lecture 24 Flashcards
what is the positive of biocides which combat pest, insect, weed, pathogens, bacteria, tumour, viruses?
good in short term, relieves us of pests, pathogens, relieves agricultural field of competitive weeds, insects, antiobiotics relieve bacterial infenction
what are the downsides of biocides?
we’re creating enormously strong pressure for resistance
selection imposed by biocides/chemicals kill the majority of individuals, having any resistance wld provide huge fitness advantage and so is strongly selected for
why is designing evolution proof biocide important for agriculture?
weeds cause 1/3+ loss of crop yields anually
if we care abt food security, needing to feed more ppl as pop grows and airable land stays constant, then yield loss cld become a problem
if we cld get more yield out of same problem we cld address food security, enviromental security issues, also save lots of money
how does mating system affect herbicide resistance?
outcrossing weeds have more unique preexisting resistance variation than selfing weeds,
what are three possible ways for plants to become resistant to herbicide?
preexisting genetic variation for herbicide resistance, new mutations arising, resistance to herbicide came from elsewhere/epidemic spread
what are two methods which could combat herbicide resistance?
multi-herbicide treatment might make adpation less likely as more complex adaptions must happen for mutants to be resistant to both herbicides at once, if herbicides are targeting diff componenets of biology/diff enzymic pathways of weed than this will be very unlikely
rotating herbicides regularly cld keep resistant alleles which help weed detoxify any one herbicide from getting too high in frequency, downside means cld select for general resistance which makes weed resistant to mutiple herbicides at once
what are two methods which could evolution-proof insecticide for mosquitos be created?
rough idea is to change timing of when insecticide is sprayed, if mosquitos are targeted later in life then number of mosquito /mosquito density will be reduced which wld reduce malaria transmission and if the mosquitos are later in live/have alrdy reproduced natural selection for resistance might be minimized (read)
an alternative approach (mideo) is using less agressive drug treatment, we cld lower evolution of resistance which leads to reduced infectioness of malaria
what are two methods can drug resistance be combatted against?
multi-drug cocktails which hiv patients take slow evolution of hiv resistance to these cocktails, dramatically reduces retrovirus load, multi-drug cocktails target diff componenets of hiv virus and each independantly inhibit its replication and so its unlikely for any indivdual viral particle to be resistant all drugs of anti-retroviral cocktail
if there is cost of resistance, we can cycle drugs to prevent takeover of resistant strains
this is manageable in situations where we know something abt the particular viral/load of whats making the person ill at that time and so requires monitoring
stop taking drugs only works if there is a cost of resistance which makes non-resistant forms more prevalent when drug aren’t taken
if there’s no cost of resistance mutiple drugs might be cycled through in the same way
why is there a genetic diversity issue in conservation biology?
genetic issues in conservation biology, population decreasing lead to loss of genetic diversity which increases genetic drift and inbreeding
there will be loss of heterozygosity and inbreeding causes inbreeding depression
fixation of deletrious alleles do to strong effect of genetic drift on small pop, lower overall demographic output of pop
overall genetic loss might mean pops are unable to further adapt in future
what point are conservationists hoping endangered animals will reach?
he hope is that the population will finish demographic decline and evolve and reach evolutionary rescue and pop size will recover which will maintain these species
what is the mutation rate and how does it relate to the probability a species will adapt to environmental changes?
input of new mutations to pop which is related to number of individuals and mutation rate
higher combined probability of number of individuals and mutations, more new variation entering pop to potentially fueld ability to adapt to enviromental change
what is the mutation rate and how does it relate to the probability a species will adapt to environmental changes?
input of new mutations to pop which is related to number of individuals and mutation rate
higher combined probability of number of individuals and mutations, more new variation entering pop to potentially fueld ability to adapt to enviromental change
what is wild type fitness?
how much fitness has been reduced compared to what it had been before the environmental change occurred
what is wild type fitness?
how much fitness has been reduced compared to what it had been before the environmental change occurred
what 3 factors contribute to a species likelyhood to adapt to environmental changes?
probability species will evolve irself out of a problem is combo of pop size, number of mutations, strength of selection/how much fitness was reduces
