D4 Flashcards
1
Q
Selection pressure
A
- An environmental factor that can influence the success of a population
- Can be abiotic, biotic and anthropogenic
- Can lead to natural selection
2
Q
Fitness
A
- An organisms ability to pass on their genes, and have a strong genetic contribution
- Linked to survival, as passing on genes is easier when alive
- Also organism should be adapted to environment
3
Q
Sexual Selection
A
- Similar to natural selection, some organisms are more successful at producing offspring
- Related to the ability to attract a mate
4
Q
Antibiotic resistance
A
Natural selection where non-resistant bacteria die and therefore resistant bacteria survive and reproduce until whole population becomes resistant.
5
Q
How did Darwin’s theory lead to a ‘paradigm shift’ in scientific understanding
A
- Changed the way we viewed evolutionary change
- Before: Lamark’s theory of acquired traits
- Afrer: Darwin’s theory of heritable traits
- Change in evolutionary framework= paradigm shift
6
Q
What are 3 causes of genetic variation which drive natural selection?
A
- Mutation
- Meiosis
- Sexual reproduction
7
Q
What role does carrying capacity play in natural selection?
A
- Only the more fit/ better adapted organisms survive due to competition if over carrying capacity
- If a population is under carrying capacity, it will not evolve through natural selection
8
Q
How do abiotic factors impact natural selection
A
- Can act as a selective pressure
- Extreme abiotic conditions can limit the survivability of a species
- This allows differential success of those with suited adaptations
9
Q
What is the difference between an acquired and a heritable trait?
A
- Acquired trait: obtained during lifetime, result of behaviour
- Heritable trait: coded in DNA, passed to offspring, drive evolution
10
Q
Explain how sexual selection has played a role in the evolution of birds of paradise
A
- Females are camoflaged, but males have big, bright plumage, as long as they are healthy and have good nutrition
- Males with bright feathers have been sexually selected for as they are more attractive to females
11
Q
Explain the work of John Edler with guppies in Trinidad and Tobago
A
- Investigated whether the presence of predators influenced the colouration of guppies
- Bright coloured males- good for getting mates
- Dull coloured- good for camoflage
- He found that the presence of predatory fish resulted in less colouration
12
Q
Gene pool
A
All genes and their different alleles present in a population
13
Q
Allele frequency
A
- Proportion of total alleles that each individual allele occupies
- Given as a decimal
- Shows how common an allele is
14
Q
Polymorphic
A
- many forms- traits that have more than 2 variants
- can be at a phenotypic level as a result of one or multiple genes
- Single nucleotide polymorphism- greater than 2 variants at a base
15
Q
Directional selection
A
- One extreme phenotype has an advantage
- Population shifts to that extreme
- Still variation, but all will move closer to the favoured extreme
16
Q
Stabilising selection
A
- Natural selection favours the average
- Shortens the continuum, less at either extreme
- Reduced variation and possibility of speciation
17
Q
Disruptive selection
A
- Either extreme is favoured over the average
- Each extreme provides a specific advantage, often different niches
- Can be the start of speciation if they stop breeding and occupy different niches
18
Q
How does geographic isolation impact allele frequency?
A
- First step to speciation- prevents gene flow
- Evolution can favour one allele in one location, and a different one in another location
- Over time, allele frequency in each location differs
19
Q
What is neo-Darwinism?
A
Darwin’s theory of heritable traits + our current understanding of DNA and alleles and how they are inherited
20
Q
Similarities and differences between artificial and natural selection
A
- Human interference- active breeding = artificial selection
- If humans only add environmental selective pressure= natural selection
- Both lead to change in allele frequency
21
Q
Genetic equilibrium
A
- Opposite of evolution. No change in frequencies over time
- Usually in reference to one trait, therefore one gene
- Attributed to Hardy and Weinberg who created a mathematical model to assess allele frequencies.
22
Q
What 5 conditions must be met for a population to be in equalibrium, according to Hardy and Weinberg?
A
- Large population size- too small, if a few die, gene pool shifts— genetic drift
- No immigration or emigration- no new alleles arrive or alleles leave
- No favoured phenotype/ selective pressures- no survival difference between genotypes
- No sexual selection- random mating
- No generation of new alleles by mutation
23
Q
What do the letters represent in the Hardy-Weinberg equation, and what is the equation?
A
p+ q= 1
p2+ 2pq + q2= 1
p= dominant allele (A)
q= recessive allele (a)
p2= frequency of 2 dominant alleles (AA)
2pq= frequency of heterozygotes (Aa)
q2= frequency of 2 recessive alleles (aa)
24
Q
What order do you solve things in a Hardy- Weinberg calculation?
A
- q2
- q= square root q2
- p= 1-q
- 2pq
- q2
25
frequency, percentage and number of organisms- Hardy-Weinberg equation
* Frequency= decimal
* Percent= frequency x 100
* Individuals= frequency x pop size
26
Sustainability
A sustainable ecosystem can fully support itself without outside interferences- not unchanging, but changes slow enough that the organisms can adapt.
27
Tipping points
The point where an ecosystem can no longer sustain itself and starts to collapse. Often not known until it has been crossed.
28
How is the Amazon rainforest maintained a long period of sustainability?
* Due to large amounts of plant coverage
* This means it can maintain its own water cycle through transpiration
* How?
1. Plants absorb water from soil
2. Water travels up and out their leaves
3. High transpiration forms clouds (water vapor)
4. When the temperature drops, this turns into rainfall
5. Cycle begins again
29
What is the threat to the long-term sustainability of the Amazon rainforest?
DEFORESTATION
* The removal of plant life means a decrease in transpiration
* This impacts its own climate cycle
* If we disrupt the water cycle, this disrupts the climate- increased temp, decreased rainfall
* This causes forest fires- further decreases plant life
* When it cannot maintain forest anymore- becomes grassland= TIPPING POINT
* This is already happening in regions of the Amazon
30
What are the four requirements for an ecosystem to remain sustainable?
1. A sufficient supply of energy- enough plants to photosynthesise sunlight and provide for successive trophic levels
2. Nutrient recycling- finite nutrients, so decomposers help with cycling of Carbon, Nitrogen and Phosphorous
3. Genetic diversity- more likely to withstand smaller changrs, less disruption of food webs and ecosystem diversity
4. Response to climate change- human activities causing rapid and severe changes that challenge even resilient ecosystems. Can be combatted by a large tolerance range
31
What are some challenges to sustainable ecosystems- sufficient supply of energy?
* Loss of producers due to deforestation
* Trophic imbalances- invasive species, extinction of keystone species, eutrophication
32
What are some challenges to sustainable ecosystems- nutrient recycling?
* Logging and poaching- removal of biomass and nutrients
* Erosion washing away topsoil- removal of nutrients
33
What are some challenges to sustainable ecosystems- high level of genetic diversity?
* Competition from invasive species- reduces population size and increases inbreeding
34
What are some challenges to sustainable ecosystems- response to climate change?
* Can occur faster than species can adjust.
35
What is a mesocosm?
* A small experimental area set up as a working model of an ecosystem
* Can be set up in nature as fieldwork, or created in a lab
* It is common to use sealed containers with the necessities to function as a self-contained sustainable ecosystem
* Can be used to manipulate variables to understand impact
36
Why is a sealed mesocosm a better model than an open tank?
* Open tanks are not true models of sustainable ecosystems as matter can enter and exit e.g water vapour, O2, CO2
* A sustainable ecosystem should recycle these in a sealed environment, with only sunlight entering through clear sides
37
What is a Winogradsky column?
* Microbial mesocosm with layers that differ in abiotic environments
* This allows different bacteria to thrive in different layers
* There is more sulfur lower down and more oxygen higher up- this impacts where they can live
* Able to observe the difference between facultative and obligate anaerobes
38
What is the purpose of the components of a mesocosm?
* Bottom layer of pebbles: drainage tp prevent over moist soil
* Activated charcoal: absorbs extra water, odours and prevents bacterial overgrowth
* Soil: room for growth of roots, provide nutrients including nitrogen and phosphorous
* Plant: photosynthesis- convert sunlight into carbon compounds
* Water: add at the start to create water cycle
39
What is a keystone species?
* Any type of organism that has a disproportionate effect on the structure of an ecological community
* Disproportionate= larger impact than population size would predict
* Ecosystem collapse is likely if they are removed
40
What is trophic cascade?
* When the removal of a top predator destabilises the trophic levels below it and disrupts the balance of the ecosystem
* Note: top down population control/ impact
41
What is soil erosion?
* The loss of upper layer of soil
* Can be due to excess wind and rain
* The topsoil is the most nutrient rich layer so its loss can have large impacts on an ecosystem
42
What is leaching?
* Dissolving of nutrients (N,P) into rain or irrigation
* Water carries the nutrients away from the roots
* Also the nutrient-rich runoff can enter the water system and cause problems
43
What are agrochemicals?
Chemicals used in agriculture, including pesticides and fertilisers- can cause other problems
44
What is carbon footprint?
Total amount of greenhouse gases (including CO2 and methane) generated by an activity
45
What is tillage?
Preparing soil for a crop- involves loosening by plowing, harrowing and cultivations, usually with fossil fueled machines.
46
What is the method to determine if a species is a keystone species, and how does it work?
* The method is called the removal method
* It is done by removing a species from the area and observing the impact
* Can also be done by adding a species back into an area and observing the impact
47
How can resources be harvested sustainably?
If rate of removal is lower than rate of replacement
48
What is an example of un/sustainable harvesting of resources- plant?
Black cherry trees
* Colour makes them desirable for furniture
* Before: clear cutting caused extinction, lost from some ecosystems
* After: Have been replanted and replaced with regulation and logging is only done through selective removal- only the large older trees are removed, leaving younger ones to reproduce
49
What is an example of un/sustainable harvesting of resources- fish?
Chilean Sea Bass
* Discovered by tourists in the 1970's, known for taste
* Before: Widespread overfishing and longlining (which can harm other species) in the 1980's to 2000's
* After: regulations in term of technique and yield have been in place since 2000
50
What sustatainable agriculture technique can be used to combat soil erosion?
Planting cover crops
51
What sustatainable agriculture technique can be used to combat mechanical tillage?
Using non-mechanical alternatives to tilling and reduction of tilling all together
52
What sustatainable agriculture technique can be used to combat nutrient leeching?
Mindful irrigation practices and reduction in use of fertilisers- only use as much as required
53
What sustatainable agriculture technique can be used to combat monocultures?
Growing multiple crops to create a more diverse environment
54
What is eutrophication?
55
What is biochemical oxygen demand?
Biochemical oxygen demand is the amount of oxygen required for bacteria to effectively recycle nutrients. This includes the decomposition of excess algae from eutrophication. If the decaying algae increases so does the biochemical oxygen demand of the bacteria.
56
What is biomagnification?
The increasing toxicity for higher trophic levels from trace toxins in the water.
57
What is meant by biodegradable?
If something can be broken down completely, and dissolve into soil.
Note: can leave microplastics behind
58
What are macroplastics and examples?
Macroplastics are debris larger than 5mm, including single use plastic bottles and bags. Often are dangerous to aquatic life- get stuck on organisms and suffocate them, or they eat them by mistaking them for food.
Note: can break down into microplastics through mechanical wear and tear inc. rocks, tides and UV
59
What are microplastics and examples?
Debris smaller than 5mm, often found in cosmetics and cleaning products, but are illegal in most places. Can be unknowingly digested by organisms esp. marine- drunk with water, accumulate and block intestines.
60
What is the process of eutrophication from fertilisers
1. Excess fertiliser used on farms- a fixed nitrogen source
2. Runs off into bodies of water due to poor irrigation and leaching
3. Surface level algae thrive due to abundant nutrigen source
4. The surface algae exceed carrying capacity and block light for lower aglae
5. This casues them to begin to die
6. The bacteria then have to increase rate of decomposition to recycle nutrients, which requires higher BOD
7. Bacteria take all the oxygen, so fish die due to low oxygen availability
61
Explain the process of biomagnification
1. Small toxin is dissolved in water or soil
2. Small organisms (primary consumers) ingest a small amount of toxin (harmless to them but stays in tissue)
3. Secondary consumers eat biomass of primary consumers, so eat a larger amount of toxin, but not enough to harm them
4. Tertiary consumers then consume secondary consumers and thus a larger amount of toxin
5. Apex predator eats a large amount of tertiary consumers, thus having large amounts of toxin in their body. Causes harm e.g neurological damage
TOXIN LEVELS INCREASE AT EACH TROPHIC LEVEL
62
What are 2 examples of toxins that get biomagnified?
* Mercury- released by industry plants and making cement
* DDT- sythetic insecticide- overused, sprayed from planes. Is linked to weak eggs in predatory birds and cancer
63
What is rewilding and some examples?
* In situ conservation effort that is restoration based
* Efforts aimed at restoring a still present ecosystem through minimal human intervention
* Examples include:
- Stopping negative human interference through stopping overharvesting or removal of invasive species **(Hinewai Reserve)**
- Distribution of seeds
- Re-introduction of apex predators/ keystone species (Yellowstone National Park)
64
What is ecological succession?
A predictable series of change over time in the species that live in an area. Triggered by biotic or abiotic factors.
65
What is a pioneer species?
The first species to live in a newly established ecosystem. e.g moss and lichen in primary succession, small grasses and flowers in secondary succession
66
What is a climax community?
The most diverse and populated ecosystem. It is stable and will remain until a dramatic change in factors or a natural disaster occurs.
67
What is cyclical succession?
* Some communities do not reach one stable climax community, but have a changing cycle of community e.g wood pasture that cycles between grassland, woodland and scrub.
68
What is primary succession?
Establishment of an ecosystem in a place where there was not one previously. There needs to be no pre-existing soil. Often starts with moss and lichen to break down rock into soil.
69
What is secondary succession?
The rebuilding of a previously fully formed ecosystem that was significantly disturbed by fire, deforestation etc. This event does not remove soil so succession occurs quicker.
70
What are the differences between primary and secondary succession?
1. Begins with:
P: No existing life previously
S: Previous ecosystem
2. Ground:
P: Rock, sand etc (no nutrients)
S: Soil
3. Causes:
P: New surface formed through volcanic eruption, erosion, concrete
S: Major disturbance e.g natural disaster, deforestation, fire
4. Pioneer species:
P: Moss and lichen
S: Pre-existing seeds e.g small grasses and flowers
5. Biomass:
P: Low at start, will increase with time
S: High- increases with time until climax community is reached
6. Primary productivity:
P: Begins low due to low amount of plants, will increase with time
S: Increases at each stage- Increased plants, Increased productivity, Increased animals, Increased complexity of food webs
71
What can cause succession to arrest?
If succession starts, it should continue unless: HUMANS INTERFERE
This can cause it to
1. Stall and not reach climax community
2. Go backwards
72
What are some examples of succession arrest?
* Grasslands not reaching forest due to overgrazing by livestock
* Wetlands not reaching peat bogs due to drainage of wetlands
73
What is the greenhouse effect?
The addition of greenhouse gases in the atmosphere means more heat is trapped than necessary- this causes the Earth to heat up
74
What is infrared radiation?
When sunlight (visible/ UV light) hits an object, some is reabsorbed and re-emitted as infrared radiation (longer wave). This is the type of heat that gets trapped in the atmosphere and warms earth.
75
What is the definition of climate?
The long term patterns of temperature and precipitation. Weather changes frequently, but climate should be consistent.
76
What is permafrost?
Soil frozen solid below surface in arctic environments. Plants and microbes cannot survive, and lots of organic matter is trapped.
77
What is albedo?
The ability of a surface to reflect light.
Dark objects- low albedo, high absorbtion of light
Light objects e.g snow- high albedo, low absorbtion of light
78
What is the positive feedback loop of climate change?
| In relation to albedo
Ice and snow have a high albedo, so reflect a lot of light and do not warm up. Increased temp= ice and snow ments= lower albedo= less reflection= increased temperature
79
What are montane species?
Species that live in the mountains. Note: most have a preferred altitude
80
What is upslope migration?
When a species changes altitude (often upwards) to stay within range of abiotic factors it can tolerate.
81
What is poleward migration?
When a species changes latitude (towards a pole) to stay within range of tolerated abiotic factors.
82
What is a correlation and what are the two types?
A correlation is a pattern between two variables
Positive: When variable 1 increases, so does variable 2
Negative: When variable 1 increases, variable 2 decreases
83
What is a climate change tipping point?
When an ecosystem changes from a carbon sink (storage of CO2) to a carbon source (releaser of CO2).
84
Explain how the boreal forest has turned from a carbon sink into a carbon source.
Used to be:
1. Cold snowy winder
2. Snow melts in spring to form liquid water
3. Water from snow prevents drought in summer
4. Plants thrive and photosynthesise- CARBON SINK
But now:
1. Less snow in warmer winters
2. Insufficient water in spring causes a drought
3. Trees die and create fuel for forest fires, further decreasing plant lifr
4. Low plant life and high decomposition means that it has become a CARBON SOURCE
85
What is landfast ice?
A frozen layer of seawater attatched to the land. Important part of an ecosystem as some organisms prefer to breed on it.
86
How has climate change impacted emperor penguins?
* Emperor penguins breed on landfast ice
* Normally- ice breaks off in summer when chicks are ready to find food and swim
* Now- ice breaks too early and the young don't survive
* Some penguins are adapted to breed on land, but increased warming could threaten survival
87
How has climate change impacted walruses?
Walruses breed on landfast ice, which helps reduce the distance that mothers have to swim to get food for the babies. With the decrease in landfast ice, there is less space to care for the pups. This means that the wulruses have to either move further north or onto land, which means that the mothers have to spend longer getting food, leaving pups vulnerable for predation.
88
How has climate change impacted ocean stratification?
* Before: small layer of warm, salty, dense water on top, with large layer of colder nutrient rich but oxygen poor water underneath. Currents would allow nutrient upwelling into the warm top water, and oxygen to go to the deep parts.
* Now: larger layer of warm, salty water on top than before. Reduced currents means that there is a lack of nutrients in top water and lack of oxygen in bottom= increased ocean stratification
89
Explain the process of ocean acidification and its impact on marine organisms
1. CO2 dissolves into H20 to make H2CO3
2. H2CO3 dissasociates into H+ ions and CO3
3. When pH is stable- CO3 bonds with Ca to form CaCO3- Calcium carbonate
This is used by molluscs and coral to create their exoskeletons
4. When there are excess H+ ions present due to an increase in dissolved CO2, the CO3 will form HCO3, or bicarb- this is unable to bond with calcium to make calcium carbonate
90
What is carbon sequestration?
The capture and storage of carbon compounds
91
What are some natural forms of carbon sequestration?
Photosynthesis, growth of biomass and shell formation
92
What are the methods of carbon sequestration we could use to help climate change?
1. Plant more trees
* Planting trees increases photosynthesis, carbon compounds stored as biomass
* Afforestation: planting trees in areas where there were no trees previously e.g farmlands into forests
* Reforestation: plant seeds to recover clear cut areas
2. Increase peat bogs
* Increase peat bogs which pull down carbon compounds to form fossil fuels
* Peat bogs form from partially decomposed matter in swamps, so we cannot drain them
93
What is phenology?
The study of the timing of periodic events in living organisms.
94
What are some examples of the events studied in phenology?
* Breeding seasons
* Migration
* Hibernation
95
What is a photoperiod?
The number of hours a day that the sun is shining
96
What is trophic mismatch?
Where the annual cycles of one organism which used to align with the annual cycle of another organism, however they have become out of sync. This can impact the survival and reproduction of an organism, particularly if they rely on the other as a food source.
97
What are some examples of activities that are time specific in plants?
* Flowering- hours of daylight directly cause flowers to bloom in spring or autumn
* Bud set/ burst in deciduous trees- buds form in winter to store energy and prevent growth. As the days get longer, the buds burst to grow new leaves and flowers.
98
What are some examples of activities that are time specific in animals?
* Migration- birds migrate during winter then return to breed- triggered by photoperiod
Note: must be food and nesting sites available at new habitat
* Hibernation- Insects who use pollen as a food source hibernate in winter and then exit hibernation when flowering is set to occur
99
How has climate change impacted the life cycles of some insects and what impact can this have on spruce trees?
Insects e.g spruce bark beetle beetles can be monovoltine (1 generation produced per year) or bivoltane (2 generations produced per year). Warmer temperatures are correlated with more beetles undergoing the bivoltane cycle. The beetles burrow into spruce trees to eggs and the larvae feed on the bark. Increased number of life cycles means an increase damage on the trees, leading to increased tree deaths.
100
Explain how the actic mouse-ear chickweed and reindeers are an example of asynchrony.
* The chickweed uses temperature as its phenological cue for leaf bud burst and leaving dormancy (impacted by climate change)
* The reindeer uses hours of daylight as a phenological cue to migrate home and breed (not impacted by climate change)
* Ideally, these are synchronised for maximum productivity (most leaves) when the reindeers are breeding
* However, due to climate change, the peak productivity is now too early for breeding season so there is less music available for young reindeer
* THIS IS A TROPHIC MISMATCH
101
Explain how the great tit and catepillars are an example of asynchrony.
* Catepillars- when they reach peak biomass is related to temperature, food source and easier conditions
* Great tit- egg laying period coincides so that the babies are born at peak catepillar biomass
* This is due to the co-evolution of the species- where one species evolution is triggered by another
* Due to climate change, there are milder winters and warmer temps, meaning the catepillars reach peak biomass earlier
* The great tit has not evolved to the new peak biomass of catepillars, as natural selection occurs much slower than climate change
* This results in a trophic mismatch, where baby great tits are born with less food available
102
What is microevolution?
* Specifically tracking the changes over time to a single phenotypic trait, and its associated gene and allele frequencies. This can be done using the Hardy Weinberg equation to track changes in allele frequencies over time.
103
What is polymorphism?
2 or more common phenotypes of a train.
Normally- many genes but one primary form and possible mutations
Polymorphic- 2 or more common and successful variations
Note: to remain equally present, neither would have to be more advantageous.
