Shared Flashcard Set

Details

Comparative Anatomy
Exam 2 @ MO State
68
Biology
Undergraduate 4
10/02/2007

Additional Biology Flashcards

 


 

Cards

Term
Taxonomy
Definition
the process by which groups are named described and classified, usually in hierarchical categories
Term
Taxon
Definition
a general name for a hierarchical category
Term
How are animals assigned to categories?
Definition
Individuals in the same taxon are more similar to each other than to individuals in other taxa
Term
What types of “similarities” are important to classification?
Definition
- Homologous characters: similarity between characters is due to inheritance from a common ancestor.
- What clues are used to determine whether morphological characters are homologous?
 Similarity of position (with respect to other body parts)
 Similarity of vascular and nerve supply
 Similarity of embryonic development
Term
What types of similarities are not important to classification?
Definition
- Analogous characters: Characters have similar functions, but the functions are not necessarily due to common ancestry
- Example: wings of bats and birds
Term
Phylogeny
Definition
Taxonomic arrange based solely on homologous traits. Phylogenies should reveal evolutionary relationships among groups
Term
- Primitive
Definition
not changed from the ancestral form
Term
- Derived, modified, or specialized
Definition
changed from the ancestral form; these terms are preferred over the more subjective “advanced”
Term
- Rudimentary
Definition
ancestral traits that become better developed in the descendant
Term
- Vestigial
Definition
not as well developed as in the ancestor; preferred over the term “degenerate”. E.g., the eyes of cave fishes are vestigial, not rudimentary
Term
Preservation is...
Definition
...selective:

- Fossils typically form only in sedimentary rocks
- Hard parts (bones, teeth, scales…) fossilize better than soft parts
Term
Stratification
Definition
new deposits are laid on top of old deposits
Term
characteristics of vertebrate fossils
Definition
- Mostly bone
- Some soft parts through rapid freezing (e.g., mammoths), drying (e.g., tar pits) or other special circumstances
- Indirect clues: fossil eggshells, footprints, feces
Term
Divergent evolution
Definition
descendent lineages become different from each other and from the ancestral state
Term
Convergent evolution
Definition
unrelated lineages come to resemble each other; usually due to similar selection pressures operating in similar environments
Term
Parallel evolution
Definition
Different lineages change in similar ways so that the descendents in the two lineages are very similar
Term
Ontogeny
Definition
-Individual development

-it can provide clues to the evolutionary development of lineages (Phylogeny)
Term
Phylogeny
Definition
evolutionary development of lineages
Term
Linking Development of Individuals to the Development of Lineages
Definition
- Individual development (Ontogeny) can provide clues to the evolutionary development of lineages (Phylogeny)

- Embryos of recent forms resemble embryos of ancestral forms

- During embryonic development, divergence proceeds from general to specific structures
--Limb buds → limbs → wings

- New structures usually arise as modifications of existing structures
Term
Evolution occurs when...
Definition
Evolution occurs when mutations cause changes to occur during development:

(1) New characters can be added to the embryo
(2) Existing characters can experience a change in developmental timing (called Heterochrony)
Term
Heterochrony
Definition
Existing characters can experience a change in developmental timing
Term
Types of Heterochrony
Definition
(1) Paedomorphosis
(2) Peramorphosis
Term
Paedomorphosis
Definition
(“child” + “form”): characteristics of adults resemble the same characters of the juveniles of the ancestors. This occurs when characters:
a. Stop development: Progenesis
i. Example: Webbed digits in some amphibians form when limb development of hands and feet stops early
b. Slow development: Neoteny
i. Example: In amphibians, gills usually disappear at metamorphosis; when development of gills dramatically slows, gills can be retained in adults
c. Are added late: Post-displacement
Term
(1) Peramorphosis
Definition
(“beyond” + “form”): Characteristics of adults are exaggerations of the same characters in the adult ancestors.
a. Example:
i. The antlers of Irish elk (now extinct) are much larger than the antlers of their ancestors (or of any other living antelope)
ii. The homocercal caudal fin of flounders is a result of prolonged development; the ancestral tail was heterocercal and so is the embryonic tail of flounders
b. Peramorphosis occurs when changers experience:
i. Longer developmental time: Hypermorphosis
ii. Faster growth: Acceleration
iii. Early onset of the character: Predisplacement
Term
Integument Layers
Definition
(1) Epidermis: - Thin outer layer
- Ectodermal origin
- Layer is mostly composed of cells

(2) Dermis:
-Thicker inner layer
- Mesodermal origin
- Layer is mostly composed of connective tissue (cells scattered in a noncellular matrix)
Term
Amphioxus Epidermis
Definition
- A single layer of columnar epithelial cells (cells packed closely together)

- No extracellular glands

- The epidermis secretes a noncellular cuticle that covers the surface (the cuticle is absent in most vertebrates)
Term
General Vertebrate Epidermis
Definition
- The epidermis of vertebrates is stratified into two or more layers

- The innermost layer is the stratum basale

- Cells in the SB undergo mitotic divisions and the new cells push outward, becoming the superficial (surface) skin cells as they mature

- In some taxa, the mid-layers of the epidermis contain glands scattered amongst the epithelial cells; these glands produce mucus or proteins such as poison or pheromones.

- The outer layer of cells in the stratum corneum. It contains varying amounts of the protein keratin, which can make the skin tough in certain areas (e.g., palms). The SC becomes elaborated in some taxa, forming reptile scales, claws, feathers, and hair.
Term
Epidermis of Fishes (fig. 6.9, 6.10)
Definition
- Thin and glandular
- Little or no keratin
- Replacement of worn cells is constant
Term
Epidermis of Amphibians (fig. 6.12)
Definition
- Contains numerous flask-shaped (“alveolar”) multi-cellular glands that grow down into the dermis. Ducts lead from the glands to the surface.
- The stratum corneum is thin and is lost every few days, usually in large patches
Term
Epidermis of Reptiles
Definition
- The stratum corneum forms a body covering of scales
(A) Squamates (lizards and snakes) (Figure 6.13a):
- Scales are connected in overlapping folds (keratin is thin in the joints)
- Outer layer sloughs off several times a year
(B) Crocodilians:
- Scales do not overlap
- No shedding (growth rings added)
(C) Turtles:
- Small, nonoverlapping scales on legs and head
- Large thin plates called scutes on upper (“carapace”) and lower (“plastron”) shells
- No shedding (growth rings added)
Term
Epidermis of Birds
Definition
- Hind legs and toes are covered with small scales similar to those of reptiles
- Glands typically limited to a large alveolar uropygial (uro = “tail”, pyg = “small”) gland above the tail that secretes oil used in preening (fig. 6.15c)
- Feathers are heavily keratinized epidermal outgrowths
- Feathers are hypothesized to have evolved from reptile scales as an adaptation for insulation (important for endotherms); they were secondarily adapted for flight (see next page of handout, figures 4-4 and 96).
Term
Feather types (figs. 6.14b and 6.15b)
Definition
(A) Flight: large; provide air foils for flight; structure:
- Hollow quill is embedded in the dermis within a follicle that is lined with epidermal tissue (ectodermal origin)
- Solid central vertical shaft (aka rachis)
- Horizontal barbs extend from the shaft; barbs are connected by vertical barbules
(B) Contour: smaller than flight feathers; shape body surface
(C) Down: underlie contour feathers, providing insulation
(D) Filoplumes: scattered; usually hairlike; function in displays
Term
Mammal scales
Definition
Absent in most mammals; present on the legs and tails of some rodents insectivores, and marsupials
Term
Mammal Tissue layers
Definition
Often contains a third distinct layer - the stratum granulosum - between the stratum corneum and the stratum germinativum (sometimes more layers)
Term
Mammal Stratum corneum
Definition
Often thickened on areas subject to abrasions (e.g., the soles of the feet) or where hair is sparse)
Term
Mammal Claws
Definition
Keratinized structures that wrap around the terminal bones of digits; hooves are derived from claws
Term
Glands unique to mammals (fig. 6.20):
Definition
Sweat (Sudoriferous) glands:
 tubular, simple, coiled at the end
 evaporation of sweat acts as a cooling device
 also acts as an accessory kidney by secreting salt and urea
 develop from ectoderm, but sink into the dermis

Sebaceous glands
 alveolar
 usually empty into hair follicles
 have an oily secretion that protects the hair and skin from excessive drying

Mammary glands
 form as ectodermal (epidermal) ridges that sink into the dermis
 compound and alveolar
 secrete milk to suckle young
Term
Mammal Horns and Antlers
Definition
(some epidermal, some from bone)
Rhinoceros horns: keratinized fibers compacted together; growth is from the epidermis; never shed (fig. 6.28c)

 Other horns/antlers are not strictly epidermal derivatives, but are bone capped by “skin”. The differences are primarily in shedding:
 Giraffe horns: bone permanently covered with skin; never shed (fig. 2.28b)
 Pronghorns: bone is permanent; horny epidermal cap is shed each year (fig. 6.28a)
 "True" horns (cattle/antelope): both bone and epidermal cap are permanent (fig. 6.25a; 6.27)

 Deer antlers: Skin ("velvet") sheds when antlers reach full size; bone is branched shed annually (fig. 6.25b; fig. 6.26)
Term
Mammal Hair (fig. 6.20)
Definition
 Probably did not evolve from reptile scales
 May have arisen from reptilian mechanoreceptors that are found between scales
 Function: insulation
 Made of heavily keratinized epidermal cells
 Has a projecting shaft and a root projecting into the dermis in an epidermis-lined pit called the follicle
Term
Amphioxus Dermis
Definition
A gelatinous layer with fibers primarily confined to the inner and outer borders.
Term
Dermis of Vertebrates in general
Definition
 All have connective tissues with collagen (protein), blood vessels, nerves, and pigment
 A bony dermis was the primitive condition
 The potential to produce bone is persistent: all classes of vertebrates (except birds) have at least one member with a bony dermis
 The origin of the bony dermis is poorly understood; it may have arisen from dermal papillae formed by neural crest cells
Term
Fish Dermis
Definition
 A deep layer of connective tissue
 A more superficial layer of bony tissue (scales); (fig. 6.10a)
 Shark scales are not made of bone but are made of enamel over a layer of dentin; fig. 6.9b
Term
Tetrapod Dermis
Definition
 Primarily connective tissue (collagen and elastic fibers)
 Some nerve fibers
 Abundant blood/lymph vessels (especially important for cutaneous respiration by amphibians)
 In mammals, the deep layer of the dermis has fatty tissue (serves for insulation)
 Some taxa have bone in their dermis called osteoderms
-->Caecilians have bony ossicles
-->Turtle shells
-->Crocodilians and some lizards have bony plates; osteoderms in the abdominal area are called gastralia
-->Armadillo shells
Term
All eggs have
Definition
-An animal pole: where the embryo develops

-A vegetal pole: where yolk globules concentrate (yolk is heavy and so globules sink to the “bottom” of the egg)
Term
Types of eggs
Definition
o Microlecithal
o Mesolecithal
o Macrolecithal
o Mammalian microlecithal
Term
Microlecithal (Fig. 5.2a)
Definition
 Have little yolk
 Typical of amphioxus and other protochordates
 Only a slight concentration of yolk at the vegetal pole (= isolecithal)
 Holoblastic cleavage: cleavage planes extend through entire egg
 The third cleavage plane is slightly above the equator; division is through the center of the living protoplasm (the yolk is inert)
 Blastula stage: A cavity (the blastocoel or segmentation cavity) forms in the center
 The blastocoel has no function; it will later disappear
Term
Mesolecithal: (Fig. 5.2b)
Definition
 Have a moderate amount of yolk
 Typical of Primitive fishes, amphibians
 Holoblastic cleavage
 Yolk concentrated in vegetal pole (= telolecithal)
 Cleavage slows in the vegetal pole due to thickness of yolk
 Third cleave plane is substantially above equator
 Because cell division is slow in the vegetal pole
-- The blastocoel is smaller than in amphioxus and is present only at the animal pole
-- Cells in the animal pole are smaller than in the vegetal pole
Term
Macrolecithal: (Fig. 5.2c)
Definition
 Have a large amount of yolk
 Typical of modern fishes, reptiles, birds, and monotreme mammals
 Most of the egg is yolk, with only a small amount of protoplasm
 Meroblastic cleavage: cleavage planes extend only through protoplasm
 Blastula is a mass of cells slightly lifted off the underlying yolk
Term
Mammalian microlecithal: (Fig. 5.2d)
Definition
 Have very little yolk
 Typical of placental mammals
 Holoblastic cleavage
 Segmentation cavity (blastocoel) forms beneath protoplasm, merging with an empty “yolk” sac
 A superficial (= surface) layer of cells separates from and surrounds the embryo. This trophoblast will become part of the placenta.
 The embryo is a compact cluster of cells within the trophoblast called the inner cell mass.
Term
Gastrula
Definition
Stage of development when 3 distinct tissue layers are formed
Term
Amphioxus Gastrula
Definition
(microlecithal egg) (Fig. 5.7a)
 Blastula becomes flat at one end
 Plate bends inward forming blastopore
 Cells bending inward form endoderm
 Cells on the outside are the ectoderm
 Some migrating cells (mesenchyme) move inward and form a layer called the mesoderm
 The blastocoel gets smaller and eventually disappears
 The new cavity is the archenteron (aka primitive gut or gastrocoel)
Term
Amphibian and Primitive Fish Gastrula
Definition
(mesolecithal egg) (Fig. 5.11a)
 Blastopore forms at boundary between animal and vegetal poles
 Cells role inward forming endoderm
 Mesoderm follows endoderm inward
 Archenteron forms at blastopore
 Blastocoel becomes smaller and eventually disappears
 Endoderm lines gut
 Ectoderm is outer layer
 Mesoderm is between Ecto- & Endoderm
Term
Modern Fish Gastrula
Definition
(macrolecithal egg) (Fig. 9)
 The macrolecithal egg arose independently in fishes and birds; the two groups solved the problem of germ layer formation in different ways.
 Cells roll inward at blastocoel
 Endoderm and mesoderm separate into two layers
Term
Reptile, Bird, and Monotreme Mammal Gastrula
Definition
(macrolecithal egg) (Fig. 13.d)
 Bottom layer of blastoderm (“hypoblast”) separates, forming endoderm
 Groove (primitive streak) forms in center of blastoderm
 Mesenchyme cells move into embryo through primitive streak, forming the mesoderm.
 Outer layer (“epiblast”) is ectoderm.
Term
Placental Mammal Gastrula
Definition
(microlecithal egg) (5.32a—c)
 Inner cell mass splits into two layers (epiblast & hypoblast).
 The amniotic cavity forms above the epiblast
 The yolk cavity forms below the hypoblast
 The Blastoderm is located between the amniotic cavity and yolk sac
 Primitive streak forms on top of blastoderm
 Mesoderm migrates in through the primitive streak
 Epiblast forms ectoderm; hypoblast forms endoderm
Term
Formation of Coleom in Placental Mammals
Definition
(Amphibian example: Fig. 5.11)
 Coelom: Cavity surrounding the gut
 Unlike other Deuterostomes, the coelom of vertebrates forms by splitting of mesoderm around the gut (Schizocoely)
 The notochord pinches off from the other mesoderm
Term
Formation of Nerve Cord from Ectoderm in placental mammals
Definition
(Amphibian example: Fig. 5.11)
 Ectoderm dorsal to notochord Flattens forming the Neural Plate
 Neural Plate curls inward, forming the Neural groove
 Neural groove pinches together, forming the nerve cord
 Body ectoderm grows over the Nerve Cord
Term
Formation of Accessory Nervous Tissue in placental mammals
Definition
(Amphibian example: Fig. 5.11)
 Neural crests pinch off of the dorsal end of the Nerve Cord
 Neural crests form various neural structures: E.g., peripheryl nervous system; see Table 5.2 for complete list
 In the head, swellings called placodes form along lateral surfaces
 Placodes form various sensory/nervous structures (in above example, the eye)
Term
Derivatives of Embryonic Germ Layers (Fig. 5.17)
Definition
 Ectoderm
 Mesoderm
 Endoderm
Term
Ectoderm
Definition
o Body Ectoderm:
 Outer layer of Skin
 Derivatives of outer skin (hair, feathers, glands)
 Lining of mouth and cloaca
 Lining of nose and ear
 Outer portion of eye (lens)
 Outer layer of teeth (enamel)
o Neural Ectoderm:
 Nervous system
 Inner part of eye (retina)
Term
Mesoderm
Definition
-Connective tissue: blood, bone, cartilage, mesenteries, etc.

-Muscle Most of excretory/reproductive organs

-Notochord
Term
Endoderm
Definition
o Part of digestive tract
o Accessory digestive organs (Liver, pancreas)
o Endocrine glands
o Lungs
o Part of excretory/reproductive organs
Term
Subdivisions of Mesoderm (Fig. 5.9)
Definition
1. Epimere
2. Mesomere
3. Hypomere
4. Mesenchyme
Term
Epimere
Definition
• Sclerotome: most medial; forms vertebrae and part of ribs
• Dermatome: most outer portion; forms connective tissues in skin
• Myotome: between sclerotome and dermatome; forms most of axial and part of appendicular muscle
Term
Mesomere
Definition
• Aka Nephrotome
• Forms kidney and part of gonads
Term
Hypomere
Definition
• Inner (Splanchnic) layer forms gut lining and muscle tissue
• Outer Somatic) layer forms lining (“peritoneum” of body cavity and muscle tissue of body wall
Term
Mesenchyme
Definition
• Amoeboid-like migrating cells
• Form connective tissue (blood, bone, cartilage) and some muscle tissue
Term
Embryonic Cavities (Fig. 5.9)
Definition
 Neurocoel: becomes cavity inside brain and spinal cord

 Myocoel: transient; disappears when dermatome, sclerotome, and myotome separate

 Coelom: Cavity around gut tract

 Lumen: Cavity inside of gut
Supporting users have an ad free experience!