biodiversity Flashcards
what is species richness
number of species within an ecosystem / community
what is species diversity
number of different species in an ecosystem, and also the abundance across the different species present
what is genetic diversity
diversity of alleles and genes in the genome of species
how can genetic differences arise between populations of the same species
the two populations occupy slightly different ranges in their habitat and so are subject to slightly different selection pressures that affect the allele frequencies in their populations
in what type of populations is genetic diversity limited
in populations that are very small or isolated as inbreeding is small, isolated populations leads to a high proportion of individuals being homozygous (e.g. AA to aa) for many genes, resulting in lower genetic diversity
This can mean that genetic diseases caused by recessive alleles can become more common in these populations
what is endemism
species found in only one location
how are fertilisers bad for the level of biodiversity
Fertilisers can leach into waterways, causing eutrophication, which can lead to the death of many aquatic invertebrate and fish species
why are pesticides bad for the level of biodiversity
used on crops kill insect pests but also kill many non-target species, including important insect pollinators like bees
how does global warming have a threat on marine biodiversity
Increasing atmospheric CO₂ is leading to more CO₂ dissolving in seawater, decreasing its pH (known as ocean acidification). This is negatively affecting organisms that require calcium carbonate for shells
Increased ocean temperatures have also led to an increased frequency of coral-bleaching events, where the tiny organisms that live inside corals and help keep them alive leave due to temperature stress. Without these organisms, the corals die and are broken down, eventually leading to the loss of whole coral reefs
why can species richness be misleading indicator of diversity
as it does not take into account the number of individuals of each species
what is species abundance
measure of the relative number of individuals in the different species within a given area
what is random sampling used to estimate
The distribution of a species
The abundance of a species
how can sampling bias be avoided
Quadrats must be laid randomly in the area
what techniques are used for sampling animal species
Sweeping nets used to catch flying insects and insects that live in long grass by sweeping the net back and forth through the grass
Pitfall traps : cans or jars that are buried in the ground that are used to catch insects and other invertebrates as they fall into the trap
Kick-sampling catch freshwater invertebrates living in streams or rivers
what are hetrozygotes
Organisms that have two different alleles at a particular gene locus
formula for heterozygosity index
number of heterozygotes / number of individuals in the population
index of diversity formula and what happens as the number obtained gets larger
The larger the number obtained, the higher the level of diversity
N(N-1) / {n(n-1)
N = total no. of organisms in the community
n = total no. of organisms for a single species in the community
Step 1: Calculate N(N-1) to find value A
Step 2: Calculate n(n-1) for each species and add all these numbers together to find value B
Step 3: Divide value A by value B
what is a niche
The role that a species plays within its habitat
what happens if two species try occupy same niche
compete with each other for the same resources
One of the species will be more successful and out-compete the other species until only one species is left and the other is either forced to occupy a new, slightly different niche or to go extinct from the habitat
three types of features of an organism that increase their chances of surviving and reproducing
Anatomical, which refers to structural features
Behavioural, which refers to behaviours such as courtship of defensive behaviours
Physiological, which refers to processes inside the body, such as venom production or the ability to digest cellulose
how can selection pressures increase chance of individuals with specific phenotypes surviving and reproducing over others
advantageous alleles that code for the favourable phenotype will be passed on to offspring
When selection pressures act over several generations of a species, they have an effect on the frequency of alleles in a population through natural selection
what conditions must be met for Hardy Weinberg principle to be true
Mating must be random between individuals
The population is infinitely large
There is no migration, mutation or natural selection
what is hardy weinberg principle
allele frequencies of a gene within a population will not change from one generation to the next
what is the letter for
homozygous dominant
homozygous recessive
p2
q2
what is reproductive isolation
when changes in the alleles and phenotypes of some individuals in a population prevent them from successfully breeding with other individuals in the population that don’t have these changed alleles or phenotypes
3 causes to reproductive isolation
Seasonal changes - some individuals in a population may develop different mating or flowering seasons to rest of population
Mechanical changes - some individuals in a population may develop changes in their genitalia that prevent them from mating successfully with individuals of the opposite sex
Behavioural changes - some individuals in a population may develop changes in their courtship behaviours, meaning they can no longer attract individuals of the opposite sex for mating
how does speciation occur
when populations of a species become separated from each other by geographical barriers
creates two populations of the same species who are geographically isolated from each other, and as a result, no gene exchange can occur between them
If there are sufficient selection pressures acting to change the gene pools (and allele frequencies) within both populations then eventually these populations will diverge and form separate species
The changes in the alleles/genes of each population will affect the phenotypes present in both populations
Random mutations within each population will also change allele frequencies in each
Over time, the two populations may begin to differ physiologically, behaviourally and anatomically
what is each group called when grouping organisms
taxa
what type of species are grouped together in the same genus
different species with similar genotypes and phenotypes
why are species in the same genus seperate species
because they cannot produce fertile offspring
This is known as the species concept
what are the 3 domains
Archaea (prokaryotes)
Bacteria (prokaryotes)
Eukarya (eukaryotes)
what is phylogeny
evolutionary history of different groups of organisms and can specify how closely related they are
what does molecular phylogeny rely on
similarities or differences of molecules (such as DNA, RNA or proteins) between groups of organisms to determine how closely related they are
The more similar the molecules, the more recent the common ancestor is that they share
how do seed banks conserve plant diversity
drying and storing seeds in a temperature-controlled environment
seeds of the same species are collected from different sites to maintain genetic diversity
After a certain period of time the stored seeds are grown into plants and fresh seeds for storage are taken from those plants
X-rayed to check for { viability / viable embryos
advantage of seed bank
It provides an opportunity to investigate how to successfully grow plants from seeds
They provide a stock of endangered plants that could be useful to humans (e.g. medicinal plant species, crop plant species) taking pressure off of wild populations
disadvantage of seed banks
testing for viability is expensive and time consuming
what are the problems with zoos
Captive breeding of small species populations can reduce genetic diversity
ethics of keeping animals in captivity
benefits and negatives of reintroduction
prevent them from going extinct in the wild
Organisms that rely on these plants and animals for food or habitat may also benefit from their presence
These organisms may carry new diseases that will harm other organisms living in that habitat
Reintroduced animals may lack the ability to find food or communicate effectively with members of their own species
why is the use of protected reserves more successful for conservation of animals over captive breeding
less stress and trauma
natural interspecific relationships exist
disease is less likely to wipe population
animals more likely to breed in natural environment
two differences between genetic diversity and species richness
idea that, GD considers one species but SR considers {different / number} species ;
- idea that, GD considers {alleles / genotypes / eq} but SR is within a {habitat / area
why is it better to store seeds from several individual plants of one species rather than seeds from one individual plant
idea of {greater / maintain} genetic variety e.g. wider gene pool, different alleles;
idea of less chance of inbreeding;
idea of reducing chance of storing seeds with {low viability / disease / eg} ;
2 reasons why seeds need to be dried then stored in cold conditions
inhibits germination / eq;
- idea of slowing down {enzymes / biochemical reactions};
- slows down rate of { decay / microbial activity / eg } ;
- (therefore) prolongs seed survival / eq;
- idea that drying reduces freezing effect ;
how does inbreeding lead to genetic defects
closely-related mated with each other / a small gene pool / eq;
- reference to inbreeding depression;
- idea of increased chance of homozygous recessive genotypes for genetic defects;
factors needed to be taken into account when zoos carry out captive breeding and reintroduction programmes for greater flamingo
maintenance of genetic diversity (1)
by { selection of mates / use of stud books } (1)
(use of stud books in order) to prevent {inbreeding depression / genetic drift } (1)
habitat protected (from development) (1)
relevant requirement of area into which flamingos reintroduced (1)
what is biodiversity
{number / range / variety / eq} of species;
2. genetic variety within a species / number of different alleles in a {species / gene pool} ;
Suggest advantages of selecting seeds of different sizes for long-term storage.
idea of maintaining or increasing {genetic diversity / size of gene pool / genetic variation} ;
2. idea of more chance of having beneficial alleles / eg:
3. increases chance of future survival {if environment changes / due to higher adaptability } / eq;
4. less chance of all being susceptible to a disease
Describe what the seedbank will do with these seeds to ensure the long-term
conservation of the species.
details of assessment of seed viability e.g. only select seeds with a living embryo, use of X ray (to detect embryo presence) / eq;
- idea of {cleaning seeds / surface sterilisation / eq} ;
- idea of drying (of the seed) ;
- idea of storing at low temperatures;
- idea of regularly testing viability (during storage of seed);
- idea of what to do if viability decreases, e.g. if less than 75% germinate collect fresh seed for storage;
describe how zoos use captive breeding and reintroduction to conserve rare species
to increase numbers/population size;
2. to {maintain / increase} genetic diversity/ reduce genetic drift / eq;
3. protect from {predators / poachers
inter-zoo animal movement / eq;
5. selection of mates / use of stud books / records kept of breeding programme / eq;
6. process involved described e.g. IVF
preparation for reintroduction described e.g. idea of reinforcing wild behaviour / idea of hacking out / reduce food intake to encourage hunting;
select {habitat / reserves} ;
raise {awareness / education? of local population
what is difference between genetic diversity and species richness
GD considers one species but SR
considers {different / number} species
Suggest two reasons why it is better to store seeds rather than to store whole
plants.
take {less / smaller} space / eq ;
2. can have more individuals / eq ;
3. reference to {greater / more} genetic variety ;
4. idea of less {maintenance / cost} ;
5. likely to survive longer / eq ;
6. can freeze seeds / eq
why it is better to store seeds from several individual plants of one
species rather than seeds from one individual plant.
idea of {greater / maintain} genetic variety
e.g. wider gene pool, different alleles ;
2. idea of less chance of inbreeding ;
3. idea of reducing chance of storing seeds with
{low viability / disease / eq} ;
what effect transferring Rafa from one zoo to another had on genetic
diversity in this species.
Increase genetic diversity allows outbreeding and mating with genetically different individuals
Suggest why seed germination is tested at regular intervals.
idea that checking {seed viability /
germination success / eq } ;
2. allows new seeds to be produced / eq ;
3. idea that stored seeds may need replacing
e.g. due to decay / death
Describe how breeding programmes at zoos are designed to reduce the risk
of inbreeding.
selection of { unrelated / genetically different }
mates / eq ;
2. use of stud books / records of mating / DNA profiling
/ eq ;
3. exchange of animals between zoos / eq ;
4. exchange of gametes between zoos / eq ;
5. IVF / AI / eq ;
