Desert Life

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

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

Why are deserts dry? Rainshadow of mountain / middle of continent 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

Desert ecology Deserts

North American Deserts Desert ecology North American Deserts Sonoran Desert Mojave Desert Chihuahuan Desert Great Basin Desert

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

Why does any organism live where it lives? 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)

Why are most cacti only found in the American deserts? 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)

North American Deserts 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)

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

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

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

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

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

Endure: ways to cope with hot & dry climate 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

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

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

Deserts Summary 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