

• synthesise their own food/necessary compounds using inorganic substances in their environment eg. carbohydrates, amino acids, fatty acids

heterotroph

getting energy/carbon compounds from feeding

kJm^-2yr^-1

amount of energy gained per year per unit of area at each trophic level

why is so much energy lost between trophic levels?

• incomplete digestion

• incomplete consumption

• cell respiration

carbon sink

• net uptake of carbon (storing a lot of carbon, eg fossils)

• high photosynthesis

• low respiration

carbon source

• net release of carbon (releasing a lot of carbon)

• low photosynthesis

• high respiration

keeling curve (the trends)

• overall trend: constantly increasing due to human activity

• annual trend: up and down due to varying rates of photosynthesis

ecological niche

• the role a species plays in its ecosystem

• dependent on:

  • how it obtains food

  • zones of tolerance

  • interactions with other species

holozoic nutrition

whole pieces of food eaten and digested internally (in heterotrophs)

mixotrophic

can gather nutrients/energy in both autotrophic and heterotrophic ways

ways archaea get energy (ATP) (3)

1. heterotrophic

2. phototrophic

3. chemotrophic

dentition for herbivores/omnivores/carnivores

• herbivores: large and flat teeth for grinding

• omnivores: mixture of flatter and sharper teeth

• carnivores: sharper for tearing meat

predator adaptations

• chemical: venom (slowest)

• physical: teeth/claws

• behavioural: ambush (fastest)

prey adaptations

• chemical: toxic (slowest)

• physical: camouflage

• behavioural: schooling (fastest)

if fundamental niches overlap, …

one species will outcompete the other

morphology

study of inner/outer traits (anatomy)

binomial nomenclature

• genus and species

• first letter of genus is capitalized, species is not

• italics if typed, underlined if handwritten

when species do not interbreed they …

diverge

chromosome number … per species

varies

SNP

• single-nucleotide polymorphism

• most common type of mutation

• position where there is a difference in base sequences

benefits of genome sequencing

• deducing evolutionary relationships

• fighting disease

• personalised medicines

DNA barcoding

• using a small section of DNA to identify a particular species

• can be used when not the entire organism is present

• environmental DNA

different types of diversity

• ecosystem (different environment and species)

• species (variety of different species)

• genetic (gene pool within species)

anthropogenic

caused by humans (specific to current species extinction)

causes of anthropogenic species extinction (5)

1. overharvesting

2. habitat destruction

3. invasive species

4. pollution

5. global climate change

ecosystem

biotic and abiotic factors in a given area

simpson’s diversity index

• N(N-1)/sum.n(n-1)

  • N = all individuals of all species

  • n = all individuals of one species

• high = good

• low = bad

types of biodiversity conservation (2)

• in-situ: conservation in natural habitat (eg protected areas)

• ex-situ: conservation outside the natural habitat (eg zoos)

requirements for a stable ecosystem (4)

• constant energy supply

• nutrient cycling

• genetic variation within a species

• stable climate

distruptions to an ecosystem’s stability (4)

• removal of materials

• removal of species

• eutrophication (too many nutrients)

• climate change

tipping point

reaching a level of disturbance that causes quick change that is almost impossible to reverse

tipping point cycle in amazon rainforest

deforestation → less trees → less transpiration → drought → fires → deforestation (positive feedback loop)

keystone species

• species that have a disproportional effect on a community

• removing them = ecosystem collapses

factors affecting agriculture sustainability (4)

• soil erosion

• nutrient leaching (causes eutrophication)

• pollutants

• carbon footprint

rewilding

removing effects of human intervention to allow natural processes to restore ecosystems

ecological succession

biotic and abiotic changes that transform an ecosystem

example(s) of positive feedback loop in climate change

• more heat → more permafrost melting → more decay → more methane → more heat

• warmer temperatures → more droughts → more fires → more carbon release → warmer temperatures

carbon sequestration

capturing and storing carbon (carbon sinks)

afforestation

planting trees in areas where there are no trees

forest regeneration (reforesting)

planting trees that have been cut down

phenology

• study of seasonal timing of events in plants and animals

• changes in timing can indicate climate change

• temperatures and photoperiods (daylight hours per day)

factors required for natural selection

• overpopulation and competition

• variation

• survival of the fittest

• increase in trait frequency

evolution

change in the heritable characteristics of a population

homologous structure

same structure, same evolutionary origin, different function (maybe)

analogous

different structure, different origin, same function

speciation

formation of a new species

speciation requires … and …

reproductive isolation (geographical isolation), differential selection (different selective pressures)

allopatric speciation

speciation in different environments

sympatric speciation

speciation within the same environment

adaptive radiation

common ancestor splitting into multiple species due to different variations exploiting different ecological niches

polyploid

• more than 2 sets of homologous chromosomes

• similar features but cannot reproduce with diploid organisms (fertile)

gene pool

all of the different genes and alleles in a population

stabilising selection

prefers the average phenotypes over the extreme ones

disruptive selection

prefers both extremes over the average phenotypes

directional selection

prefers one extreme over the other

hardy-weinburg equation

• p²+2pq+q² = 1

• p² = homozygous dominant genotype

• 2pq = heterozygous genotype

• q² = homozygous recessive genotype

• p + q = 1

• p = dominant allele frequency

• q = recessive allele frequency

classification

placing organisms in groups based on common ancestry and/or shared traits

limiting factor

a factor that limits where an organism can live

range of tolerance

the range of a certain factor in which an organism can survive