Unit 8: Ecosystems - Stability, Change and Conservation

change in the heritable characteristics of a population

acquired traits can be passed down to offspring –> now FALSIFIED

DNA –> RNA –> Proteins Evidence = 1. new sequences arise and some become more common 2. some genes are common to many species 3. genes in closely related species are more similar

(artificial selection) selective breeding –> domestication of crop plants and animals —-> control reproduction, control offspring so that desirable traits become more common

homologous series = same structure

can persist for a very long period of time

stability depends on: - nutrient cycling - constant energy supply - genetic variation within a species - stable climate disruptions include: - removal of materials/species - eutrophication - climate change

reaching a level of disturbance that causes quick change that is difficult to reverse (i.e. amazon rainforest: deforestation = fewer trees = less transpiration = drought = fires) positive feedback loop

mesocosm adv: replicates, easy, control factors disadv: impossible to replicate all natural factors

an organism that has a disproportionate effect in a community (i.e. removal will make it likely that the entire ecosystem will collapse)

replacement rate must be > or = to harvesting rate i.e. cod -> protected breeding zones -> increase net hole size -> set harvesting limits -> monitor populations

consider the following: -> soil erosion (tilling causes soil loss) -> fertilisers leach into bodies of water (causes eutrophication) -> pollutants (pesticides) -> carbon footprint (from energy/fuels)

nitrogen and phosphorus rich fertilisers on land run off into bodies of water algae bloom on surface blocks sunlight and kills bottom plants deecomposition of plants consumes all of the oxygen, increases biological oxygen demand, killing other marine life

bioaccumulation - increase toxin levels throughout an organisms life biomagnification - increase toxin levels throughout trophic levels –> higher trophic levels higher toxin levels toxin examples: mercury and DDT

plastic waste accumulates because it doesn’t break down, can release toxic compounds macroplastic = large visible waste –> ingestion by marine life –> entanglement microplastic = small fragments from the degradation of large pieces –> found EVERYWHERE –> in animal tissues –> effect TBD

rewilding = remove effects of human intervention to allow natural processes to restore ecosystems can do this by: - stop human activities - reintroduce species - distributing seeds of plants that should occur there - control invasive species - reconnect habitats example: Hinewai Reserve in NZ shift from farmland to native forest by reducing effect of human intervention

ecological succession = biotic and abiotic changes that transform an ecosystem

succession starting w an environment w few living organisms (like bare rocks, bacteria, lichens cause erosion, soil development, shrubs, trees

increase in… - primary production - species diversity - food web complexity - nutrient cycling

patterns of change and succession that occur either naturally or due to periodic disturbances i.e. = oak forest –> grassland –> oak forest no stable climax community

a stable, relatively unchanging ecosystem

alternative climax community that results from human activity i.e. grazing -protected, artificially high population of livestock -grasses persist -no succession by shrubs or trees wetland drainage -swamps and bogs are natural carbon sinks -waterlogged and anoxic, special adaptations -drainage causes other plants to thrive

ecosystem permanently halted in an early successional, typically non forested state

normal = good - keeps earth warm enhanced = bad - thickening of greenhouse gases-BADDD