Desert Life

1. Desert Life

2. Desert ecology Desert ecology • Why are deserts dry? • What adaptations to animals and plants need to live there?

3. Desert ecology Deserts • Definition of a desert: less than 10 inches of rain per year, more evaporation than precipitation • This is caused either by dry winds (air heating up as it gets warmer), a mountain “rainshadow”, or lack of water in the middle of a continent

4. Desert ecology Why are deserts dry? • Rainshadow of mountain / middle of continent • Falling air / cool air holds little moisture • and at this latitude, air often falls from having risen at the equator

5. Desert ecology Deserts

6. Desert ecology North American Deserts • Sonoran Desert • Mojave Desert • Chihuahuan Desert • Great Basin Desert

7. Desert ecology North American Deserts Characteristic plants: • Sonoran Desert: Saguaro, cacti • Mojave Desert: Joshua tree • Chihuahuan Desert: yuccas • Great Basin Desert: sagebush

8. The abiotic environment Why does any organism live where it lives? Usually three kinds of explanations: • Abiotic environment (the right climate, nesting sites, etc.) • Biotic interactions (prey is there) • History (it evolved there and did not migrate somewhere else)

9. The abiotic environment Why are most cacti only found in the American deserts? • Abiotic environment (dry with periodic rain; not too cold) • Biotic interactions (can defend themselves against desert herbivores and compete with other desert plants) • History (evolved in the Americas, and cannot migrate to Africa, for example)

10. Desert ecology North American Deserts Characteristic plants because of characteristic climate: • Sonoran Desert: winter and summer rains (monsoon), very hot • Mojave Desert: winter rains, hot • Chihuahuan Desert: summer rains, warm • Great Basin Desert: winter rains, high elevation, colder (especially in winter)

11. Desert ecology Desert adaptations • Animals and plants that live in the desert are adapted to the hot, dry climate. • Three basic methods: • Evade • Endure • Expire

12. Desert ecology Evade Endure Expire • Migrate away in summer • Only be active at night • Adults may die before it gets too hot • Durable eggs or seeds survive to next wet season • Minimize water loss • Maximize heat loss • Store water

13. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia

14. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia

15. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia

16. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia vertical leaves, insulation with hairs

17. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia

18. Desert ecology Endure: ways to cope with hot & dry climate • Store water • Conserve water • Tolerate dehydration • Reduce heat input • Dissipate heat • Tolerate hypothermia

19. Summary Deserts • Deserts are drier than other places • But there are different kinds of deserts depending on the temperature, seasons, and when & how much rain • Animals and plants are adapted to a particular “niche”, which includes climate and other species • Where an animal/plant lives also has historic reasons