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the response of bird populations to habitat loss - Coggle Diagram

- - - - sutherland and dolman use a extened population model, which is quite complex as it has many factors inbeded ( such as mortality, productivity, forgaiging, game theory, to name a few) to simulation the impact of environmental change on bird pops that use breeding and wintering sites within the game geographical region with regular migration patterns.
        
        we learning how complex predicting future populations is, as the same geogrpahical breeding populations may winter in the the same or spereate area - with or without individuals from other populations. moreover, some individuals in a single population will apart or other at different ages or sex possibly interlinking surivals rates, population size and migration patterns
        
        they run a hypotheical system where they remove 75% of a wintering area, they found that not only did it reduce the size of the breeding population which frequentied it but there was also a knock on effect in other popuations, purhaps becuase increase cometion in displaced individuals increased winter mortality
        
        the next model is to analyse if migration stratgies can respond in fact to selection, incoping allele freq. and assosative mating, as various studies show factors like obligation, freq of partial migration, time, length, and orientation of migration are influenced by genetics
        
        in the model there were two populations A & B, A wintered at site 1 and occasionally at site 2, where B only wintered at site two. They found that if the recevive allele in pop A for mating at site 2 was high or low as well as the population partipated in assocative breeding the pop would not collape but if there was no associate breeding and low receive allele freq. there could be potential extinction
        
        again there is a vast deal of complexity in predicting how habitat loss will effect the population size of birds, what I found most intresting about this study was the importance of assositaive mating on the sucess of the species rapidly adapting their mating stratgey to tract the changing envrionment. this has led me to my next article pertaining to the blackcaps and their shifting migration.
- - - - possible of complete female breeding exclusion due to cumulative buffer effect
        
        effected by population density on individual fecundity/ breeding freq. & nest predation
      - buffer effect - as increase in pop density the greater the proportion of invidoivduls breeding in less productive territories increases diepersing avg of individuals per community
      - density in-dependent mortality
        
        winter mortality - concentrated within severe weather as individual may not be able to have adequate nutrition
        
        greater effect on indivi. of lower fitness
        
        predation mortality
        
        diffrences in indivi. vulnerability via differneces in fitness to density -dependent competion during foraging
      - survival in wintering
        
        modeled by dynamics of competing indivdi. foraging in a patchy environment
        
        the higher density the patch the greater competion therefore this is considred for the ditribution and intake rate of a wintering pop in respect the diffrent indivduals fitness using a game theory approch
      - lvl of mortailiy determined by assuming indiv. have min intake requiremnet
        
        therefore pop size can be realted to beh. measure like depletion, degree of interference, the variation in coeetive ability and strength of density depednce in the breeding ground
- - - - diff.breeding pops. may winter in sperate regions, or may winter togeather with other species -- iterlinking the surival rate with te size and migratory patterns of not only their species but purhaps other species they share time with. dynamic of sperate breeding populations while diff breeding pops may winter tgeather
        
        increased complexity if dif. individuals in single pop winter in dif. regions ( partial migration) and differntial migration - dif. ages and sex in same pop migrate to dif. areas
        
        accounts for all of these completixies by using forgaing compent to model dynamics within ea. wintering area
        
        desity dependent breeding concidered seperatly
        
        game theroy to determine evolutionary stable migration strategies + pop size of migratory pop by considering migration costs and the relative survials rates of dif. statgeies within each pop
        
        we learning how complex predicting future populations is, as the same geogrpahical breeding populations may winter in the the same or spereate area - with or without individuals from other populations. moreover, some individuals in a single population will apart or other at different ages or sex.
        
        it is therefore possible to have a hypotheical system of breeding pops and wintering sites and to remove 75% of witnering area and then re-run simulation - to see new suite of ptimal migration starts and new pop size
        
        in addtion to reducing size of breeding pop that winteried in that area -- knock on effect in other pops (reduction in breeding pop) via increased compettion with displaced indivudal --- may lead to increaced winter mortaitly --> therefore reduced breeding populations in pops that did not winter in effected area
        
        they run a hypotheical system where they remove 75% of a wintering area, they found that not only did it reduce the size of the breeding population which frequentied it but there was also a knock on effect in other popuations, purhaps becuase increase cometion in displaced individuals increased winter mortality
- - - - simulation of two pops A and B - where A winters in site one primararly and 2 occsonally - pop B only in area 2
        
        migration of pop A is determined by single locus w. 2 alleles, where site 2 reps recessive allele
        
        A will decline with loss the primary wintering site with respect to its shift in migration strategy to winter at site 2
        
        in their model area 1 disp. over 100 yrs
        
        if assortive mating occurs where birds wintering at diffrening locations return to breeding sites at diffrent times for example if pop A breeding at site 2 retunrted earlier to breeding site protenallt increaing the recesive allele
        
        assortive mating in both high freq. receive allele (10%) and low feq. allele save pop from collape howevver without assoritve mating pop A remains dependent on site A and declines to low lvls valnerable to stoacstic extinction
        
        in the model there were two populations A & B, A wintered at site 1 and occasionally at site 2, where B only wintered at site two. They found that if the recevive allele in pop A for mating at site 2 was high or low as well as the population partipated in assocative breeding the pop would not collape but if there was no associate breeding and low receive allele freq. there could be potential extinction
    - - how a pop alters migration strat crucial - as results show it depends on natural history, genetic varaition and assortative mating, allowing migration stat to track the changing envrionment
        
        assosiative mating: the blackcap in the last 30 years have increainly migrated from the southwest to the north west to witner in brtian, as assortative mating caused the black caps wintering in britian to return 10 days earlier to breeding gorund resulting in increase for allele freq.
        
        how many species may not partcipate in associatve mating as well as the completxity of factors interwining that produce the migratory behaviour it is still difficult to make predictions, and quiety glommly the author adds may be that many species will fail to repsond to global climate change.
        
        again there is a vast deal of complexity in predicting how habitat loss will effect the population size of birds, what I found most intresting about this study was the importance of assositaive mating on the sucess of the species rapidly adapting their mating stratgey to tract the changing envrionment. this has led me to my next article pertaining to the blackcaps and their shifting migration.