4.19-4.21 populations and conservation (not definitions) unit 2

describe the three types of adaptation

• anatomical - changes to physical features

• physiological - changes to bodily processes

• behavioural - changes to actions

what is the hardy weinburg equation used for

the hardy weinberg equation is used to determine whether there is a change in allele frequency over time in a population

what causes a change in allele frequencies over time

mutations in genes genes which cause natural selection can cause a change in allele frequencies over time as selectively advantageous alleles become more common

why does natural selection occur

• predation

• disease

• competition

all result in differential survival and reproduction

what is evolution

change in allele frequency in gene pool of a population , results in development of new dominant characteristics

how does natural selection lead to evolution

• random mutations results in new alleles

• some alleles provide an advantage, making an individual more likely to surivive and reproduce

• offspring receive the new allele & frequency increases over many generations , frequency of unfavourable alleles decreases

define speciation

when a population is split and reproductively isolated , there are different selective pressures on the two groups if the genetic makeup changes to the next extent the two groups can no longer interbreed , they have become separate species

what is meant by allopatric speciation

speciation resulting from a physical barrier e.g. river, mountain range the environments occupied by the two groups are different, and therefore different alleles are favoured

what is meant by sympatric speciation

speciation resulting from a non physical barrier e.g. a mutation that no longer allows two organisms to produce fertile offspring, any changes in anatomy or behaviour may also prevent breeding

describe what is meant by an endangered species

a species that due to a loss of habitat or rapid decrease in population numbers is at risk of extinction

describe how conservation can be acheived

• protection of habitats e.g. nature reserves , national parks , SSSIs

• protection of endangered species, e.g. making hunting illegal, breeding programmes increase population size

• international cooperation e.g. restricting trade of endangered species and their parts

• species reintroduction

• gene and sperm banks

• seed banks

why is the conservation of gene pools important

• many plant species are yet to be discovered and may contain chemicals that could be used in future medicines

• protection of potential future food sources

• some alleles may provide selection advantages preventing extinction

• each species and its genes precious

what are the advantages of in situ conservation methods

• the whole habitat and environment can be conserved rather than just a specific species

• organisms can interact with their natural environment and occupy their appropriate ecological niche

• more organisms can be conserved at the same time as there are less spatial restrictions

• it is typically cheaper to set up in situ conservation sites than ex situ conservation sites

what are the disadvantages of in situ conservation methods

• conservation may be harder as certain factors which were threatening the populations are likely to still be present

• it is often difficult to devote large portions of land to conservation where land is needed for growing populations

what are the advantages of ex situ conservation

• predation and natural threats to the population are eliminated

• some ex situ conservation sites can bring in money from tourism to help cover conservation costs

• ex situ conservation sites can be used for education

• close monitoring and scientific investigations are much easier as there are fewer uncontrolled variables

• the health of the organisms can be monitored closely and medical care can be given much more easily

what are the disadvantages of ex situ conservation methods

• reintroduction into their natural habitat may be difficult as the animals will not be used to the environment and may be less likely to survive

• genetic diversity will be significantly lowered in captive populations

• ex situ sites are expensive to establish and maintain

• animals may be behave differently which might make breeding programmes difficult