Evolution, Adaptation, Species, Biology, Climate variability and change PES Unit 9.10 Human Impacts on Biodiversity Part 2 of 2
We are going through section 9.10, the final section. This is actually going to be the final video, because i promised that every video in this uh unit would be less than 10 minutes, or so i think my greatest video was 12 13 minutes. So this will be the last video because we are almost done with everything and i promise you. This is the last video all right let’s. Do it so um more problems that cause habitat loss include decline in genetic diversity, all right, so sorry, i had to step away for a moment. Anyways there’s been a decline in genetic diversity that’s another one of these downsides right. So when you have a wild species that’s, where you have more genetic diversity, some of the harmful effects means that there’s no genetic insurance for an environmental change in the future. Massive events cause more devastation to a species. We also see an inbreeding depression, because if there are fewer alleles in a population, there are lower there’s, a lowered fitness for the species, for example. Here, if you have a dominant allele and a recessive deterior deleterious allele, you know we have a dominant species and a non dominant species, but if there is interbreeding it allows for this, not so great recessive trait that might be bad for the species. An example is cheetahs, cheetahs have had their population bottleneck twice in their evolutionary history, which cause has caused reproductive difficulties and high susceptibility to viruses.
So just a breakdown of the different species of cheetahs. We have the asiatic cheetah there’s between 60 and 100 of them. The north african cheetah they’re only about 250, the central african cheetah 2000, the east african cheetah and the southern african cheetah, so you can imagine with less subspecies less protection for the species overall. So when you have a population bottleneck essentially it’s, where a large number of the population dies off, which means that only a certain genetic variation will be able to go on so the population size here, and the amount of variation is up high with it. When there’s a bottleneck, that genetic variation has a harder time getting back up to a normal rate, so here’s two scenarios for you. If a female cheetah mates with multiple males there’s variability in in those cubs and that’s, a high variability and the chance that all the cubs will be susceptible to a new pathogen is actually low, whereas if a female cheetah mates with only one male, all of those Cubs are going to have low variability, which means they are going to have a higher susceptibility to a pathogen. So more genetic diversity allows a species to be able to change over time and be more resistant resilient. The florida panthers another example where there’s been genetic restoration they’ve had eight females translocated from texas to florida in 1995.. The population is up three times, but heterozygous heterozygosity fitness and survival are up significantly by introducing different genetics into that population.
It has allowed better survival. So here’s the current range of the florida panther biologists noticed that by that the small panther population was in poor health, the cats had low fertility, physical deformalities, heart problems and abundant parasites that could be caused by inbreeding. So, like i said what did they do so they had this, this grass sorry, this graph shows just survivability survivorship, remember the survivorship curve. The florida texas hybrids had a higher survivorship than the descendants of the hybrids that mated with texas pumas, where everglades partners and the pure florida panthers had the lowest survivability. So, by introducing new species, we now have a wider variety of species, so you have the pure everglade panthers, which are actually the e, the smaller one they were being wiped out. The pure florida panthers, the pure texas, pumas and then panthers that descended from crosses between locals in texas and then panthers of unknown descent, so that’s just to show you all the different branching off of those species. We also have domesticated species. This is something that i am petting right now. I have a cat next to me because he meows, if i don’t pet him, the majority of livestock species in the world include seven mammals and four birds. Oh yeah, here we go. I think you know them all. This is the majority of livestock species. Oh any cute, Music, just a reminder: seven mammals, four birds, so two, three, four, five, six one more mammal.
Can you guess it it’s, a pig of course, so sheep cattle pigs, all that goats and we have four birds. Oh everybody loves chicken. What else might there be what other bird might we have domesticated? Oh yeah, the duck oh yeah, delicious, delicious delicious duck. Are those ducks? No are those ducks? No, i think those are geese and, of course, turkeys. We’Ve also seen a genetic diversity declining because we concentrate on the most productive varieties of livestock and crops. So common wheat, for example, is the most widely cultivated wheat species in the world. We are in turn, causing more um genetic we’re, causing less genetic diversity, so plant genetic diversity declines. As we are able to concentrate on higher yields, it leaves us vulnerable to biotic or abiotic uh changes. One example is the corn blight fungus that killed half of the corn crops in the 1970s. If we rely on one species of plant or animal and something is able to wipe them out, it is not going to be good for us, so this is an example. A little reading for you, if you really want to i’m, not going to you know you can pause and read it if you want to i’m just going to skip on through. This is a video on the doomsday seed vault deep in the arctic. Um remind me to watch this in class and we’ll watch it in class, or you can watch it on your own there’s.
The link you can find the link on the powerpoint, but basically the seed vault is where we are storing seeds to make sure that we can keep genetic diversity in the case of mass extinction. Species diversity around the world um has is changing. The major extinction event is where at least 75 percent of all species within a period of two million years are wiped out. Okay, so that’s, where you get these deep dry, drops right, so there’s, the first, the second, the third, the fourth the fifth and the sixth. What the heck something? Oh, this isn’t yeah! This is just yeah. Okay, sorry, anywho! So remember this graph don’t forget it it’s very important as we look at our likelihood of species extinction. So how can we mitigate the biodiversity loss? One of the things we can do is we can create protected areas right. We can create wildlife habitats, we can create national parks national protection, we can also make habitat corridors. This is real right. We create essentially an a an overpass for animals to be able to travel over these areas that we are causing habitat, um degradation – hey. What are you doing? My cat just jumped on my lap? I’M? Sorry uh, where we are seeing these habitat habitat fragmentation. We can also promote sustainable land use practices like contour plowing, for instance. Like this remember the video we watched, we can restore lost habitat, we can take a lost habitat and bring it back or try to bring it back to what it once was and at the very least i leave you with this wonderful calvin and hobbes comic wow.
It really snowed last night, isn’t it wonderful everything. Familiar has disappeared. The world looks brand new a new year. A fresh, clean start, it’s like having a big white sheet of paper to draw on a full day of possibilities. It’S, a magical world hobbs old, buddy let’s go exploring. We can solve these problems, we just have to have the will. This is the end, i hope you’ve enjoyed it.