All Lectures Flashcards
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Systematics
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Scientific discipline focused on classifying organisms and determining their evolutionary relationship
1
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Phylogeny
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The evolutionary history of species/group of related species
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Molecular systematics
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Scientists specialising in systematics look at DNA/genome to discover which species are closely related
3
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Fossil Record
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Each layer of strata represents a period of time (the deeper the strata, the older the fossil) these strata show fossils from each period which can give an insight as to which species went through which evolutions. Also species that are now extinct.
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Analogy
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Similarities between species that occur through convergent evolution
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Convergent evolution
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Two entirely unrelated species evolving into very similar looking species, species in similar environments and niches are often forced to come to the same evolutionary conclusion
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Homoplasies
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Similar molecular sequence/structure between two unrelated species that has evolved independently
7
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Binomial
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Two part name, always Latin, always italics. Consists of Genus and specific epithet. Also called binomen
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Hierarchical classification
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Groups species into increasingly broader taxonomic categories
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
9
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Domains of Life
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Archaea - prokaryotic, lives in extremes
Bacteria - prokaryotic
Eukaryotic - includes kingdom plantae, fungi, protists and animalia
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Taxon
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A named taxonomic unit at any level of classification e.g fungi, mammalia, loxodonta etc
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Clade
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Group of species that includes an ancestral species and ALL of its descendants
Also known as a monophyletic group
Paraphyletic group is an ancestral species with some of its descendants
Polyphyletic groups don’t share the same ancestor
Cladistics (type of systematics) is the study of clades
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Shared derived character
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Evolutionary novelty that is exclusive to one clade e.g mammal fur
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Shared ancestral/primitive character
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A character shared by members of a particular clade that originated from an ancestor that is not a part of the clade
E.g eyes, backbone
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Outgroup
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A species from an evolutionary lineage that diverged before the lineage of a group of related species being studied. Closely related to the group but not as close as the group members to each other
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Phylogram
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Tree of branches that show how many DNA or RNA changes a have taken place in lineage. The longer the branch, the more changes that have occurred. Regardless of the branch lengths, all lineages have survived the same amount of time.
16
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Orthologous and Paralogous
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Orthologous - Homologous genes are found in different species from speciation
Paralogous - homologous genes that are found in different genomes of an organism through gene duplication
17
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Homologous
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Shared characteristics through shared ancestry
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Molecular Clock
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A method for estimating how long certain evolutions take based on observations that some regions of genomes evolve at different rates
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Evolution
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Decent with modification, the idea that all species descended from ancestral species with different characteristics
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Natural theology
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In 1700s natural theology viewed adaptation as evidence the creator had designed every species for a purpose
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Taxonomy
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Naming and putting all species into classes of increasingly complex hierarchies
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Catastophism
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Theory that instead of evolution, species in each strata were killed off from catastrophe rather than evolved into new species
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Gradualism
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Geological changes. Slow but continuous identical processes over a long period of time. E.g canyon carved from water
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Uniformitarianism
Theory that geological processes have not changed throughout earths history
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Descent with modification
Darwins way of avoiding the word evolution
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Adaptations
Inherited characteristics that enhance an organisms survival and reproduction in a specific environment
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Population genetics
Study of how populations change genetically over time
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Modern synthesis
A comprehensive theory of evolution, shaping future ideas of how populations evolve
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Gene pool
The total aggregate of genes in a population at one time
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Hardy Weinberg theory and Equation
Describes the gene pool of a non changing population.
Non changing means no genetic drift(big population) no gene flow, no mutation, no natural selection and random mating
Equation helps determine the frequencies of alleles in a population.
p + q = 1
Once we know the frequency of alleles we can work out the frequency of genotype
p^2 + 2pq + q^2 = 1
Once calculating is finished, a punnet square can be used to confirm.
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Genetic drift
Random fluctuations in gene frequencies in a gene pool due to a small population
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Mutation
A change in the nucleotide sequence of an organisms DNA by insertion, deletion and substitution
Somatic mutations aren't passed on
Gamate mutations are passed on
Only mutations that cause a change in the protein it codes for will result in a change
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Bottleneck effect
When a population comes back from the brink of extinction the amount of genes in the gene pool for future generations to have is severely reduced giving the future populations very little genetic diversity
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Gene flow
When genes from other populations enter the gene pool, due to migration or overlapping populations
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Directional selection
When natural selection selects for one extreme e.g smaller. Usually due to an environment change
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Disruptive selection
Selects for traits on either side of the norm, often leads to speciation.
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Stabilising Selection
Selects for the norm by removing extreme variants. Due to population genes being ideal for current unchanging environment
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Development
Evolutionary formation of a novelty over time e.g eyes
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Macroevolution
Evolutionary change above the species level
| E.g origin of a new group through speciation events or impact of mass extinction on the diversity of life
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Exaptation
A shift in the function of a particular trait during evolution
E.g bi pedal evolution frees up from legs for using tools rather than walking
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Current utility
The way a species utilises its current traits.
Evolution improves the way a a trait is used (current utility) it will not evolve to anticipate its future utility
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Heterochrony
Evolution differences in developmental rates, leads to big phenotypic differences
E.g humans and chimpanzee skulls, during foetal development parts of the chimps skull grow much faster than humans while other parts are slower, this results in very different looks in two very similar species
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Allometry/allometric growth
The study of how different organs/parts of an organism grow and develop at different rates and times. Leading to different proportions and shapes throughout the organisms life
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Paedomorphosis
A type of hetrochrony where reproductive development occurs at a different rate as somatic development
E.g salamanders retaining their juvenile gills even at sexual maturity
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Microevolution
Minor changes in a species, changes in allele frequencies. All changes below the species level
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Homeotic genes
Determine basic features like where wings and legs will develop on a bird
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Species selection
Like natural selection but instead of affecting populations it affects species group, the species that can disperse further, have more daughter species has a greater effect on the direction of the future evolutionary trends.
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Function
The purpose of a certain evolutionary trait
| E.g jaw of a hyena determines that the purpose of hyenas is to scavenge meat
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Behavioural ecology
The study of the ecological and evolutionary basis for animal behaviour
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Fixed action pattern (FAP)
A sequence of unrelated acts linked to a simple stimulus
E.g stickleback males have red bellies and attack other males, the red on the belly lets them know there's a threat. However anything red e.g a truck will trigger aggression - the fixed response towards red.
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Behaviour
An action carried out by muscles controlled by the nervous system
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Proximate questions
1. What stimulus elicits the behaviour and what physiological mechanisms mediate the response
2. How does the animals experience during growth influence the response
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Ultimate questions
1. How does the behaviour aid survival and reproduction
| 2. What is the behaviours evolutionary history
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Ethology
Studying animal behaviours with scientific and objective study
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Sign stimulus
An external sensory cue that triggers a fixed action pattern response
E.g red for stickleback fish
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Imprinting
Establishing a long lasting behavioural response to a particular individual or object
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Sensitive period
The time period at the beginning of an animals life that imprinting can occur
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Innate behaviour
All individuals in a population behave alike
E.g fixed action pattern, courtship/response, and pheromone signalling
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Kinesis
Non directional reaction to external stimulus
E.g wood louse slowing down due to humidity
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Signal
A stimulus transferred from one organism to another
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Communication
Transmission and reception of signals between animals
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Pheromones
Animals that communicate through odours and tastes emit chemical substances called pheromones
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Habituation
Animal stops responding to stimulus after being exposed to stimulus many times
E.g animal learn a loud noise has no negative consequence so stops reacting to it
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Spatial learning
Establishment of a memory that reflects an environment
E.g wasps knowing which nest is theirs among many other by natural landmarks
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Cognitive map
A representation in an animals nervous system of the spatial relation between objects and its surrounds
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Associative learning
The ability to associate one environment feature with another
E.g birds associating a colour with a bad taste, knowing green berries don't taste as good as red
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Classical conditioning
False stimulus becomes associated with a particular outcome
E.g ringing a bell before a dog gets fed, the dog eventually starts salivating anytime a bell rings, even when no food is present.
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Operant Learning
Animal learns to associate one of its behaviours with a reward or punishment
E.g bird learning not to eat monarch butterflies after vomiting
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Cognitive ethology
Studying how animals think
70
Maximum Parsimony
When constructing phylogenetic trees the one with the least evolutionary changes is the most parsimonious. This maximises parsimony
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Artificial selection
Humans have selectively bred certain species for certain traits over many generations to create very different phenotypes
E.g selecting traits from wild mustard to create broccoli, cauliflower, cabbage, Brussel sprouts, kale and kohlrabi
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Comparative embryology
Anatomical homologises in embryo not visible in adults organisms
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Vestigial Structure
Remnants of features that served important functions
Eg kiwi wings
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Introns and exons
Introns - non coding segments of DNA
Exons - regions retained in MRNA after RNA processing
Mutations can occur in both however only mutations in the exons will end up in the gene pool
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Founder effect
A few individuals who do not reflect their gene pool, start a new population. The new population has a very different (small) gene pool from the parent population
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Sexual recombination
Half of each parents Genes are combined and rearranged forming an offspring with a gene combination that has never existed before
Three mechanisms
- crossing over
- independent assortment of chromosomes
- fertilisation
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Relative fitness
How well adapted one organism is prepared for the environment compared to another, higher fitness (better adapted) will live longer, reproduce more and their genes will be present at a higher rate in future gene pools
Can also be decide through combat/mating displays
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Allele
Genes with alternative versions that produce a phenotypic effect
E.g eye colour
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Gene
Unit of hereditary information, consisting of a specific nucleotide sequence in DNA (or RNA in some viruses)
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Locus (loci - plural)
Specific place along the length of a chromosome where a given gene is located
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Chromosome
Cellular structure carrying genetic material, found in Nucleus. Consists of on very long DNA molecule and associated proteins
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Point mutation
Change of one base in a gene
E.g C-T, becoming G-A
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Silent mutation
Causes no protein effect therefore has no effect on anything
84
Heterozygote Advantage
Describes the case in which Heterozygote genotype has a higher relative fitness than a homozygote dominant or recessive genotype
E.g people heterozygous for sickle cell disease are immune to malaria and do not suffer the disease, however homozygous individuals for sickle cell disease suffer sickle cell disease.
85
Natural selection
Individuals equipped to survive to maturity and reproduce will pass on their genes, the fact they have reached maturity and have reproduced means their genes are likely well suited for the environment, whereas individual with less ideal genes may not survive and therefore their less ideal genes aren't as highly represented in the gene pool/leave the gene pool in future generations
Adaptive evolution
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Sexual selection
Natural selection for mating success
Can result in sexual dimorphism- marked differences between the sexes in secondary sexual characteristics
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Intrasexual selection
Competition between sexes (often makes) for mating rights
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Intersexual selection
Individuals of one sex (usually females) are choosey in selecting their mates.
Selects for ornamentation, bright colours, extravagant courtship, complex songs
Good gene hypothesis suggests if a trait is related to male health, both the male trait and female preference for the trait should increase in frequency
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Speciation and types
A species evolving into two separate species
- allopatric speciation occurs through isolation of population
- sympatric speciation occurs within a population (maybe due to disruptive selection)
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Punctuated equilibrium
One species splits into two species, often from a major environmental change, the two species remain the same
91
Gradualism model
Common ancestor gradually diverges into two very different species
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Adaptationism
A set of methods in the evolutionary sciences for distinguishing the products of adaptation from the traits that arise through other processes
E.g adaptation = umbilical cord, trait = belly button
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Adaptive radiation
Common ancestor diversified into many species over many environmental opportunities
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Adaptive radiation
Common ancestor diversified into many species over many environmental opportunities
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Cross fostering
Exchanging young between different species nests to decide what behaviours are nature and nature
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Social Learning
Learning an exercise off other in population - roots of culture
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Culture
A system of information transfer through social learning or teaching that influences behaviour of individuals in a population.
98
Optimal foraging
Using the least amount of energy as possible in order to feed eg drop height of molluscs for crows
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Mating system
Promiscuity - no strong pair bonds
Monogamy - prolonged pair bond
Polygyny - one male with multiple females (often sexually dimorphic
Polyandry - one female with multiple males (females more showy)
Polygamous - having more than one partner
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Foraging
Searching for food in the wild. Reflects animals fitness as finding food is key to survival
101
Altruism
Selflessness in the welfare of others. Eg helping others get a mate, grooming others
102
Inclusive fitness
An organisms success is based on the altruistic behaviour of the population
103
Coefficient of relatedness
Probability that two relatives share the same genes
104
Hamiltons rule
Natural selection favours altruism when the benefit to the recipient multiplied by the coefficient of relatedness exceeds the cost to the altruist
rB>C
B benefit
r coefficient of relatedness
C the cost to the altruist
105
Kin selection
Natural selection that favours altruistic behaviour by enhancing reproductive success of relatives
106
Reciprocal altruism
Altruism towards unrelated, requires reciprocation eg grooming
107
Game theory
Alternative behavioural strategies where outcome depends on all individuals involved.
108
Mark recapture model
Capturing a group (100) of animals from an area, mark them, release them, then repeat.
```
N = total number of individuals in a population
n = total number captured
m = total number marked
x = ratio of marked
```
```
x/n = m/N
N = mn/x
```
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Mate choice copying
Individuals in a population are influenced by the mate choice of others
110
Population ecology
The study of populations in relation to their environment
Eg environmental influences on population density and distribution, age structure and variations in population size
111
Density
The number of individuals per unit, area or volume
112
Dispersion
The pattern of spacing among individuals within the boundaries of a population
Clumped
Uniform
Random
113
Territoriality
Being aggressive about a territory, leading to a uniform dispersion
114
Life table
Tracks individual from birth and records how many make it through each year of their life until all a dead. Shows death rates, life expectancies and proportions alive each year in both sexes
115
Survivorship curve
Track the number of deaths in a population at each age,
some populations have a rapid decline at birth-1 year and then the remaining few who make it live for a long time e.g oysters
Some have consistent rates of death throughout all ages e.g animals who are preyed on
Some (like humans) tend to live until old age and then have a big drop off due to age related deaths
116
Population growth (exponential, logistic)
Population growth rate is birth - deaths (exclude immigration and emigration (equal birth and death numbers is zero population growth)
Exponential growth Occurs when a population grows under idealised conditions
Under these conditions the rate of reproduction is at its maximum
Called intrinsic rate of increase
dN/dAt=rmaxN
N population size
t time
r per capita growth rate
When a growing population becomes too large for its environment it will either stop growing and remain at carrying capacity or will grow too much, experience large death rates and then return to carrying capacity. Logistical growth model takes carrying capacity (K) into account.
Logistic model starts with exponential growth and then begins to slow as K is approaching.
dN/dt=rmaxN (K-N)/K
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Life history traits
Life histories are selected for, populations that need to grow will select for individuals who have larger clutches of small offspring(r selection), whereas populations that are at carrying capacity select for larger offspring and smaller clutches (K selection)
r and K referring to per capita and carry capacity growth
