FINAL revision Flashcards
Independent Assortment
when genes segregate independently from each other
Epistasis
Genes that modify the phenotypic expression of others
Addition Rule
mutually exclusive outcomes
“either, or”
Multiplication rule
outcomes that can occur simultaneously, and the occurance of one has no effect on the likelihood of the other
“yellow and wrinkled”
Dominant
Trait that can be seen
Recessive
Trait that can’t be seen
Alleles
Different forms of a gene
Genotype
the particular combination of alleles present in an individual
Phenotype
the expression of the trait as described by the genotype
Incomplete Dominance
phenotype of heterozygous genotype is intermediate
eg red x white –> white
Meiosis I
homologous chromosomes separate form each other
Meiosis II
sister chromatids separate
Prophase
chromosomes condense
Prometaphase
spindles attach to kinetochores
Metaphase
chromosomes/chromatids align in the center
Anaphase
separation of chromosome/chromatids
X-linked genes
genes located along the X chromosome
Autosomal gene
affects males and females the same way
y-linked genes
genes that are present in the unique region of the Y chromosome
only males affected
Frequency of recombination
a measure of genetic distance between the genes
max=50%
Nondisjunction
the failure of a pair of chromosomes to separate during anaphase
First Division Nondisjunction
2 gametes with extra chromosomes; 2 gametes with missing chromosomes
Second Division Nondisjunction
2 normal gametes; 1 gamete with extra chromosome; 1 gamete with missing chromosome
Unbalanced Translocation
only part of a reciprocal translocation is inherited from one of the parents
Haplotype
Unique combination of nucleotides
Heritability
the proportion of the total variation in the trait that is due to genetic differences
Regression toward the Mean
offspring exhibit an average phenotype that is closer to the population mean than the phenotype of the parents
- environmental effects
- segregation and recombination break up genes of extreme phenotypes
Environmental Risk Factor
a characteristic in a person’s surroundings that increases the likelihood of developing a particular disease
Complex Traits
quantitative traits, affected by many genes
Short Term Carbon Cycle
marine/terrestrial photosynthesis and respiration
- photosynthesis is seasonal –> higher rates in summer, lower in winter
- follows trend in Northern Hemisphere
Long Term Carbon Cycle
Fossil fuels–> moves carbon from long-term to short-term cycle
Fluxes
The rate that carbon moves between reservoirs
Gene Pool
all the alleles present in all individuals in a species
Intrasexual selection
interactions between same sex
Intersexual
interactions between females and males
Genetic Drift
the random change in allele frequencies from generation to generation
- if population is small, genetic drift is large
Non-random mating
(effect on phenotype and alleles)
preferential mating according to genotypes
- phenotypes increase/decrease
- allele frequencies don’t change
Hardy Weinberg Equilibrium
p2 + 2pq + q2 = 1
when evolution doesn’t occur, allele and genotype frequencies don’t change
Hardy Weinberg Equilibrium Conditions
- No natural selection
- No migration / immigration
- No mutations
- Random mating
- Sufficiently large population to prevent sampling errors
Morphospecies
members of the same species usually look alike/ have similar DNA sequences
Ring Species
species with populations that are reproductively but not genetically isolated
Types of Reproductive Isolation
pre-zygotic
behavioral
gametic
mechanical
temporal/geography
post-zygotic
genetic incompatibility
Speciation
the development of reproductive isolation between populations
Allopatric populations
geographically separated populations
Dispersal
when individuals colonise a distant place
Vicariance
when a geographical barrier arises within a single population
Sympatric Populations
populations in same geographic location
- natural selection must strongly counteract the homogenising effect of gene flow
Co-speciation
when 2 groups of organisms speciate in response to each other at the same time
Monophyletic
all members share a single common ancestor not shared with any other species
Paraphyletic
some, bu not all of the descendants of a common ancestor
(two ‘cuts’ on the tree)
Polyphyletic
groupings that don’t include the last common ancestor of all members
Synapomorphies
evolutionary innovations that are shared by some members of a group
Analogous
similarities due to independent adaptation by different species (as opposed to homologous)
–> result of convergent evolution
Convergent Evolution
the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
Sister Groups
groups that are more closely related to each other than either of them is to any other group
Ectomycorrhizal Fungi
surround root cells
Endomycorrhizal Fungi
penetrates root cells
Cephalisation
concentration of nervous system at one end of the body
- bilaterians
- to encounter things in environment
Abiotic
organisms tend to be adapted to a specific range of physical conditions
Biotic
Interactions with other organisms
Interspecific competition
competition for resources between individuals from different species
Intraspecific competition
when individuals within a population compete for resources –> natural selection
r-strategists
organisms that produce large number of offspring without a lot of parental investment
k-strategists
organisms that produce few offspring but put in a lot of parental investment
Density-Dependent Factors
factors such as resource availability, predation, diseases etc
Density-Independent Factors
factors that influence population size without regard for population density eg drought, temperature, flood
Survivorshipt
the proportion of individuals from the initial cohort that survive to each successive stage of a life cycle
Type I
mortality occurs late in life
Type II
mortality is even throughout life
Type III
mortality is concentrated early in life
Metapopulation
a large population made up of smaller populations linkd by occasional movements of individuals between them
Facilitation
indirect interaction between 2 attacking species that benefits them both
Keystone Species
pivotal populations that support a community
Disturbances
severe physical impacts on habitats have effects on density independent populations
Succession
the process of species replacing each other in time
Symbiosis
close interactions between species that have evolved over long periods of time –> increases interdependence
Obligate
when one/both sides of a mutualism can’t survive without the other
Facultative
when one/both participants can survive without the other
–> reinforced by natural selection into obligate
Commensalism
one partner benefits with no apparent effect on the other
Fundamental Niche
the full range of climate conditions / food resources that permits the individuals in the species to live
- where species could live
Realised Niche
the actual range of habitats based on interactions with other species
–> the space species actually occupy
Competitive Exclusion
competition between 2 species prevents one from occupying a particular niche
–> leads to resource partitioning
Trophic levels
Tertiary consumer - 4
Secondary consumer - 3
Primary consumer - 2
Primary producer - 1
Endemic Species
species found in one place and nowhere else
Invasive Species
non-native species that become established in new ecosystems
Latitudinal diversity gradient
species diversity highest around equator, declines toward poles
–> spcies at high latitudes are adapted to a greater range of conditions
Movement of air
Hot air rises –> cools –> generates rainfall –> air dries, heads toward poles –> air cools then falls –> air warms and moves to equator, bringing moisture with it
