this is the video for b 4.1 on adaptation to the environment which is all part of the standard level or Core Curriculum now a big section of this topic is just understanding vocabulary so when we say habitat what we're talking about are the physical conditions um where an organism or species or population lives so we're talking about kind of like those AB biotic things right so these emperor penguins so cute they live on this uh Antarctic land fast ice that ice is their habitat and I just mentioned this word abiotic abiotic means non-living so bio means living abiotic non-living so these are those things in an ecosystem like water or temperature or sunlight or precipitation um that give that ecosystem its characteristics it tends to have more of an influence in extreme environments so like deserts or like this Antarctic um ice here so when we're thinking about what drives the natural selection processes in different organisms we really want to have these abiotic components in mind and here's a great example of that so let's take a look at these grasses these are grasses that grow on sand dunes and this is really challenging because these sand dunes tend to have very low water availability um and partially that's due to having a high salt concentration also just sand is messy and it gets in the way of lots of things so there are adaptations that these grasses have to deal with these abiotic components again water salt and sand are all abiotic so we'll find that these grasses have a thick waxy cuticle that reduces water loss from transpiration that's on the outside of their leaves they're going to have stamata in the bottom of their leaves but they will be in pits so so if you look at the underside of their leaves instead of just having stomata those stomata those openings will be in pits and those pits are often lined with hairs to help capture moisture and reduce the difference in humidity between the inside of the leaf and the outside so that's pretty cool they will also roll up their leaves to reduce wind exposure they may have ryom that can extend upwards if they're covered by sand so these are kind of root-like structures and they have fruit tans in their roots and these are structures that are going to have um some influence over how much osmosis can occur in the root tissue again we want to make sure if we're a grass living in this environment with low water availability that we're taking advantage of every bit of water um availability that we can so just in general it's not that we need to know every single structure but we need to have this concept of form and function from theme B Form and Function in mind when we're thinking about how the abiotic components um can really Drive some evolution in the organisms that live in those habitats similarly these mangrove trees um have some unique adaptations to their environment so their environment is not necessarily dry it's water logged and they are covered with water and anerobic soil so this is soil that lacks um or has very low oxygen availability there's also a very high salt concentration in there so some great and really cool adaptations of these plants they can have special glands that expel that excess salt um their roots are coated in Cork to prevent too much salt from being absorbed and they tend to also grow closer to the surface so you'll see these roots here and it's unusual to see tree roots so normally under the soil but remember remember in this case the soil is anerobic so increasing that um you know oxygen availability by growing roots in different places is very cool same thing with vertical root branches and then having a high mineral content in the roots that can drive that osmosis process and end up with more water in the roots okay remember water always follows a high solute concentration so again examples of how organisms have evolved and adapted dealing with some of those abiotic challenging components in their habitat now animals and plants don't live everywhere I know sometimes I think that mosquitoes must live everywhere I always find them but even things like mosquitoes are only going to be distributed in some parts of the planet right so we call those the species distribution when I think about where a species um can be found and can live that's its distribution animal distributions tend to um revolve around where is the water available um is that a temperature that they are evolved to live in um and this can be different for different life stages so um especially with aquatic animals we may have them living in one part um during one of their life stages and another part in others plant distributions often also depend on water availability and temperature but they also have to be specially evolved for light conditions and soil conditions um some plants prefer acidic soil other plants not so much they need different mineral contents or they're adapted to live in different salinity so these are all abiotic components that can affect distribution of species these components are all called limiting factors they are things in the environment that limit where something can live and so when we think about this idea of limiting factors we Al often have to think about a range of tolerance okay so range of tolerance means I'm going to think about a specific Factor like let's say temperature and I know that humans can live between this temperature and this temperature but mosquitoes um have a different range and polar bears have a different range so this range of tolerance um is a range of a certain factor that an organism can survive in so again we talked about temperature for animals for plants maybe some of them are going to thrive in the shade and not the Sun so how do we find these things well the first thing you might do is take a species any species that you have in mind and make a map of where that species lives then you can crosslay that or overlay that with a map of abiotic variables so I can take a map and I can look at okay is there a similar pattern in rainfall or is there a similar pattern in temperature or is there a similar pattern in sunlight okay and so this helps determine the range of tolerance for that species again cross referencing where it actually lives with some of the abiotic variables one of the sampling methods that we want to take a look at here is something called a transect so a transect is a line that's going to span several different levels of a specific variable so let's say I want to take a look at this mountain that's what this is this is a mountain and when I think about what makes Mountain habitats different they're at different altitudes okay so let's say at the bottom of this mountain we're at like I don't know 500 m above sea level and at the top of this mountain we're at like 2,000 m above sea level that difference in altitude could potentially make a huge difference in um where species is able to live so what you would do is you would take a line that spans those different ranges so I have a line from 500 M to 2,000 M and if I want to look at like let's say some trees a species of tree what I can do is I can measure that abiotic variable so I would measure my altitude and then I can count the number of organisms so at 500 M I'm counting a lot more trees as I start to go up to maybe like 1,000 M there's less and less at like 1,500 there's really not a lot and then at 2,000 there's none so this transect is again going to help me determine the range of tolerance um of that variable for that species now one of the ecosystems that we'll highlight here is a coral reef and a lot of students make the mistake of thinking that a coral reef is just one organism but a coral reef is actually an ecosystem there are lots of different populations down here here so I see not only different types of corals but I'm looking at different types of fish and then also there are algae living inh here so the zanelli algae has a mutualistic relationship with the coral so all of these living things combined with the abiotic factors make coral reefs an ecosystem not a single uh organism or population now that mutualistic uh relationship between the algae and the coral um requires the algae to photosynthesize and so that's going to determine the range of tolerance for those algae okay so it's going to need a shallow depth so that light can reach it that water needs to be clear again to make sure the light is reaching the algae it needs a slightly alkaline pH which is a problem if we have things like lots of carbon dioxide that's acidifying the ocean water and it needs a certain range of salinity so in order for this mutualistic relationship to persist we need a relatively narrow range of tolerance for all of these things and it's one of the problems with coral reefs and our changing ecosystems due to climate change is that we're finding ourselves out of this range of tolerance for these algae and the corals are actually expelling the algae so we need to make sure that we have a full understanding of how all of the organisms in an ecosystem depend on this range of tolerance um when we're trying to consider how human impacts um Can potentially um affect these ecosystems so let's jump back to land for just a second okay we're going to look at abiotic factors so non-living things that determine terrestrial biomes now this word terrestrial means on land so we are looking at biomes that are on land things like Tundras or things like deserts okay rainforest that kind of stuff and the distinction between those different biomes is caused by a difference in either temperature or precipitation or both and I want to take a look at this biome called a grassland okay now when we say biomes what we mean are collections of ecosystems that share similar abiotic um conditions right so you can tell that this grassland where this emu lives okay is very similar to the grassland where this ostrich lives okay and so even though emus are living in Australia and ostriches are living in Africa they have a very similar ecosystem what's interesting about this is that similar biomes or similar ecosystems tend to produce similar challenges and these challenges tend to produce uh organisms that evolve to have similar features okay so this is an example of convergent evolution where you have two different ancestors okay that don't necessarily they don't converge into a single um organism but they tend to produce organisms that have similar traits that's different than divergent evolution so divergent evolution is one common ancestor that diverges into two separate ancestors or two separate species these convergent evolution two separate ancestors that produce still separate species but they tend to have similar adaptations because they're facing similar challenges in their habitats and so when I'm looking at a map here even um organisms that are separate seated we would still expect them to have similar features if they have similar biomes so for example even though this part of Canada and this part of Russia are separated I would still expect organisms that are native to those parts to have similar adaptations because these environments have similar um abiotic features okay and we can look at that the same with multiple biomes okay so we talked about um the biomes like where the ostrich and the Emu live being the same we can make that case here too a great example of how convergent evolution works now let's look at a couple of examples so we'll start with hot deserts yes you have to say a hot desert because deserts can also be cold okay remember there are two abiotic factors that determine a biome the temperature and the precipitation okay so there are cold deserts and they are different hot deserts have really hot days um but the nights are very cool so we tend to get these large fluctuations in temperature throughout a 24-hour cycle there's also very low rainfall and because of that limited soil availability and the soil is usually very nutrient poor so the organisms that have evolved to thrive in these conditions will have very specific adaptations including this saguaro cactus so this is a cactus um that has really cool adaptations like these big fat stems those are there to store water they also have modified leaves so they don't have these big flat leaves like a house plant they have modified leaves they've turned into spines and that's to reduce the surface area they also have this big thick coating of a waxy cuticle along the outside to reduce water loss from transpiration a really wide root system to collect as much water as possible and then they have something called cam metabolism so you don't have to know the ins and outs of this but what we should know is that this is a way to do photosynthesis at night and that's really great because that means the stomata can open for gas exchange at night when it's cooler outside therefore losing less water due to transpiration now this is just an example of one organism in one hot desert I would expect other plants in other hot deserts to also have very similar adaptations but what about animals well how about this cute animal this is a fenic fox and it is well adapted for life in the hot desert it's nocturnal like a lot of desert animals are and so that allows it to be most active during the parts of the day where it's cooler it has long hair to help it moderate its body temperature again that's a protection against those wild swings in temperature between daytime and nighttime these ears you might think that they are for listening but they're actually there to radiate heat this fox can send blood to its ears okay and that blood can then spread out and then you have more contact with relatively cooler air outside that blood cools down a bit and then returns back to the body so very cool adaptation much like the African elephant ears it also has hairs covering its paws to allow it to walk on hot ground and this light fur allows it to reflect sunlight so again I would expect very similar adaptations in other animals um that are adapted for similar conditions tropical rainforests have um a very different set of uh temperature and precipitation um and then that means that the species that live there are also going to have really different adaptations when you compare them to Desert organisms so things living in the rainforest have to be adopted for like really hot temperatures with a lot of rainfall and there's a lot of light intensity most of these are found near the equator and a great example of an organism well adapted for that is this moranti tree now this is a tree that is able to grow very tall and relatively quickly and that's really amazing to be able to out compete other trees for light so even though there is a high light intensity in the rainforest there are also lots of other things that can live there right because the temperature is pretty nice and all kinds of things so it's got to be able to out compete those other organisms all right so if it's growing really tall that means there's a lot of Mass to support So this very dense trunk helps to support um it's very tall growth it also has enzymes for photosynthesis with optimal temperatures that are a little bit above what we might find in other ecosystems and it has these nice broad leaves to disperse rainfall these leaves are also Al going to stay on all year long they're Evergreens so that they can utilize that light intensity and photosynthesize all year round so just like the sawaro cactus and the moranti tree are different because they have different habitats so are the spider monkey and the Fini Fox Okay so this spider monkey has much different adaptations than the fox I don't see huge ears on this monkey what I see are things that are well adapted for its environment so long limbs for climbing through those trees there's not a lot of trees in the desert so it's not surprising that I'm not finding organisms with long limbs there um it's active during the day so that's much different than the fox which was active during the night and this is because it's got to be able to see and it needs to be able to find food and it's also got another tail that can act almost like another limb um great for grasping or for climbing so the key here is not memorizing individual adaptations of every single organism and every single type of ecosystem it's about understanding the relationship between Form and Function this is theme B so Form and Function what physical adaptations do organisms have to help them cope with the challenges in their environment