Download Lecture - Mammals

Final Examination
Wednesday, June 10th, from 8:00 A.M. – 9:50 A.M.
Laboratory Examination
Tuesday and Thursday, covering Birds and “some” Mammals
Birds
Reproduction:
• Clutch size variable (2 – 16 eggs); (1 to 3 clutches/year); single v. multiple nesters:
1) Trade-off Hypotheses: Driving force is maximization of lifetime reproductive success
• Physical strain on females / exposure to predation during food collection
2) Predation Hypotheses: Driving force is minimization of nest detection by predators
• More eggs / young =  detection (sound / smell / trips to nest / etc.)
3) Seasonality Hypotheses: Driving force is food availability during breeding season
• More eggs / young =  food reserves /  competition
• Young at differing levels of development at hatching:
Precocial
Semiprecocial
Altricial
High yolk
Moderate yolk
Low yolk
Down present
Down present
Down Absent
Eyes open
Eyes open
Eyes closed
Mobile
Semi-mobile
Not mobile
Self-feeding
Not self-feeding
Not self-feeding
Ducks
Hawks
Incubation may last
from 10 – 80 days
Altricial < Precocial
Growth Rates:
Altricial > Precocial
Infanticide
Passerines
Birds
Ducks: (~ 35 species in North America)
Shared Characteristics:
1) 3 front toes completely webbed
2) Penis present in males
3) Bill typically flattened / blunt-tipped
Characteristic
Dabbling Ducks
Examples
Northern Shoveler
American Widgeon
Cinnamon Teal
Legs
Relatively long;
centered under body
Feet
Smaller
Diving Ducks
Sea Ducks
Redhead
Canvasback
Lesser Scaup
Bufflehead
Eider
Merganser
Short but strong;
set far back on body
Short but strong;
set far back on body
Larger; long outer toes
Larger; long outer toes
Feeding
Dip head underwater;
skim surface with bill
Dive from surface;
wings pressed to body
Dive from surface;
wings open (steer / paddle)
Diet
Invertebrates;
aquatic vegetation
Invertebrates
Invertebrates;
fish (rare)
Wings
Big, broad wings;
lower wing loading
Smaller wings;
higher wing load
Smaller wings;
higher wing load
Flight
More maneuverable;
can fly slow
Less maneuverable;
need room to take off
Less maneuverable;
need room to take off
Habitat
Shallow edges of lake;
surface in deeper areas
Center of lake;
deeper water
Marine coastlines;
fast, clear streams
Birds
Ducks: (~ 35 species in North America)
Duck Life Histories:
Mating Behavior:
• Initiated late fall / early winter (wintering grounds / migration)
• Skewed sex ratio – many ♂; fewer ♀
• Form monogamous pair bond (seasonal)
Tufted Duck – head raise
• Males attract females via:
1) Visual Displays:
• Coloration (♂s more colorful than ♀s)
• Most elaborate in dabblers
Ruddy Duck – tail raise
2) Vocal Displays (primarily dabblers)
• Dabblers have louder, deeper voices
Dabbler Specialty:
Iridescent speculum on wing
Lift wing to display speculum
Birds
Ducks: (~ 35 species in North America)
Duck Life Histories:
Nesting Characteristics:
• Location of Nest:
• Dabblers = Ground
• Divers = Emergent / Floating vegetation
Mallard
• Sea = Tree cavities
• Age at 1st reproduction:
• Dabblers / Divers = 1 year
• Sea = 2-3 years
Brood parasitism
does occur…
• # of Eggs in Nest:
• Dabblers / Divers = 8 – 12 eggs
• Sea = < 8 eggs (space issues in cavity)
Incubation:
Scaup
• Females only (20 – 30 days)
• Pair bond only lasts until eggs are laid
Parental Care:
• Females: 2 – 6 weeks; guard from predators
Merganser
Birds
Ducks: (~ 35 species in North America)
Duck Life Histories:
Seasonal Migration Patterns:
• Benefit = Net increase in lifetime reproductive output
• Spring – Summer:
Reduce Cost…
• Breed at high latitudes (e.g., Canada / Alaska; long days = increased foraging)
•  insect population for young
• Fall – Winter:
• Fly south to avoid physical stresses of extreme cold / lack of food
• Costs = 1)  death rate for young
2)  food acquisition for energy to travel
3) Restricted stops (fewer wetlands to choose from)
4 major N-S flyways in North America
10%
50%
25%
10%
(Ducks heading to Alaska…)
• Fly at night; usually < 1000 ft.
• Variety of orientation methods:
• Sun / star compasses
• Magnetic field
Mammals
Chapter #19 – “Geography and
Ecology of the Cenozoic”
Pg. 509 – 518.
Cladogram of Tetrapods:
Mammals
Amniotes
Sauropsids (“reptile-like appearance” - Greek)
Diapsids (“two arches” - Greek)
Lepidosaurs
Squamates
Archosaurs
Mammals
Cladogram of Synapsids:
Mammals
Mammal-like Reptiles
Pelycosaurs (“sailbacks”)
Late Carboniferous - Permian
Temperature-regulating
device
Cynodonts = Multi-cusped cheek teeth
Cladogram of Synapsids:
Primitive turbinates (warm / humidify air)
Reduced size (~ size = dog or smaller)
Mammal-like Reptiles
Mammals
Therapsids
Therapsids
Mid Permian – Early Cretaceous
Derived Features:
• Increased metabolic rate
• Enlarged temporal fenestra
“too ugly to survive”
- Larry Gonick
Evidence:
Radiation into
colder climates
• Large canine present (maxilla)
• Dentition differentiation
• Upright posture
Mammals
Features Shared by Mammals:
1) Lactation:
• Mammary glands  milk for feeding the young
• Benefits = Production of offspring dissociated from seasonal food supply
Females need not rely on paternal care (Males - who needs them…)
Viviparity less strenuous (young born underdeveloped…)
• Evolution of Lactation:
• Mammary glands anatomically similar to sebaceous glands (hair follicles)
1) Glands secreted pheromones – offspring  mother recognition
2) Glands secreted anti-microbial proteins; protected eggs in nest
• Similar to current milk proteins; later  more copious / nutritional
 Suckling = unique mammalian feature
• Fleshy seal (tongue / epiglottis)
Allow for breathing while suckling
• Facial muscles (later = facial expressions…)
Mammals
Features Shared by Mammals:
2) Hair (Fur = hairy covering):
• Composed of keratin; functions in insulation, communication, and sensation
• Color = quality / quantity of melanin placed in developing hair
• Replacement = continued growth / molting (loss & replacement of hairs)
• Hypothesized origin of fur:
• Sensory bristles between “reptilian” scales
•Bristles increased in size; scales decreased in size
• Guard hairs (protective – longer / stronger); underfur (insulation)
3) Specialized Glands in Skin:
A) Sweat Glands – release water on skin for cooling (evaporation)
How Do Birds Cool Off ?
1) Panting (> 250 breaths / minute)
2) Regulating blood flow to feet
3) Behavioral modifications
B) Apocrine Glands – Scent; pheromonal signals
C) Sebaceous Glands – lubricate fur / hairs & protect skin
Mammals
Features Shared by Mammals:
4) Teeth Features:
• Heterodonts: Elaborate shapes / functions within single species
• Increased dietary specializations
• Multicuspid – broader / flatter
• Diphyodonts: 2 sets of teeth; no continuous replacement
• Allows for continual occlusion (contact between upper / lower teeth)
• Allows for crushing / grinding food (mastication = chewing)
5) Turbinates (Nasal Conchae) in Nasal Cavity:
• Whorls of bone covered with mucous epithelium
1) Adds moisture to air (prevents desiccation of lungs)
2) Warms air (prevents loss of body heat)
3) Improves filtering of air to keep airways clean (mucus)
4) Increases sense of smell ( surface area)
Mammals
Cladogram of Synapsids:
Mammal-like Reptiles
Therapsids
Mammals
Therians
“One Hole”
Reproductive / urinary / digestive
systems all exit via single opening
(cloaca)
Mammals
Monotremes:
Retain Various Reptilian Features:
1) Oviparous – lay eggs
• Small; rubbery (nutrient material absorbed through egg)
10 day incubation period
2) Retain reptile-like gait (legs on side rather than underneath)
3) Reduced operational body temperature (Mean body temp ~ 32 ºC (~ 89.5 ºF))
• Endothermic (homeotherms)
• May enter periods of hibernation (cool weather)
• Testes located abdominally (unusual for mammals)
Mammalian Features:
1) Females lactate
• Milk secreted onto skin; lapped up by young
2) Fur present
Other Features:
1) Lack teeth as adults
2) Spurs present on ankle
(do not have nipples)
Intraspecific fighting /
predator defense
Contain venom (Platypus)
Mammals
Geographically restricted
to Australia / New Guinea
Fossil evidence from
South America
Ornithorhynchidae (“bird beak”)
Tachyglossidae (“rapid tongue”)
Duck-billed platypus
Spiny Anteaters (2 species)
• Habitat / Description:
• Primarily aquatic (freshwater – Australia)
• Stream-lined body; webbed feet
• Habitat / Description:
• Primarily terrestrial (Australia / New Guinea)
• Coat = course hair w/ spines (modified hairs)
• Horizontally flattened tail
• Dense fur (inner insulation layer)
• Diet / Foraging:
• Benthic invertebrates; frogs (1/2 BW / night)
• Rubbery bill (grind food via gum plates)
• Electrosensitive pores present
• Reproduction:
Defensive Behavior
Curl into ball with spines extended
Dig vertically; cover body with loose soil
• Diet / Foraging:
• Termites / ants / earthworms
• Strong diggers / sticky tongue
• Reproduction:
• Seasonal breeder (Mature = 2 years of age)
• Seasonal breeder (Mature = 1 year of age)
• Incubate eggs (1 – 3) between tail / body
• Incubate egg (1) in pouch
• Young suckle ~ 4 months (fur = 6 weeks)
• Young suckle ~ 2 months (lifespan = 40 yrs)
Mammals
Cladogram of Synapsids:
Mammal-like Reptiles
Therapsids
Mammals
Therians
Placenta:
Complex of embryonic and maternal tissues
1) Anchors fetus to uterus
2) Transports nutrients from mother to fetus
3) Excretes metabolites from fetus to mother
4) Produces hormones (regulate reproduction)
Mammals
Placental Development:
Marsupials – Limited Placenta:
Opossum
newborn
(~ 0.13 g)
• Developing embryo forms shallow depression in endometrium of uterus
• Surface area for adhesion / absorption limited (slight wrinkling)
• Primary nutrient source = yolk sac
• Short gestation (Bandicoot = 12.5 days); long lactation
• Finish development in pouch / skin fold
• Nipples utilized for lactation (swell to hold young)
At birth: < 1%
maternal body mass
Placentals – Advanced Placenta:
• Developing embryo embeds deeply into endometrium
• Chorionic villi (finger-like projections) enhance adhesion / absorption
• Primary nutrient source = Maternal blood (does not mix with fetus)
• Long gestation (African elephant = 22 months); short lactation
• At birth: 5% - 50% maternal body mass
 By the time young are weaned, the parental investment between
marsupicals and placentals is similar
Precocial compared
to marsupials…
Mammals
Reproductive Variations:
1) Delayed Fertilization:
• Copulation (fall) dissociated from fertilization of egg (spring)
• Sperm stored in uterus / vagina
• Benefit = Efficient use of seasonal resources
2) Delayed Development:
• Embryo implants in endometrium; development continues very slowly
• Benefit = Synchronize young with unpredictable food resources
New / Old world bats
Armadillo
(obligate)
3) Delayed Implantation:
• Development of embryo arrested following early cleavage
• Embryo free-floating in reproductive tract
• Obligate (build into system) or facultative (environmentally induced)
• Benefit = ??? (Dissimilarity in closely related species in same area…)
4) Embryonic Diapause:
• Development of embryo arrested following late cleavage
Roe Deer
(facultative)
Mammals
Red Kangaroo
(embryonic diapause)
“Box” with hind limbs
(can be fatal)
♀ often supporting young of 3 litters
(uterus / pouch / outside pouch)
Joey #1 – Lactation (outside pouch; ~ 1.5 years)
Joey #2 – Lactation (inside pouch; ~ 9 months)
Joey #3 – Held in embryonic diapause
• Arrested due to Joey #2 suckling
Benefit:
Opportunistic reproduction in harsh
environments (Australian Outback…)
• Lost / abandoned
offspring can be
quickly replaced
Mammals
Marsupials (“little bag” – BUT only ~ 50% have permanent pouch):
1) Ameridelphians (New World Marsupials)
• Didelphimorphia (Opossums; ~ 77 species)
• Neotropical region / temperate North America
“Play Dead”
• “…the opossum will fall on its side, curl its body,
open its drooling mouth, and excrete droppings…”
• Nervous “shock”
Mammals
Marsupials (“little bag” – BUT only ~ 50% have permanent pouch):
1) Ameridelphians (New World Marsupials)
• Didelphimorphia (Opossums; ~ 77 species)
• Neotropical region / temperate North America
• Paucituberculata (Rat Opossums; ~ 5 species)
• Neotropical region
2) Australidelphians (Australian Marsupials)
Dasyuromorphia
(Carnivorous Marsupials)
e.g., Tasmanian Devil
Tasmanian Wolf – 1930’s
Paired sperm:
Sperm coupled at
the head region…
Mammals
Marsupials (“little bag” – BUT only ~ 50% have permanent pouch):
1) Ameridelphians (New World Marsupials)
• Didelphimorphia (Opossums; ~ 77 species)
• Neotropical region / temperate North America
• Paucituberculata (Rat Opossums; ~ 5 species)
• Neotropical region
2) Australidelphians (Australian Marsupials)
Paired sperm:
Sperm coupled at
the head region…
Peramelemorphia
Insectivores
Syndactyly (hindfeet)
e.g., Bilby
Dasyuromorphia
(Carnivorous Marsupials)
e.g., Tasmanian Devil
Diprotodontia
Rodent-like incisors
herbivores / omnivores
Syndactyly (hindfeet)
e.g., Koala / Kangaroo
Mammals
Placentals:
Insectivora
• Primitive characteristics
• Morphologically diverse
Chiroptera
• Only flying mammals
• Echolocation
Primates
• Elaborate brain
• Refined hands / digits
(e.g., mole, shrew, colugo)
(bats)
(e.g., look in a mirror)
Xenarthra
• Low metabolic rates
(e.g., armadillo, anteater)
Pholidota
• Overlapping scales
(scaly anteaters)
Mammals
Placentals:
Carnivora
• Mammalian predators
• Carnassial teeth
Cetacea
• Modified for aquatic lifestyle
• Largest mammals on record
Rodentia
• Largest mammalian order
• Enlarged incisors
(e.g., wolf, lion, weasel)
(e.g., whales, dolphins)
(e.g., capybara, squirrel, mouse)
Tubulindentata
• Smallest mammalian order
(aardvark)
Hyracoidea
• closest relative = elephant
(Hyrax)
Mammals
Placentals:
Lagomorpha
• Herbivorous
• Saltatory locomotion
Perissodactyla
• “odd-toed”
• Hindgut fermenters
Artiodactyla
• “even-toed”
• Ruminating stomachs
(e.g., rabbits, hares, pikas)
(e.g., horses, tapirs, rhinoceroses)
(e.g., pigs, deer, hippopotamuses)
Proboscidea
• Largest terrestrial mammals
(elephants)
Sirenia
• Only marine herbivore
(e.g., manatee, dugong)