D4 Continuity and Change of Ecosystems Flashcards
Polymorphic trait
definition
a trait that has more than 2 but less than 4 genetic variations (can eb at a phenotypic or genotypic level)
directional selection
definition
when a trait has two or 3 categorical phenotypes and natural selection favours one
stabalising selection
definition
when there is a continuum of phenotypes for a trait and natural selection favours the average not the extremes
disruptive selection
define
either extreme phenotypes are prefered to the average on a continuum of phenotypes for a trait (can be the begining of speciation)
genetic equalibrium
define
when there is no change in allele frequencies over time, usually in reference to one trait/gene
conditions needed for a population to be in genetic equalibrium
- large population size
- no immigration or emigration (gene flow)
- no favoured phenotype
- no sexual selection (random mating)
- no generation of new alleles that change the phenotype by mutation
ecosystem sustainability
define
the ecosystem can support itself without outside influences. Allowed when changes to an ecosystem are slow enough that organisms can still adapt to and thrive
tipping point
define
the point where an ecosystem has endured too much damage and can no longer be self-sufficient or sustained
requirements for an ecosystem to remain stable
- sufficient energy supply
- nutrient recycling
- enetic diversity
- good response to climate change
keystone species
define
a species that has a disproportunate effect on the ecosystem
trophic cascade
define
when a top predator is removed and consequently destabalises the lower trophic levels and ecosystem balance
soil erosion
define
the loss of nutrient rich topsoil by excess rain or wind
leaching
define
when rain or irrigation water disolves nutrients in the soil and pulls it down past plant roots so that they can’t be absorbed by roots
agrochemicals
define
chemicals like pesticides and fertilisers used by farmers, that lead to eutrophication and water pollution
carbon footprint
definition
the total amount of greenhouse gasses that is generated by an activity
tillage
definition
preperation of soil for crops that uses machinery that emitt carbon emissions
eutrophication
definition
an abundance of nutrients running into water causing algae to overgrow on surface, increase in decomposers, decrease in oxygen, decrease in fish
biochemical oxygen demand
definition
the amount of oxygen needed by bacteria decomposers in water to carry out cellular respiration
biomagnification
definition
when there are traces of toxins in the water that get passed up trophic levels
macroplasitcs
size
larger than 5mm
microplastics
size
smaller than 5mm
pioneer species
definition
the first species to exist in a newly established ecosystem
climax community
definition
a stable point of peak biodiversity and population in an ecosystem
cyclical succession
definition
when an ecosystem does not reach one stable climax community but many in a repeating cycle
permafrost
definition
the soil in very cold climates below the surface that is frozen solid
albedo
definition
the ability of a sureface to reflect light (dark object = low albedo)
landfast ice
defintion
a frozen layer of seawater that is attached to the land, important in some organisms breed here
ocean stratification
definition
the layers of the ocean where warmer less salty water floats on the top of the cold, nurtient dense layer
carbon sequestration
definition
the capture and storage of carbon that can happen naturally or to combat climate change
phenology
definition
the study of the timing of periodic events in living organisms
photoperiod
definition
the number of hours a day when the sun is shining
trophic mismatch
definition
when an abiotic change disrupts the annual cycle of a species, causing it to fcall out of sync with other species
microevolution
definition
tracing changes over time in a syngle phenotypic trait (often using hardy weinburg)
polymorphism
definition
when there are two or more phenotypes for a trait that are equally present and neither provides an advantage
