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Hello everybody! I am going to present to you a broad perspective on how XXXXX niche model has been used for understanding XXXXXXXXXXXXXXX regarding the effects of climate change on biodiversity and the distribution of species sorry for that well, the way that you model the distribution of species in one time and then in anothr time is very simple XXXXXXXXXX an exercise. you just need one set of variables for your time 1 and the same set of variables for a different time either to the future or to the past continent environmental conditions the you give your niche model and you calibrate calibrational time period which is in XXXXX one and the you project this model on the 2 environmental scenarios and produce the maps , one for the present time and one for the other alternative time then what you do is, you have here in the map say for the presence and then for the future or for the past and in GIS you overlay these 2 maps and what you get is a comparison of the ditributions of these 2 times so you can see and calculate the differences in the 2 areas and say which areas correspond an expansion XXXXXXXXXXXX XXXXXXXXXX from time 1 to time 2 so it is very simple in terms of the way it's working let's see how this has helped us to learn nor about the responses of species from XXXXXXXXXXX XXXXXX there are several ways in which species can respond to climatic changes and all of them have some XXXXXXX station at dstributional XXXXXXXXXXX so depending on genetic plasticity of species they me adapt different routes when they face climatic changes paleophysiology of genetics phenology is important in this XXXX adaptation in relation to the distribution of species imagine we have this hypothetical area of species in green means that environment is XXXXXXXXX and in blue means that it's occupied in that space before climatic change then comes the warming and cooling and this area becomes unsuitable which is indicated here in red but some areas might become XXXXX we here only put a XXXXXXX to make it more interesting well, if a species can adapt to the changes what we can expect here is that there won't be very important variations in terms of size and the position of the geographic matrix and actually if the species is able to disperse across this XXXXX it might expand to the new suitable areas well, when another strategy that species have followed to deal with climatic changes id by migrating or shifting XXXXXX there are elements from the past and elements in the present that species have moved in these climatic change heads that we are XXXXX actually this is a study that XXXXXXXXXXX did on the abundances of North American birds trends in the abundances of hundreds of species of American birds and we compared the distribution of abundances before and after the eighties and we XXXXX the document that XXXXXX have shifted basically north for most of the species this is an indication that species are shifting distributions we are going to look for shifts on the distribution itself in this case when we have the situation of migration but we would expect that the original former distribution would shift local extinction to the XXXXX here will XXX colonize in new areas so we would see a shift in the distribution and when adaptation or migration don't happen we would expect that species or the first population and species go extinct of course we have the extinction documentation for the species in the past for those who we have documentation of extinction of populations and species XXXXXX in this XXXXXXXX this is a very XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX they work in the extinction of several populations of XXXXXXXXXXXXXXX and they attribute these extinctions to climate change and of course this is the most famous phase of extinction XXXXXXX XXXXX due to climate change this is the golden talk in XXXXXXXXXXXXXXXXXXXXXXXXXXXX so we would expect from the distribution of XXXXXXXX is that first shrinking the distribution of species and if this trend continues we would expect a whole collapse on the event of the extinction of the species well, we have in the exercise of modern distribution of species in the phase of climate change we have to mix several conditions in order to make it in a XXXXXX first as we told you yesterday and before we need to use the same set of environmental variables in time 1 as well as in time 2 and we have to make sure that the variables we are using are informal for distribution of the species this is the case in which we use 9 variables and XXXXX here this is the present and this is the future we are using XXXXXXXXX of environmental variables we may know since models so it's very important that you pay attention to the information that you are using another important aspect here is that the species you are modelling in the present for example have to be in a very XXXXXXXXXXXX with the environment This means that species is XXXXX that field of the potential distribution XXXXXXXX actual distribution actually feeling of XXXXXXXXXXXXXXXXXX otherwise if you have a species with very narrow distribution with a broad niche distribution and you project that into the future you don't know if those changes are going to be well known for the species or not so next thing is that you have to produce reliable models for the present in order to be able to project into different times if you are not able to do models on the present conditions it makes no sense to project the models to XXXXXXXX because if the modelling present is wrong it's going to be even worse in different scenarios but what you conjugate from that analysis is just XXXXXXXX well there is a key assumption here when we work with XXXXX models in time, niches are basically static that's XXXXXXXXXXX assumption XXXXXXXXXX and in relatively fast processes of climatic change this is a safe assumption for many species basically for species with relatively slow XXXXXX rates but think of this, the ecological niche modelling approach is a static method we are like looking at one place or time and we are trying to model climatic processes in this case so that's an increasing limitation of this approach for this problem never the less it's probably the most popular approach for addressing climate change in such XXXXX

Video Details

Duration: 13 minutes and 57 seconds
Country: United States
Language: English
Views: 73
Posted by: townpeterson on Jul 12, 2013


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