1 / 81

California Deserts

California Deserts. Deserts. Defined as a region that receives less than 10” of ppt a year Irregular Temperature extremes Windy Nutrient poor alkali soils Low rates of primary productivity High rates of evapotranspiration. Low Irregular Precipitation. High Light Intensity.

quasar
Download Presentation

California Deserts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. California Deserts

  2. Deserts • Defined as a region that receives less than 10” of ppt a year • Irregular • Temperature extremes • Windy • Nutrient poor alkali soils • Low rates of primary productivity • High rates of evapotranspiration

  3. Low Irregular Precipitation

  4. High Light Intensity • 90% reaches ground • High solar radiation • High UV

  5. Temperature Extremes • Dry desert air holds little moisture • Water moderates temperature • 50 F temp change between night & day

  6. WINDY!!

  7. Nutrient Poor Soils • Low rates of decomposition • Aeolian soils • Low primary productivity • Alkali & salinity

  8. High rates of evapotranspiration • Potential evapotranspiration is higher than precipitation

  9. California Desert Animals • Amphibians- 16 • Reptiles- 56 • Birds- 425 • Mammals- 97

  10. Desert Challenges for Animals • Water loss • Temperature

  11. Water Loss • Cutaneous water loss • Insensible perspiration • Excretory water loss in urine and feces • Respiratory water loss • During breathing

  12. Temperature • High summer daytime temperatures • Direct & reflected solar radiation • Conduction • Radiation • Convection

  13. Desert Strategies • Expire • When the going gets tough…. die • Evade • When the going gets tough….leave • Endure • When the going gets tough…take it

  14. Expire • Die or go into dormancy during harshest times of year

  15. Alkali Fairy Shrimp • Live in desert playa • Only wet after rains • Water must persist for 1 week • Spend most life as dormant egg • 1/125 of an inch • 50-600 per sq ft • Salinity prevents eggs from hatching

  16. Evade strategies • Seasonally migrate to an area where conditions are more hospitable

  17. Deer • Mule • Larger • Stiff legged gait • Antlers branch in equal forks • Black tipped tail • White tailed • Bobbing gait • Antlers branch from main beam • Migrate up in elevation in summer • 100+ miles

  18. Torpor/Estivation • Reduces water loss • Saves energy • Decrease temperature difference between body and outside • Rate of energy expenditure goes down • Saves water • Lower metabolism decreases water loss • Less evap by less breathing • Less urine & feces

  19. Crepuscular Activity • Active at dawn and dusk when temperatures are moderate

  20. Nocturnal • Active at night • Allows escape from hot daytime temperatures • Bats, snakes, rodents, foxes

  21. Banded Gecko • Nocturnal • Escape heat and predators • Active body temperature 18F cooler than daytime active lizards • Distribution limited to regions with above 75F night temperatures

  22. Ways to endure… • Adaptations t be able to function during

  23. Endure lack of water • Store water • Tail fat • Bladder • Conserve water • Microhabitat choice • Minimize water loss in skin • Reduce loss from breathing • Reduce water loss in urine or feces • Tolerate dehydration • Lose lots water out of their bodies without dying ex desert toads

  24. Banded Gecko • Store water to endure dry summer months • Tail fat storage • Can survive up to 9 months • Caudal waving to attract predators

  25. Desert Tortoise • In spring eat moist foods • Green annuals and fruits • Plantago, legumes • Consume 3-4% of weight/day • Stores water in bladder • Up to 1 cup • Water stored in bladder used to process waste during drier times • Uses uric acid instead of urea to minimize water loss

  26. Water Conservation • Strategies for reducing water loss

  27. Microhabitat Choice • Stay in cool or moist microclimate • Moisture in environment reduces water lost through evaporation and respiration

  28. Desert Tortoise • Hottest & driest months of year spent in burrow

  29. Tarantula • Burrows in unsuitable times of year • Uses fangs and pedipalps to construct a burrow • Up to 20in deep • Provides escape from heat of day • At night moves to entrance to hunt • Plugs opening during winter • Dormant up to 28 months

  30. Scales • Reduces cutaneous water loss • Skin with keratinized scales • Keratin water repellant • Reduce water loss

  31. Western Coral Snake • Related to cobra • 2x toxic as rattlesnake • Neurotoxic • Small short fangs • Nocturnal • Active after rains

  32. Scorpion • Cuticle on carapace reduces water loss • Nocturnal • Subterranean • Underground most year active 3-6 mo • Tolerates high body temp • 113F for over 1 hr • Low metabolic rate • Reduces respiration rate • Spiracles close • Guanine • Eliminates more nitrogen and requires less water

  33. Don’t Sweat It! • Not using evaporative cooling conserves water

  34. Reducing Excretory water loss • Protein waste product is urea • Requires significant water to eliminate • Elimination of waste in the form of uric acid reduces water required to eliminate waste • 10x less water than urea to eliminate the same amount of waste • Semisolid paste

  35. Concentrated Urine & Dry Feces • Add more waste product (solutes) to urine so eliminating more for a given loss of water • Reabsorb more water during feces production

  36. Nasal Water Condensation • Evaporative cooling in the nasal passageways cools exhaled air • Cooler air holds less water than warm air • Water in cooled air in nasal passageways condenses • Causes “rain” in nasal cavity • Retains water • Longer narrower nasal passages found in many desert rodents cools air further and condenses more water

  37. Water from food • Acquire water metabolically from the breakdown of food • Carbohydrates & lipids release water • 1g carbs yields .5g of water • 1g lipids yields 1g of water • Protein consumes water

  38. Kangaroo Rat • Long hind legs • Saltatorial locomotion (hopping) • Saves energy when moving in an environment with widely dispersed food resources • Allows turning and bobbing to escape predators • Large head with large hearing apparatus • Large eyes • External cheek pouches

  39. Kangaroo Rat • Nocturnal • Days spent in cooler humid burrows • Block burrow entrance to keep temp & predators out • Metabolic water from carbohydrates & fat in seeds • Can survive entire life w/out drinking water • Concentrated urine • Kidneys concentrate urine 4-5x more than humans • Dry Feces • 50% less water content than human feces • 5x as dry as lab rat feces • Nasal water condensation

  40. Desert Toads • Amphibians breath through moist skin • Results in 15x more water loss/hr than rattlesnake • Spend most of year underground buried in soil or in deep rock crevices • Couch’s Spadefoot up to 2 years buried

  41. Desert Toads • Water storage in bladder • Up to 30% body weight • While dormant store waste (urea) in tissues to save water • Tolerate levels that would be toxic in other species • Excess solutes in tissues assists toads in absorbing water from surrounding soil

  42. Endure Temperature • High temperature challenging for body function • High temperatures increase water loss

  43. Reduce Heat Input • Minimize solar

  44. Common Chuckwalla • Large herbivorous • Leaves, flowers, fruits • Large size accommodates diet • Extract 60% of energy from food (vs 90% of insectivorous lizards) • Large intestine in large torso can fit greater volume food needed to get equal energy

  45. Common Chuckwalla • Summer moisture and food are at critical low • Remain in rock crevices for days at a time • Reduces temperature & energy requirements up to 70% • Survive on stored fat and water • Water acquired metabolically only, do not drink

  46. Common Chuckwalla • Dry vegetation of late spring has little water and high levels of salts • Reduce water use by eliminating salt by discharging out of nostrils

  47. Microhabitat choice • Stay out of sun

  48. Long-tailed Brush • Hides in creosote bush • Early morning orients in direct sun • Late morning increases time in shade • Afternoon moves to base of bush to exposed roots • May bury in sand

  49. Woodrat • Creates midden • Elaborate nest built of tunnels and piles of debris • Debris acts as thermal blanket • Up to 4ft tall • Provides protection from predators and temperature

More Related