1. Unit A – Biological Diversity Topic 2: Habitat and Lifestyle

2. Variation and Adaptation The goal of life is to survive long enough to reproduce and pass on your genes. (R. Dawkins). The goal of life is to survive long enough to reproduce and pass on your genes. (R. Dawkins). Adaptations allow organisms to have a higher chance of survival and reproduction. Adaptations allow organisms to have a higher chance of survival and reproduction. The more variations in a species the better the chance that adaptations will arise, causing the species to survive and thrive. The more variations in a species the better the chance that adaptations will arise, causing the species to survive and thrive. Variations can allow living things to live in very harsh conditions, from the Arctic to the Sahara to maybe Mars itself? Variations can allow living things to live in very harsh conditions, from the Arctic to the Sahara to maybe Mars itself?

3. Competition Because resources such as mates, food, shelter, etc. are scarce, species and organisms in the same species must compete for them. Because resources such as mates, food, shelter, etc. are scarce, species and organisms in the same species must compete for them. Competition allows the best species and organisms to survive and pass on their genes improving the gene pool of the species. Competition allows the best species and organisms to survive and pass on their genes improving the gene pool of the species.

4. Avoiding Competition Some species are better than other species at certain activities, so it doesn’t make sense for the weaker species to compete. Instead they assume a different niche in the ecosystem. This increases the variation between species. Some species are better than other species at certain activities, so it doesn’t make sense for the weaker species to compete. Instead they assume a different niche in the ecosystem. This increases the variation between species. Eg. Lions are stronger and better hunters than hyenas, so the hyenas evolved into scavengers, eating the scraps left behind by the lions. Eg. Lions are stronger and better hunters than hyenas, so the hyenas evolved into scavengers, eating the scraps left behind by the lions.

5. Broad Niches Broad niches exist in areas that are harsh on organisms such as the Arctic and desert. Broad niches exist in areas that are harsh on organisms such as the Arctic and desert. Species that live in broad niches must make the best of the available situation. They must become generalists or perish. Species that live in broad niches must make the best of the available situation. They must become generalists or perish. Generalists are species that can adapt to different situations: eating a variety prey, living in different shelters. Generalists are species that can adapt to different situations: eating a variety prey, living in different shelters.

6. Broad niches Cont’d Broad niches can only support a few different kinds of generalists as resources are very limited. Broad niches can only support a few different kinds of generalists as resources are very limited. Because species are few, the population sizes can become very large as they are very good at adapting to different conditions. Because species are few, the population sizes can become very large as they are very good at adapting to different conditions.

7. Specific Niches and Specialists As conditions improve near the equator, the conditions become hospitable to life and a wide variety niches are available allowing for a wide variety of species. As conditions improve near the equator, the conditions become hospitable to life and a wide variety niches are available allowing for a wide variety of species. In the rain forests, each species can survive in a tiny area (specialists), therefore there are millions of species with very small population sizes as competition is much greater. In the rain forests, each species can survive in a tiny area (specialists), therefore there are millions of species with very small population sizes as competition is much greater.

8. The Trend for the Future As humans spread their influence throughout the world, resources and niches are becoming scarcer for living things. As humans spread their influence throughout the world, resources and niches are becoming scarcer for living things. These conditions are favourable to generalists, and harmful to specialists. Superb generalists such as rats, black bears, and cockroaches are increasing in numbers. These conditions are favourable to generalists, and harmful to specialists. Superb generalists such as rats, black bears, and cockroaches are increasing in numbers.

9. Trend for the Future Cont’d Specialists species such as tigers, eagles, and whales are now endangered or threatened species. Specialists species such as tigers, eagles, and whales are now endangered or threatened species. A specialist depends on having its small, specialized niche, but these niches are much more fragile than broad niches and so its easy for them to go extinct. A specialist depends on having its small, specialized niche, but these niches are much more fragile than broad niches and so its easy for them to go extinct.

10. Symbiosis Symbiosis – a relationship between two organisms where at least one of them benefits. There are three kinds of symbiotic relationships. Symbiosis – a relationship between two organisms where at least one of them benefits. There are three kinds of symbiotic relationships. Parasite – is the organism which attaches onto the larger host and lives off them in some way. They are usually smaller than the host. Parasite – is the organism which attaches onto the larger host and lives off them in some way. They are usually smaller than the host. Host – is the organism which can exist without the other. The parasite needs the host more than the host needs the parasite. They’re also usually bigger than the parasite. Host – is the organism which can exist without the other. The parasite needs the host more than the host needs the parasite. They’re also usually bigger than the parasite.

11. I. Commensalism A symbiotic relationship the parasite benefits, and the host organism is not affected either way (neutral). A symbiotic relationship the parasite benefits, and the host organism is not affected either way (neutral). The Remora fish benefits from hanging around sharks, eating its scraps, while the shark is not affected. The Remora fish benefits from hanging around sharks, eating its scraps, while the shark is not affected.

12. II. Mutualism A symbiotic relationship where both the parasite and host benefit. A symbiotic relationship where both the parasite and host benefit. Certain species of birds live on the back of large mammals such as hippopotamuses and eat the insects and pests which bite and irritate the hippo, therefore both benefit. Certain species of birds live on the back of large mammals such as hippopotamuses and eat the insects and pests which bite and irritate the hippo, therefore both benefit.

13. III. Parasitism This is a symbiotic relationship where the parasite benefits, but the host suffers. This is a symbiotic relationship where the parasite benefits, but the host suffers. An example of a parasitic relationship would be lice and humans, or bedbugs and humans, or fleas on dogs. An example of a parasitic relationship would be lice and humans, or bedbugs and humans, or fleas on dogs.