ENM - CC2
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Now what kinds of topics can we address with niche modelling in the context of climate change
as we mentioned there are studies in which you look for forcasting ditributions
and in order to this you go back in time
there is an important difference between these two approaches
and it is as Richard mentioned for future we don't have any data to evaluate our resources
so what we get is only hypothesis of what can happen in the future
on the other hand when we project models back in time we have data to XXXX this information
so XXXXX we can get from one study and the other is very different
it's much more solid from the XXXX
we can learn more from looking at the past that we can gain from the future
so let me show you some examples of how these models have been used by different people including us
like the XXXXXXXXX once just to understand when you hind test the models
XXXXXXXXX the responses of the species to climatic change from the past
so in this, what is a part of my PhD dissertattion we modelled the distribution of 23 mammals
first we did models in the present and then on past conditions
and the reverse to see if the species here were, trcking there niches across space
or did they expand their distribution
or they XXXXX their distribution
the general sort of this is called the XXXXXXX from the 23 mammal species we were able to get data from
the last XXXXXXXXXXX and the present one, present in the last climatic change XXXXXX
is that for most of them we find a correspondence between model of distribution at present and in the past
with XXXXX rate from the present and the XXXXXXX rate from the past
this means that those species have been able to make changes in distribution of their niches
for XXXXXXXX 6 species results were not solid and for 5 species we find no correspondence between the model and the distributions
to the past and the present and these 5 species are large species but in pleistocene those species were not the biggest ones
because the megafauna were present, mammals and sabre-toothed tigers
so what XXXXXXXXXXX is that these medium sized species in present they are large species
found like XXXXX ecological reigns so they can have XXXXXXXXXXXXXXXXXXXXXXXXXX
so they can expand across the space
well these hand casting has been used also to find pleistocene XXXXXXXXXXXXX
they combine different approaches in this case phylogeographical techniques with geological modelling techniques and see
how the conclusions match
in terms of geographical position of refugia in the pleistocene
we have also used phylogeographic information to understand geographic processes and the combination of particular niche models
to see looking at the genetic patterns in a species and XXXXXX the genetic structure of populations between species
and then we compare that with phylo distributions we can get insight to geographic distributions like bottlenecks
XXXXXXXXXXXXX
one of the neatest works I have seen using ecological niche modelling for XXXXXX species is this one of XXXXXXXXXXXXXXXXXXXXXXXXX
to explore the two hypotheses behind mega fauna in this case the wooly mammoth
in one extreme of this XXXX is that mega fauna was driven extinct by human colonization
and the other extreme is the people that think the extinction was driven at the end of the pleistocene then XXXXXXXXXXX
so what XXXXXXXX his study was to model the distribution of man using fossil beds for different periods of time
in the last glacial maximum and in the last inter glcial to see if the distribution tended to shrink in one period and expand in the cold periods
in this XXXXX of the pleistocene
and what his result gave him is like here presents, the expansion of the first humans XXXXXXXXXXXX
so what he observed is that in warm periods the distribution of the mammals was reduced and expanded during the cold period
and in the last warming process 10000 years ago humans arrived at the very north of the continent
so XXXXXXXXXX that the debate between which of the 2 drivers might have been extinction XXXXXXXX
XXXXX combination of XXXXXXXXXXX populations were natural like this warming process
and humans came in this process and XXXXX the extinction
this is XXXXXXXX that you have in your XXXXXXXXXXXXX
then you have this other bulk of studies that project models to the future instead of going to the past
and in this case there are XXXXXXXXXXX thousands of papers on modelling one species with differnt aims at the end
this is one of the XXXXXX studies XXXXXXXXXXX in which they model XXXXXX in Mexico
species of mammals, birds and 4 families of XXXXXX
with the idea of taking XXXXX of here extinction turnovers XXXXXXXXX etc
then there are also a bunch of studies on XXXX projections to future
for conservation purposes like Richard mentioned
for his field of conservation planning
there have been efforts from different XXXXX on projecting the models to the future
to see for example XXXXXXXX protected areas XXXX are useful for future XXXXXXX distribution of XXXXXXXXX
and you can find all sorts of studies and projects into the future
there is a XXXXXXXXX in this part of the study which is called uncertainty
the problem with the models to the future is that we have several sources of uncertainty starting with
uncertainties of how the climate is going to be
we have the same situation with past that we don't have XXXX climatic models to the past
and no fine resolution models to the past
and also that the XXXXXXXXXXXXX has a lot of problems in terms of representation
in terms of geographic distributions of the species from the from the XXXXX backwards
in terms of dating
so one main isuue here is the uncertainty of climatic varients
it is like a common practise to run models on different climatic scenarios
there are hundreds of scenarios out there for the future
and much less for past and present
so you run models for several scenarios and XXXXXXXXXXXX XXXXXXXX there are techniques for sensing of these models
still what you didn't get is an analysis of the uncertainty associated with this type of XXXXX
there is also XXXXXXX certainty which Richard mentioned XXXXXXX in which we compared distribution of species of the south XXXXXXXXXXX
under the same XXXXXX we project niche model to the same scenarios using 9 different algorithms
and these are the results. you can see for some algorithms distribution would expand
and for others would collapse
but these studies XXXXXX was that the fate of the species depends on the XXXXXXXXXXXXXXXXXX
which is XXXXXXXXXXX and XXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXX so differently
when we project it to future conditions because that didnt happen for the current conditions
all these methods were XXXXXXXXXXXX and modelling the current distributions
the problem was in projecting the difference
and it has to do with how do each one of these XXXXXXXXXXXX deals with environmental combinations XXXXXX in the calibration
scenario
and we find them in the projected scenario
and you have no environments
some of the other readings would extrapolate some others good XXXXXX some others good XXXXXXXXX
so it does not take a different decision on how to manage these novel environments
so discusses the huge differences among them
and this is the problem. How can we know which of these algorithms is doing a good job
there is no way to do that for the future. we don't have data
but we are doing it in my lab with student of mine and Richard's
is that she developed environmental services XXXX of the 20th century
so we have XXXXX data for birds, herps and for mammals
for the beginning of the 20th century and all along the 20th century
so we are using historic data which is XXXX environmental levels to project on to current environmental XXXXXX
and through current occurence data which XXXXXXXXXXXXXX
and that way we can see that we can harvest like an idea which