Lecture 1 - Conservation Biogeography, automated transcript
May 28, 2021
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Hi there. So this is the first of three lectures, looking at Tropical biodiversity.
So these teaching materials were originally designed for the type project focusing
on participants in my own mom, so obviously it was very relevant for them to have
some sessions on tropical, biodiversity as their country forms. Part of that, however,
regardless of where you're from is important as a student of the environment.
Aunt and of conservation ecology Evolution, any of these things to have an understanding
of the biodiversity that is found in the tropics and there's many reasons for this,
but one of the most important is that it's the most bio diverse region of the world.
So potentially over two-thirds of all species have been described originated in
rainforest. So just one of the ecosystems that makes up the tropical biosphere.
But to start with, we're not going to directly focus on the tropics. We're going
to start with cover conservation biogeography. So we're going to try and explain
why different ecosystems occur in different places and used by Drew biogeographic
principles. And to look at why, why the tropics are so by diverse and what that
means for conservation and and other fields.
Fields that we look at and in these courses. So this is a slide that comes up in
the introductory lectures as well looking at biodiversity and human impacts in the
natural world. So the of the foundational premise of biogeography is that biodiversity
is not equally distributed around the world and we don't find the same species everywhere.
So some biomes are more diverse than others. So, as we can see here tropical
In forests cover, only around 7% of the world's surface but I home to over half
of terrestrial species, including invertebrates vascular plants. So I said 2/3,
a second ago, so estimates vary depending on the data are using and the sure you're
looking at but there is a vast kind of concentration of biodiversity in those ecosystems
relative to the area. So why does that occur? And why is it important
So by geography, is the study of the distribution of organisms. I'm just organisms,
as we said in the introductory lectures, and lots of the other lectures, you'll
come across in this course, I genetic diversity is also it's not only part of biodiversity,
but it's vital to consider in lots of these things. So distribution of organisms,
and ethnic diversity across the surface of the Earth in space and time. So, as we
say, the very start of the three instructor lectures, all the life that is,
Ever existed and exists now exist in this kind of thin layer of the biosphere around
planet Earth. So we want to understand why organisms are distributed the way they
are. So here that involves the analysis of the spatial distribution of organisms
both current and past and identification of the factors that influence that distribution.
So it's not just the descriptions. Also trying to explain why that those distributions
are on the way they are.
So patents by John Villar result of the interaction between two great engines of
our planets, so Evolution and plate tectonics. So I'm sure you know what those two
things are but just briefly so plate tectonics is the shifting of the the plates
that make up the Earth's surface over time. So she'll be aware that. The earth's
surface is made up of these tectonic plates which move relative to each other over
time. So we've had this
You can see maps of the old Earth millions of years ago, where all the continents
were together in one in, in a land, mass called Pangaea. And then they slowly drift
apart from its then into the current current format. So, life is existed, as that's
been happening. So how does that affect the life that we see, landmasses get split
up, oceans potentially get split by the uplifting of land masses. So the way the
ways that organisms can distribute
around those landmasses and Anna's oceans changes as the plate tectonics as plate,
tectonics moves occurs and as the plates move around. And as those things change
over this really really long time scale, anything is Eeveelution. So the life that
you see that is affected by this plate tectonics, doesn't stand still it evolves
over time. It adapts it undergoes, other evolutionary processes so it's those two
things and interaction between them, that gives rise to the dish.
Some organisms that we see in the modern world and there's a fundamental divide
between ecological biogeography. So look at the factors that control patterns of
distribution in the present. And so in the introductory lectures, we had we talked
very briefly about our niches and things like that. So which environmental conditions
are organisms adapt to
And then also historical by geography, which tries to understand how these ecological
patterns came into existence. So again, we need to consider both plate tectonics
and evolution when we think about this.
I'm so conservation by drug thing, which is the name of this lecture is applying
those by traffic be at biogeographic principles to answer conservation questions.
And so it's a relatively new discipline defined by Robert Whittaker in 2005. And
it's also the middle bit here is just kind of repetition of what was on the previous
slide. But why is that kind of malleable to buy drug Rafi?
Where is essential to understand the ecological and historical processes that generate
and maintain biodiversity. So the conservation strategies can be designed to maintain
the dynamic processes. So as as we said in the introductory lectures,
Conservation isn't just about taking a snapshot in time and trying to maintain the
natural world in that state. It's about allowing the dynamic processes that can
write that diversity and have given rise to the diversity. We see today, allowing
those to continue into the future so that the new diversity can arise. And so that
those things can continue to occur into the future.
So when we think about, by geography, this man here, Alfred Russel Wallace is often
cited as the father biogeography is extremely interesting man. So not only did he
found this discipline of biogeography really but he also independently came up with
evolution by means of natural selection. So the same theory that Charles Darwin
is very famous for coming up with. So you came up with that independently and it
was actually Alfred Russel Wallace sending a manuscript.
Darling, the outline, the theory in a very similar way to what dominant done. That
prompted diamonds friends to force him to publish his work, which have been written
at quite a long time before. And so, very interesting man, but he's been extended
periods, studying the distribution and diversity of plants and animals in Southeast
Asia.
A lot of this was on collect some trips, and things like that. So he was, he had
those kind of self-fund. He had a quite different life to Darwin. Looking at the
differences between the two. Men is very interesting. So Darwin came from quite
a wealthy background, whereas Wallace came from her less wealthy background. So,
I had to fund these trips by collecting specimens for museums and things like that,
but he was also a very brilliant man, and he looked at the distribution of animals
and plants in Southeast Asia and showed that Geographic barriers mark.
Boundaries in any species ranges. He also found that places with similar climates,
did not always have the same species. So this is what kind of prompted him to come
up with the theory of natural selection himself. So when we talk about Darwin and
other people think about the Galapagos finches, so the beak size changing depending
on what food is available on each island and the giant tortoises and similar thing
with the shape of the shells.
But what is thought about it from this point of view, where you found that, if you
take two places, even if they're relatively close together and they can have very
similar climates and very similar ecology, these species, you find might be very
different and he did you see that? That was because life had descended from different
ancestors in each of those places. So, you get different species. The fulfill similar
ecological niches in different places, and we'll talk about Wallace.
Line in a minute and Not only was he did he write about natural selection and also
by geography and he also had quite a future thinking mindset when we looked at when
he was thinking about sort of conservation issues, he was aware that the natural
world was being degraded and destroyed with this quote here at the bottom future
ages will certainly look back upon us as a people. So immersed in the pursuit of
wealth as to be blind to hire considerations
So he's quite Forward Thinking, in terms of conservation and protecting the natural
world.
And this is just what we mentioned here. Whether you trace the clear boundary between
islands in Southeast Asia, that Mark the transitional zone between Asia and Australia.
So, there's this Wallace Line here on this diagram and, and it marks a kind of a
deep Channel, a very deep water. And on the west side of this line, you get the
The kind of Asian fauna and Flora, which we see on the left hand side of this little
diagram, at the bottom, and the other side of this line, even though they're, it's
very close geographically. And also the ecology and the climate were very similar,
we get a very different form for which is a descended from australasia. So we get
marsupials and, and different animals over there and so he did use that these places.
Must've been separate a long time ago, the animals on each Place evolved separately
and then they've come back together. So then I'll close together and but they maintain
this evolutionary distance even if there isn't a massive spatial difference between
them
and some of the things that
Wallace looked at were biogeographic Realms. So these he split the world up into
these kind of big areas that had similar where the the wildlife had descended had
evolved separately to other areas perhaps and and so the fauna and Flora are slightly
different in each place. You can see the bottom right there, we have The Wallace
Line Between the Australian and what is described on here is an oriental Floral
Fauna and Flora. And the interesting thing about this is that these Realms reflect
history rather than current climate or land mass distribution. So because a plate
tectonics is shifted. These continents around over a long period of time. We can
get places that are very far apart but have quite in evolutionary terms of quite
closely related species. So we can see it here in in South America at the very southern
tip of South Africa and
In New Zealand, we have this Antarctic biogeographic realm, so these places would
have been closer together in the past but they know move very far apart due to plate
tectonics. So the interaction of plate tectonics and evolution gives us these very
interesting patterns which were really important for people when they were discovering
evolution by natural selection and it's a very big source of evidence for or that
being a process that has given rise to the diversity. We see today.
I'm Honey's big beard, biogeographical Realms. Sorry are divided into formal and
floral provinces. So within these big rounds, we get smaller provinces. So here's
just an example from Australia.
And this is not quite the same as the idea grip, biogeographic Realms here. So it's
not that there's often very sharp boundaries between them. As there is with the
by decrepit biogeographic Realms. So lots of the boundaries here occur at places
are very difficult for plants and animals to distribute across. So you can see here,
we have the Himalayas and the Sahara Desert. So those places are very difficult
for
Organisms to move across because they're quite in hospital. So we have very high
altitude record temperatures and then in the Sahara we have very hot and dry. So
it's very difficult for species that live on the metadata, around the Mediterranean
to migrate south across the land down to sub-Saharan Africa and because of the Sahara
Desert. So we kind of get these quite sharp boundaries and lots of places here when
we're looking at the level of the realm and also there's obvious boundaries in terms
of the sea because the sea is going to
event a lot of terrestrial species from moving. And that's why we get one of his
line there because that place is far apart. It's now close together. So even though
potentially there could be some distribution, there is a very deep sea there. So
that might stop some and also some distribution and also there's now you know quite
complete fauna and Flora communities on each side. So potentially movement across
is difficult and it's hard to species to get a kind of a foothold on the side of
that line.
However, only Province level. The boundaries are not sharp and they can be movement
of tax in between these realms.
Provinces. Sorry.
And by geography is also very important when it comes to looking at phylogenies
in trying to work out evidence from histories as well. So we also have these things,
we can have Philo geography, which is something I'm gonna have a little bit of a
look at here, which is how phylogeny is interact with biogeography. So the interplay
between the distribution of different species and their evolutionary history,
So here's an example of how we can test we can use phylogeny is to test how speciation
may have occurred over over a period of time. So phylogeny is a relationship between
11 who evolutionary relationship between a group of species. So the phylogeny is
we see at the bottom here and these are the kind of shapes that you tend to expect.
So we get this kind of branching structure so each branch is a speciation event
where two groups of
Of organisms became reproductively isolated from each other and each shape here
tells us something. If we can work this out using traditionally, we've done using
morphology generally. It's not often done with their genetics methods, which are
talked about in one other courses.
These shapes here using those methods. We can use it to try and infer, The evolutionary,
the biogeographical history of those groups of species. So if we look at the left
here, we start with this. We start with two populations, no two areas. Sorry, we
have this big area a and this small area B. And within a, we have a population of
this species W and so time is moving down.
Down and the top of this diagram and up for the phylogeny. So we start at the bottom
of this screen, phylogeny here at the root. We call it as I move up and then W splits
into X and Y, are sorry into W and X. So, we get this speciation event here, which
is the first fork in this green tree at the bottom here, and then we're still within
area. A, we get another speciation event. So w and X become become X and Y, but
by looking at this
Originally, we can tell that W is existing kind of by itself now, and then X the
X population species into X on y. So now we have w x and y all into BL an area.
A, so we're getting this shape of the tree here and then finally species, why has
migrated to area B, and when they're it, Divergence new tax on Z. So, this is why
this we get a shape here because w
became W and x x became X on Y, and then y in the new area became said. So this
is kind of shape. We get here. And then you can have a think through how this occurs,
how these other two colors have blue here and read how you can follow through the
same process. And you can think how this biogeographic history has given rise to
this phylogeny at the bottom here, so I'm not going to run through them because
it's a little bit tedious.
It just kind of letters and letters over and over again, but it should make sense.
You should be able to work through that history. Like I've just done there and show
how the to match up.
So islands are particularly interesting to study both dispersal and also Evolution,
as I said earlier on Darwin, famously used a lot of the patterns of biogeography
on the Galapagos to help formulate his theories of natural selection. So Oceanic
archipelagos that we have in Hawaii which is similar to the vagus in terms of, it's
a volcanic archipelago in the middle of the sea.
Long way from a content from a continent. So the Hawaiian Islands formed as a tectonic
plate movement with Westward over a hotspot causing the sequential formation of
volcanic cones. As we can see, we have the oldest items at the top left here and
then as this plates moved over the hot spot. So it's moved to the Northwest, we're
getting younger and younger islands. And what this allows us to do is to look at.
So when these islands first,
It arrived at the see there, there's no treasure life on them. No terrestrial species.
So they have to be colonized from somewhere else. So the first one was probably
colonized from the mainland in various ways which we'll talk about in a while from
a continent which the nearest continent here will be North America.
Then as each island Rises up its then available to be colonized by other species
from the archipelago. So that allows for really interesting studies of how migration
and evolution take place on Within These archipelagos.
As we can see here, there's evidence that the Carnation colonization of the Hawaiian
Islands. Proceeded from the older to the younger Islands. So as I said, the first
Islands to up to be uplifted from the sea to be formed from volcanic activity. So
this green one here. So that must have been colonized from. If that was the first
island to appear here, it has to treasure species. Must to colonize it from a continent
or another Oceanic Island further away.
From from outside of this archipelago and then by tracing the biogeographical, Sorry
by tracing a phylogeny. We can tell phylogeny is of this group of Hawaiian crickets
here. We can see that the oldest, the root of this tree is species, that colonized
this Green Island here.
And so they've Diversified a bit. So we have more than one species on the screen
Island. But then they've, as these islands have appeared over a long period of time
and the species already exists within each, the Audis, this one in the archipelago
progressively colonize these new items the movement from one time to another doesn't
just have to happen once. As we can see brown, the brown lineage here has turned
as
Given rise to really lineages twice. So once here at the top where it says Molokai
and then once at the bottom here as well, so distribution events colonization events.
Don't just necessarily happen once and they can have more than once but allowing
by following this phylogeny, we can really see how this dispersal has happened.
And it's a really interesting case study about the interaction between evolution
and dispersal.
So looking at what is biogeographic Realms as we did earlier on, he determined them
largely based on the distributions and taxonomic relationships of particular vertebrate
families.
which isn't necessarily wrong but as you see with a lot of these
Kind of early scientists who were foundational and lots of the fields that we look
at here, there's now much more technology and better knowledge available.
So, for example, we now have a the ability to sequence genomes and that gives us
a more detailed view of these phylogenies and in terms of biogeography as well.
We also have access to remote sensing Technologies and GIS Technologies to mapping
software and
And so these kind of things can give a small precise analysis of things, like being
biogeographic Realms. So an example of this is the re delineation of these biogeographic
Realms by Holt account 2013. So this paper will be cited in the PowerPoint notes
below, the slide, and so he Quantified Holt. Sorry, quantify the change in phylogenetic
competition among species assemblage assemblages across the globe to identify it.
Total of 20 Zoo, geographic region regions nested within 11 larger rounds. So so
what I've kind of had a bit of a rough ago at this really because he didn't wasn't
able to use in-depth file o genetic information so there was no genetic sequencing
techniques available to him. But now there is that kind of information and that
technology available so we're able to use that information to refine some of the
ideas from Wallace.
And you're also able to use many more species. So here were using over 21,000 and
doing this. We now have, you know how these 20 regions mr. Within 11 larger Realms.
So it's actually remarkably similar to what Wallace produced. So his biogeographic
Realms, but there is a bit different. Okay, different. So we have things like Madagascar
becoming its own group and
and so here in New Zealand and Australia are grouped together rather than New Zealand
being grouped with the south of South America, and South Africa. So some differences,
but it's remarkably similar any. And also the very north of Canada and Greenland,
I think Vaughn was group with the rest of North America as you see here, but in
the new system is grouped with this in this patriotic region.
I'm so it's not just,
it's not just looking at differences in BIO to it, that makes this interesting.
We can also look at uniqueness of the zoo geographic regions, which is based on
here, as the mean of pairwise phylogenetic beta. Biodiversity estimates between
any one region and all other regions. So, when we looked at, in the, in the biodiversity
introductory lectures, so, in the first lecture of that, set of three, we looked
at how you measure by diversity. So we have Alpha diversity.
Is the number of species often as you'd often than other species. It's used in a
particular site or as beta diversity, is the difference between that site and another
site. So, here we're using kind of beta diversity on a very much larger scale to
show show pairwise. So the whether or not certain species occur in more than one
region here. So do they occur in Australia and Africa? For example, do they occur
occur?
In North America and South America. So that's what it means by pair. I say I'm comparing
whether or not a particular species occurs in two different places. And by doing
this, we can see that this particular area of the world that are very unique. So,
particularly Australia. So, the interesting thing about Australian, actually mammals
at least is that a lot of marsupials, which is a different group of mammals to what
most men ones are, which is placental you Syrian, which means that they have completely
Have a placenta. I'm Steve Berry label on the pregnancies, much more development
of the fetus inside the mother, whereas marsupials give birth to very small babies.
Which then developed further, in a pouch, some sort of usually Madagascar also falls
out as being quite unique and then lots of the northern hemisphere has quite low
scores here of terrestrial uniqueness. And it's probably largely because there's
Log landmass here and it means that animals and plants can disperse a relatively
easily across the latitudes there. Whereas The evolutionary history and their plate
tectonic history of some of the Southern regions Australia. And Madagascar means
that they've been separated from larger land masses for a long period of time.
So distribution have been much more difficult.
So, it's not just, so the biogeographic maps that we've been looking at, their not
the same for every every taxpayer, every group of species.
So these maps on the left here, show the differences in biogeographic regions, for
amphibians birds. And mammals this interesting about why this might be different.
So why is it that? There's slightly different delineations of regions between these
different taxa and Stephen pause. And think about it before I explain some of the
reasons you're more than welcome to. But before we do that,
Some of the differences are caused by by whether or not a species can exist in a
certain area. So if you look at the top here, there's gray areas for the amphibians
in the Sahara in the Arabian, peninsula in some of the Himalayas. So as amphibians
have permeable skins, they struggled as file off the time in very dry areas. So
that's probably why there's just because it does not fit into those places because
know I've been species can survive there because of their permeable, skins.
But other reasons why we might have these differences is due to differences. In
dispersal ability is probably the one of those important. So, we think about birds,
most species of birds discounting penguins and ostriches can fly what that means
is that this person will becomes a lot easier for them than it does compared to
many mammals and many amphibians.
And if we can see here, especially across Europe and Asia, we have a kind of a large
turquoise band, their of similar ish bird species. And again it's because this is
one large land mass and birds can fly to the probably able to fly east and west
across that land mass fairly easily and then because alna, similar latitude, it
means that they have probably had similar environments all across there. So birds
can Traverse that
Uneasily, and gene flow can happen quite easily.
So we don't get as much evolutionary separation as we do for some of the other taxa.
So I think in general here not quite the case but if we look in general that birds
tend to have slightly fewer of these regions in the mammals possibly just because
they're able to disperse a bit more easily. And this isn't, the only reason why
these differences might occur. As you say, then fabian's, they might just be
And they might be less able to Traverse obstacles over evolutionary history so they
might be able to cross mountain ranges as easily as mammals. So so dispersal is
one of the reasons why he's by Jupiter Geographic Maps different, according to the
tax that you're looking at,
Okay, so now look the biogeographic regions, we're going to look at the at the species
level. We're going to think about some major types of it by Geographic distributions
that you get off particular species. So the first one we look at here is Cosmopolitan.
So this is a species that are found almost anywhere around the world. So, lots of
these, this happened with because humans transport them around. So, especially the
case with rats andwith drosophila, which is that little fly.
The red eyes that the top right humans have transported them all around the world,
either accidentally or on purpose. And that means that many of these species now,
have these Cosmopolitan distributions where they occur almost everywhere around
the world.
Other one is endemic. So this is, these are species that are defined to quite small
geographical locations. So lemurs are a type of primate, only occur on Madagascar
naturally. They'll be found in zoos now cause some stuff like that across the world
but naturally only occur Madagascar. So they are endemic to Madagascar. And another
example, here, these silver swords. That's a only occur on Maui island in Hawaii.
I'm on is disjunct. So if you only looked at Wallace's of biochar by geographical
Realms up here, so it might not be, this is correct now, but it's just interesting
to think about. We have these red areas, hit these Antarctic regions which are very
separate very far apart from each other.
That's how we get these disjunct distributions here. So these are distributions
with gaps basically. So these can be species that have been around for a long time.
As we get with alligators and as they've as history has gone, after they evolved
as a species plate tectonics, may have separated different parts of their range.
And then those two parts
Evolved separately and they become different species but we can still recognize
that they're both alligators. It can also be that distribution processes have moved
individuals, very long distances so you do get these disjunct. Just don't do distributions
without evolutionary history. But basically you need to have some sort of distribution
happen and then for
Four.
At the individuals in between the two extremes to die out or you get vicariance,
where two different regions are separated by plate tectonics. And then you get again,
separate populations in different areas.
Interesting thing in there is that you'll still need because we're going to talk
a little bit about Niche conservatism in a while which means that it's difficult.
It can be difficult for species to evolve into entirely new ecosystems and entirely
new environmental conditions. So even though these species all these, taxa have
disjunct,
I just dropped distributions, it means that they still have to in have it relatively
similar environmental conditions. So even though they can be far apart they still
have to we'll have to have kind of relatively similar environmental conditions.
And that's how we get on to looking at ecological niches here. So ecological factors
determine a species species, Geographic distributions. And one way of conceptualizing
this is to think about a niche. So
And the diagram here shows a kind of a two-dimensional Niche space that just is
just defined by two environmental variables. So we largely going to talk in terms
of two variables like this because it's easier to visualize. However when you thinking
about this in in reality, an organism's Niche, will be defined by lots and lots
of different environmental variables, which so they'll be lots and lots of different
axes on this graph way, past three dimensions. And we get into
Too kind of, we get into hyper volume. So volume is that have much more than three
dimensions because, you know, it is dependent on temperature and rainfall, and nutrient,
availability and all these other things. So it's not just two or not, even just
three environmental variables that Define and organisms Niche. That becomes very
difficult to visualize. So we're just going to focus on a kind of simple eyes model
of it here. So,
The.
Women looking at niches, we need some sort of crossover of realize environmental
space and fundamental Niche space. So the real realize that room I'm environmental
space are the conditions that actually occur on Earth. So if we're saying this is
temperature and rainfall temperature on environmental variable 1 and rainfall on
environmental variable to, it may be that certain certain
Nations of those things never occur together. So say it can't be over a certain
temperature every day and also guessing thousands of millimeters of rainfall every
year. So because I hate those high temperatures occur in deserts.
So it's impossible for those things to occur together. So first of all, we need
to think about what environmental conditions actually exist on Earth. And then we
need to think about the potential environmental conditions that species can actually
live in. So those two things crossover, then it means that there is a a potential
Niche space here for that organism.
And then within that potential Niche space. So the space that could fill we have
the realized Niche which is slightly smaller and is determined by the actions of
other species generally. So normally a
Normally that that realized Niche is is smaller because of the actions of competition
or predation or the actions of other species. It can be other things as well, that
reduce it slightly but we tend to think of it in terms of interactions with other
species that restrict the areas of that our Focus species can actually inhabit.
And so that realized Niche, there will be the actual distribution that we observe
of this species in the modern world.
I'm just it's just outlines what it because logically Niche is and why it's important
to think about it when we're looking at distributions.
and then briefly, before I mention about phylogenetic Niche, conservatism,
so this is the concept that it can be. That generally even after speciation, the
each species will tend to inhabit a very similar Niche to the other one. So here,
that's closely related species, are ecologically, similar
I'm making this because because it hasn't been enough time for these two for these
closely related species because they didn't have urge very long ago to evolve to
be adapted to very different environmental conditions are very different, ecological
niches.
So this Theory gives us some predictions, gives rise some predictions that we can
then test. And one of these is that you can largely determine a traditional distribution
of one species by. Looking at distributions of it's over different closely related
species. So here, we're looking at two different hummingbirds that are separated
on either side of this dotted line here. So the blue dots are places where we know
that species one occurs,
I'm and then using that data, we can predict what environmental conditions there.
They are able to survive in and we can predict their potential. Yeah. Potential
Niche base, hit as specified here. There's some problems with doing this kind of
work because it may be that we're actually measuring their realized Niche. So we're
not capturing the full, I mental conditions, they're adapted to, but it's probably
good estimate of the places where they can survive in this.
Part of Mexico and then using that we can look at this very closely related on the
road species and we can predict where this species will occur on the other side
of this dotted line which is this kind of brown color here. And then using actual
real distribution data, we can test whether or not, this seems old true and then
these red dots are actual observed distributions of this other species. So they
seem to fall within this brown predicted
Distribution here. So this this is interesting. It gives rise to some testable hypotheses
and it also means that
It means that we can use this when we're thinking about the distributions of species,
like we talked about the disjunct ones here. So even if two, populations of species
are in very different places are likely to occur in similar environmental conditions,
This also, we can also look at the tree frog example here and what phylogenetic
Niche conservative. And also means is that there will be a delay in the ability
of lineages of lineages to fill new nice. It niches colonize new places and take
advantage of new opportunities.
So this can also be used to try and figure out where certain groups, originated
and other things like that. By thinking about phylogeny is in terms of this phylogenetic
Niche conservatism. So, looking at tree frogs we do here and they're very diverse
in tropical America. So all these green lineage is here.
And then the red ones are lineages. That have colonised North America and other
places other temperate regions. We can see that these are there many fewer with
Majors here. So they're much less diverse in temperate zones and they are in the
tropics and only a few lineages have more recently adapted to the temperate zone.
And as we can see the origins of these red lines are more recent than some of the
origins of some of the green lines, which occurred
Much longer ago.
And not only that. So, not only do, we expect these temperate lineages to originated
more recently. We also expect there to be a more species that occur in the tropics
because it had more time to diversify. And that holds true as we see here, the number
of species is correlated with the time since diversification in that region.
Which is the graph on the bottom right now. When we're thinking about by geography
and fired, I think these conservatism and ecological niches, we have to remember
that organism to don't just look similar because they have, because they are closely
related.
So, phylogenetic Niche, conservative predicts. That closely related species. Not
only will inhabit similar areas, but they're also likely to be adapted to similar
ways of life, which means, which is part of their ecological niche. So those do
hummingbirds, will probably still both drink nectar and will have similar diets
to each other.
However, being close related isn't the only reason that animals can fulfill can
inhabit. Similar niches, look, similar have similar life histories. So we can also
have this thing called convergent evolution where independently to species have
evolved to or adapted to fill a similar niche.
One of the best examples of this is when you compare marsupial, mammals from australasia
to placental mammals, and from other areas of the world. And even though these pairs
of species that on this diagram are not closely related at all, because they come
from two, completely different branches of of the mammal evolutionary tree. They
do often look remarkably similar, they cannot remarkably similar and they can fulfill
very different very similar.
Roles in their ecosystems.
So we got to think about the ecological regions for current for current species
distributions. And I'm going to think about some of the historical factors that
affect Geographic distributions, so being evolved to a particular Niche. And our
this is, these are kind of the important ecological factors that determine species,
Geographic distributions. And I'm going to look at historical factors. So the first
one is extinction.
So as I said in the introductory lectures, even though humans are giving rise to
much larger HP Extinction than is normal in the history of the world, Extinction
is a natural process. So an example here is that the whole family spread from North
America but then became extinct there. So only zebras Asian horses and Asian wild
asses survived which don't exist in North America. So also Is What It Wants, been
much more
a widely distributed around the world and our lesser because of this Extinction.
And then my dog is another example here. The next one is dispersal. This can either
be range expansion through favorable habitat, or jump dispersal across unfavorable
habitat. So this is different because if we think about the movement of a species
across a landscape, if that habitat is favorable, then individuals will stop and
kind of live their lives in that oval habitat and is usually a particular age.
Particular sex disperses and they'll continue to move to a kind of. So to reduce
the competition with their Concepts, Civics and find new habitats. Although if the
middle is in hospitable so say it's moving from a species moving from a continent
to an island. It's not going to stop in to see if it's a directional species. So
there's kind of this jump dispersal across this unfavorable habitat and we can also
look at different ways that's
happens. They can be Pathways such as corridors and we can also get these Sweepstake
events, which is when there's a large fast dispersal event that moves, lots of species
or lots of individuals and one go.
But there is you we can look at the results of these recent dispersals. And so one
examples of this was looking at volcanic archipelagos so if they've risen out of
the sea then by definition they don't have any terrestrial species on them but there
are now terrestrial species on Hawaii on the Galapagos so they must have got somewhere.
So that is evidence that dispersal even across oceans can occur but more recently
in 1883 the Krakatoa,
Option called all life on the island but within 50 years the island was covered
with forest and habitats that clearly came from java and Sumatra. So how that those
are special happens, can be a range of methods. So tree seeds can travel across
the sea if birds are flying and they can sometimes take seeds and things and they're
in my detached of the feet, certain species, insects and arachnids can blow in the
wind for really long distances. Lots of species.
Fly. So that's where this can happen or they can be like rafts of wraps of Driftwood
and or seaweed and things like that. Things that float can also carry particular
species across large Oceanic distances. Another example here is the Great American
interchange when the Isthmus which is a word I struggle to say of Panama formed
in the pliocene so that's when the little strip of land. Where Panama is now kind
of rose out of the sea in the pliocene and
That caused a great interchange of biota from the previously separated and evolutionary.
Distinct, North American South American biota came into contact with each other
which led to assume which led such changes in the the biotech both areas.
As we talked about earlier, when we thinking about why there's different biogeographic
regions different Zoo, geographic regions with different taxa, the ability to disperse
varies greatly from group to group. So for example, bats are the only mammals needed
to New Zealand and Hawaii as they can fly, it can disperse much more easily than
other treasury or mammals. And so, they've been able to get these relatively isolated
Oceanic Islands,
So this is some of the looking looking at some of the methods of dispersal I was
talking about before. So air currents can transport seeds, spores and small animals
all around the world. And so that movement is is very much affected by prevailing
wind directions. So that will control, which species can move in, which directions
if they're not, if they're kind of passively traveling with other actively, if there
are right relying on this movement of the air.
Another one is ocean currents.
Which is mostly looking at marine species, but can also transport seeds. There are
actually some tree species that seem to be adapted to float, so they can colonize
new islands. The largest trees seed in the world. Does this? If you look it up and
coconuts as well, our thoughts, it would be adapted to be able to float from Ireland.
And so there's been an interplay here with Evolution and these special processes
And so now we've looked at Extinction and dispersal We're not gonna look at vicariance
which is the splitting of attacks on drange, so talked about this a couple times
already in this lecture. So want when we're thinking about how we can test hypotheses
of the interplay between biogeographic history and phylogeny is, and once we're
looking at looking at disjunct distributions of species. So here populations of
a widespread species. Are
To do the berries, resulting from changes in geology, climate or habitat. So there
can be, like we said, the Isthmus of Panama coming out of the sea. So that's separated
Marine biota on either side of that. So from the Pacific side, and the Caribbean
side. So those
So species that current previously existed across. There were populations of the
other of those species were separated as a gene flow. Stopped, and that's a type
of reproductive isolation, which can lead to speciation.
So we have land if we're looking thinking about marine species and then in the opposite
way, sea level rise can lead to separation of different land masses. We have the
uplift of mountains and a hundred different things that can lead to this kind of
vicariance and which kind of leads a Divergence in speciation. And as we said at
the beginning to plate, tectonics over a longer time scales also can give her a
gives rise to this kind of by Karen's. So for example, the break
I will come to one land in the Mesozoic can explain the distribution of some ancient
groups like rat sites and marsupials.
So that's Australia, becoming becoming isolated, but there are some obstacles that
exist on in South America. So if Australian South America were join more recently
and then separated that explains why we get marsupials and those two places, which
are now very far apart
So, dispersal fi current Extinction can interact to explain a species distribution.
so, for example, if we look at
It was a cold adapted species. They can occur with quite, just jump distributions.
And that's probably due to this to over during the pleistocene kind of glaciation
and, and then integrate your period. So we get ice sheets moving down from the North
and then we get actually is retreating. And so we get these called adapted species
that don't just occur in kind of the northern northern European areas. They also
occur in some mountainous.
Or high altitude regions such as the Alps to the Pyrenees.
Well, it kind of got. So when ice came down in the past, these would have these
cold-adapted species would have occurred all across Europe as the ice retreated.
They've had to remain in these high altitude places where they can exist in cold
areas but they are separated from the larger regions of the north. Oh, northern
Europe, where they wear these cold called habitats occur.
Sorry, that's just a repeat of the account, I would normally. And then, yeah, we
can also, look at it with a sexy fridge and which are this type of plant here. So,
again, called adapted yet, it's just junk distribution here, where they occur in
the Arctic, but also in places, where, where ice sheets have in the past travel
down, and this plant has trouble down with them, and then when they've retreated,
they've got stuck in these kind of pie, high-altitude areas. So,
these relict populations, which are separated from the larger distributions in the
Arctic
And camelids as well. So these are, this is a family that includes, not only camels
but also, by kunas llamas alpacas. So, we get camels in Northern Africa and Central
Asia here. But the other ones I talked about that also llamas, and alpacas come
from South America. So, how do we get this? Such disjunct distribution here. So
this is really separated distribution.
And so again, we can explain this using using the interplay of those three species
with Extinction of icarians and of dispersal, the dark blue. Here is the current
distribution of this family like lose the historic distribution, and then green
and Australia's, because camels have been introduced by humans to Australia but
camels probably evolved where this yellow dot in is in the middle and then migrated
to South America.
And then down to Central Asia, Middle East and Africa, but they've gone extinct
in all this in the, in the kind of areas in between those two extremes. So again,
we can think about distribution. So, this family moved away from the area of origin,
then we get think about Extinction. So there's now extinctions of that family in
the middle. So we now get this very disjunct distribution.
History of a clade is often complex and they include both icarians and dispersal
of it's a different time periods. So, this is the one thing I'm plus, we've looked
at are relatively simple. They just show how the principles work, but if you're
going to be looking at the evolutionary history, or the geographic issue, entire
clade, it becomes complicated quite quickly, and can become quite hard to figure
out exactly what's happened when
But just to induce some terms before we get into after lecture, taxi can be described
as a lock thinnest, if they originated elsewhere or autochthonous if they were if
they hold within that region. So if we think about Regional boaters, so this is
not just looking at a species level now, but looking at the community compositions
It's a look at South America, some autochthonous taxa that have evolved in South
America. So, remnants of the gondwana and biota that includes long, fishes. And
these, these pine trees and their example of the disjunct distribution earlier on
groups that Diversified from a lock thinnest prejudices after South America became
isolated. So this means that these are groups that did not evolve in South America.
The group itself didn't have guinea pigs, didn't evolve in South America, but guinea
pigs arrived in South America and in Diversified so species, speciation has occurred
there but that's not originally where that group came from.
And then some blocks in his taxes arrived from North America during the Great American
interchange. So, as I said earlier, lecture, that is when the Isthmus of Panama
Panama. So the thin strip of land between North America and South America arose
around three and a half million years ago when that happened these kind of traditionally
very separate by odors from North and South America kind of came together in a big
Exchange in a big clash and
Unfortunately, we lost the South American mammals, they lost out. So, South American
mammalian, biota had lots of marsupials, which is not always a hard and fast rule,
but can often be out competed by placental mammals due to various reasons.
So lots of the the gondwana and biota. So lots of the mammals that evolved in South
America and also these autochthonous species and groups became extinct shortly after
this great American interchange. Okay, let's give the lecture. Thanks so much for
listening to. These are the readings. I recommend you. Look at for this lecture
it should be in the folder along with this but yeah, thanks so much for listening.