II. Physiological Adaptations to Heat and Water StressA. Finding cool TaB. Lowering MRC. Evaporative cooling

PantingSweating Saliva spreading

D. Kidney functionE. Preferential Cooling

C. Adaptationsfind warm Tadrop Tbincrease insulation (decrease C)raise MR (and energy needs)

I. Winter Ecology of MammalsA. Stresses of Winter

B. Heat Balance

Mammalian Adaptations to Extremes of Temperature (Winter and Deserts/Summer)

02040

Snow depth (cm)

60

Temperature at Ground level

Hie

mal

thre

shol

d =

15 to

20

cm

Ta -

-10 0 10 20 30 40 50

LCT = lower critical temperatureUCT = upper critical temperature

Met

abol

ic R

ate

MR atrest

Thermal Neutral zone

LCTTb

Ta

Graph of Heat Balance Equation

LCT

Lethal Temp.

Feldhammer et al., 1999

Feldhammer et al., 1999

Stages of Mammalian ReproductionStages of Mammalian Reproduction

Copulation Copulation

OvulationOvulation

FertilizationFertilization

ImplantationImplantation

GestationGestation

ParturitionParturition

LactationLactation

Delayed Ovulation and FertilizationDelayed Ovulation and Fertilization(bats that hibernate(bats that hibernate

Delayed Delayed ImplanatationImplanatation(diversity of (diversity of eutherianseutherians))

Delayed development (bats)Delayed development (bats)Embryonic Embryonic diapausediapause (some kangaroos)(some kangaroos)

Body Temperature (Tb) in MammalsRegulated Lethal

Tb high TMonotremes 28-33 37Marsupials 35-36 41

Eutherians 36-38 43

Insectivores 34-36 41

Humans 37 43

Birds (non-passerine) 39-40 46

Birds (passerine) 40-41 47Source: Schmidt-Nielsen 1975

Body Temperature (Tb) in MammalsRegulated Lethal

Tb high TMonotremes 28-33 37Marsupials 35-36 41

Eutherians 36-38 43

Insectivores 34-36 41

Humans 37 43

Birds (non-passerine) 39-40 46

Birds (passerine) 40-41 47Source: Schmidt-Nielsen 1975

Marchand, 1987

Feldhammer et al., 1999

Schmidt-Nielsen, 1975

Feldhammer et al., 1999

Vaughn et al., 1999

Feldhammer et al., 1999 Schmidt-Nielsen, 1975

Medulla, Dry(High NA+)

Arterial blood (to be filtered)

Venous blood

Loop of HenleMostly long loopsin desert adapted species(short loops in aquatic species)

3 - Water

1 – Filtration2 – Secretion and reabsorption of Na, creates high concentration Na3 – Reabsorption (longer loop, higher [Na] in medulla, dryer urine)

Urine, withWastes and excesswater

Renal blood flow = 1.25 L/min = ¼ cardiac output

Not to scale

2

Feldhammer et al., 1999