A4 Unity and Diversity of Ecosystems Flashcards
What is biological evolution?
Change in the heritable characteristics of a population / change in allele frequency overtime in a population
What was Lamarck’s theory of evolution?
Adults acquired characteristics over their lifetime, based on environmental stressors and pass this on
Why was Lamarck’s theory of evolution falsified?
Offspring inherit DNA. Changes during lifespan cannot be passed on
What was Charles Darwin’s theory of natural selection?
Only traits are heritable can be passed on. Alterations to heritable material give rise to different traits. Some traits aid survival/reproduction, and organisms that survive are able to pass on successful traits. This means that the frequency of this allele increases.
What does it mean for a theory to be falsified?
Shown not to be true
What generates strong support for a theory?
If many lines of evidence fail to falsify it (i.e. evidence for lack of falsification)
What are three different forms of molecular evidence for evolution that are studied?
DNA
RNA
Proteins (indirect way to study DNA)
What patterns would be found in DNA comparisons that suggest evolutionary similarity?
A high level of DNA similiarity between species supports the idea of common ancestory with evolution occuring via small changes to DNA overtime
What are the Hox genes?
Gene family that plays a role in determining the body plan of organisms during development.
How are Hox genes related to evolution?
The similarity in these genes across very different types of organisms would be hard to explain without looking at common ancestry/evolution
What are phylogenetic trees?
Visual diagram that shows similarity via organisms being on closer branches.
What have we added onto Darwin’s theory of evolution?
That inheritance is due to DNA, which does not change during the lifetime.
That differences/variation arise because of changes to DNA due to mutation.
Variation is genetic
What is the outcome of Natural selection?
Evolution
What are the steps involved in natural selection (according to Darwin)
Differences exist in heritable material.
This leads to variation in a population.
There are threats to survival.
In this environment, some variations increase likelihood of survival.
Those with the adaptation produce more offspring, because they survive longer (survival of the fittest)
Since adaptation is heritable, the adaptation is passed onto their many offspring
Over many generations, there is an increased frequency of this adaptation + evolution has occured
What are some threats to survival?
Abiotic factors
Competition for resources
Predators + disease
What is fitness (in relation to survival of the fittest)?
Ability to pass on more offspring (by surviving longer)
How is a base sequence comparison of DNA molecular evidence for evolution?
More similiar the DNA is, the more closely related.
If evolution is true, similiar organisms will have…
Very similar DNA
What are the strengths and limitations of DNA modelling?
Difficult to isolate and sequence. Overly complex if not closely related
Provides more information. All differences are detected including silent mutations. Good for if closely related
When is RNA sequencing used?
Studying viral evolution, that only has RNA
How is RNA used for molecular evidence for evolution?
Using mRNA, base sequencing concept.
Usually difficult to sequence, harder to isolate
Where does most older data about molecular evidence for evolution come from?
Protein studies
How are proteins used as molecular evidence for evolution?
Compare amino acid sequences of a shared protein.
What are the strengths and weaknesses of using proteins for molecular evidence for evolution?
Easier to sequence and obtain
Less data/differences detected. Does not include silent mutations
What is selective breeding?
When breeders choose the males and females with the most desirable traits to breed
What is artificial selection?
Change in the frequency of heritable material caused by human selective breeding
What is a homologous structure?
Structures with similar internal structures used for different purposes
What are pentadactyl limbs?
Limbs with five digits. Same set of bones across organisms
What are analogous structures?
structures that carry out similar functions but are very different structurally
What is convergent evolution?
When independent species develop similar adaptations to similar environments
What are examples of organisms that have undergone selective breeding?
Modern corn
All modern dog breeds
Cannabis
How has modern corn been shaped by selective breeding?
Originated from teastine plant with very small, hard kernels. Large kernels and protective leaves were favoured. Across many generations, the modern corn we have today has been developed
How have all modern dog breeds been shaped by selective breeding?
All originate from the grey wolf. Breeders choose different prefered traits leading to different breeds
How has cannabis been shaped by selective breeding?
Breed for high THC content. Lead to the average THC content quadrupling over 23 years
What are examples of functional variations in pentadactyl limbs across animals?
Walking (most animals)
Hands (bipedal humans)
Fin (aquatic mammals)
Wing (bat0
What evolutionary pattern do homologous structures provide evidence of?
Divergent evolution
What is divergent evolution?
When a common ancestor evolves into increasingly different species overtime, because of different selection pressures
Are central nervous systems considered to be homologous or analogous structures?
Analogous. Many have similar structures but no common ancestor
How is artificial selection evidence for natural selection?
Similarity between the processes and the similar end result offer evidence that the natural selection model is correct
How is natural selection different to artifical selection?
Different selection pressures
Natural: pressures in environment choose which survive
Artificial: human preferences are the selection pressure
How are artificial and natural selection similar?
Both start with genetic variation
Both end with one variation with more offspring, causing an increase in frequency
What is an example of divergent evolution?
Mammals (common ancestory) with pentadactyl limb (homologous structure)
Due to different selection pressures, this structure developed into:
Hoove/leg (Horse)
Fin (dolphin)
WIng (bat)
What is an example of convergent evolution?
Different ancestors: insect, bird, mammal
Similiar selection pressure: ability to fly in sky
Leads to:
Wings with no bones (butterfly from insect)
Wings with one bone and feathers (robin from bird)
Wing with bone and skin (bat from a mammal).
No recent common ancestor. Analogous structure: wings.
What is speciation?
Formation of two new species by splitting an existing species
What is reproductive isolation?
When two species are unable to successfully interbreed -> no gene flow/exchange of genetic material. Can lead to speciation
What is geographical isolation?
Physical barrier that leads to no contact between male and female (mating not attempted). Type of reproductive isolation
What is sympatric speciation?
When speciation occurs with no physical barrier / new species arises within same habitat where mating could occur but didnt
What is allopatric speciation?
When speciation occurs because of a physical barrier. Causes lack of contact and distinct habitats
What is behavioural separation?
Isolation when mate-attracting behaviours are different between groups, to ensure successful breeding
When is behavioural separation most common?
species with elaborate rituals
What is temporal separation?
Different mating/release of gametes times that can lead to sympatric speciation
What can temporal separation be good for?
Preventing unsuccessful mating
What is adaptive radiation?
When similar but distinct species evolve rapidly from a common ancestor. Groups move into different niches and therefore, with different adaptations
What is required for speciation to occur?
Reproductive isolation
Differential selection
How do speciation and extinction interact to impact the number of species on Earth?
Opposite forces to control. Speciation = new species added. Extinction = new species removed
When speciation > extinction, increased biodiversity
What is an example of adaptive radiation?
Darwin’s Finches. 14 species from 1 common ancetor. Migrated + adapted to different food sources, therefore very different beaks
What is allopatric speciation a product of?
a geographic barrier that prevents mating
What is differential selection?
When exposure to different selection pressures causes the isolated populations to evolve.
What causes adaptive radiation usually?
Migration event
What is hybridisation?
Fertilisation of gametes from one species by gametes of another species, forming unsuccessful offspring who cannot survive/reproduce
What are interspecific hybrids?
The result of (usually) artifical hybridisation betweeen two species.
What is a polyploidy?
When a species has three or more of each chromosome, due to an error in meiosis or hybridisation
What is autotetraploidy?
Formation of a polyploid organism from members of the same species
What is allotetraploidy?
Formation of a tetraploid via combining gametes from two different diploid species.
What is abrupt speciation?
rapid formation of a new species over a few generations (can occur when new species are formed via tetraploidy)
Why are mules sterile?
Incompatible chromosomes. Horses = 64 chromosomes. Donkey = 62 chrosomes. Therefore, mule = 63 chromosomes. Uneven numbers = difficult meiosis b/c pairing of chromosomes is needed for functional gametes
Why have so many species evolved barriers to prevent hybrid offspring from developing?
B/c the genetic differences lead to
Miscarriage (reduced hybrid viability)
Born fragile/diseased (reduced hybrid viability)
Infertile (hybrid sterility -> gametes do not form in meiosis, especially because of odd number of chromosomes.
This is a bad outcome because
- Waste of energy
- Poor for survival of the fittest
What are barriers to hybridisation?
Behavioural isolation
Temporal isolation
Incompatible genitals
What is tetraploidy?
4 sets of every chromosome
Why are autotetraploidies not always classified as their own species, even though they are?
Often very similar appearance
What is the process of autotetraploidy?
Diploid parent cell goes through a genetic event to make them an autotetraploid.
When meiosis occurs, they form diploid gametes (b/c even chromosome numbers)
If they reproduce with another tetraploid, they have tetraploid offpsring and become a self-sustaining species.
If they reproduce with a diploid species, this leads to a sterile triploid offspring
Are allotetraploids classified as their own species?
Yes!
What is allotetraploidy a result of?
Hybridisation
What is the process of allotetraploidy?
Diploid parents (AA) + Diploid parent (BB) go through meiosis. Hybridisation produces a sterile hybrid (AB).
A genetic event occurs, making the hybrid an allotetraploidy.
Meiosis makes diploid gametes, that can only reproduce together.
This leads to tetraploid offpsring, and a sustainable species that only reproduces within itself
What is biodiversity?
variety of living organisms in all forms, levels and combinations
What is species richness?
Measure of biodiversity that specifically considers the number of different species in a community
What is species evenness?
Description of the distribution (%) of the species in an ecosystem
What is the gene pool?
All the alleles of a population
What are the three types of biodiversity?
Ecosystem diversity
Species diversity
Genetic divserity
What is anthropogenic species extinction?
Extinction caused by humans
What are the five major causes of the current sixth mass extinction?
C: climate change
H: habitat loss
I: invasive species
P: pollution
O: overharvesting
What is overharvesting?
Removing plants and animals for food/medicine/materials/fishing faster than they can regenerate
What is habitat destruction?
Destroying ecosystems for agriculture/homes/urbanisation
What is an invasive species?
Introduction of an alien species who outcompete endemic species, leading to extinctionW
What is pollution?
Release of substances into the environment that directly/indirectly cause harm to living organisms
What is global climate change?
Change of temperature faster than natural selection (leading to temperatures out of the abiotic zone of tolerance)
What are some causes of ecosystem loss?
Land use for agriculture
Urbanisation
Overharvesting
Mining and smelting
Building dams
Diversion of water for human use
Overfertilisation
Climate change
What are some forms of data that can be gathered for evidence of a current biodiversity crisis?
Decrease in population size
Calculations of species diversity
Number of threatened species
Change in range of species
Genetic diversity measured within species
What are two organisations that release data on biodiversity loss?
IPBES
IUCN
What is the IPBES?
Intergovernmental Science-Policy Biodiversity and Ecosystem Services
Published a report with guidelines for policy makers. Does data pooling and updates
What is the IUCN?
International Union for Conservation of Nature. Make red list for all species rating their current level of threat
What are three extinction case studies?
North Island Giant Moa
Carribean Monk Seal
Mount Glorious Torrent Frog
What is the extinction case study of the North Island Giant Moa?
1000 years ago
B/c overhunted for food by Maoris
New Zealand
What is the extinction case study of the Carribean Monk Seal?
1957 last sighting
Blubber was boiled and turned into oil (main source of power for lamps)
the Carribean
What is the extinction case study of the Mount Glorious Torrent Frog?
By 1980
Deforestation + alien feral pigs (ate them)
Rainforests in Northeastern Australia
What is the ecosystem loss case study of the Mixed Dipterocarp Forest?
In Asia
Current
Logging for area for palm oil + using trees
Why is the Amazon Rainforest being deforested?
Agricultural practices
Deforestation
What is ecosystem biodiversity?
Diversity within the biomes of the world
What to consider in terms of ecosystem biodiversity?
Amount of biomes, areas covered by biomes, % degradation
What is species diversity?
Diversity with the amount of species
What to consider in terms of species diversity?
Amount of species, sum of species richness/evenness, population sizes, % endangered, ranges
What to consider in terms of genetic diversity?
Amount of alleles in gene pool, balance of alleles
What is Simpson’s Diversity Index?
Measure of diversity
D =
N x (N -1)
/
Σ n (n - 1)
Where N = total number of species
n = number of that species
When was the biodiversity crisis first identified?
1970
What criteria does the EDGE of existence project use to identify animal needing conservation efforts?
ICUN ranking
DNA sequencing information for unique evolutionary history
What do anthropogenic impact come from?
Human need for food and shelter
Food = hunting and harvesting
Shelter = habitat loss
How has the increase in human population size increase contributed to the biodiversity crisis?
Increase in population size
Leads to
1. More need for food -> overharvesting
- More need for shelter (and urbanisation) -> habitat loss
- More travel (including airtravel) -> invasive species, pollution
- Industrial revolution (more people = more fossil fuels used) -> pollution, climate change
What are in situ conservation efforts?
Management of biodiversity within natural habitat
What are ex situ conservation efforts?
Management of biodiversity outside of natural habitat
What are in situ conservation efforts examples?
Establishment of national parks and nature preserves
Rewilding: introduce helpful species and/or remove potential human interferences (dams, invasive species, etc.)
Reclamation of damaged areas (replanting, short term management)
What is an example of rewilding?
Wolves in Yellowstone
What are examples of ex situ conservation efforts?
Establish a botanical garden (creation of artificial habitat for species)
Zoos with breeding programs for endangered animals (artificial insemination across different zoos -> more genetic diversity)
Seed banks and animal tissue banks
(create before endangered)
How are botanical gardens different to national parks?
Botanical gardens are artificial and created outside of natural habitat, while national parks are natural
What do tissue banks need?
Cryogenic care
What can seed banks be for?
Reclamation of damaged areas, botanical gardens
What can animal tissue banks be used for?
Cloning
