classification and biodiversity Flashcards
phylogeny
study of evolutionary history of a group of organisms
all organisms evolved from shared common ancestors
tree shows relationships
first branch shows common ancestor of all family members
closely related species diverged most recently
what is taxonomy?
study of classification
naming organisms and organising them into groups
takes into account phylogeny (evolutionary relationships)
easier to identify and study them
what is meant by a hierarchy?
larger groups contain smaller groups
with no overlap
how is taxonomy done?
levels of groups (taxon) used to classify organisms
arranged into hierarchy with largest groups at top
- only belong to one group at each level, no overlap
highest = domain - eukarya, bacteria and archaea
as move down
- more groups but fewer organisms in each
- more closely related
8 taxa
domain
kingdom
phylum
class
order
family
genus
species
binomial naming system (+ use)
genus name (capital letter)
species name (lower case)
written in italics or underlined
all organisms given one internationally accepted scientific name in latin
- avoid confusion of common names
what is courtship behaviour?
carried out by organisms to attract a mate of the same species
results in reproduction
species specific - only members of same species will do and respond to that behaviour
- more closely related = more similar
means it can be used to classify organisms
allows species recognition and prevent interbreeding
= reproduction more successful = fertile offspring
technologies used for classifying evolutionary relationships
used to be done by observable characteristics now based of DNA sequences
- genome sequencing
- immunology
how can genome sequencing be used to classify organisms
base sequences on DNA
base sequence of mRNA
amino acid sequence
more similar = more closely related
those less closely related have had time to introduce mutations into DNA, making it less similar
how can immunology be used to classify evolutionary relationships?
immunological comparisons
- similar proteins = similar shape so bind to same antibodies
- antibodies for a human protein will bind more to a closely related organisms proteins as they have more similar shapes
more antigen antibodies complexes (more binding) = more closely related
how can proteins be analysed to determine genetic relationships?
proteins made from amino acid sequence
sequence determined by DNA base sequence
so more similar proteins = more similar DNA, so more closely related
what is biodiversity?
variety of living organisms in an area
high = lots of different species
measured by
- species richness (doesn’t consider population sizes)
- index of diversity
what is a community?
all the populations of different species in a habitat
difference between species richness and index of diversity
both show the number of different species in a community
index also shows the population sizes of each species
what is species richness?
measure of the number of different species in a community
take random sample
count number of different species
simple measure of biodiversity
- doesn’t take into account number of individuals in each species
index of diversity
shows relationship between number of species in a community and the number of individuals in each species
N = total number of organisms of all species
n = total number of organisms of each species
why are ecosystem with a high index of diversity more stable?
have a higher number of species in a community, and are equally sized species populations
more resilient to environmental changes
ways agriculture is made more productive
removing hedgerows = bigger fields
monoculture = cans specialise
fertilisers and pesticides increase yields
how does agriculture reduce biodiversity? (5)
woodland clearance
- increase area of farmland
- reduces number of trees
- removes habitats so less species
hedgerow removal
- increase area by making small fields into larger ones
- removes plants
- removes habitats so reduces species
pesticides
- directly kills pests
- species that feed on pests loose food source, die
herbicides
- reduces plant species (weeds)
- and species that feed on them
monoculture
- reduce variety of species
- supports fewer organisms (less food source)
balancing agriculture and conservation
conservation aims to protect biodiversity
eg legal protection to endangered species
protected areas
ways of measuring genetic diversity
- frequency of observable characteristics
- base sequence of DNA
- base sequence of mRNA (amino acids)
- proteins coded for by DNA and mRNA
what is genetic diversity?
number of different alleles of genes in a population
increased by:
- mutations
- gene flow (introduction of alleles by migration and breeding)
what can affect allele frequency in a population?
natural selection
founder effect
genetic bottleneck
genetic drift (chance)
genetic bottleneck
event that causes big reduction in a population
reduces number of alleles in gene pool
so reduces genetic diversity
survivors reproduce and large population created from few individuals
with reduced genetic diversity (fewer alleles)
(founder effect)
founder effect
when a few organisms from a population start a new colony
- only a small number of different alleles in the initial gene pool
frequency of alleles change
may be more but less variety of different alleles
- can increase genetic disease if with a mutated allele
occur due to:
- migration (leading to geographical isolation)
- genetic bottleneck
natural selection
changes allele frequency overtime
increases advantageous alleles in a population
= organisms more adapted
- individuals with beneficial allele (better adapted to selection pressures) more likely to survive and reproduce
- genes and beneficial allele passed on
- greater proportion of next generation inherit allele
- they are also more likely to survive and reproduce
frequency of beneficial allele increases from generation to generation
(beneficial allele from a random mutation, if harmful, dies out as organisms die)
adaptations due to natural selection
behavioural - way an organism acts
eg basking in sun to keep warm
psychological - processes within an organism
eg hibernation
anatomical - structural features of an organism
eg camouflage
leads to evolution as organisms become better adapted to their environment
have increased chance of survival
ways of studying genetic diversity
observable characteristics
- less reliable, only infer relationships
base sequence of DNA
- abstract from nucleus
base sequence of mRNA
- easier as abstracted from cytoplasm
- create complementary strand (DNA sequence)
amino acid sequence
- easier to obtain proteins than DNA
- proteins evolve much slower, more likely to be similar to ancestors
more similar = more closely related
directional selection
individuals with alleles for extreme characteristics more likely to survive and reproduce
could be in response to environmental changes
eg antibiotic resistance
those with resistance allele survive, passed on, increased number with resistance allele
stabilising selection
individuals with characteristics towards middle of range more likely to survive and reproduce
occurs when environment isn’t changing - reduces range of phenotypes
eg human birth weights
those with mid weights more likely to survive, range smaller
why is there variation between and within species?
variation between species as they have different genes
variation within species as they have different alleles
or face different selection pressures in the environment
random vs systematic sampling
random
- points chosen by chance (eg grid and using random number generator)
- avoids bias
systematic
- chose areas to sample
- bias, could chose areas with less or more species
- creates unrepresentative sample
calculating % cover
count number of squares in quadrat with species
each square = 1%
calculating abundance of species
count number of quadrats with species
number with species / number of quadrats
eg 3/10 = 30%
what is a gene pool
complete range of allele in a population
