Field techniques for biologists Flashcards
Define sampling
The gathering of data from part of a population
How is sampling effective
If it measures and records data that is representative of the whole population
What is important within sampling
It should be carried out in a way that minimises the impact on the species/habitat
What in particular is essential to consider before sampling
If it is a rare species or vulnerable habitats
What is a rare species
Those that are found at low density or have a small total population
What is a vulnerable habitat
Those that are easily damaged by human activities
What is fieldwork
Work carried out outside the laboratory/office.
What are the 3 main hazards of fieldwork
terrain, weather conditions, isolation
Give examples of a hazardous terrain
mountains, cliffs, trees, mud, water, ice
Give examples of a hazardous weather condition
cold, wet, windy, electrical storms
Give examples of a hazard associated with isolation
medical transport, moving supplies/equipment
Explain a suitable/sufficient risk assessment
- Identifies hazards associated with the trip and travel
- Evaluates risks (how likely)
- Evaluates the severity (how harmful)
- Identifies appropriate control measures to reduce the risk/hazard
- Records these
List some sampling techniques/types of species
- Point count
- Transect
- Remote detection
- Quadrats
- Mobile species
- Elusive species
Define point count
Gathering observational data, used for determining species abundance (associated with birds)
Define transect
Used for determining changes in a community across an environmental gradient such as a shore, can be in the form of a line which is narrow or a larger band. The higher the variability the wider the band has to be in order for it to be representative.
Define remote detection
Monitoring is carried out at a distance using censors like a satellite. Used for things like global vegetation surveys
Define quadrats
The sampling area is standardised which reduces bias and increases reliability, used for sessile/slow moving organisms, the diversity influences the number of samples to be taken.
How would you monitor a mobile species
May involve capture techniques like nets/traps, used for birds/bats/some insects, allow the animal to be released unharmed
How would you monitor an elusive species
Camera trapping to provide direct evidence/scat sampling (counting droppings) to provide indirect evidence.
What is a classification guide
A guide which focuses on an order of organisms from one geographical location that provides information that allows us to separate the species through descriptions/key features
What are biological keys
A series of questions which focus only on the characteristics that allow species to be separated
Whats a paired statement key
A biological key where each option leads to another paired statement or the conclusive identification of a species
Whats a powerful technique to separate species
Analysis of DNA/proteins from both organisms
What is taxonomy
The organisation of life into a hierarchy of groups of increasingly closely related species
What is a model organism
The best known species within a taxonomic group
species that is easiest to keep/study or most useful/harmful
How can a model organism be useful
The information given by one can be applied to other species in its taxonomic group that are more difficult to study
What are the major divisions in plants
Mosses, liverworts, ferns, conifers and
flowering plants
What are the major phyla in the animal kingdom
Chortada Antrhopoda Nematoda Platyhelminthes Mollusca
What are some of the more useful model organisms that have recentely been studied
E. coli Arabidopsis thaliana (flowering plant) C. elegans (nematode) Drosophila melanogaster (arthropod) Mice, rats and zebrafish
What are the 3 domains life has emerged from
Archaea
Bacteria
Eukaryota
What is divergent evolution
The development of differing life forms from a common origin which results in closely related lifeforms with different phenotypic characteristics
What is a method of monitoring a population
Using an indicator species (eg for something like pollution)
What is convergent evolution
The separate evolution of phenotypic adaptions in lineages who’s ancestors did not share the same adaptations.
How does convergent evolution occur
When very similar selective pressures are acting upon the different lineages
What is useful about indicator species
Allows us to identify if environmental conditions in an area meet its niche conditions
How do you measure an environmental condition
Monitor an indicator species that is very tolerant or very intolerant to the condition
What are useful indicators when it comes to freshwater sampling
Mayflies - indicate unpolluted water, high levels of oxygen
Bloodworms - indicate low levels of oxygen
Name methods of marking
Banding Tagging Surgical implantation Painting Hair clipping
Describe banding
A visible coded metal or plastic loop attached around part of the organism
Describe tagging
A visible coded metal or plastic tag inserted into or onto the organism
Describe surgical implantation
A microchip inserted into the organism; read by an electronic reader
Describe painting
A code painted onto the surface of an organism, such as a shelled mollusc
Describe hair clipping
A distinctive area of fur trimmed on a small mammal
What aspect of animal behaviours ensures experiments have a careful design
Behaviour is variable
What categories of data is used to quantify animal behaviour
Latency
Frequency
Duration
Define latency
Interval of time between a stimulus and its response
Define frequency
How often a behaviour occurs
Define duration
The length of time a behaviour occurs
Define anthropomorphism
The attribution of human motivation, characteristics or behaviour to non-human animals
Define an ethogram
Describes all the behaviours shown by a species in a wild context, allowing observation and recording of the amount of time spent exhibiting each type of behaviour
How does evolution occur
Happens to a population over a number of generations
Individuals show genetic variation as they carry different versions of inherited traits
What is a novel allele
If a mutation results in a base sequence which codes for a different amino acid in the polypeptide (a new version of the gene)
What are the three effects of mutations
Neutral
Harmful
Beneficial
How does evolution occur
Through genetic drift and natural and sexual selection
What is genetic drift
The random increase/decrease in frequency of inherited traits over a number of generations
What is the cause of genetic drift and why
Neutral mutations as there is no selective pressure
Why is genetic drift more effective on small populations
The population is small so alleles are more likely to be lost if there is chance event
What is the meaning of natural selection
A non-random process which affects the allele frequency in the population over generations.
How does natural selection work
It selects individuals based on their survival chances and thus increases their chances of passing on their inherited traits
Describe the actual process of natural selection
Organisms produce more offspring that the environment can support
Individuals with variations that best fit their environment are more likely to survive and breed
Favoured traits are inherited so they are more likely to become more frequent in later generations
What is the meaning of sexual selection
The non-random increase in the frequency of alleles that make mating and reproduction more likely
What is the difference between natural and sexual selection
The more popular alleles brought about in sexual selection do not increase survival chances
What is absolute fitness
The ratio of frequencies of a particular genotype in one generation compared to the previous generation
What is relative fitness
It compares the absolute fitness of one genotype with the absolute fitness of the most successful genotype
List factors that increase the rate of evolution
Higher selection pressures Shorter generation times Warmer environments Sexual reproduction Horizontal gene transfer
Why does higher selection pressures increase evolution rate
Higher selection pressures means certain traits (from alleles) are more favoured (and less favoured) so rate of evolution will be more favoured
Why does shorter generation times increase evolution rate
Evolution occurs over generations, the more generations there are the more chances for selection pressures to operate
Why does warmer environments increase evolution rate
Most organisms don’t regulate their body temperature, germline cells that produce gametes produce gametes more which means more DNA replication which means more chances for DNA to mutate and new beneficial/disadvantageous alleles to arise
Why does sexual reproduction increase evolution rate
Combining 2 sets of DNA increases variation shown by offspring, greater variation means more selection which means higher evolution rate
Why does horizontal gene transfer increase evolution rate
Allows sharing of beneficial DNA sequences between different lineages of bacteria using plasmids. This process is rapid.
When does co-evolution occur
When two species have frequent, close interactions.
Describe the red queen hypothesis
States that both species must keep running in order to stay still in evolutionary terms
List examples of co-evolution
Herbivores and plants
Plants and pollinators
Predators and prey
Parasites and hosts
Describe the co-evolution of herbivores and plants
Plants have special defences like thorns/toxins which animals have specifically evolved to eat, now they can only eat that type of plant
Describe the co-evolution of plants and pollinators
An animal evolves to get nectar more efficiently, the evolution of the animal allows plants to transfer pollen more easily
Describe the co-evolution of predators and prey
Predation is a strong selection pressure, the prey evolves through natural selection to have a better chance of survival, it also produces animals that have a less chance of survival which the predators make use of.
Describe the co-evolution of parasites and hosts
Hosts evolve to resist and tolerate parasitism, parasites evolve to be better at feeding, reproducing and transmitted to new hosts
What is the speed and metabolic cost of asexual reproduction
Metabolic costs are lower because it is based on the normal cell cycle and produces many identical offspring
The production of offspring is rapid because the process is simple and every member of the population can reproduce
What is the speed and metabolic cost of sexual reproduction
Metabolic costs are higher since gametes are made by a special type of cell division and many are infertile
Only females can reproduce so production is slower
What are the disadvantages of needing males in a population
Only half the offspring can reproduce which reduces efficiency
Combining 2 sets of DNA means only half of each set is passed on which disrupts successful parental genomes
What is the benefit of having males in a population
Allows for genome to increase in variation so organisms can continue to adapt
What types of vegetative cloning has evolved in plants
bulbs, corms, tubers, stolons, rhizomes
How do fungi and non-flowering plants asexually reproduce
Using spores
What is parthenogenesis
An animal process - can produce offspring asexually without males or fertilisation
How does parthenogenesis work
Hybridisation between sexual species and they use modified versions of meiosis to produce diploid eggs that develop into female clones
Where is parthenogenesis more likely to be found
Areas with lower parasitism - cooler climates disadvantageous to parasites and regions of low parasite density/diversity
What are conditions that favour asexual reproduction
Very narrow and stable niche.
Recolonising disturbed habitats - buttercups getting free ground before other plants colonise it.
What is the chromosome diploid number in humans
46
What is a homologous chromosome
A chromosome where each parent chromatid is the same size, has the same centromere position and the same genes in the same loci (location/region)
What is the difference between the chromatids in a homologous chromosome
The genes are in the same place, but the type of alleles they code for may be different
What is fertillisation
When the haploid nuclei of two gametes fuse together to form a new diploid nucleus
What does the combining of 2 haploid genomes ensure
Variation of alleles occurs
Describe the cell cycle of a cell undergoing meiosis
Interphase stages of a normal cell cycle, chromosomes duplicate in s-phase, the gamete mother cell then divides twice by meiosis (I and II)
What are the two mechanisms of meiosis I that ensure variation of genes
Crossing over
Independent assortment
Describe meiosis I
2 homologous chromosomes pair up and become aligned to form a bivalent
Chiasmata (crossovers) form between homologous pairs which allow the crossover of DNA sections
The nuclear membrane breaks down so microtubules can connect from centrosomes to the centromere (spindle fibres are made which align the chromosomes on the equator - independent assortment)
Microtubules shorten and pull chromosomes apart
A nuclear membrane forms and cytokinesis separates the cells
Describe meiosis II
Nuclear membrane breaks down of both cells
Microtubules align, then separate chromosomes, a nuclear membrane forms and cytokinesis separates the cells
4 genetically different cells have been produced
When does meiosis occur in human males
Once puberty starts and all haploid cells develop into sperm cells
When does meiosis occur in human females
After puberty, gamete mother cells at chiasmata stage of meiosis (from birth) divide during each menstrual cycle but only one will reach the chromosome alignment stage of meiosis II before stopping again.
Meiosis I division is asymmetric so the future ovum is larger than the other cell.
The future ovum only completes meiosis II after being penetrated by a sperm cell - the division is asymmetrical and the haploid nucleus of the larger cell fuses with the sperm.
What is independent assortment
Each pari of homologous chromosomes is positioned randomly with no dependance on the way any other pair is lined up.
It is irrespective of maternal/parental origin.
What is crossing over (homologous chromosomes)
Where DNA of the chromosomes are exchanged by chiasmata which allows new combinations of alleles - recombination
What are linked genes
Genes on homologous chromosomes that must be located
What is another way of genetic variation that isn’t independent assortment or crossing over
Fertilisation - the genetic material of 2 different gametes merges into one.
Where do chiasmata form
At random positions on the chromosomes
What is linkage mapping
A way of using the percentage of recombination to map the distance between genes - the further apart 2 genes are, the more likely a chiasmata will form between them and make a new allele
Describe the lifecycle of haploid organisms
Haploid cells produced by meiosis immediately undergo mitosis to form a haploid organism which produces gametes later by cell differentiation. These gametes take part in fertilisation to produce a diploid organism.
What determines the sex of a diploid animal
The chromosomes
What does diploid mean
The organism has 2 full sets of homologous chromosomes
What are the names of the sex chromosomes
X and Y
What are the sex chromosomes present in a female and a male
Female = XX Male = XY
Which process ensures there is a sex chromosome in each gamete
Meiosis
What is the term given to the female gamete which carries an X chromosome
Homogametic
What is the term given to the male gamete which can carry an X or a Y chromosome
Heterogametic
What causes an embryo to develop as a male
A single gene on the Y chromosome called SRY
How does SRY work
Triggers a cascade which activates all male developmental genes in the genome.
Why do sex linked patterns of inheritance occur
The X chromosome has many genes which do not have homologous alleles on the Y chromosome.
Why can males express a trait from a recessive allele
There is no allele on the Y chromosome to mask off the recessive allele.
How is there only a single working copy of the x chromosome genes in females
Most genes on one X chromosome are inactivated during early embryonic development
What is dosage compensation
A way of ensuring females having the same level of gene products as males and don’t get double the products
What is special about the males phenotype
It shows the effect of genes that are inherited on the X chromosome.
Whats special about a deleterious allele in a females X chromosome
It will less likely be affected because X chromosome inactivation is random and half of all cells will have a working copy of the gene
List environmental factors that can determine sex
Temperature
Size of organism
Competition
Parasitic infection
What is parental investment
The use of resources by a parent to benefit future or existing offspring
What is the benefit of parental investment
It can result in increased numbers of offspring and improves chance of survival
Increases evolutionary fitness
List examples of parental investment
Resources used for gamete production
Resources used to provide a safe place of fertilisation
Resources to protect and nurture offspring
Whats the difference between egg production and sperm production
There are far more sperm being produced
What is the term given to an organism fixed in one place
Sessile
How do sessile organisms reproduce
Asexually to form clonal colonies - self-pollination, synchronised spawning of gametes…
What is the difference between internal and external fertilisation
Internal:
Gametes are released into reproductive tract in female rather than into environment
Finding a mate increases risk of predation and parasitism
Fewer gametes need to be released as higher chance of success
Less gametes produced as there is less competition
What are r-selected organisms
Small species that produce many offspring, each of which has a low chance of survival. Suitable in unstable environments (r = rEpRoDuCtIvE)
What are k-selected organisms
Longer lived organisms subject to intra-specific competition for resources in a stable environment. Large parental investment and less offspring
What is polygamy
A reproductive strategy where each individual mates with several others eg: lekking
What is monogamy
A reproductive strategy where each individual shares gametes with only one individual eg: schistosoma
What does an increase in sexual selection lead to
Increase in evolutionary fitness
What is sexual dimorphism
Elaborate and intricate courtship displays
What does a sign stimulus lead to referring to ritualised courtship behaviours
Fixed action pattern response which is instinctive
What is mating choice influenced by
Imprinting early in life
What is imprinting
An irreversible developmental process that occurs during a critical time period in young animals
How does imprinting increase fitness
An attachment is formed with a parent which provides care and increases survival chances
How can imprinting influence mating
Offspring may select mates that resemble certain parent phenotypes
What is sexual dimorphism
The differences between characteristics between the two genders of the same species (other than sex organs).
What are typical differences referring to sexual dimorphism
Size and colour.
Males are usually more conspicuous.
What is reversed sexual dimorphism
When the female is larger/more brightly coloured (more conspicuous).
What does success in male-male rivalry lead to
Greater access of males to females
What determines success in male-male rivalry
Males which are stronger/have greater weaponry which are advantageous to offspring.
Males which act as sneakers which can resemble a female appearance to avoid rivalry altogether.
What is female choice
When females choose a mate based on the males honest signals - characteristics shown by males ie. good phenotype which indicates good genes and low parasite burden.
What is lekking
A communal displaying by groups of males which females go to to select a mate.
Ho are males successful in lekking
Larger dominant males win in aggressive encounters.
Satellite males intercept females at the periphery of the lek area.
What is the difference between isogamy and anisogamy
Isogamy = similar sized Anisogamy = differently sized
What is the difference between polygyny and polyandry
Polyandry = 1 female many males Polygyny = 1 male many females
