bio 455 lab study notes

lab final

Systematics

field of science concerned with phylogeny and taxonomy

Phylogeny

evolutionary history or development of a group of organisms.

Taxonomy

is the discipline devoted to classifying organisms

Classification

the process by which living and extinct organisms are arranged into various named groups (taxa)

Taxa

(sing, taxon) are groups of organisms ranked in a hierarchy of specific categories or levels of classifications

Nomenclature:

the system for giving distinctive names to different taxa

Identification

assigning of particular specimens to already established and named taxa

how many living orders of mammals are there

26 orders

polytpic

taxon contains more than one taxon at the next lower level, (Class Mammalia –contains many orders)

monotypic

taxon at any level contains only a single taxon at the next

lower level, (genus Antilocapra - only one species Antilocapra

americana, but several subspecies)

Zoological Nomenclature

system of scientific names applied to taxa of animals, living and

extinct. Created by Carolus Linnaeus –Systema Naturae (1758)

Speciation

splitting off of a new species – occurs when a group of interfertile individuals become geographically and reproductively isolated and evolve separately

Subspecies

uniform and genetically distinct portion of a species, representing a separately or recently evolved lineage with its own evolutionary tendencies

species

basic unit of taxonomy; groups of interbreeding natural populations that are reproductively isolated from other such groups

Sympatric Species

overlap geographically, do not interbreed

Parapatric Species

contiguous ranges, do not interbreed

Allopatric Species

non-overlapping ranges, likely not to interbreed

Sibling species

sympatric species that are reproductively isolated but morphologically indistinguishable

animalia

• Eukaryotic, multicellular

• Heterotrophic

• Motile during at least part of their life

chordata

Dorsal nerve tube

vertebrata

Brain and spinal cord enclosed in, and protected by, a bony skeleton

defining characteristics of Mammalia

skeletal, hair/fur, mammary glands, 4 chambered heart, enucleate erythrocytes, muscular diaphragm

Mammalia skeletal

- Lower jaw (mandible) composed of the dentaries: a single pair of bones (body and ramus) which articulate directly with the cranium

- Articulation between the dentary and the squamosal

- Three ossicles in the middle ear (modified articular and quadrate bones)

- Two occipital condyles

4 chambered heart

heart with functional left aortic arch

muscular diaphragm

separating the thoracic and abdominal cavities

Compare the position of the orbits

-Chimpanzees & Lynx → Forward-facing orbits (binocular vision for precision and depth perception)

-Beavers → Slightly lateral orbits (balance between predator detection and binocular vision)

-Deer → Lateral orbits (wide field of view for predator awareness.

Compare the placement of the foramen magnum

opossum:

posterior placement of foramen magnum,quadrupedal locomotion and semi-arboreal posture.

gorilla:

More anterior placement of foramen magnum. Knuckle-walking locomotion and semi-bipedal posture.

moose:

Posterior placement of foramen magnum, Quadrupedal locomotion and large herbivore posture.

squirrel:

Slightly ventral placement of foramen magnum, Quadrupedal locomotion and arboreal posture.

beaver:

Posterior, angled downward placement of foramen magnum,

Quadrupedal locomotion and semi-aquatic posture.

crown of tooth

above the gumline

root of tooth

below the gumline (fitting into alveolus or socket)

dentine of tooth

bonelike majority of the tooth

enamel of tooth

covers the crown of the tooth

cementum of tooth

covers the root of the tooth

pulp of tooth

supplied with blood vessels and nerves

lingual

side of a tooth closest to the tongue

buccal

side of a tooth closest to the cheek

mesial

front side of a tooth

distal

back side of a tooth

anterior

teeth on front of the mouth

posterior

teeth on the back of the mount

occlusal surface

surface of a tooth that meets with a tooth in the opposing jaw

Diphyodont Tooth Replacement

deciduous milk dentition, Most mammals. 2 sets, baby and adult.

Polyphyodont Tooth Replacement

multiple replacements - Elephants, manatees, kangaroos

Monophyodont Tooth Replacement

one set of teeth - Toothed whales, rodents

heterodont kinds of teeth

several forms of teeth

homodont kinds of teeth

all the same teeth

edentulous kinds of teeth

without permanent teeth

kinds of teeth

incisors, canine, premolars, molars

teeth quadrants

there are 4

incisors

-Never more than three incisors in each jaw quadrant (some exceptions for marsupials)

-Unicuspid teeth with a single root

-Usually chisel-shaped teeth that function primarily for nipping

-Many modifications

canines

• Never more than one per quadrant

• Long, conspicuous, unicuspid teeth with a single root

• Usually used to capture, hold and kill prey

In herbivorous species reduced or absent (forming diastema)

premolars and molars

• Premolars usually have milk predecessors

• placental mammals with four premolars, 1 premolar does not have a milk precursors

• Molars do not have milk predecessors

• Premolars are smaller than molars and have fewer cusps

• Both premolars and molars are referred as cheek teeth or post canine teeth

dental formula

ICPM

• Shorthand method to indicate the numbers of each tooth type in a particular mammal species

• Teeth are listed and counted in the order they occur in each half of the upper and lower jaw

Tribosphenic tooth

occurs in primitive placental and marsupial mammals

Quadritubercular tooth

addition of the hypocone (hypoconid) to have 4 cusps

omnivory molar shape

bunodont

carnivory molar shape

they have a carnassial pair, P4 and M1.

secondont.

herbivory molar shape

selenodont (u)

lophodont (w)

Brachyodont molar height

low-crowned teeth in Omnivory

hysodont molar height

high-crowned teeth, Herbivory

Insectivory → commissures

modified tribosphenic teeth in which the 3 cusps elongate into sharp crescent-shaped cristas (useful to get through insects exo-skeleton).

Piscivory

cheek teeth reduced to a series of sharp unicuspids (holding slippery food)

Edentulous

lack of teeth (anteater)

epidermis

-only living cells in the deepest layers, stratum basale and stratum spinosum
-Stratum corneum: flattened, keratinized dead cell layer

dermis

• Connective tissue, muscles, nerves, blood vessels, sensory structures
• Sometimes bones

hypodermis

fat layer

true dermal bone

True bone formed in dermal layer of integument

epidermal scales

Modified stratum corneum cells create flattened epidermal plates

hair anatomy

• True hair unique to mammals
• Medulla: central core
• Cortex: bulk of hair
• Cuticle: outer layer, composed of cuticular scales
• Pigment granules: melanin
• Erector pilli muscle

angora hair growth

continuous growth, may never be shed

Definitve hair growth

grows to defined length, shed periodically

vibrissae

long, stiff hairs primarily serving as tactile receptors

guard hairs

• Spines: primarily defensive
• Bristles: long, firm with angora growth
• Awns: firm, expanded distal region (warmth)

underhairs

• Wool: angora growth, soft, insulative
• Fur: definitive, fine, densely covering
• Velli: definitive, downy/fuzzy, very fine

molting hair replacement

Most hair types replaced periodically via molting
• Annual molt: once/year
• Seasonal molt: twice/year

juvenile pelage hair replacement

distinct pelage patterns differing from adults
• Typically greyer/duller, but many forms

hair colour

eumelanin- darker colours

pheomelanin- lighter colours

Agouti- each hair displays two or more colours

hair function

for concealment or communication

concealment

Cryptic coloration (polar bear)

Disruptive coloration (leopard)

Countershading (dolphine)

communication

warning coloration (skunk)

reverse countershading (honey badger)

flag (white tail deer)

albinism

lack of all external pigment

leucism

partial loss of pigmentation

melanism

unusually dark pigmentation due to deposition of large amounts of melanin

piebald

exhibits patches of white fur on body

hairless mammals

-Naked mole-rats: Naked mole‐rats have a few hairs on their body but lack a fur coat.
-Marine mammals: hair is significantly reduced in many groups.
o Sirenians (manatees, dugongs, etc.)
o Cetaceans (whales, dolphins)

sweat glands

• Unique to mammals (though some families lack)
• Sudoriferous (empty into hair follicles, be scented)
• Eccrine (onto surface of skin, cooling and tactile)

sebaceous glands

• Secrete fatty substance to prevent brittle hair and
waterproof pelage

scent glands

• Sebaceous or sudoriferous
• Defense, marking territory, and social interactions

mammary glands

• Unique to mammals (MAMMAls)
• Derived from integumentary glands, develop from milk lines
• Present in both sexes, but only reach full maturity in females

monotremes (A)

milk secreted into abdominal depressions

Eutherians (B)

nipples or teats

marsupials (C)

circular arrangement of nipples

horns and antlers

in orders Artiodactyla and Perissodactyla

true horns

• Bovidae family
• Inner bony core extension of frontals, sheathed in keratinized epidermis (horn)
• In both males and females
• Growth throughout life, no shedding
• Growth rings

pronghorns

• The only extant species is Antilocarpa americana
• Shed sheath annually
• Form ”prongs” from new sheath
• Females have no prongs or absent horns

antlers

• Found in members of family Cervidae
• Males only (except Rangifer genus)
• Forms from pedicel, permanent extension of frontal bone that connects to deciduous antlers via burr
• Growing antler “fed” by velvet
• Consists of main beam and tines, shed after mating season

girafffe horns

• Permanent bony processes arising from suture between parietals and frontals
• Ossified from ossicones (centre) and fuse to skull
• NOT projections of the frontal bones
• Permanently covered in skin and hair
• 3rd “horn” sometimes present as a protuberance of the frontals

rhinoceros horns

• Only extant non-artiodactyls with horns
• Hardened epithelial cells formed from
dermal papillae, not fused to bone
• Skin bearing the horn situated over fused
nasal bones (second horn over frontal bones)

function of antlers/horns

Mating, social dominance, and fighting for territory and protection. To help with food.

claws

encase the most distal Phalanx, many variations across orders

nails

modified claw, only covers the dorsal surface of
the distal phalanx, less protection but more dexterity